Fig. 5: Suppression mechanisms of LHS in polycrystalline thin films.
From: Strain-activated light-induced halide segregation in mixed-halide perovskite solids
a The schematic illustration of three distinct regimes for LHS in mixed-halide perovskites MAPb(I1-xBrx)3. With more Br, MAPb(I1-xBrx)3 goes through from LHS-free regime (e.g., MAPb(I0.85Br0.15)3) to strain-activated LHS region (e.g., MAPb(I0.65Br0.35)3) and then to LHS-intrinsic region (e.g., MAPb(I0.35Br0.65)3). b, c PL evolution for the mixed-halide perovskite films (35%Br/45%Br/80%Br) with 20 mol.% KI passivation. The excitation wavelength is 490 nm and the laser intensity is approximately 100 mW cm−2. d The XRD patterns of mixed-halide perovskites with and without KI passivation. Note that the XRD patterns of samples with KI additive are aligned with the XRD of the control samples. e Initial PL spectra for 35%Br perovskite films without and with 20 mol.% KI, showing a similar PL intensity. The excitation wavelength is 490 nm and the laser intensity is approximately 100 mW cm−2. f The schematic of surface passivation by KI/PEAI to release the strain in perovskites.
