Optoelectronic Properties and Defect Physics of Lead-Free Photovoltaic Absorbers Cs2AuIAuIIIX6 (

The mixed-valence gold iodide Cs${}_{2}$Au${}_{2}$I${}_{6}$ shows promising photovoltaic properties, such as excellent simulated absorption and low exciton binding energy. The authors use hybrid density functional theory to evaluate the family of inorganic and organic gold mixed-valence halides from a photovoltaic perspective. While all of these inorganic halides exhibit high efficiency, several deep-level defects are possible, which may hinder practical performance. These results should provide the basis for further studies of these materials, and help our overall understanding of defect physics in this class of lead-free perovskites for solar power.