Fig. 1
From: Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites
Spectroscopic observations of halide phase segregation. a Time evolution of MAPb(I0.5Br0.5)3 (MA = CH3NH3 +) emission spectra (PL, photoluminescence) under 405 nm continuous wave excitation (I exc = 20 mW cm−2). Times for selected spectra (from red to purple): 0.05, 1.41. 1.64, 1.69, 1.83, 1.93, 2.26, 2.40, 2.58, 2.68, 2.87, and 3.10 s. Inset: Emission spectra between 475 and 600 nm. b Corresponding time evolution of the MAPb(I0.5Br0.5)3 absorption spectra under 405 nm continuous wave (CW) excitation (I exc = 25 mW cm−2). Times for selected absorption spectra (from blue to green): 0, 1, 30 min. Inset: Absorption-based phase separation kinetics from absorption changes at 720 nm where the dashed red line represents an exponential fit to the data. c I iodide /I sat (I iodide – iodide-rich emission intensity, I sat – saturation emission intensity) under different I exc (I exc – excitation intensity). Dashed lines are fits using Eq. (4). The bottom solid red line shows I iodide /I sat when I exc = 40 μW cm−2. Excitation intensities for selected curves (from red to purple): 0.27, 0.79, 1.05, 1.46, 1.56, 2.27, 3.81, 5.04, 18.56, 57.28 mW cm−2. d I exc-dependent emission-based first order rate constant for phase separation. The dashed red line represents a fit to the data using Eq. (5)
