Fig. 2

Optical properties. Temperature-dependent photoluminescence (PL) of a (HOCH₂CH₂NH₃)₂PbI₄ (2D_EA) and b (C₆H₅(CH₂)₂NH₃)₂PbI₄ (2D_PEA) perovskite single crystals. c Exciton dissociation rate extracted from temperature-dependent photoluminescence quantum efficiency (PLQE) in both 2D_EA and 2D_PEA perovskites. d Absorption of 2D_EA and 2D_PEA perovskites