Fig. 1. Basic characterization of FACsPbBr₃ thin films with different Cs doping concentrations. (a)-(d) 3D-AFM images; (e) XRD patterns

Fig. 2. Ellipsometry analysis of FACsPbBr₃ thin films with different Cs doping concentrations. (a) Ellipsometric experimental (dots) and simulated (dotted lines) spectra of FA_0.95Cs_0.05PbBr₃ thin film; (b) complex dielectric functions of FACsPbBr₃ thin films with different Cs doping concentrations

Fig. 3. Current density curves of FACsPbBr₃ solar cell with different Cs doping concentrations (inset is structure diagram for PSCs)

Fig. 4. Complex dielectric functions of FA_0.95Cs_0.05PbBr₃ thin film with different temperature

Fig. 5. Optical properties of FA_0.95Cs_0.05PbBr₃ at different temperature. (a) Second-derivative of imaginary parts of complex dielectric function, and inset is bandgap calculated by absorption spectrum; (b) temperature-dependence bandgaps of FA_0.95Cs_0.05PbBr₃ for tetragonal and orthorhombic phases

Fig. 6. Simulation of FA_0.95Cs_0.05PbBr₃ films. (a) EQE spectrum of FA_0.95Cs_0.05PbBr₃ layer and 1-R of component layers in Glass/FTO (100 nm)/TiO₂ (43 nm)/FA_0.95Cs_0.05PbBr₃ (500 nm)/spiro-OMeTAD (200 nm)/Ag structure; (b) EQE spectrum of FA_0.95Cs_0.05PbBr₃ layer at different temperatures; (c) J_sc values for PSCs with thickness of FA_0.95Cs_0.05PbBr₃ from 0 to 1400 nm at different temperatures