Bio-Inspired Ideas for Sustainable Energy: Poster Session Day 1
1
Sayeh Sinichi
2
Mabel Ting
Wong
3
Solmaz
Tabtabaei
4
Minakshi
Goyat
5
6
Levente Diosady Bio synthesis of
(Toronto)
chemicals and
energy
Emma Master
(Toronto)
Bio synthesis of
chemicals and
energy
Levente Diosady Bio synthesis of
(Toronto)
chemicals and
energy
Simultaneous production of high quality Isopropyl and methyl esters from canola oil via mixed alcohol transesterification. Biodiesel is an attractive
alternative to conventional fuels because it is a renewable resource that can easily be used in existing engines. Additionally it is environmentally friendly
and can be readily synthesized from vegetable oils and animal fats. The presence of isopropyl esters in biodiesel can improve the cold flow property of the
fuel due to its lower crystallization temperature. When compared with methanol, isopropyl alcohol (IPA) has superior solubility in oil. A comparison between
isopropyl ester and methyl ester formation in mixed alcohol transesterification at different IPA: oil: methanol molar ratios showed that although the
presence of IPA as co-solvent has increased the total ester conversion, excess IPA in the system can hinder the production of methyl esters. At 10:1:25
IPA: oil: methanol molar ratio (IPA: methanol (w: w) ratio of 1:1) the formation of isopropyl ester was negligible, making this an alternative technique for
biodiesel processing.
Enzymatic conversion of lignocellulosic biomass to valuable chemicals and energy is key to establishing a sustainable plant-based economy. Whilst
technologies for lignocellulose conversion have advanced dramatically in recent decades, the economic viability and further diversification of bioproducts
requires new enzyme activities and synergistic enzyme combinations. Metagenomic analysis of lignocellulose-degrading microbial communities presents a
powerful approach to enzyme discovery. In this project, lignocellulose-degrading microbial consortia in the digestive systems of Canadian beaver (Castor
canadensis), North American moose (Alces alces) and pulp mill anaerobic granules were enriched for over three years using various lignocellulose
conditions, encompassing i) cellulose alone, ii) cellulose and lignosulphonate, iii) cellulose and tannic acid, and iv) poplar hydrolysate.To our knowledge,
this is the first microbial survey of the investigated sites with strategic lignocellulose amendments. The generated results provide insights on key wooddegrading microbes for future bioprospecting.
Sustainable Production of Biodiesel and Food-Grade Protein Ingredients. Increased demand for biofuels results in competition for agricultural land that
can lead to higher food prices which adversely affects the living standards of poor people. Therefore, it is essential to find compromises that meet the
demand for both food and renewable transportation fuels. Yellow mustard is a Canadian food crop that is a viable source of both oil and protein. We
developed an economically optimal two-stage alkaline aqueous extraction process for dehulled yellow mustard flour with the aim of recovering both foodgrade protein isolates and fuel-grade oil in the form of skim and stable oil-in-water emulsion fractions. The application of this processing approach could
help increase Canadian production of both food ingredients and biofuel, without impacting the cost of edible oils.
Yaser Dahman
(Ryerson)
Bio synthesis of
chemicals and
energy
This briefly summarizes the developments related to Bacterial Cellulose (BC), its structure and biosynthesis. Major development related to structure of
cellulose is the discovery of its new sub-allomorph that it is found in two crystalline form i.e. Cellulose І and Cellulose ІІ. The difference between these two
crystalline forms is based on their orientation. In cellulose І, glucan is oriented in parallel chains, whereas in Cellulose ІІ, the chains are anti-parallel. Microfibril is the basic structural unit of Cellulose. This report focuses on recent diversity of Cellulose, dis-similarity between plant and Bacterial Cellulose, its
synthesis and characterization and its properties. BC synthesized from A.Xylinum has drawn lots of attention and interest from the biomedical device field
due to its unique structure and properties. BC has become a favorable material for wound healing, neuron protection, and vascular grafts etc. In this
review, the various methods, observatio n and their application are summarized. In the end, the future expectation of BC is briefly discussed. Overall, this
low cost, biocompatible, and versatile nanomaterial could eventually be developed as an excellent platform for a new generation of bio-medical devices.
Xiang Cheng
David Sinton
(Toronto)
Bio synthesis of
chemicals and
energy
In-situ algae-to-biofuel conversion on a microfluidic reactor. Climate change is primarily caused by the greenhouse gas CO2 emissions associated with
fossil fuel combustion. Algal biofuel is widely considered as a more sustainable and domestic secure energy source to meet the increasingly global energy
demand. Hydrothermal Liquefaction (HTL), as an economic and reliable algae-to-biofuel conversion method, since it involves directly converting wet
biomass to biodiesel without an expensive drying process. However, the chemistry of HTL is not clear due to the lack of both precise parameter control
and in-situ visualization. Using microfluidics, we can precisely manipulate and control fluids to achieve ultra-high heating rate under high pressure and
high temperature which was recently found critical to biofuel production. The objective of this research is to study the conversion chemistry in a continuous
reactor which has significant impact on the next generation biofuel production.
Scott Pierobon
David Sinton
(Toronto)
Bio synthesis of
chemicals and
energy
Microalgae-based biofuel production is limited by reactor-scale light and chemical gradients permitted by current photobioreactor designs. A modularly
scalable architecture employing thin, breathable waveguides limits these gradients to the microscale and reduces the need for active aeration and mixing.
Development of this architecture is presented, toward enabling scalable, cost-effective biofuel production.
David Sinton
(Toronto)
Bio synthesis of
chemicals and
energy
The light concentrating and scattering properties of nano-scaled plasmonic metals have been used to improve the efficiency of many solar energy
conversion technologies. Relatively little attention has been given however, to how these phenomena can be used to improve light harvesting by
photosynthetic microorganisms cultivated in photobioreactors. Efficient cultivation of these organisms will become increasingly important since microalgae
based biofuels have the potential to displace fossil fuels as our primary transportation fuel, a major step in curbing global carbon emissions. Due to issues
associated with uneven light distribution however, cultivation has been limited to low density cell suspensions resulting in sprawling facilities that are
expensive and difficult to maintain. This work demonstrates new methods of high-density and high efficiency cultivation using plasmonic nanoparticles to
contain incident light inside cultures of photosynthetic bacteria, paving the w ay for the next generation of high-density photobioreactors.
7
Matthew
Ooms
8
Leila Mazaheri Jean-Michel Nunzi Nanocrystals and
Spontaneous photoinduced surface relief gratings were inscribed on thin films of a disperse red 1 functionalized with glass-forming compound. These sub(Queen's)
Semiconductors for mirometer patterns could couple the light into the sample plane in four directions. The self –organized surface relief gratings diffract the incoming
polarized beam. The first-order diffracted beams cross the polymer layer, and reflect on the back of the glass substrate, and then they cross the polymer
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layer again and induce periodic structuration. These self-organized structures depend on parameters such as light polarization direction, irradiation angle,
wavelength and intensity. The dependence of pattern formation with the irradiation time has been studied for different irradiation intensities. A YAG laser
(λ= 532nm) is used as pump beam. We studied formation of the patterns, by measuring the probe beam (He–Ne laser, 632.8 nm, and 5mW) diffraction
intensity and atomic force microscope (AFM) scans.
9
Peter Mirtchev
Geoff Ozin
(Toronto)
Nanocrystals and
We report the synthesis of colloidal γ-Fe2O3/Cu2O hetero-nanocrystals (HNCs) using a solution-phase seeded-growth approach. γ-Fe2O3 nanocrystals
Semiconductors for were used as seeds for the nucleation of metallic Cu followed by oxidation of the Cu domain to Cu2O upon exposure to air. The resulting dimer, trimer,
and oligomer HNCs were characterized by high resolution electron microscopy, energy dispersive X-ray spectroscopy, and powder X-ray diffraction. The
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iron oxide component was found to be mainly γ-Fe2O3 using a combination of Raman and X-ray photoelectron spectroscopy. A maximal HNC yield of
72% was achieved by reducing particle growth time to a lower growth temperature with respect to the individual component particles. Size-selective
precipitation was used to enrich the nanoparticle mixture in γ-Fe2O3/Cu2O dimers by removing the larger aggregates. Ultraviolet photoelectron
spectroscopy was used to determine that γ-Fe2O3 and Cu2O are n-doped and p-doped respectively and form a stag gered, type II band alignment. As
such, γ-Fe2O3/Cu2O HNCs may be attractive candidates for applications in solar energy conversion and represent a valuable addition to the growing
library of oxide–oxide heteronanocrystals.
10
Milad
Abolhasani
Eugenia
Kumacheva
(Toronto)
Nanocrystals and
Unique physicochemical properties of semiconductor nanocrystals (NCs) have enabled a variety of applications in light emitting diodes, biological imaging
Semiconductors for as well as in devices such as solar cells and displays. Over the past decade, different Microfluidic (MF) platforms have demonstrated promising
alternatives to the batch scale process by overcoming some of the aforementioned challenges. Owing to the reduced axial dispersion compared to singleSolar Devices
phase flow format and the utilization of an inexpensive solvent, gas-liquid segmented flow format can be employed for high throughput on-chip preparation
(or screening) of high quality NCs. In this work, we present a multi-pass MF platform which enables on-chip control over nucleation and growth stages of
NCs. Employing this MF strategy, we aim to predictably screen over the rich library of various types of NCs (e.g., CdSe, CdS, ZnS, ZnSe and CdTe), and
to characterize the growth stage of NCs with different morphologies for experimental conditions that cannot be addressed in current macroscale or other
MF approaches. In continuous MF approaches, the microreactor length increases exponentially against the peak emission wavelength of the NCs. Utilizing
the sequential growth strategy, our automated MF platform removes the residence time limitation associated with the currently available continuous
microreactors.
11
Benoit Mahler
Geoff Ozin
(Toronto)
Nanocrystals and
Colloidal Synthesis of 1T-WS2 and 2H-WS2 Nanosheets: Applications for Photocatalytic Hydrogen Evolution. In recent years, a lot of attention has been
Semiconductors for devoted to monolayer materials, in particular to transition metal dichalcogenides (TMDCs). While their growth on a substrate and their exfoliation are well
developed, the colloidal synthesis of monolayers in solution remains challenging. This paper describes the development of synthetic protocols for
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producing colloidal WS2 monolayers, presenting not only the usual semiconducting prismatic 2H-WS2 structure, but also the less common distorted
octahedral 1T-WS2 structure, which exhibits metallic behavior. Modifications of the synthesis method allow for control over the crystal phase, enabling the
formation of either 1T-WS2 or 2H-WS2 nanostructures. We study the factors influencing the formation of the two WS2 nanostructures, using X-ray
diffraction, microscopy and spectroscopy analytical tools to characterize them and we investigate the integration of these two WS2 nanostructured
polymorphs into an efficient photocatalytic hydrogen e volution system to compare their behavior.
