Self-regulation mechanism for charged point defects in hybrid halide perovskites

Abstract

Hybrid halide perovskites such as methylammonium lead iodide (CH3NH3PbI3) exhibit unusually low free carrier concentrations despite being processed at low-temperatures from solution. We demonstrate, through quantum mechanical calculations, that the origin of this phenomenon is a prevalence of ionic over electronic disorder in stoichiometric materials. Schottky defect formation provides a mechanism to self-regulate the concentration of charge carriers through ionic compensation of charged point defects. The equilibrium charged vacancy concentration is predicted to exceed 0.4% at room temperature. This behaviour, which goes against established defect conventions for inorganic semiconductors, has implications for photovoltaic performance.

References in corpus (3)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Molecular ferroelectric contributions to anomalous hysteresis in hybrid perovskite solar cells

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