The growth of a CH3NH3PbI3 thin film using simplified close space sublimation for efficient and large dimensional perovskite solar cells

Abstract

A way to fabricate pin-hole-free perovskite thin films with optimal crystalline morphology and full coverage is crucial for highly efficient and large scale perovskite solar cells (PerSCs). Herein, we demonstrate a new approach of simplified close space sublimation (CSS) deposition to grow a high quality CH₃NH₃PbI₃ thin film in a low-vacuum and even non-vacuum oven. In this method, a highly crystallized and uniform perovskite film can be easily obtained by simply controlling the thickness of the PbI₂ and CH₃NH₃I films, the reaction time of CH₃NH₃I vapor with the PbI₂ film, and the distance of the sublimation space. With this approach, a large area of 100 mm² can be easily obtained. The crystallinity of the perovskite film was investigated using X-ray diffraction (XRD) and the morphology of the perovskite thin film was examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The planar heterojunction PerSCs with a structure of FTO/PEDOT:PSS/CH₃NH₃PbI₃/PCBM/Al were fabricated and power conversion efficiencies of 16.2%, 12.9% and 10.8% were achieved for the devices with a photoactive area of 4 mm², 25 mm² and 100 mm², respectively.