Systematic Bottom-Up Assembly of Nanoscale
Photonic Materials
SFI Investigator Award 12/IA/1306
Overall Goals and Overview
This substantial and highly topical interdisciplinary Nanomaterials–NanophotonicsNanoelectronics project will present a systematic investigation of new versatile functional
Nanomaterials based on precise organised nanostructure formation of large dye and
Nanocarbon self-assemblies. Our clean approach is a new pathway to derive transformative
functionalities. Our "bottom-up" approach enables us to correlate the molecular arrangement
of the assembled nanostructures to their linear and nonlinear optical, optoelectronic and
charge transport properties. Our main research thrust of improving the efficiency of
conversion of light into electronic signals has immediate and direct implications on solar
energy conversion. With an estimated one third of the sun’s incident light detected on earth
beyond the 1 m wavelength range, the harvesting of incident irradiation in this region is of
crucial importance to current and future solar energy conversion efficiencies. Successful
implementation will pioneer a new kind of industrial development in cutting-edge
nanotechnology, opto/electronics and photonics, strengthening the competitive position of
Ireland in the global photonics and ICT sectors.
Research Aims and Significance
Nanocarbons, i.e. single-walled nanotube (SWNT) and graphene surfaces can mediate the
self-assembly of polymers, large conjugated organic and
organometallic, e.g. dye, molecules and small Nanocarbons, e.g.
Fullerene C60, C70 or C84 structures, on their surfaces. In this
manner it is possible to generate organised hybrid structures that
would not form in solution or free space. Such assemblies,
particularly in the case of supramolecular J-aggregates of dye
molecules, can possess wavelength tailorable, sharp optical
absorption bands and large optical cross sections so that they can photosensitise nanocarbon
devices with high selectivity and sensitivity. In addition, these aggregates can locally modify
the intrinsic electronic structure of the underlying nanocarbons and thereby generate locally
defined electronic structures which are not available in neat nanocarbon particles.
Ultimately, this research will lead towards all-Carbon heterojunction structures with precisely
controlled all-Carbon hybrid nanomaterial interfaces. Self-assembly of electron accepting
Fullerene and electron donating, e.g. large diameter semiconducting single-walled carbon (sSWNT) nanotube interfaces offer promising efficiencies for solar energy conversion
applications.
The following are fundamental scientific issues to solve while developing dye aggregatefunctionalized nanotube and graphene nonlinear optical and light harvesting devices:
 Structure of dye and small Nanocarbon aggregates on nanotube and graphene
surfaces.
 Impact of direct  interaction between smolecules and graphitic surfaces.
 Fundamental mechanism of photosensitisation of nanotubes and graphene sheets
using tailored dye aggregates, as measured by ultrafast nonlinear optical and
photoconduction responses.
 Fundamental mechanism of local modulation of nanotube and graphene electronic
structure through aggregate electric fields and polymerised aggregate pressure.
These results could have a broad impact on nanoscale carbon nanotube and graphene
photonics, as their well-defined and enhanced optical properties will open up new
applications in nonlinear optics, photodetection and opto/electronic transport. Particularly,
improving the capture efficiency of light by aggregates and subsequent translation of the
capture event into electronic signals is relevant for solar energy generation.
Project Structure
A schematic outline of the complete project concept and its potential industrial impact is
shown below.
Presently, little is known about basic physical processes governing such hybrid carbon
nanomaterials with heterogeneous energy levels and exciton binding energies. Under the
leadership of Prof Werner J Blau, an internationally well-known principal investigator, the
project will explore and understand the self-assembly and charge transfer of these nanoscale
heterostructures, predict and measure their structural and optical properties, and investigate
the properties and technological feasibility of the resulting nano-diodes and nanophotovoltaic devices.
The strongly anticipated success of the project is based on the demonstrated expertise of the
PI, augmented by several established and highly productive collaborations with specialist
colleagues who will be involved as official collaborators as follows:
•
Prof. Mathias Senge, TCD Chemistry – Synthesis of dye molecules with controlled
morphology and aggregation properties
•
Prof. Georg Duesberg, TCD Chemistry – Synthesis of structurally extremely well
defined Nanocarbon, especially graphenes
•
Prof. Valeria Nicolosi TCD Physics and Chemistry – High Resolution TEM Specialist
•
Dr. Mazhar Bari Solarprint Ltd. Dublin – Fabrication and Testing of Nanomaterials in
Practical Dye Doped Solar Cell Devices