Whether Addition of Phenethylammonium Ion is Always Beneficial to Stability Enhancement of MAPbI3 Perovskite Film?

The recent studies widely believe that the stability of (PEA) 2 PbI 4 /MAPbI 3 perovskite solar cells (PSCs) can be progressively increased with the addition of phenethylammonium ion (PEA + ). Herein, it is reported on the stability variations after the addition of PEA + into the MAPbI 3 film and it is demonstrated that excess PEA + has negative effect on the stability of (PEA) 2 PbI 4 /MAPbI 3 perovskite film. X-ray photoelectron spectroscopy, nuclear magnetic resonance, and X-ray absorption fine structure spectroscopy are utilized to testify that the excess PEA + damages the MAPbI 3 crystal structure and generates defects due to the strong coordination between NH 3 + from PEA + and I − from [PbI 6 ] 4− . This work reveals that the stability of (PEA) 2 PbI 4 /MAPbI 3 perovskite films is not proportional to the addition of PEA + , which is of interest for the developing of stable 2D/3D PSCs.