Hole Selective NiO Contact for Efficient Perovskite Solar Cells with Carbon Electrode

In this study, we communicate an investigation on efficient CH₃NH₃PbI₃-based solar cells with carbon electrode using mesoporous TiO₂ and NiO layers as electron and hole selective contacts. The device possesses an appreciated power conversion efficiency of 14.9% under AM 1.5G illumination. The detailed information can be disclosed with impedance spectroscopy via tuning the interfaces between CH₃NH₃PbI₃ and different charge selective contacts. The results clearly show charge accumulation at the interface of CH₃NH₃PbI₃. The NiO is believed to efficiently accelerate charge extraction to the external circuit. The extracted charge could improve photovoltaic performance by shifting hole Fermi level down, achieving a high device photovoltage. A fast interfacial recombination at the interface of CH₃NH₃PbI₃/electron selective contact layer (mesoporous TiO₂), occurring in millisecond domains, is the critical issue for charge carrier recombination loss. (Graph Presented).