Engineering Surface Orientations for Efficient and Stable Hybrid Perovskite Single-Crystal Solar Cells

We synthesized two types of MAPbI3single-crystalfilms with dominant (001) and (100) surface orientations for solarcells. We found that both MAPbI3(001) and (100) single-crystalfilms have efficient hole transfer into poly(triaryl)amine (PTAA),as evident from the reduced photoluminescence (PL) intensity andlifetime, as well as the type-II energy alignment. Unlike a MAPbI3(100) single-crystalfilm with a strong PL quenching due toefficient electron transfer to phenyl-C61-butyric acid methyl ester(PCBM), the MAPbI3(001) single-crystalfilm exhibits an increasein PL intensity in the presence of PCBM, which can be attributedto surface passivation. Interestingly, different from the conven-tional MAPbI3(100) that suffers from a significant decrease in thePCE (from 19.3 to 14.4%), the MAPbI3(001) single-crystalfilm shows an increase in the PCE (from 16.0 to 17.2%) and muchbetter stability under ambient conditions thanks to the dual passivation on the PbI2-rich surface by PCBM and O2.