Crystallization and defects regulation of efficient inverted perovskite solar cells via glycine ethyl ester hydrochloride

Crystal quality and defects at grain boundaries (GBs) or grain surfaces are two dominant factors in perovskite solar cells (PSCs) that determine device performance. Here, a novel amino acid salt named glycine ethyl ester hydrochloride (GEECl) is first introduced into perovskite to improve crystal quality and reduce GBs. Owing to fewer GBs and better vertically extended crystals, PSCs with GEECl exhibit improved carrier transport ability. The defects at GBs or grain surfaces can be well controlled by filling the MA+ vacancy with –NH3+ and the interaction between the carbonyl group (C═O) and uncoordinated Pb2+. As a result, the GEECl-modified devices based on MAPbI3 achieved a higher efficiency of 19.86 % with an FF close to 80 %. Furthermore, the GEE+ cations locate at GBs or grain surfaces protect the perovskite films against moisture, which enhanced the stability of PSCs. This work provides a promising route to further accelerate the development of PSCs.