H-Center and V-Center Defects in Hybrid Halide Perovskites

The self-trapping of holes with the formation of a molecular X-2(-) anion is a well-established process in metal halide (MX) crystals, but V-center (2X(-) + h(+) -> X-2(-)) and H-center (X- + X-i(-) + h(+)-> X-2(-)) defects have not yet been confirmed in halide perovskite semiconductors. The I-2(-) split-interstitial defect is predicted to be a spin radical in CH3NH3PbI3 with an optically excited state in the semiconductor band gap.