Electronic structure of polymers for photovoltaic applications and strongly correlated electron systems

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This research program proposes the use of electronic structure methods to calculate the properties of novel materials. There are two main topics to this proposal: the first is polymers for photovoltaic applications and the other is strongly correlated electron materials such as the high-Tc and the newly discovered iron pnictides. Through method developments, we intend to better describe the properties of these materials such that calculations can be more useful in assisting experimental efforts. For polymers used in photovoltaic applications, the specific goals are to be able to accurately calculate the optical spectrum of proposed polymers in order to evaluate if their synthesis should be pursued. This will be done by improving the GW method to be able to apply it to polymeric systems. We will also be able to directly calculate the ionization potential and the electron affinity which will help to design the best combination in devices. Our ultimate goal will be to propose polymers that can help us reach 10% power conversion efficiency so that organic solar cells can be a real alternative to the present more expensive technology. For the strongly correlated electron materials, the goal is to develop functionals that include more correlations. These improvements will be tested by calculating the phonon properties to compare them to existing experimental data. Another test will be the comparison of experimentally measured de Haas-van Alphen frequencies with calculated ones which can be obtained from the morphology of the Fermi surface calculated.