High-Efficiency Planar-Structure Perovskite Solar Cells via Homemade Chamber with Low Pressure and Low Temperature Process

The sequential deposition process is widely used to fabricate planar structure perovskite solar cells because of better uniformity and perfect surface coverage of perovskite films. However, it is difficult to control the crystallization of perovskite finely. Here we improve the sequential deposition process by using a low-pressure proximity evaporation technique (LPPET). The slow grain growth rate of perovskite (CH3NH3PbI3) would make large crystallization and high quality of perovskite film. Moreover, we manipulate an innovative double-side interdiffusion process, that is, sequentially deposit CH3NH3I/PbI2/CH3NH3I to fabricate the perovskite layer. In this way, PbI2 can be effectively converted into perovskite from a double side and also achieve good control of CH3NH3I deposition on the surface. The devices reach efficiency over 14%, which is the first time for TiO2 free cells fabricated by a low-pressure approach.