The role of defects in thin film solar cells explained using Density Functional Theory

Thin film solar cells are a competitive option for energy production with a number of companies expanding their capacity. Crucial to the optimum performance of the solar cells is the need to limit the number of electrically active defects. Recently at CREST, High Resolution Electron Microscopy (HRTEM) has shown that chlorine at the grain boundaries removes electrically active stacking faults. The scientific reason for this is not understood. By using a combination of first principle quantum mechanical calculations and HRTEM, we aim to understand the role of defects and use this knowledge to design photovoltaic cells with improved efficiency.