FY2010 - Oak Ridge National Laboratory

Director’s R&D Fund—
Science for Extreme Environment: Advanced Materials and Interfacial Processes for Energy
(acceptors) and semiconducting polymers (donors) that make up the photoactive layer of a PV cell. This
project addresses major needs in the fundamental design of photoactive layers and integrates expertise in
computation, scattering, spectroscopy, and polymer science and physics to address challenging problems
in soft and hybrid materials for energy conversion technologies.
Mission Relevance
Driven by the need for energy security and reinforced by the need for a cleaner environment, technologies
that harness renewable energy sources are receiving increased interest. In this regard, the development
and deployment of large-area, low-cost, and efficient PV systems is of considerable importance and
wholly consistent with Laboratory and DOE Office of Science missions. Through this research program,
barrier issues in polymer-based PV systems are being addressed, existing capabilities across the
Laboratory in computational, neutron, and soft matter sciences are being integrated, and new capabilities
in these areas are also being developed. The interdisciplinary research team developed here will be well
positioned to respond to future, anticipated calls in the area of materials for energy conversion
technologies (solar, battery, etc.).
Results and Accomplishments
A variety of accomplishments related to understanding morphology development and excitonic processes
and improving charge transport in PV systetms based on conjugated polymers and nanoparticles,
including both SQDs and fullerene-based derivatives, have been attained during the first year of activity.
For example, new capabilities in the synthesis of well-defined conjugated polymers with appropriate
chain-end functionality have been developed, and a new block copolymer-based compatibilizer approach
has been used to optimize the nanoscale morphology of donor-acceptor blends. Insight into the
thermodynamic origin of the ability of the block copolymer compatibilizer to tune morphology has been
gained using computational methods. The photophysics of oligomeric para-phenylenes (OPPs) was
investigated using large-scale quantum density functional calculations, and simple models were used to
determine what level of theory is needed to understand the photophysics of OPPs. Results from
computation were compared to measured optical absorbances of OPPs in thin film form and end-tethered
poly(para-phenylenes) that were used to compatibilize electrode-like surfaces. Finally, new capabilities in
spectroscopic imaging of donor-acceptor blends, light- and thermal-aging studies of PV blends, and
sample environments for carrying out neutron scattering studies have been developed. All of these
capabilities are being brought to bear in studies of structure-property relationships of donor-acceptor
blend systems.
05423
New Multinary Materials for Solar Energy Utilization
Michael A. McGuire, Gerald E. Jellison, Jr., David J. Singh, and Mao-Hua Du
Project Description
The goals of this work are to expand the frontiers of inorganic photovoltaics and our understanding of
fundamental physics and solid state chemistry of multinary semiconductors, and to use these advances to
develop new classes of complex materials with enhanced photovoltaic properties. We will achieve this by
using our combined expertise in materials synthesis, optical and photovoltaic measurements, and firstprinciples
calculations. State-of-the-art photovoltaic materials CdTe and CIGS (CuIn 1-x Ga x Se 2 ) have
relatively simple crystal structures, related to that of silicon. We will investigate more complex ternary
structure types as candidate photovoltaic materials. Increasing complexity often leads to discovery of
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