Unusual defect physics in CH3NH3PbI3 perovskite solar cell absorber
Thin film solar cells based on Methylammonium triiodideplumbate (CH3NH3PbI3) halide perovskites have recently shown remarkable performance. First principle calculations show that CH3NH3PbI3 has unusual defect physics: (i) Different from common p type thin film solar cell absorbers, it exhibits flexible conductivity from good p type, intrinsic to good n type depending on the growth conditions; (ii) Dominant intrinsic defects create only shallow levels, which partially explain the long electron hole diffusion length and high open circuit voltage in solar cell. The unusual defect properties can be attributed to the strong Pb lone pair s orbital and I p orbital antibonding coupling and the high ionicity of CH3NH3PbI3.