Origin of the Hysteresis in I-V Curves for Planar Structure Perovskite Solar Cells Rationalized with a Surface Boundary-induced Capacitance Model

For efficient hybrid solar cells based on organometal halide perovskites, the real origin of the I-V hysteresis became a big issue and has been discussed widely. In this study, simulated I-V curves of different equivalent circuit models were validated with experimental I-V curves of a planar perovskite solar cell with the power conversion efficiency (PCE) of 18.0% and 8.8% on reverse scan (from open circuit to short circuit) and forward scan (from short circuit to open circuit), respectively. We found that an equivalent circuit model with a series of double diodes, capacitors, shunt resistances, and single series resistance produces simulated I-V curves with large hysteresis matching with the experimentally observed curves. The electrical capacitances generated by defects due to the lattice mismatch at the TiO2/CH3NH3PbI3 and CH3NH3PbI3/spiro-OMeTAD interface are truly responsible for the hysteresis in perovskite solar cells.