Eugenia
Kumacheva
(Toronto)
Nanocrystals and
Chiral plasmonic nanostructures offer new perspectives in diverse fields such as materials for energy, metamaterials, asymmetric catalysis and
Semiconductors for bio(chemical)sensing. Development of this incipient field critically depends on the availability of methods of preparation of chiral plasmonic materials.
Herein, we present a new bio-inspired and cost-efficient route for the preparation of macroscopic chiral plasmonic films. The approach utilizes the
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incorporation of guest gold nanorods (NRs) into a cholesteric solid film formed by self-assembled cellulose nanocrystals (CNCs). Biocomposite NRsCNCs films revealed strong plasmonic chiroptical activity, dependent on the photonic properties of the CNCs host and plasmonic properties of the NRs.
Such chiroptical plasmonic properties were tuned by changing the conditions of film preparation.
12
Ana QuerejetaFernández
13
Yasser Hassan
14
Anna Klinkova
Eugenia
Kumacheva
(Toronto)
Nanocrystals and
Self-Assembled Chains of Plasmonic Nanocubes: Study of Structural and Optical Properties. Self-assembly of nanoparticles in solutions provides a
Semiconductors for powerful strategy for creating nanostructures with unique morphologies and properties. Here, we report solution-based linear self-assembly of plasmonic
Au/Ag core-shell nanocubes and examine structural characteristics - shape of interparticle junctions and co-linearity of the chains formed by polymerSolar Devices
capped nanocubes with varying dimensions. Chains, in which the nanocubes assembled predominantly in the face-to-face manner, exhibited a higher colinearity, a stronger surface enhanced Raman scattering enhancement and additional plasmon coupling modes, in comparison with linear assemblies of
spherical nanoparticles with similar dimensions, composition and surface chemistry. The experimental results were in agreement with finite difference time
domain simulations.
15
Mutalifu
Abulikemu
Osman Bakr
(KAUST)
Nanocrystals and
Synthesis and characterization of colloidal Sb2S3 nanocrystals and its application for nanocrystals sensitized solid-state solar cells. Antimony sulfide is a
Semiconductors for direct band gap semiconductor with a band gap 2.2 eV in its amorphous orange color Sb2S3 and 1.7 eV of crystalline black color Sb2S3, which holds
potential applications in solar cells and optical data storage.No systematic studies about synthesis of amorphous and crystalline Sb2S3 NCs have been
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reported. Herein, Phase and shape-controlled Sb2S3 NCs is s ynthesized by hot inject colloidal method and cation ion exchange. The effect of different
Antimony and Sulfur precursors on the shape and size of Sb2S3 NCs is examined. Foreign ion’s effect on the shape and crystallinity of as-prepared
Sb2S3 NCs is studied. We found out that Chlorine ion can change of shape of Sb2S3 NCS from spherical to hyper branched NCs. In addition, Sb2S3
NCs is ligand exchanged with 1-Thioglycerol and Sb2S3 paste is prepared. It is diluted in Isopropanol before spin coating. Photovoltaic devices are
fabricated as FTO/d-TiO2/meso-TiO2/Sb2S3 /Spiro-OMETED/Au, and its highest power conversion efficiency is 1.13% so far.
16
Jixian Xu
Ted Sargent
(Toronto)
Nanocrystals and
Wireless direct water splitting built on solution-processed PV represents a new field in visible-light photocatalyst. To reduce the difference between
Semiconductors for bandgap and open-circuit voltage is a challenge in the underlying physics and device engineering. We want to demonstrate the first perovskite tandem cell
for under-water wirelss, direct water splitting. Photons used for photocatalyst are extended to near IR region.
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Gregory Scholes Nanocrystals and
Direct Synthesis of CdSe Nanocrystals with Ferrocene-based Ligands. During past years, the applications of colloidal semiconductor nanocrystals (NCs)
(Toronto)
Semiconductors for in solar cells have received significant attention. Facile transport of charge carriers between the individual nanocrystals was found to be an essential
requirement in order to apply these nanocrystals to solar cell devices. Ligands help to passivate the NC surface--removing surface traps--and for some
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applications facilitate charge transport. Ligand exchange process enables the surface of colloidal NCs to be adapted for diverse applications. Usually
ligands are exchange post-synthesis. However, a high efficient ligand exchange process is difficult to be achieved. Instead, here we report a new synthetic
technique of CdSe preparation directly with electro-active ligands like ferrocene and cobaltocene phosphine and phosphinoxide derivatives. These
metallocenes are bound directly to the inorganic core of the QD. These metallocenes are interesting for electro-active and photoredox systems. Ferrocen e
phosphinoxide derivatives were found a good candidate as a starting point toward our goal of direct synthesis of CdSe NCs in electro-active ligands. The
preparation, properties and characterization of these materials are presented.
17
Nicholas
Tulsiram
Jennifer Chen
(York)
Nanocrystals and
Fabrication and characterization of a 3D photonic TiO2/P3HT nanocomposite for enhancing charge generation in a bulk heterojunction solar cell. Photonic
Semiconductors for crystals are highly ordered structures that exhibit unique light controlling abilities, such as being able to theoretically reduce the group velocity of light to
zero. They have been shown to increase light absorption and reduce charge-carrier recombination, which would be desirable for solar conversion
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processes. We present an organic/inorganic nanocomposite for bulk heterojunction cell applications using a titanium dioxide (TiO2) inverse opal 3D
photonic crystal coated with poly (3-hexylthiophene) (P3HT). Inverse opals were fabricated by infiltration of an opal template of polystyrene spheres that
were deposited onto a glass substrate via colloidal self-assembly. We fabricated TiO2 inverse opals with different periodicities, number of layers and wall
thicknesses to systematically study the effects of different factors on charge generation. Charge generation is probed by photoinduced absorption
spectroscopy (PIA) under different excitation wavelengths and modulation frequencies. We investigate the possible photonic effects of the
nanocomposites and address the potential of charge enhancement by photonic crystals for organic photovoltaics. The proof of concept may serve as
blueprint which can be applied to different photovoltaic devices in the future.
18
Cao Thang
Dinh
Trong-On Do
(Laval)
Nanocrystals and
A new type of Au-TiO2 hybrid nanostructured photocatalysts was constructed by three-dimensional ordered assembly of thin-shell Au-TiO2 hollow
Semiconductors for nanospheres. The designed materials exhibit not only a high surface area but also photonic behavior originating from periodic macroscopic voids from both
the inside and the outside of the very thin shell hollow spheres. The multiple-light scattering and slow photon effects resulting from this unique architecture
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greatly enhance the surface plasmon resonance of Au nanoparticles. As a result, these photocatalyts exhibit a several times higher photocatalytic activity
compared to conventional Au-TiO2 hybrid nanopowders in the decomposition of volatile organic compounds under visible light illumination, and have a
high potential in environmental applications.
19
Lei Jin
Federico Rosei
(INRS)
Nanocrystals and
TiO2 thick film sensitized with quantum dot through electrophoretic deposition . Electrophoretic deposition (EPD) is a technique based on application of
Semiconductors for an external electric field to colloidal nanoparticles (NPs) suspended in a liquid medium to induce their migration and their final grafting to a desired
electrode. It has been demonstrated for preparation of high efficiency photoanodes in which QDs are grafted to a mesoporous TiO2 NP thick film. As the
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performance of photoanodes is highly dependent on not only the loading amounts, but also the QDs dispersion in TiO2 film, it is very important to control
the QDs loading process, while a systematic investigation of the physical chemical QD loading dynamic by EPD is still missing. Here, for the first time, we
systematically investigated the dynamics of near infrared QDs loaded into TiO2 mesoporous film via EPD, including the determination of the main
parameters regulating the process. In addition, we also demonstrated the increased stability of the core/shell structure compared to PbS QDs after EPD in
terms of structure and optical properties. Based on our previous studies that confirmed a fast charge transfer from PbS/CdS to TiO2, QD sensitized TiO2
can be strong candidates for the development of highly efficient and stable photoanodes in PV devices and H2 generation through water splitting.
20
Ariella Lukach
Eugenia
Kumacheva
(Toronto)
Nanocrystals and
The resemblance between colloidal and molecular polymerization reactions is very useful in fundamental studies of polymerization reactions, as well as in
Semiconductors for the development of new nanoscale systems with desired properties. Future applications of colloidal polymers will require nanoparticle ensembles with a
high degree of complexity that can be realized by hetero-assembly of NPs with different dimensions, shapes, and compositions. A method has been
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developed to apply strategies from molecular copolymerization to the co-assembly of gold nanorods with different dimensions into random and block
copolymer structures (plasmonic copolymers). The approach was extended to the co-assembly of random copolymers of gold and palladium nanorods. A
kinetic model validated and further expanded the kinetic theories developed for molecular copolymerization reactions.
21
Lisa Rollny
Ted Sargent
(Toronto)
Nanocrystals and
Colloidal Quantum Dot Solar Cells Printed From Hydrogen Bond Stabilized Inks. For many industrial and scientific applications colloidal stability is the
Semiconductors for most important parameter in need of control. The repulsive energies between colloidal particles determine the stability of the dispersion, when balancing
out van der Waals attraction of the colloids. However, in solid state applications, molecules that used to serve colloidal stabilization in solution usually
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result in undesirable electronic effects, such as insulation (in case of steric stabilization) or traps (in case of electrostatic stabilization). Both of these can
be lethal to high performance in optoelectronic devices, such as photovoltaics. Hence, the focus of this work is to create a new way of stabilizing PbS
colloidal quantum dots in order to avoid these obstacles and to then make a solar cell device with this single step ready to deposit CQD ink.
22
Oleksandr
Voznyy
Ted Sargent
(Toronto)
Nanocrystals and
Deep traps pose major limitations on allowed device thickness and charge collection in colloidal quantum dot (CQD) photovoltaics. In this work we explore
Semiconductors for theoretically and experimentally the possibility of detrapping the carriers in CQD films using molecular inclusions with high electron-phonon coupling,
leading to energy level vibration between the conduction band and deep trap level, inspired by environment-assisted transport in photosynthetic systems.
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Effect of inclusions with various band alignment and degree of vibrations is explored on carrier mobility, photoluminescence and photovoltaic device
performance.
