Hole transporting material-free and annealing-free thermal evaporated planar perovskite solar cells with an ultra-thin CH3NH3PbI3−XClX layer

Abstract High efficiency and stable hole transporting material-free (HTM-free) planar heterojunction (PHJ) perovskite solar cells are constructed by directly thermal evaporating perovskite materials onto indium tin oxide substrate. A condense and homogeneous morphology is found for this perovskite film even without any annealing process. The optimized HTM-free CH 3 NH 3 PbI 3− X Cl X /C 60 PHJ device with a 35 nm ultra-thin CH 3 NH 3 PbI 3− X Cl X layer presents a high hole extraction efficiency and a low charge carrier recombination probability, which results in a high short circuit current and fill factor. The HTM-free device shows a high power conversion efficiency of 8.37%, which is one of the highest efficiency among reported inverted HTM-free perovskite solar cells even that a thinner perovskite film is used. More importantly, the device also exhibits a superior stability in ambient conditions.