Fig. 2. (a) Photoluminescence (PL) spectra of an x = 0.4 thin film over 45 s in 5 s increments under 457 nm, 15 mW cm–2 light at 300 K. Inset: temperature dependence of initial PL growth rate. (b) Normalized PL spectra of (MA)Pb(BrxI1–x)3 thin films after illuminating for 5–10 minutes with 10–100 mW cm–2, 457 nm light. (c) PL spectra of an x = 0.6 thin film after sequential cycles of illumination for 2 minutes (457 nm, 15 mW cm–2) followed by 5 minutes in the dark.