23
Afsoon Soudi
Nanofemtolab
(INRS)
24
Pelayo Garcia
de Arquer
Gerasimos
Konstantatos
(ICFO, Spain)
25
Isaac Tamblyn
(UOIT)
Nanocrystals and
In advancing photovoltaic technologies, quantum dot (QD) based solar cells has shown great promise in reducing the cost and enhancing the efficiency of
Semiconductors for light-harvesting systems compared to single crystal silicon cells - the efficiency of which is limited by the Shockley Queisser limit. In depth knowledge of
exciton dynamics is required for design of the cells with optimum efficiencies. The quantum confinement effect in QDs enables bandgap tuning which has
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been widely adapted to facilitate exciton generation and separation, therefore harnessing more photons in a single device. However, the precise control of
band-edge alignment between the QDs and the electron transporting material (typically a wide band gap semiconductor like ZnO or TiO2) is critical in
enhancing the performance of the device by regulating charge generation, separation and collection. Here we present the study of diameter and
composition dependence of the surface potential of single Lead and Cadmium Chalcogenide quantum dots and their composite configurations using
Kelvin probe force microscopy and determined the energy-level arrangement at nanoscale, charge injecting configuration and the PbS/CdS composition
for optimum photoconversion efficiency. Our findings are also consistent with QD solar cell performance using the same configurations
Nanocrystals and
Optical sensing at visible and infrared wavelengths is of paramount importance for a vast number of applications. Optoelectronic functionalities of
Semiconductors for photodetection and light harnessing rely on the band-to-band excitation of semiconductors, thus the spectral response of the devices is dictated and
limited by their bandgap. A novel approach, free from this restriction, is to harvest the energetic electrons generated by the relaxation of a plasmonic
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resonance in the vicinity of a metal-semiconductor junction. In this configuration, the optoelectronic and spectral response of the detectors can be
designed ad hoc just by tailoring the topology of metal structures, which has tremendous applications in solar energy harvesting and photodetection. Fully
exploiting hot electron based optoelectronics yet requires a platform that combines their exotic spectral capabilities with large scale manufacturing and
high performance. Herein we introduce the first implementation of a large area, low cost quasi 3D plasmonic crystal (PC), for hot electron photodetection,
showcasing multiband selectivity in the VIS-NIR and unprecedented responsivity of 70 mA/W. We will also discuss the importance of the metalsemiconductor interface in these devices, and show how this is critical for light harvesting applications to concurrently sustain high open-circuit voltages
and short-circuit currents. By modifying the properties of the interface at the nanoscale, we show that the photovoltaic performance of plasmonic-hot
electron solar cells can be tuned. By doing so, we report IPCE over 5% and power-conversion-efficiency under simulated solar illumination up to 0.11%.
The presented technology can be extended for energy harvesting into other bio related systems such as solar powered catalysis and solar fuels.
Nanocrystals and
The excited state dynamics of d0 vanadium (V) oxo ligand-to-metal charge transfer complex, VOLF, were investigated via a combination of static optical
Semiconductors for and X-ray absorption, ultrafast transient optical absorption spectroscopy, time-dependent density functional theory, and second-order perturbation theory.
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Upon excitation of the LMCT transition in the visible region, time-resolved data revealed two primary relaxation path- ways with several orders of magnitude
difference between time constants–τb = 574 fs and τ2 = 438 ps–for the decay back to the ground state. The two pathways are differentiated by their
transient d1 excitations. The long-lived (438 ps) charge transfer state is ascribed to an S1 electronic state of occupied 3dx2−y2 character whose coupling to
a S0 distorted ligand centered ground state is optically disallowed and has very little Franck-Condon overlap, inhibiting vibrational relaxation. This is the
longest reported charge transfer state in a 3d metal centered complex that decays non-radiatively (i.e. without an identifiable triplet state and associated
luminescence). This long lifetime, in conjunction with its strong visible absorption and reduction/oxidation potentials, suggests its use as a chromophore
for energy conversion applications. Furthermore, the results present the first time that the decay of electrons through different 3d orbitals on the metal
center can be used to form a long-lived LMCT charge-transfer excitation, informing the synthesis of 3d metal centered optical absorbers experimentally
and theoretically.
26
Mark Wilson
Moungi Bawendi Nanocrystals and
Energy Harvesting of Non-Emissive Triplet Excitons in Tetracene by SWIR-Emitting PbS Nanocrystals. Triplet excitons are ubiquitous in organic
(MIT)
Semiconductors for optoelectronics, but they are often an undesirable energy sink as they are both spin-forbidden from emitting light, and strongly bound relative to free
electron-hole pairs. Harvesting their energy is, consequently, an important technological challenge. We demonstrate direct exciton energy transfer from
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‘dark’ triplets in the organic semiconductor tetracene to colloidal PbS nanocrystals, thereby successfully harnessing molecular triplet excitons in the shortwave infrared. (SWIR) Steady-state excitation spectra demonstrate that the transfer efficiency is at least 90±13%. Transient photoluminescence and
magnetic field-dependent studies show that the mechanism is a Dexter hopping process – the simultaneous exchange of two electrons. Triplet exciton
transfer to nanocrystals is expected to be broadly applicable in solar and SWIR-emitting applications, where effective molecular phosphors are lacking. In
particular, this route to ‘brighten’ low-energy molecular triplet excitons may permit the sensitization of conventional silicon solar cells with singlet exciton
fission materials.
27
Changxu Liu
Andrea
Fratalocchi
(KAUST)
Nanocrystals and
Millions of years of evolution in Nature have demonstrated a plethora of complex biological structures, which can stimulate the design of a new generation
Semiconductors for of photonic technologies. A very interesting example is provided by the Cyphochilus beetles, which shows an exceptionally bright white color. Quite
interestingly, physical studies show that such exceptional brightness is not the result of a specific pigment, but conversely originates from the presence of
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a complex network of random scatterers, which chaotically reflects light in all directions and producing a striking white colour.
28
Elsa Cassette
Greg Scholes
(Toronto)
Nanocrystals and
Free-standing two-dimensional semiconductor nanostructures composed of few monolayers in thickness and with an optical bandgap have garnered
Semiconductors for considerable attention over the past few years. In these systems, the strong 1D quantum confinement and low dielectric screening lead to the formation of
strongly bound excitons, which make them very attractive for applications in photovoltaics and light-emitting devices. Here we study by two-dimensional
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electronic spectroscopy the ultrafast dynamics of excitons in two different types of nanostructures: colloidal nanoplatelets of II-VI semiconductor materials
and nanosheets of a transition metal dichalcogenide.
29
Lena Simine
Dvira Segal
(Toronto)
Renewable Energy
Sources
We propose the thermopower as diagnostic tool for transport mechanisms in molecular junctions. Focusing on the case of quasi-degenerate electronic
molecular states we demonstrate that thermopower allows to differentiate between elastic and inelastic decoherence mechanisms.
30
Sami Yamani
Cristina Amon
(Toronto)
Renewable Energy
Sources
Recently the health and environmental impacts of onshore wind farms is receiving major attention from both governments and wind farm designers. As
land is more extensively exploited for wind farms, it is more likely for wind turbines to be in proximity with human dwellings, natural habitats (e.g. rivers,
lakes, forests), and infrastructure (e.g. roads, transmission lines). This proximity makes noise minimization essential for the wind farm neighbours and
introduces a set of land-use constraints. In this study, we conduct a constrained, continuous variable multi-objective optimization that considers energy
and noise as its objective functions using a stochastic evolutionary algorithm (NSGA-II). Results of this study illustrate the effect of the constraint severity
and the spatial distribution of unusable land on the trade-off between energy generation and noise production. To enrich the optimization model in the
context of complex terrains, a new wake interaction model is devi sed to take the effects of terrain complexities such as hills into account. This wake model
is implemented successfully to an unconstrained, single-objective optimization model and will be included to the main optimization model in future.
31
Francisco
Contreras
Cristina Amon
(Toronto)
Renewable Energy
Sources
Several studies have shown that stand-alone Hybrid Renewable Energy Systems (HRES) are a cost-effective electricity generation alternative for specific
remote communities and system configurations (e.g., wind-diesel; PV-diesel). However, in order to design and develop efficient policies that will encourage
the implementation of stand-alone HRES, it is essential to study the performance of such systems across a range of communities that exhibit different
climate conditions, and load profiles. Therefore, a method capable of optimising the HRES design and dispatch strategy that can be used to evaluate any
remote community is a valuable tool for informing policy makers or private investors. Consequently, in this study we developed a multi-level optimization
approach that takes into account the component selection and dispatch strategy of HRES, and can evaluate the implementation of these systems in any
community. The proposed method considers a wide array of renewable energy tech nologies (i.e. wind, solar, hydro, diesel, batteries, fuel cells,
electrolyzers, and hydrogen tanks) and a database of commercially-available components. Therefore, this approach can provide accurate insight into the
benefit and advantages of using HRES to replace the diesel-based electricity generation infrastructure currently found in most remote locations.
32
Jonathon Moir
Geoff Ozin
(Toronto)
Solar to chemical
Activation of Ultrathin Films of Hematite for Photoelectrochemical Water Splitting via H2 Treatment. Surface Activation of Ultrathin Films of Hematite for
Photoelectrochemical Water Splitting via H2 Treatment - The thermal treatment of ultrathin films of hematite (α-Fe2O3) with 5% H2 in Ar is presented as a
means of activating α-Fe2O3 towards the photoelectrochemical splitting of water. Spin-coated films on fluorine-doped tin oxide (FTO) were annealed in air
to induce crystallization. The photoelectrochemically inactive films were then activated via high temperature treatment under a flow of 5% H2 in Ar, after
which they exhibited a photocurrent response. X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy results show that the H2treated films contain oxygen vacancies, suggesting improved charge transport within the films. However, Tafel slopes, scan-rate dependent
measurements, and kinetic analyses using H2O2 as a hole scavenger reveal that surface modification of the iron oxide films is responsible for their
photoactivity.
Geoff Ozin
(Toronto)
Solar to chemical
The solar-to-chemical energy conversion of greenhouse gas CO2 into carbon-based fuels is a very important research challenge, with implications for both
climate change and energy security. Herein we experimentally identify key attributes of hydroxylated indium oxide nanoparticles, In2O3-x(OH)y, that
function in concert to reduce CO2 under simulated solar radiation. In2O3-x(OH)y nanoparticles are prepared with varying surface hydroxide and oxygen
vacancy content to investigate the effects of these parameters on light-driven, gas-phase CO2 reduction rates. By optimizing these parameters, CO2 can
be converted to CO, in the presence of H2, at a rate as high as 0.60 µmol gcat-1 hr-1 under 0.8 suns of simulated solar irradiation at 150°C. 13CO2
isotope labeling experiments identify CO as the sole carbon product of CO2 photocatalytic reduction. Significantly the surface hydroxide and oxygen
vacancy concentrations correlate well with the CO2 adsorption capacity and CO production ra te, suggesting both play a key role in the reaction
mechanism. This advance provides insight towards the rational design and optimization of single-component gas-phase CO2 reduction photocatalysts to
be incorporated into current advanced systems for solar fuels generation.
