Fig. 2: Photo-induced degradation mechanisms and edge-stabilization strategy.

a Schematic illustrating imperfect edges in n = 3 reduced-dimensional perovskites of PEA₂Cs_n−1Pb_nBr_3n+1 and proposed reaction pathway of superoxide production under photoexcitation, including (1) missing Cs⁺ or PEA⁺ at the edge sites, (2) missing Cs⁺ or PEA⁺ at the corner sites, (3) desorbed CsBr or PEABr near the defect. b Energy level alignment obtained from DFT calculations. c PLQYs of the perovskites treated using different molecules.