Multifunctional dual-anion compensation of amphoteric glycine hydrochloride enabled highly stable perovskite solar cells with prolonged carrier lifetime

Throughout years, the two-step spin-coating process is the most common method to prepare organic lead halide perovskite materials. However, the short reaction time of dropping the solution at the second step means that PbI2 cannot be completely transformed into perovskite phase. To solve this problem, we report the introduction of glycine hydrochloride (GlyHCl) into the second step of the two-step spin-coating process to prepare a FA0.9MA0.1PbI3-x%-GlyHCl perovskite material (namely FAMA-x%-GlyHCl, where FA = formamidinium, MA = methylammonium, and x% stands for the molar ratio of GlyHCl added in FA iodide/MA iodide (FAI/MAI) precursor solution). The Cl− ion in GlyHCl assists the formation of α-phase perovskite, and the −COO− group coordinates with Pb2+ cation in a bridging way, making up for the anion vacancy in perovskite lattice and resulting in high absorption intensity. The perovskite solar cells (PSCs) based on FAMA-9%-GlyHCl achieve a long carrier lifetime (527.0 ns), a photoelectric conversion efficiency (PCE) of 19.40% and good thermal stability, maintaining 85.8% of the initial PCE after being continuously heated at 60 °C for 500 h. This study helps to solve the problem of incomplete reaction in the two-step spin-coating process and puts forward a new solution for preparing high coverage perovskite films with large grain size.