Thomas
Burdyny
David Sinton
(Toronto)
Solar to chemical
The next generation commercial production of solar fuels will require photocatalytic reactors that achieve both high efficiency and scalability. In an attempt
to obtain the high reactive surface areas necessary for high conversion rates, many designs increase reactor complexity which ultimately inhibits economic
scalability. We thus introduce a new paradigm in solar fuel technology, a bioreactor that exploits the self-assembly of photocatalytic nanoparticles at a gasliquid interface. These low-cost, highly scalable and easily produced Pickering emulsions boast stabilities on the order of weeks or longer. Each resulting
microbubble inside the high surface area foam acts as a miniature reactor: the photocatalysts positioned at the bubble’s surface are surrounded by both
gas and liquid reagents. This work will highlight the physical characteristics of the particle foam and present reaction rates for both methylene blue
degradation and CO2 reduction to solar fuels.
35
Scott Pierobon
David Sinton
(Toronto)
Bio synthesis of
chemicals and
energy
36
Zhijun Ning
Ted Sargent
(Toronto)
Nanocrystals and
Air-stable n-type Colloidal Quantum Dot Solids. Colloidal quantum dots (CQDs) offer promise in flexible electronics, light sensing and energy conversion.
Semiconductors for These applications rely on rectifying junctions that require the creation of high-quality CQD solids that are controllably n-type (electron-rich) or p-type (holerich). Unfortunately, n-type semiconductors made using soft matter are notoriously prone to oxidation within minutes of air exposure. Here we report highSolar Devices
performance, air-stable n-type CQD solids. Using density functional theory we identify inorganic passivants that bind strongly to the CQD surface and
repel oxidative attack. A materials processing strategy that wards off strong protic attack by polar solvents enabled the synthesis of an air-stable n-type
PbS CQD solid. This material was used to build an air-processed inverted quantum junction device, which shows the highest current density from any
CQD solar cell and a solar power conversion efficiency as high as 8%. To cut the device cost and simplify fabrication process, solar cells based on inks of
n-type CQD by using iodide ligands was developed, which provide a promising route to reduce CQD surface defects and improve device performance
further.
37
Paul O`Brien
Geoff Ozin
(Toronto)
Nanocrystals and
Decoupling Photothermal and Photochemical Methanation of Gaseous CO2 over Ru/Silicon Nanowire Catalysts. High-rate photomethanation of CO2 in a
Semiconductors for H2-rich environment was recently reported to occur over group VIII nanocrystals on Al2O3 catalyst supports. The reaction was activated by a
photothermal effect, driven by heat generated from absorbed photons. CO2 photomethanation was also reported to occur over Ni on silica-alumina catalyst
Solar Devices
supports. This reaction was driven by a photochemical effect, whereby photogenerated electron-hole pairs (EHPs), primarily generated with UV light,
activate Ni-H species that reduce CO2 to CH4. Here we show the photomethanation of CO2 is activated both photothermally and photochemically over Ru
catalysts supported by Si nanowires (Ru/SiNW). We decouple the photochemical and photothermal effects on the overall reaction rate and show that the
photochemical contribution can be 5 times greater than the photothermal contribution. Further, we show a direct linear correlation between the
photomethanantion rate and the number of incident photons impinging on the Ru/SiNW catalyst throughout the UV- Vis- and NIR- spectral regions.
33
Laura Hoch
34
Microalgae-based biofuel production is limited by reactor-scale light and chemical gradients permitted by current photobioreactor designs. A modularly
scalable architecture employing thin, breathable waveguides limits these gradients to the microscale and reduces the need for active aeration and mixing.
Development of this architecture is presented, toward enabling scalable, cost-effective biofuel production.
38
Thomas Wood
Geoff Ozin /
Charles Mims
(Toronto)
Nanocrystals and
Multi-reactor screening using 13CO2 isotope tracing for the discovery of gas phase CO2 reduction photocatalysts. Discovery of a photocatalyst capable
Semiconductors for of converting carbon dioxide in the gas phase using light is necessary for the advancement of the exciting new technology known as the artificial leaf.
However, reported CO2 photoreduction rates are often low and carbon contamination from materials synthesis methods calls into question the validity of
Solar Devices
previously reported results. These issues are addressed using a multi-reactor photocatalyst screening system designed to test multiple samples
simultaneously under similar reaction conditions. Additionally, isotope tracing experiments using 13C-labelled CO2 (13CO2) are applied to study
photocatalytic reduction of CO2 to provide evidence that the observed products arise from CO2 and not adventitious carbon sources. In this work over 100
catalyst compositions were tested for photocatalytic activity. Using this methodology, it was discovered that hydroxylated indium oxide nanoparticles, In2O3x(OH)y, are capable of reducing CO2 into CO under simulated solar irradiation. This system provides an effective and economic approach for screening
materials for gas phase CO2 photocatalytic reduction.
39
Andrew Flood
Nazir Kherani
(Toronto)
Photovoltaics and
Devices
40
Joel Y.Y. Loh
Nazir Kherani
(Toronto)
Photovoltaics and
Devices
41
David Barchet
Nazir Kherani
(Toronto)
Photovoltaics and
Devices
42
Petar Lachkov
Cathy Chin
(Toronto)
Selectively Transparent and Conducting Photonic Crystals (STCPCs). Photonic crystal device architectures utilize light control and confinement effects
readily observed in nature. Inspired by these effects, Selectively Transparent and Conducting Photonic Crystals (STCPCs) are a unique type of onedimensional photonic crystal structure with numerous applications in optoelectronic devices. STCPCs are novel in that they both exhibit an optical band
gap and are electrically conductive throughout. The high spectral tunability of the STCPC allows it to be integrated into several photovoltaic technologies.
We have performed simulations showing increased efficiencies in silicon-based thin-film micromorph tandem cells and also in thin crystalline silicon
bifacial cells. Building integrated photovoltaics (BIPV) based on amorphous silicon have been fabricated and demonstrate improved efficiencies with little
change in transmitted light. By using STCPCs, one can also create semi-transparent solar cells that transmit light at specific wavelengths which may have
aesthetic benefits in BIPV.
Porosity Tuned Multilayer Anti-reflecting Coatings. Low index silica films suitable as anti-reflection coatings were prepared by porosity tuning following
polystyrene pyrolysis within a silica colloid. Multilayer stacks of nanoparticle films with varying degrees of porosity were prepared by sequential spin coating
and sintering of various silica-polystyrene matrix. The average transmittance was improved from 91% to 95.2% using a 3 layer stack on one glass-air
interface, and to 99% using 3 layer stacks on both interfaces- the highest reported values for facile synthesized multilayer structures.
Native Oxide Based Passivation of Crystalline Silicon. As crystalline silicon photovoltaic cells become ever thinner the carrier lifetime of the device
becomes more dependent on passivation of the surface of the device. The current gold standard for passivation is thermal oxide which has resulted in
silicon solar cells with photovoltaic conversion efficiencies of 25%. Thermal oxide growth however involves processing at temperatures of ~800-1000 oC
which can exacerbate crystalline silicon bulk properties through defect migration, induce thermal stresses particularly in the context of ultra-thin silicon,
and has a significant thermal budget. In this poster we present the attainment of high passivation using a 1 nm layer of facile grown native oxide (in air
ambient) followed by a deposition of a 70 nm layer of amorphous hydrogenated silicon nitride. This leads to a surface recombination velocity of less than 8
cm/s and effective minority carrier lifetimes exceeding 1.7 ms. This novel approach has been incorporated in Back Amorphous-Crystalline Si
Heterojunction (BACH) solar cells achieving efficiencies approaching 17% on untextured silicon. We also show the ability to attain equivalent passivation
quality using an ozone-oxygen ambient albeit the growth time is reduced from a month to an hour at room temperature.
Nanocrystals and
Semiconductors for Solution-processed solar cell reports to date have relied on lab-scale batch-processing methods such as spin-coating. Here we report spray-coated
colloidal quantum dot (CQD) solar cells whose performance is superior to that of reference spin-cast devices. We identify a key organic-inorganic complex
Solar Devices
– an impurity in the quantum dot film – that we show is responsible for limiting diffusion length in prior CQD solar solids. We prove that if, instead, one
exercises monolayer control over deposition and purification of films using the new spray process, the undesired impurity species is thoroughly removed.
Using a suite of experimental measurements and theoretical simulations, we identify the composition and energetics of an organo-lead complex that
creates a deep recombination centre and limits diffusion lengths in prior CQD solids. The new, manufacturable process is scalable, uniformly covering
large areas exceeding 60 cm2. We report the first flexible CQD solar cells with power conversion efficiency of 7.2%, and we prove that the new process is
compatible with the application of quantum dot active layers to curved substrates.
43
Illan Kramer
Ted Sargent
(Toronto)
Nanocrystals and
Semiconductors for High-Purity Colloidal Quantum Dot Solids via Spray-Coating of Ultrathin Layers. Solution-processed solar cell reports to date have relied on lab-scale
batch-processing methods such as spin-coating. Here we report spray-coated colloidal quantum dot (CQD) solar cells whose performance is superior to
Solar Devices
that of reference spin-cast devices. We identify a key organic-inorganic complex – an impurity in the quantum dot film – that we show is responsible for
limiting diffusion length in prior CQD solar solids. We prove that if, instead, one exercises monolayer control over deposition and purification of films using
the new spray process, the undesired impurity species is thoroughly removed. Using a suite of experimental measurements and theoretical simulations,
we identify the composition and energetics of an organo-lead complex that creates a deep recombination centre and limits diffusion lengths in prior CQD
solids. The new, manufacturable process is scalable, uniformly covering large areas exceeding 60 cm2. We report the first flexible CQD solar cells with
power conversion efficiency of 7.2%, and we prove that the new process is compatible with the application of quantum dot active layers to curved
substrates.
Bio-Inspired Ideas for Sustainable Energy: Poster Session Day 2
1
Jonathon
Caguiat
2
Jocelyn Zuliani
Charles Jia
(Toronto)
Energy storage
Biochars are currently a low-value waste used to offset heating requirements or to amend soil. Biochars have the potential to be used in higher value
applications with the addition of nanoporosity. The current understanding of these devices shows that nanopores are of particular importance to the
storage of energy. In this work, it is proposed that nanoporous biochars are ideal in that they contain nanopores in addition to having a macrostructure that
effectively transport electrolyte to them. There are two challenges in this work: the synthesis of the nanoporous carbon and the characterization of it. When
synthesizing these materials it is necessary to create nanostructures without destroying macrostr uctures and vice versa. As for characterization, the
complexity of the materials makes it necessary to use multiple, advanced analytical techniques to understand; however, no clear framework yet exists
around the use of these techniques with biochars. We set out to test and develop an analytical framework in order to optimize the synthesis of nanoporous
biochars. In this work we combine physisorption and Raman spectroscopy to assess a set of biochars, and discuss the feasibility of microwave activation
to synthesize nanporous biochars.
Charles Jia and
Donald Kirk
(Toronto)
Energy storage
Petroleum coke (PetCoke), a by-product of oil sands processing, represents an increasing environmental issue for Canada. Because of its high level of
impurities, PetCoke is not an environmentally acceptable fuel since combustion would release copious quantities of harmful gaseous emissions such as
sulphur dioxide. In this research, PetCoke is activated and then used as the electrode material in supercapacitors – an emerging energy storage device.
