Defects or dopants in solar cells can strongly affect optical properties and excitonic lifetime, which drastically change the efficiency of those solar cells. Current theoretical techniques for investigating these properties, such as the supercell approximation, are effective at simulating homogeneous systems, like pure crystals or periodically occurring defects. These calculations can correspond well to experiment in the limit of low defect concentration, but fail at higher concentrations. Since real systems do not have periodically distributed defects, new theoretical models are necessary to efficiently investigate realistic condensed matter systems. My research will focus on developing time dependent models for heterogeneous condensed matter systems to explicitly simulate exciton dynamics. Specifically, I will couple real-time time dependent density functional theory to more approximate, but more efficient, models such as X-Pol. I will apply these to vacancy defects in silicon as both a proof of concept (symmetric defects) and a case study (asymmetric defects).
Advisor: Xiaosong Li – Chemistry