Fig. 5. (A) Tracking of difference absorption spectra at the mixed halide peak (at 445 nm) and kinetic fittings recorded for 2D mixed halide perovskite films with BA, BzA, BDA, PEA and PDMA. (B) Kinetic rate constant obtained from the monoexponential fits corresponding to the kinetics of disappearance of the mixed halide phase upon photoirradiation (100 mW cm⁻²). (C) Degree of phase segregation plots for 2D perovskites with BA, BzA, BDA, PEA and PDMA, which is calculated by dividing the absorption intensity upon light irradiation by the initial absorption intensity at the mixed halide phase (440–450 nm). (D) Quantum efficiency calculation for 2D perovskites with BA, BzA, BDA, PEA and PDMA under light irradiation of 40 and 100 mW cm⁻² for 15 min. In panel D, normalization was performed based on the highest Q. E. as 1.