Energy storage is a critical barrier limiting the widespread commercialization of sustainable energy initiatives. Supercapacitors are promising for many
energy storage applications where they can replace or complement batteries. These devices have high power density, high cyclability, and rapid
recharging rates compared to batteries, as well as improving energy density. The current research has confirmed that supercapacitors produced with
activated PetCoke electrodes demonstrate very promising results including a high energy density, up to 11 W-h/kg of carbon, which is comparable to other
top performing, more expensive materials being researched for supercapacitors. Using activated PetCoke for energy storage also presents a unique
environmental opportunity to upgrade a current waste by-product into a useful material which can further improve the energy storage.
3
Purandhar
Vittal &
Randeep Gabhi
Charles Jia
(Toronto)
Energy storage
Supercapacitors are energy storage devices that have properties shared by both batteries and capacitors. Batteries can store high energy but charge or
discharge slowly, whereas, capacitors can charge nearly instantaneously but have less storage capacity. Resistivity of electrodes which is a key factor,
affects power density. In this work, carbon is used in solid and powder form as it is a good conductor of electricity. The source of the carbon material used
in this work varies. As resistivity can vary depending on the pressure exerted upon them, this work measures resistivity versus load and also the effect of
heat treatment. The solid samples were carbonized wood, known as biochar. These samples exhibited resistivity values as low as 2.5*10-3 Ohm•m, which
is close to the resistivity of amorphous carbon (3 to 5*10-4 Ohm•m). However, the type of wood and its structure after carbonization lead to large
resistivities (up to [6.34*105 Ohm•m]). High carbon content and low vo latile matter was found to improve the properties of biochar. As for the powdered
samples, they were sourced from petroleum coke and peat moss activated carbon (PMAC). The resistivity of the petroleum coke, depended strongly upon
the heat treatment times (HTT). The sample with a HTT of 5 h exhibited the lowest average resistivity (2.1*10-2 Ohm•m). Upon compression, the
resistivity decreased for low HTT samples whereas for high HTT samples remained constant. The PMAC has a trend that is different from both low and
high HTT petroleum coke samples: the resistivity reaches a minimum (1.4*10-3 Ohm•m) and upon higher loading increases, which is unobserved before.
It was observed that solid biochar had lower resistivity than powder samples.
4
Paul DiCarmine
Dwight Seferos
(Toronto)
Energy storage
We have explored mechanisms for controlling the morphology of template synthesized conjugated polymer nanostructures. We have shown that molecular
structure and polymerization conditions play an important role. A range of monomers was studied to elucidate the relationship between the molecular
structure and the morphology of polymer nanotubes. The results illustrate that interaction of the side-chain with the solvent has a dramatic effect on
nanotube morphology. The wall thickness of linear polythiophene nanotubes can be changed by the use of different solvents and electrolytes. Solvents and
electrolytes that increase the rate of polymerization yield solid nanowires, systems that decrease the rate of polymerization yield thin-wall nanotubes and a
system that leads to an intermediate polymerization rate yields thick-wall hallow nanotubes. With this knowledge we turn attention to donor-acceptor
building blocks for electrochemical energy storage investigations. We will specifically present capacitance data on Type III supercapacitors composed of
electrochemically polymerizable donor-acceptor monomers.
5
Tyler Schon
Dwight Seferos
(Toronto)
Energy storage
Energy storage devices using organic polymer electrodes are becoming increasingly attractive due to their low cost, flexibility, and lower environmental
impact compared to their metal/ metal oxide counterparts. An important parameter that can be used to judge the performance of a device is its power
density. An effective way to increase the power density is to widen the operating voltage by using a positive charge-accepting polymer as the positive
electrode and a negative charge-accepting polymer as the negative electrode. While there are numerous well-studied examples of the former, there is a
deficiency of negative charge-accepting polymers that have been used for energy storage. The development and use of a fullerene polymer as negative
charge-accepting material for high power polymeric supercapacitors will be discussed.
6
Matthew
Genovese
Keryn Lian
(Toronto)
Energy storage
Realizing the potential of supercapacitors for advanced applications like hybrid electric vehicles and renewable energy storage requires the development of
high performance electrode materials that can be produced sustainably at a low cost. In this work we have developed a method which utilizes corn cob, an
inexpensive and abundant waste biomass feedstock, as a precursor for the production of a biochar carbon with high capacitive performance. A novel
thermal-chemical exfoliation procedure was used to create nanostructured biochar which demonstrated a capacitance of 221 F g-1, over 100 times larger
than that of the natural corn cob biochar produced without exfoliation. The exfoliated biochar also showed excellent performance at fast discharge rates
and good durability upon repeated cycling. Developing a method for the production of high performance carbon materials from inexpensive agricultural
residue is a promising step toward the engineering of commercially viable super capacitors for large scale energy storage applications.
7
Joyprokash
Chakrabartty
Nanofemtolab
(INRS)
Energy storage
Photocapacitor is a device that converts solar energy through photovoltaic effect, and stores the converted energy by maintaining the charge concentration
difference across a membrane upon light irradiation. It eliminates additional storage devices, for example, extra battery towards device miniaturization by
enabling generated charge storage facilities in the same system. Until now published reports show those devices that used artificial layer within single
structure to make storage facility. Here we show some preliminary results on Bi-Mn-O thin film systems that differ from others in such a way that it will
employ self-assembled system converting and storing solar energy.
8
Gabriella
Lestari
Eugenia
Kumacheva
(Toronto)
Microfluidics
Microfluidic Investigation of CO2-mediated liquid-liquid phase separation. We report a microfluidic (MF) strategy for fundamental studies of CO2mediated liquid-liquid phase separation of switchable water (SW) and organic solvent. A single set of experiments, conducted in segmented flow, provided
qualitative and quantitative information on the kinetics and completeness of water-tetrahydrofurane phase separation, the minimum amount of CO2
required for completion and the rate of CO2 uptake by liquid mixtures. This approach offers a unique capability to simultaneously explore complex
concurrent processes. The wealth of information obtained from this study will facilitate rapid development and optimization of new additives for switchable
solvents. The strategy can be extended to other separation processes, e.g., extraction.
9
Phong Nguyen
David Sinton
(Toronto)
Microfluidics
Nanoparticle stabilized CO2 in water foam can overcome the low stability challenges facing surfactant foams in reservoir conditions. Foams are effective
in mobility control against viscous fingering during gas injection in enhanced oil recovery. This study presents a microfluidic approach to image and
quantify the stability of foam at pore scale and the dynamics of the oil recovery process during water flooding, CO2 gas flooding, and nanoparticle foam
flooding. In addition to chip scale flooding visualization, micro-scale imaging reveals the mechanisms of the viscous fingering in gas flooding and the high
sweep efficiency of foam; micro-emulsion size and distribution in gas and foam flooding. Coated silica nanoparticle CO2 foam is significantly more stable
than sodium dodecyl sulfate (SDS) foam at both pore scale and bulk foam. Nanoparticle foam can improve oil recovery an additional 17% IOIP after water
flooding, this is 10% IOIP more efficient than CO2 gas flooding as a res ult of high sweep efficiency and increase in effective viscosity.
10
Huawei Li
David Sinton
(Toronto)
Microfluidics
Microfluidic and Nanofluidic approaches to understanding transport in hydraulic fracturing. Glass/silicon micro/nanofluidic chips are developed for direct
visualization of hydrocarbons and hydraulic fracturing fluid transport, capillary trapping and proppant delivery in hydraulic fracture networks. Understanding
the transport dynamics in the micro and nano-scale flow paths has significant impact on optimization of hydraulic fracturing design and well performance.
However, direct visualization of transport dynamics in conventional core flooding experiments is not possible. The micro/nanofabrication techniques can
fabricate micro/nanochannels networks on a silicon substrate to mimic hydraulic fracture networks in shale, and covering the substrate with transparent
glass enables direct visualization of transport dynamics in the fractures in real time. The transport dynamics of hydraulic fracturing fluids and proppants
delivery as well as the interactions between hydrocarbons and injection fluids (brine, polymers, surfactants, etc.) in different fracture geometries under
reservoir conditions (pressure, temperature, surface wettability, etc.) are investigated.
These approaches offer unique insight through direct visualization of the porescale processes under reservoir-relevant conditions. They quantify for the
first time the dependence of the transport of hydraulic fracturing fluids and hydrocarbons, capillary trapping and proppants delivery on the fracture
complexity, so as to optimize fracture design for higher hydrocarbon recovery in shale.
11
Jason Riordon
David Sinton
(Toronto)
Microfluidics
On-chip visualization of microbial enhanced oil recovery mechanisms. A full two-thirds of known petroleum reserves remain unrecoverable using
conventional methods. The solution to extracting the remainder of this valued resource may very well come from nature itself. Microbial enhanced oil
recovery (MEOR) is an unconventional recovery technique whereby the in-situ growth of selected microbes native to oil reservoirs are given a boost
through nutrient injection. In turn, bacteria liberate oil by mechanisms including interfacial tension reduction, bioclogging and viscosity reduction. While
field trials have been promising, deciphering the relative impact of each of these recovery mechanisms has been challenging. Micromodels provide an
opportunity to visualize bacterial activity, while maintaining growth conditions typical of deep underground reservoirs. In this work, we apply cell labeling
techniques and fluorescence/confocal microscopy to track the bioactivity of cells within porous media during the recovery process, and shed light on
previously obscure processes.
12
Md
Almostasim
Mahmud
Brendan D.
Microfluidics
MacDonald (UOIT)
Cooling is of critical importance for a number of fields, particularly in microelectronic devices and other miniaturized technology. Current cooling
technology requires refrigerants that are harmful to the environment and is not keeping pace with the rapidly expanding technologies and their cooling
demands. Nature provides an example of an efficient cooling strategy through perspiration, whereby sessile droplets evaporate to provide cooling in
situations with high heat removal requirements. Evaporation is a very efficient form of heat transfer since a large amount of heat is removed from the
system as the liquid water changes phase to a vapour. We investigate the influence of interfacial phenomena at the surface where the phase change is
taking place, since it has been found to have a significant impact on the evaporation rates, and these phenomena become more important as the
technology decreases in size to the micro- and nano-scales. Understanding how to increase evaporatio n rates by controlling surface effects, such as
surface tension-driven flow within droplets, will lead to the development of efficient evaporative cooling techniques.
David Sinton
(Toronto)
Microfluidics
This poster reports a liquid crystal display (LCD) based multiplexed microfluidic cell culture platform for studying the role of illumination on the growth of
photosynthetic cells. This platform is capable of irradiating cells with different light intensities, spectral compositions and duty cycles. Control over spectral
composition and operating at sub-second duty cycles are important capabilities not present in previous microfluidic cell culture platforms for photosynthetic
cells.
