High voltage in hole conductor free organo metal halide perovskite solar cells

Organo metal halide perovskite has attracted considerable attention recently due to its distinctive properties that make it especially useful in photovoltaic solar cells. In this work we demonstrate high open circuit voltage of 1.35 V using Al₂O₃/CH₃NH₃PbBr₃ perovskite solar cells without a hole conductor. The contact potential difference under light measured by surface photovoltage spectroscopy of CH₃NH₃PbBr₃ was more than twice that of CH₃NH₃PbI₃, which results in smaller surface potential for the Al₂O₃/CH₃NH₃PbBr₃ cells. Incident modulated photovoltage spectroscopy shows a longer recombination lifetime for the Al₂O₃/CH₃NH₃PbBr₃ cells than for the TiO₂/CH₃NH₃PbI₃ cells or for the TiO₂/CH₃NH₃PbBr₃ cells, further supporting the high open circuit voltage. The possibility to gain high open circuit voltage even without a hole transport material in perovskite solar cells shows that the perovskite/metal oxide interface has a major effect on the open circuit voltage in perovskite based solar cells.