Thin-film photovoltaics such as Cu(In,Ga)Se2 (CIGS) and CdTe are among the most promising solar cell technologies. We study these materials using computational materials methodologies, such as density functional theory (DFT), molecular dynamics (MD), kinetic lattice Monte Carlo (KLMC), and continuum-scale models. One of my primary goals is developing atomistic models of diffusion in these materials, for both native species and extrinsic dopants. Knowledge and control of diffusion is necessary for optimizing device performance, such as In/Ga interdiffusion in CIGS, which must be understood to spatially tune the bandgap. I use DFT to predict defect formation energies, defect complex binding, and defect migration barriers. These results then are used to devise rate expressions for defect migration, which are built into KLMC and continuum models. From this, we can model diffusion behavior and predict the diffusivity under variations in composition, temperature, and other conditions. In addition to diffusion, I look at questions such as carrier capture and phase segregation.
Advisor: Scott Dunham – Engineering & Computer Engineering