13
Percival
Graham
14
Kaustubh Basu
Nanofemtolab
(INRS)
Nanocrystals and
Performance enhancement of Dye Sensitized Solar Cells with TiCl4 and TiOx precursor solution treatment of SnO2 Photoanodes. Over the last two
Semiconductors for decades, Dye Sensitized Solar Cell (DSSC) has been emerging as an alternative to conventional silicon photovoltaic devices because of its low cost,
abundant raw material, facile fabrication process, efficient photovoltaic performance and stability. For becoming a potential candidate to replace traditional
Solar Devices
solar cells, DSSC has to undergo a lot of challenges in enhancing the device performance, one of the key role, for which, is being played by the
photoanode material. We investigate the performance of DSSC fabricated with pre-treatment with TiCl4 and TiOx precursor solution separately to form a
blocking layer between the FTO layer and electrolyte to inhibit electron recombination from FTO to the elctrolyte and post treat our SnO2 photoanodes with
both TiCl4 and TiOx precursor solution separately so as to passivate the SnO2 anode layer with titania layer and reduce recombination from the
photoanode to the electrolyte. The pre-treatment and post treatment of SnO2 as a photoanode can improve the Voc, which is necessary since the
conduction band minima of SnO2 is located below that of TiO2 and in turn decides a low Voc in SnO2 anode DSSC. The crystallinity of the nanoparticles,
pre and post treatment of photoanode influence the functional properties of the solar cells, and call for optimization of the photoanode to maximize the
photo conversion efficiency.
15
Lisa Kozycz
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
The field of organic photovoltaics has seen a tremendous amount of progress over the last decade, largely due to the rational design of new donor and
acceptor materials. Two parameters that define the overall device efficiency are (1) the open-circuit voltage (Voc) – related to the energy offset between the
HOMO of the donor and LUMO of the acceptor, and (2) the short-circuit current (Jsc) – related to the light-absorbing properties and optical bandgap of the
light-absorbing materials. We present three distinct copolymer systems, including both n-type and p-type materials, that have been rationally designed to
maximize both the Voc and Jsc through the control of the polymer energy levels and absorbance spectra. These copolymers contain multiple
chromophores that absorb different wavelengths of the solar spectrum and we demonstrate how varying the monomer composition and polymer
architecture (eg. block versus statistical) affects polymer properties and device performance. Examples presented include diblock and statistical
copolymers containing the benchmark 3-hexylthiophene unit and a 3-thiohexylthiophene monomer possessing a deep HOMO energy. When used as
donor materials in solar cell devices, we measure Voc values as high as the highest Voc of the pure poly(3-thiohexylthiophene) device down to minimum of
just 15% incorporation of the 3-thiohexylthiophene monomer. This is the first example of an upper limit Voc being reached when any amount of the second
component is present. We also present a series of one donor-two acceptor copolymers containing perylene diimide (PDI), naphthalene diimide (NDI) and
carbazole units with various amounts of the two acceptors. These n-type copolymers are potential alternatives to fullerene-based acceptor materials and
due to their strong absorption of visible light they have the potential to contribute to light harvesting and current generation when used as acceptors in
photovoltaic devices.
16
Andrew Tilley
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
Enhancing the Light-Harvesting and Charge Transport Properties of Perylene Diimide by Sulfur Atom Substitution. The ability of plants and select bacteria
to convert sunlight into chemical energy represents one of the most remarkable photophysical processes in nature. In the aim of developing synthetic
mimics of the photosynthetic reaction centre, the development of new compounds capable of strong light absorption and efficient charge transport is
required. To this end, perylene diimides (PDIs) are an attractive target as their optical and charge transport properties can be altered by chemical
modification of the perylene core and imide nitrogens. In this poster the synthesis, ultrafast photophysics and semiconducting properties of a series of
sulfur-substituted (thionated) PDIs will be presented. As the degree of thionation increases, the electron affinity is increased resulting in a narrowing of the
optical band gap and systematic red shift in optical absorption. Interestingly, thionation renders the PDIs completely non-emissive which is due to subpicosecond intersystem crossing to triplet states, as determined by ultrafast pump-probe spectroscopy. Solid state optical absorption spectra of the PDIs
suggest an increase in molecular H-aggregation as the degree of thionation is increased. Bottom gate, bottom contact organic field effect transistors
employing the PDIs show an increased electron mobility proportional to the degree of sulfur atom substitution, leading to a mobility of 0.18 cm2 v-1 s-1 in
pristine films of the fully thionated analogue. AFM and 2D XRD experiments are used to explain this trend. These result s demonstrate the potential of
thionation to enhance optoelectronic and materials properties of PDIs, opening up possible pathways for the utilization of PDIs in artificial photosynthetic
arrays.
17
Elisa Carrera
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
The group 16 metalloid tellurium offers unique chemical properties and reactivity that sets tellurium-containing compounds apart from their lighter
chalcogen analogs. Organotellurium compounds are known to undergo reversible oxidative addition, a property that has allowed for their use as catalysts
for organic transformations. Tellurophene, the tellurium analog of the well studied sulfur-containing heterocycle, thiophene, is of interest as a material for
organic electronics because of its optoelectronic properties, however, the reactivity at the tellurium center has not been extensively studied. We are
particularly interested in using visible light to drive reactions at the tellurium center of conjugated tellurophenes. We have synthesized a small molecule
conjugated tellurophene flanked with isoindigo units, a strong light absorbing dye, to give 2,5-bis[5-(N,N′-dihexylisoindigo)]tellurophene. The reversibility of
oxidative addition reactions with halogens through therma l- and light-driven activation was studied. Bromine and chlorine add across the tellurium atom of
the tellurophene and these compounds undergo thermal reductive elimination of halogens in the solid state. More importantly, low energy light-driven
reductive elimination occurs in solution in the presence of a halogen trap with quantum efficiencies around 0.2%. This is the first example of
photoreductive elimination of halogens from a mononuclear organotellurium compound. The electronic properties of the tellurophene can be tuned by
changing the flanking substituents in order to improve the photochemical reactivity. This is currently being studied and will also be presented here. By
replacing the isoindigo units with phenyl rings, we are able to achieve photochemical quantum efficiencies up to 17%.
18
Anjan Mahrok
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
Platinum acetylide oligomers and polymers have attracted attention in molecular electronics due to their interesting photophysical properties. Platinum has
a large spin-orbit coupling constant which allows for efficient intersystem crossing, leading to high triplet yields and efficient phosphorescence.
Consequently, these materials are particularly interesting for fundamental studies focused on triplet state and phosphorescence in oligomers and
polymers, with possible applications as materials for organic light-emitting diodes. We have synthesized novel platinum-acetylides chalcogenophenes
copolymers, specifically platinum-acetylide thiophene, selenophene and tellurophene polymers. The polymers have been characterized using 1H and 31P
NMR, GPC and TGA. The polymers exhibit fluorescence and phosphorescence, which is affected by the heavy atom substitution. Unexpectedly, the
tellurium analogue shows quenched phosphorescence. To gain insight into the absorbed photophysical properties, the electronic structure of the polymers
was studied using density functional theory (DFT) calculations. Decreased planarity in the optimized structure of the heavier analogues may contribute to
the observed decrease in phosphorescence.
19
Dong Gao
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
The rapid development of polymer solar cell technologies has lead to the implementation of multi-chromophore polymer structures, such as donoracceptor, block, or statistical polymers that provide better energy-gap tuning ability or spectrum coverage, but also make controlling morphology more
complicated. We compare the morphology and solar cell device performance of selenophene-thiophene copolymers that have the same degree of
polymerization and composition, and differ only in their sequence (statistical vs. block copolymers). P3HS-b-P3HT spontaneously undergoes phase
separation and P3HS-s-P3HT does not. P3HS-b-P3HT performs best when the intrinsic self-assembled nanostructure is the most perturbed. P3HS-sP3HT does not undergo intrinsic phase separation, and vapor annealing can be used to optimize the polymer:fullerene morphology, where better
nanostructure is well correlated with the best device. While the block structure provides the best stability, the statistical struct ure is a valuable method to
balance the advantage of different monomers while precluding large-scale polymer self-assembly that is a strong intrinsic property of block structure.
20
Adam Pollit
Dwight Seferos
(Toronto)
Organic Solar and
light emitting
We report the synthesis of a series of dithienosilole–benzotriazole donor–acceptor statistical copolymers with various donor–acceptor ratios, prepared by
Kumada catalyst transfer polymerization. Statistical copolymer structure is verified by 1H NMR and optical absorption spectroscopy, and supported by
DFT calculations. The copolymers exhibit a single optical absorption band that lies between dithienosilole and benzotriazole homopolymers, which shifts
with varying donor–acceptor content. A chain extension experiment using a partially consumed benzotriazole solution as a macroinitiator followed by
addition of dithienosilole leads to a gradient copolymer, demonstrating that both chain-extension and simultaneous monomer incorporation are possible
using this methodology.
Greg Scholes
(Toronto)
Organic Solar and
light emitting
Singlet fission is a photophysical phenomenon that has the potential to boost the performance of organic photovoltaic devices. A simplified description of
the process invokes an intermediate correlated triplet pair with overall singlet character that evolves from the initially photoexcited singlet. While it is
generally accepted that formation of the correlated triplet pair in polyacenes proceeds through a direct, single-step mechanism where intermediate chargetransfer states are not populated, some uncertainty remains regarding the role of virtual charge-transfer states in this process. Here, we investigate the
mechanism of singlet fission in nanoparticle dispersions of several pentacene derivatives. We find that pentacene derivatives are versatile singlet fission
chromophores capable of undergoing singlet fission even in the presence of extensive local and long-range structural disorder. In relatively disordered
nanoparticles comprised of weakly coupled chromophores, for e xample, we observe singlet fission limited by energy transfer to active sites where singlet
fission occurs. In contrast, we observe more extensive and rapid singlet fission in nanoparticles consisting of excitonically shifted chromophores exhibiting
stronger coupling. We present direct experimental evidence indicating that extensive long-range order, coincident with an increasingly delocalized exciton
exhibiting more charge-transfer character, leads to even higher singlet fission rates. These results suggest that the increased charge-transfer character of
the primary photoexcitation facilitates more rapid triplet formation in the case of “direct” singlet fission. This work represents a significant step toward
understanding how simple structural modifications affect singlet fission photophysics and provides scope for the development of new pentacene
derivatives for singlet fission.
21
Ryan Pensack
22
Tham Adhikari Jean-Michel Nunzi Organic Solar and
(Queen's)
light emitting
Perylene-3, 4, 9, 10-tetracarboxylic acid diimides and their derivatives are promising candidates as electron acceptors in polymer solar cells due to their
outstanding physical and chemical properties such as high chemical and thermal stability, high absorption range (400-700nm) and high charge mobility.
