NIRT/GOALI: SELF ASSEMBLY AT ELECTRONIC AND PHOTONIC SCALES
S.M. Lindsay (PI) Hao Yan (Co-PI) Rudy Diaz (Co-PI) Devens Gust (Co-PI) Shreya Battacharyya, Ashley Kibel, Raul Chhabbra, Jas Sharma
Arizona State University, Tempe, AZ 85287
I.
Characterization
of
electron
transport through charge separation unit
MOLECULAR DYAD
STM Tip
(a)
(b)
Abstract
The optical absorption cross section of
molecules is so small that a layer many
thousands thick is required to absorb incident
sunlight, a severe obstacle to charge
extraction over such distances. We propose
to construct a ‘black monolayer’ using DNA
nanotechnology as a scaffold on which to
build photonic antennas that will enhance
optical absorption.
IV. DNA directed self-assembly of
metallic nanoparticles
(a)
(b)
(c)
Indium Tin Oxide
2.0
1000
Counts
1.8
Solvent : mesitylene
1.6
Conductance= 2.37 nS
1.4
= 3.06 X 10 -6 GO
600
0.95 nAmps
400
Current (namps)
(c)
800
Tip bias: +0.4 V
(d)
1.2
1.0
0.8
0.6
200
0.4
1.84 nAmps
0.2
0
0
1
2
Current (nAmps)
3
4
0.0
0.005
Time (s) 0.010
0.015
Figure (a): Schematic of attachment of charge separation unit
between the surface of the transparent conducting oxide
(Indium Tin Oxide) and the Gold STM tip. (b) The charge
separation unit, a “Molecular Dyad” with a donor/ chromophore
(porphyrin) and nearby acceptor (fullerene). (c) Current
histogram obtained from STM break-junction measurements
showing conductance of a single molecular dyad trapped
between surface and tip to be 2.3 nS. (d) Raw data for current
vs. time. “Constant current” steps occurs when a single
molecule trapped between surface and STM tip.
III. Theoretical calculations
Surface Plasmon
Resonances
II. Conducting atomic force microscopic
images of (a) FTO and (b) ITO
(a)
(b)
Ag
d
Ag
Antenna Mode
Figures showing the use of information guided DNA
self-assembly to organize the particles in proximal
distances thus rendering them capable of acting as
antenna molecules. (a) A cartoon showing the
organization of discrete number of Gold
nanoparticles (10 nm) on a fixed size DNA template.
The DNA template is generated by the nucleated
self-assembly process that utilizes a single stranded
viral genome as a nucleation site for self-assembly.
A set of ‘helper strands’, complementary to viral
genome, help folding the viral DNA into arbitrary
shapes, for example, a DNA tube in this context.
DNA tube is fully programmable due to the fact that
each ‘helper strand’ is addressed with a unique
sequence. (b) TEM images of the DNA tube
patterning discrete number of gold nanoparticles. (c)
TEM images of the nearly monodisperse (~25-27
nm) silver nanoparticles, to be used in the future
experiments. Silver nanoparticles interact with light
more than gold nanoparticles; thus will be an
attractive candidate for investigation of photonic
properties.
Acknowledgement
Supported by the National
Science Foundation
Conducting atomic force microscopy images of Fluorine Tin
Oxide (FTO) and Indium Tin Oxide (ITO). Topography images
are on the left sides and current images are on the right sides.
Transparent, conducting substrates, like FTO and ITO, are
necessary for the design of the solar cell in that they will allow
light to pass through to the monolayer. Conducting AFM gives
insight into the morphological and electrical properties of these
materials.
Computational evidence of a true photonic antenna
mode arising from the structural resonance of a
two-nanosphere plasmon antenna. Molecules
placed in the vicinity of such an antenna have
greatly enhanced Radiative Transfer Rate and
Absorption Cross Section.
0609362