Air-Induced High-Quality CH₃NH₃PbI₃ Thin Film for Efficient Planar Heterojunction Perovskite Solar Cells

Abstract

Efficient planar heterojunction perovskite solar cells (PHJ–PSCs) with a structure of ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PCBM/Al were fabricated using air-induced high-quality CH 3 NH 3 PbI 3 perovskite thin films, in which the air-inducing process was controlled with a humidity of ∼40%. The air exposure of CH 3 NH 3 PbI 3 thin films could dramatically improve their properties with large grains and smooth surface, as well as uniform morphology, resulting in an impressive enhancement in carrier lifetime. The ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy results proved that the CH 3 NH 3 PbI 3 film was n -doped by the absorption of H 2 O on the surface but was very stable without obvious degradation for 10 days’ exposure in air. The power conversion efficiency (PCE) of PHJ–PSCs with an air exposure process showed a significant increase up to 16.21% as compared to reference PHJ–PSCs with a PCE of 12.02%. The research work demonstrated that an air-exposure process with a suitable humidity could produce high-quality perovskite thin film for efficient PHJ–PSCs, which may pave a boulevard for fabricating high-efficiency PHJ–PSCs in atmospheric environment.