The introduction of bulky substituent molecular glass at the bay position of PDI molecule disturbs the planarity of the PDI core and reduces the
segregation of PDI. The bulk heterojunction solar cells of PDI-glass with donor polymer were made and the photovoltaic parameters (current density, fill
factor and efficiency) were studied.
23
Jin Young Kim
(KIST)
Organic Solar and
light emitting
We report a series of semi-crystalline, low band gap (LBG) polymers and demonstrate the fabrication of highly efficient polymer solar cells (PSCs) in a
thick single-cell architecture. The devices achieve power conversion efficiency (PCE) of over 7% without any post treatment (annealing, solvent additive,
etc.) and outstanding long-term thermal stability for 200 h at 130 °C. These excellent characteristics are closely related to the molecular structures where
intra- and/or intermolecular noncovalent hydrogen bonds and dipole-dipole interactions assure strong interchain interactions without losing solution
processability. The semi-crystalline polymers form a well-distributed nano-fibrillar networked morphology with PC70BM with balanced hole and electron
mobilities (h/e mobility ratio of 1~2) and tight interchain packing (π-π stacking distance of 3.57-3.59 Å) in the blend films. Furthermore, the device
optimization with a processing additive and methanol treatment improves e fficiencies up to 9.39% in a ~300 nm thick conventional single-cell device
structure. The thick active layer in the PPDT2FBT:PC70BM device attenuates incident light almost completely without damages in fill factor (0.71~0.73),
showing a high short-circuit current density of 15.7~16.3 mA•cm-2. Notably, PPDT2FBT showed negligible changes in the carrier mobility even at ~ 1 µm
film thickness.
24
Victoria Davis
UOIT
Organic Solar and
light emitting
Investigation of Dye-Sensitized Solar Cell Performance with Single Chirality Semiconducting Carbon Nanotubes. In this work, the performance, electrical
transport, and optical properties of dye-sensitized solar cells (DSSCs) assembled with single-walled carbon nanotubes (SWNTs) of a single chirality in the
photoanode were investigated. Single-chirality carbon nanotubes (CNTs) allow a selection of band-gap and electron mobility. Separating a specific chirality
from a mixture of carbon nanotubes remains a challenging task. Among separation techniques, one of the most promising is size-exclusion gel
chromatography. Although SWNTs separated by this technique has been applied in bulk heterojunction solar cells and other basic electronics, no one has
attempted to use this material in DSSCs. Single-chirality carbon nanotubes allow for adjustment Schottky barrier height at the TiO2/CNT/FTO interface
and the presence of single-chirality bundles increases electron diffusion in the photoanode. Furthermore, chirality separated CNTs are expected to absorb
less light than mixed chirality CNTs which results in better light absorption and electron injection into the TiO2. Chiralities (6,5) and (7,3) have been
separated using this technique and compared with mixed chiralities in a DSSC. Characterization includes I-V curves (performed in dark and light),
quantum efficiency, and impedance spectroscopy.
25
Daniele Benetti
26
Michael Saliba
27
Wissal Alayashi
28
29
Organic Solar and
light emitting
Dye sensitized solar cells (DSSCs) represent a viable low-cost alternative to conventional photovoltaic devices. An important tool for the interpretation of
the different photoelectron transfer processes occurring in a DSSC is the Electrochemical Impedance Spectroscopy (EIS) analysis. Here we present a
case study, in which EIS is applied to investigate the effect of addition of functionalized CNTs into TiO2 mesoporous thick films on photoconversion
efficiency of DSSCs. Introduction of CNTs into TiO2 mesoporous film increases electron collection and reduces charge recombination. Optimized device
increased the short-circuit photocurrent (Jsc ) and the photoconversion efficiency by 30% and 32%, respectively, compared to bare TiO2 cell, up to
maximum efficiency of 7.95%. We measured the two most relevant parameters describing the photoelectron transfer processes in a photoelectrochemical
system, i.e. the chemical capacitance (Cµ) and the recombination resistance (Rrec) as a function of the applied bias, to understand the role of CNTs at
the different interfaces. The results show a reduced charge recombination in the best cell, clearly identifying the physic-chemical mechanism behind the
increase of photoconversion efficiency
Photovoltaic and Organic Solar and
Optoelectronic light emitting
Device Group,
Oxford University
Film Formation in Perovskite Solar Cells Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar
cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and scanning electron microscopy to investigate the structural
evolution and film morphologies of methylammonium lead mixed halide perovskite during thermal annealing. We show that the material evolution can be
characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of
compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal
perovskite film morphology and coverage. We investigated the photovoltaic device performance with planar heterojunction architectures under different
annealing conditions. We observed that a short rapid thermal annealing at 130 °C leads to the growth of large micron-sized textured perovskite domains
and improved short circuit currents and power conversion efficiencies up to 13.5% for planar heterojunction perovskite solar cells. This work highlights the
criticality of controlling the thin film crystallization mechanism of hybrid perovskite materials and offers a simple pathway for further enhancements in
perovskite solar cells.
Nanofemtolab
(INRS)
Kevin Robbie
(Queen's)
Organic Solar and
light emitting
Branched hierarchical photoanode of titanium dioxide for enhanced performance dye-sensitized solar cells. In this study, anatase branched morphology
TiO2 films on fluorine-doped tin oxide (FTO) substrates are fabricated using a high vacuum physical vapour deposition called Glancing Angle Deposition
(GLAD). The TiO2 films consist of vertically oriented columns with tree-like branches. These fractal TiO2 films are excellent candidates as photoanodes,
capable of exhibiting improved light harvesting efficiency in dye sensitized solar cells (DSSCs)[2]. TiO2 films were characterized by scanning electron
microscopey (SEM) and x-ray diffraction (XRD). The properties of DSSCs were investigated with current-voltage measurements (I-V). DSSCs were
assembled using N719 dye as sensitizer and I−/I3− as an electrolyte. TiO2 films with a thickness ranging from 1 µm to 2.5 µm exhibit power conversion
efficiency of DSSC of 0.5% to 1.6%, respectively. The enhancement in efficiency and thus in short-circuit current density (JSC) are mainly attributed to
the significant enhancement in light scattering and the increase in the specific surface area for dye adsorption to the hierarchical structure of the films by
increasing the thickness.
Carmen
Nguyen
Zheng-Hong Lu
(Toronto)
Organic Solar and
light emitting
We study the effects of incorporating phosphorescent sensitizers into fluorescent organic-light emitting diode (OLED) devices. In the emissive layer of this
system, the host material is co-doped at low concentrations with both a phosphorescent and a fluorescent dye. Ideally, the purpose of the phosphorescent
dopant is to capture both singlet and triplet excitons from the host material and to transfer them into the singlet state of the fluorescent dye. Recombination
of excitons and the emission of light would occur solely on the fluorescent dye. This sensitized fluorescent system could potentially achieve 100% internal
quantum efficiency as both triplet and singlet states are being harvested. We have observed an almost two-fold improvement in the quantum efficiency of
a sensitized fluorescent system, utilizing rubrene as the fluorescent dye and Ir(ppy)2(acac) as the sensitizer, versus a standard rubrene-based host-guest
system. By testing various dopant concentrations, the opt imal emissive layer composition for this system was determine to be ~2 wt.% rubrene and ~7
wt.% Ir(ppy)2(acac) in a CBP host. Other sensitized fluorescent systems are also being investigated to achieve a host-sensitizer-fluorescent dye
combination that best realizes the ideal sensitized fluorescent mechanism. This system would exhibit efficiency Forster energy transfer of triplet states
from the phosphorescent sensitizer to the singlet state of the fluorescent dye while minimizing undesirable effects such as direct exciton formation on the
fluorescent dopant.
Grayson
Ingram
Zheng-Hong Lu
(Toronto)
Organic Solar and
light emitting
An exciton-stimulated molecular transformation in an organic light-emitting diode (OLED) on a time scale of a few seconds under electrical bias is shown
to reach nearly 100% under standard operating conditions, leading to color switching. It is reversible in both a thin film and an OLED when sufficient
thermal energy is supplied. Such an exciton-stimulated molecular transformation suggests a new process which may be exploited for applications such as
electrochromic and memory devices.
30
Taylor Stock
Jun Nogami
(Toronto)
Organic Solar and
light emitting
Pure Copper Phthalocyanine (CuPc) and pure Fullerene (C60) thin films grown via room temperature vapor deposition tend to be polycrystalline with 3D
island surface morphologies. When these two molecules are co-deposited to form a mixed film however, a drastic change is observed in the film structure
and morphology. Mixed films with greater than 5wt.% C60 content are found to be amorphous with a flat, featureless surface.We have investigated the
growth of CuPc:C60 mixed films using scanning electron microscopy (SEM), x-ray diffraction (XRD) and scanning tunneling microscopy (STM) and have
understood the structural and morphological changes in terms of the relative strengths of the various intermolecular interactions at play. This work is of
particular relevance for small molecule bulk heterojunction (BHJ)organic photovoltaics (OPV), for it is these same intermolecular forces which must be
controlled and balanced in order to produce mixed donor-acceptor films exhibiting the de sired BHJ nanoscale structures.
31
Yogesh Jeyara
m
David Sinton
(Toronto)
Organic Solar and
light emitting
Plasmon resonance energy transfer for enhanced photosynthesis. Plasmon resonances of metal nanoparticles provide us with a unique tool to manipulate
light at the nanometer scale, well below its free space wavelength. Recently, it has been shown that these metal nanostructures can be used to enhance
photosynthesis in microorganisms by improving light absorption [1] and by increasing optical path length [2]. In this work, we demonstrate how localized
surface plasmons in the near-field regime can also transfer energy resonantly through a plasmon resonance energy transfer mechanism, and increase
light absorption of chlorophyll molecule by 87%.
32
Emmanuel
Thibau
Zheng-Hong Lu
(Toronto)
Organic Solar and
light emitting
Photoelectron spectroscopy (PES) is a powerful characterization technique capable of determining chemical composition, bonding environment and
valence band electronic structure of certain material surfaces and interfaces. Here, we have examined interface formation processes of Molybdenum
trioxide, MoO3, deposited on eight common hole transport organic materials. By utilizing an inverted device deposition order, where the transition metal
oxide (TMO) is deposited on top of the organic semiconductor, as used in organic photovoltaic devices (OPVs) as well as inverted organic light emitting
diodes (OLEDs), a full description of the physical and electronic interaction is resolved by PES. Significant band bending by way of charge transfer from
organic to MoO3 and diffusion into the underlying organic film is observed. The Universal energy-level alignment rule is shown to be consistent even under
inverted deposition order, indicating the significant role between TMO and organic semi conductor to form charge transfer species.
33
David Josey
Tim Bender
(Toronto)
Organic Solar and
light emitting
In one hour, more energy from the sun reaches the surface of the earth than is required to satisfy the world’s energy demands for an entire year. Nature
already uses solar energy extensively, with many organisms relying on the sun’s energy to survive. Organic solar cells (OSCs) are a promising approach
to follow nature’s lead, with the potential to produce inexpensive, electrical energy directly from the sun. OSCs consist of multiple layers of organic
semiconductor materials, with the performance dependent on how well these layers work together to convert light into electricity. The layers of an OSC
can be deposited by two techniques: solution casting and thermal evaporation, each with its own benefits. The two techniques are generally not combined
due to the increased level of complexity. We have demonstrated the capability to replicate baselines from literature, using thermally-evaporated fullerene
(C60) paired with poly(3-hexylthiophene-2,5-diyl) as the solution-cast device and comparing it to thermally-evaporated C60 paired with thermallyevaporated sexithiophene. This opens up opportunities for new combinations between solution-cast materials with thermally-evaporated materials to
ultimately achieve better solar cells.
34
Yin Song
Greg Scholes
(Toronto)
Organic Solar and
light emitting
The conversion of photoexcitations into charge carriers in organic solar cells is facilitated by the dissociation of excitons at the donor/acceptor interface.
The ultrafast timescale of charge separation demands sophisticated theoretical models and raises questions about the role of coherence in the chargetransfer mechanism. Here we apply two-dimensional electronic spectroscopy (2D ES) to study the electron transfer process in poly(3hexylthiophene)/PCBM (P3HT/PCBM) blends. We report dynamics maps showing the pathways of charge transfer that clearly expose the significance of
hot electron transfer. During this ultrafast electron transfer, vibrational coherence is directly transferred from the P3HT exciton to the P3HT hole polaron in
the crystalline domain. This result reveals that the exciton converts to a hole with a similar spatial extent on a time scale far exceeding other photophysical
dynamics including vibrational relaxation.
35
Peter Schnurr
36
Hao Lin
37
Yuxuan Cai
38
Moein
Shayegannia
Grant Allen
(Toronto)
Kalai
Saravanamuttu
(McMaster)
Bio synthesis of
chemicals and
energy
Nanocrystals and
Multidirectional Polymer Waveguide Lattices (MWGLs): An Artificial Eye with a Large Field of View (FOV). There are two types of natural compound
Semiconductors for eyes: apposition compound eyes and superposition compound eyes. The former mainly exist in diurnal insects such as flies, bees and dragon flies, while
the latter are primarily found in nocturnal insects, for instance, fireflies, noctuid moths, etc. Although lacking in spatial resolution, as compared to single
Solar Devices
aperture eyes, these eyes always possess large field of view (FOV) and extra functionalities such as polarization sensitivity and fast movement detection.
These advantages of natural compound eyes has inspired several artificial structure. Herein, it is shown that an artificial compound eye with planar
geometry and a large FOV can be achieved using self-written waveguide lattices. Specifically, a quintet intersecting polymer waveguide lattices (q-WGLs)
embedded structure was employed, which was fabricated by launching five collimated white incandescent beams orientated respectively at −44°, −22°, 0°,
22° and 44° onto a common entrance face of a planar sample cell containing an epoxide-based photopolymerizable medium. The q-MWGL was
characterized through optical microscopy and careful beam-profiling measurements. Optical microscopy clearly revealed that the structure comprised five
intersecting WGLs oriented at −30°, −15°, 0°, 15° and 30°, with respect to the surface normal of the sample cell. Analysis of the spatial intensity
distribution of light coupled into the q-WGL confirmed that light propagated as waveguided-modes within the lattices. Significantly, It was found that
waveguides within the structure efficiently collected light over a large angular range, and an approximately 70% increase in the FOV was achieved, as
compared to the unstructured medium. Associated with the results of Beam Propagation simulation, the refractive index difference between the core and
cladding of individual WGs was found to be approximately ∆n = 0.001. This WGLs embedded structure has potential application in wide-FOV imaging,
wide-angled displays and wide-incident-light collection for photovoltaic (PV) cells. The planar geometry makes these systems amenable to thin-film device
fabrication, which can significantly reduce device sizes.
Javad Mostaghimi Renewable Energy
and Tom Coyle Sources
(Toronto)
Nazir Kherani
(Toronto)
Producing valuable biochemicals, including biofuels, from algae growth systems shows great promise because of algae’s rapid growth rates and high
concentrations of these biocompounds. Currently, however, a major limitation to the commercialization of these technologies is in the harvesting and dewatering of (dilute) algae biomass grown planktonically. Growing algae as a biofilm may offer potential harvesting and de-watering advantages because it
is approximately 100 times more concentrated (and immobilized) compared to planktonic algae biomass. Today, there has been a very limited amount of
research conducted on growing algae biofilms for biofuel and biochemical production. Our group focuses on understanding the key factors that influence
algae biofilm growth rates and their internal biocompound concentrations, and on algae biofilm bioreactor design and operation. These key growth factors
include light direction and intensity irradiating the biofilms, bulk growth med ium carbon dioxide concentrations, and growth surface material properties.
Additionally, we have developed a flow cytometry technique capable of differentiating and quantifying mixed communities of suspended algae and bacteria
cells.
In the past decade, mimicking hydrophobic surfaces from nature has gained extensive interest due to its potential to benefit the environment through
energy conservation. Very recently, surfaces of rare earth oxides (REO) have been shown to be inherently hydrophobic due to their electron configuration.
This work presents the first REO hydrophobic surfaces fabricated by using the plasma spraying technique. The coating formation mechanisms lead to
nano- and submicron-structured coatings. This type of structured surface is very desirable in fabricating hydrophobic surfaces since it captures the
essence of self-cleaning leaves and wings in nature. The contact angle measured on the as-sprayed surface is higher than 140°. The surface and cross
section microstructures are characterized using scanning electron microscopy.
Photovoltaics and Light Localization Using Adiabatic Tuning of Intra-groove Plasmon Coupling. In this poster we present the introduction of intragroove widths as a new
Devices
adiabatic tunable dimension in a grating structure. Smooth tapering of this dimension below 150 nm yields a gradient in effective refractive index across a
grating, which in turn controls propagation and trapping of radiation. Analytical modeling shows that varying the width of a cavity across the grating causes
a small number of the grooves to be at resonance with the incident radiation, while the off-resonant grooves guide the wave on top. This basic property
leads to the emergence of a landscape of light localization sub-wavelength structure with practical implications as a wavelength tunable infrared filter
amenable for sensing and imaging applications.
39
Hui-Lin Hsu
Nazir Kherani
(Toronto)
Photovoltaics and Rare-Earth Doped Amorphous Carbon Based Photonic Materials. The integration of photonic materials into CMOS processing requires the development
Devices
of new materials. In this poster, we explore the development of rare-earth doped amorphous carbon (a-C(X), X= Er or Yb) thin films as a potential photonic
material for direct integration with Si CMOS back end-of-line processing. The rare-earth doped amorphous carbon films were grown on Si substrates at
low temperatures (<200 °C) by a simple one-step radio frequency plasma-enhanced metalorganic chemical vapor deposition technique (RF-PEMOCVD)
technique. Prior to the synthesis of a-C(X) films, we show that a-C host films with wider optical bandgap and lower percentage of sp2 carbon bonding are
obtained on the anode. Doped amorphous carbon films were synthesized using partially fluorinated metalorganic compound, X(fod)3. Six-fold and four-fold
enhancement of room temperature photoluminescence in Er and Yb doped films, respectively, were demonstrated by deuteration of the a-C host. The
observed wide full width at half-maximum PL signal is a result of the variety of local bonding environments prevalent in the a-C matrix, and the bonding of
the Yb3+ ions to O and/or F ions as determined by X-ray photoelectron spectroscopy analyses. This technique provides the capability of doping X in a
vertically uniform profile or a designer defined concentration profile.
40
J. Kenji Clark
Nazir Kherani
(Toronto)
Photovoltaics and Diamond Like Carbon Based Spectrally Selective Coatings. Heat gain through the absorption of solar radiation transmitted through the glass of windows
is a major cause of inefficiencies in modern HVAC systems. The use of solar control coatings that reflect only the unwanted infrared portion of this
Devices
radiation have become relatively common yet have not achieved widespread market entry due to high material costs. Here we introduce a novel solar
control coating (also known as spectrally selective coating) based on low-cost diamond-like carbon. We demonstrate here a solar control coating with a
visible transmittance of 75% and a solar heat gain coefficient of 46% - metrics which are comparable or better than the industry state of the art. Diamondlike carbon has the potential of becoming a novel plasmonic platform material for building and allied thermal energy control applications.
41
Xiang Meng
Huang
Grant Allen
(Toronto)
42
Hamidreza
Fayaz
Movahed
Ted Sargent
(Toronto)
Bio synthesis of
chemicals and
energy
The pulp and paper industry produces large quantities of solid waste from the effluent of the wastewater treatment systems. The solid waste, or biosludge,
is typically burnt for energy recovery or disposed in landfills. Anaerobic digestion is the process of using microorganisms that can digest organic matter in
the absence of oxygen and convert them into biogas. The production of biogas from biosludge will allow the mills to use the gas for efficient energy
recovery, which will translate into economic savings. The anaerobic digestion process will also produce less solid waste that has to be dealt with. Thermal
pretreatment of biosludge has been shown to benefit anaerobic digestibility by solubilizing recalcitrant material. The objective of this study is to examine
the feasibility of thermally treating the digestate from an anaerobic digester and then re-injecting the treated digestate back to the digester for further
digestion. Since the digestate will contain more recalcitra nt material, it should be more efficient to treat the digestate instead of the raw biosludge. A 10L
pilot scale anaerobic digester as well as a 500mL thermal treatment reactor is used in the current study. Intermittent thermal treatment was performed on
the digestate, where roughly 20% of the reactor volume was treated once the biogas production slowed, and an overall biogas yield was observed. The
specific methane yield was approximately 110mL/g COD added in the intermittent thermal treatment experiment and 70mL/g COD added in the control
experiment with no thermal treatment.
Nanocrystals and Highly Stable Large CQD Based Thermophotovoltaic Device. Colloidal quantum dots (CQDs) combine low-cost, large-area, and light weight solutionSemiconductors for processing with quantum size effect tuning, offering a route for harnessing the abundant energy of infrared emission provided by different sources such
as industrial waste heat. Thus, thermophotovoltaic (TPV) devices made of CQDs have significant promise for efficient and economically viable power
Solar Devices
systems. However, thermal and temporal stability is a major concern in the design of TPV devices that are supposed to maintain their performances at
high temperatures. Here we report thermophotovoltaic devices constructed using layers of differently treated large PbS CQDs in a unique architecture
providing high thermal stability and extended lifetimes as well as being optimized for photovoltaic power conversion in infrared region. These TPV devices
are fabricated in ambient air which hugely favours the commercially compelling aspect. A stable power conversion efficiency of more than 5% using an
800 C black-body radiation source is achieved while the device itself is sustaining a temperature of 150 C. Mechanical stability and extended life time of
these devices together with high thermal stability in performance make them a promising step in CQD based TPV devices.