The supplementary materials for the article "Efficient luminescent solar cells based on tailored mixed-cation perovskites" provide detailed experimental data and supporting information. Key components include: - **Fig. S1**: Independent certification from Newport Corporation confirming the power conversion efficiency (PCE) of 19.90% (backward scan) and 19.73% (forward scan) and a normalized electroluminescence quantum efficiency. - **Fig. S2**: Photographs of two real devices showing the active area, high reflectivity of the gold electrode, and the opaque appearance of the perovskite film. - **Fig. S3**: Histogram of solar cell efficiencies for 40 solar cells, with the optimized PbI2/FAI ratio of 1.05. - **Fig. S4**: Initial stability test of PSCs sealed with epoxy and stored in a desiccator. - **Fig. S5**: Absorption spectra of perovskite films on m-TiO2/c-TiO2/FTO substrate with varying R_PbI3/FAL, used to estimate the relative amount of perovskite. - **Fig. S6**: Top-view SEM images of perovskite films with varying PbI2/FAI ratios. - **Fig. S7**: XRD patterns of perovskite films with varying PbI2/FAI ratios. - **Fig. S8**: Normalized (001) peaks of the PbI2 phase showing the variation in full widths at half maximum with increasing ratios of PbI2/FAPbI3. - **Fig. S9**: Cross-sectional SEM images of perovskite films with varying PbI2/FAI ratios. - **Fig. S10**: External electroluminescence quantum efficiency as a function of the injection current for the device with PbI₂/FAI = 1.16. - **Fig. S11**: Normalized PL spectra of perovskite films with varying PbI2/FAI ratios. - **Fig. S12**: PL decay of perovskite films with varying PbI2/FAI ratios. These figures and tables provide comprehensive insights into the performance, stability, and structural characteristics of the perovskite-based luminescent solar cells.The supplementary materials for the article "Efficient luminescent solar cells based on tailored mixed-cation perovskites" provide detailed experimental data and supporting information. Key components include: - **Fig. S1**: Independent certification from Newport Corporation confirming the power conversion efficiency (PCE) of 19.90% (backward scan) and 19.73% (forward scan) and a normalized electroluminescence quantum efficiency. - **Fig. S2**: Photographs of two real devices showing the active area, high reflectivity of the gold electrode, and the opaque appearance of the perovskite film. - **Fig. S3**: Histogram of solar cell efficiencies for 40 solar cells, with the optimized PbI2/FAI ratio of 1.05. - **Fig. S4**: Initial stability test of PSCs sealed with epoxy and stored in a desiccator. - **Fig. S5**: Absorption spectra of perovskite films on m-TiO2/c-TiO2/FTO substrate with varying R_PbI3/FAL, used to estimate the relative amount of perovskite. - **Fig. S6**: Top-view SEM images of perovskite films with varying PbI2/FAI ratios. - **Fig. S7**: XRD patterns of perovskite films with varying PbI2/FAI ratios. - **Fig. S8**: Normalized (001) peaks of the PbI2 phase showing the variation in full widths at half maximum with increasing ratios of PbI2/FAPbI3. - **Fig. S9**: Cross-sectional SEM images of perovskite films with varying PbI2/FAI ratios. - **Fig. S10**: External electroluminescence quantum efficiency as a function of the injection current for the device with PbI₂/FAI = 1.16. - **Fig. S11**: Normalized PL spectra of perovskite films with varying PbI2/FAI ratios. - **Fig. S12**: PL decay of perovskite films with varying PbI2/FAI ratios. These figures and tables provide comprehensive insights into the performance, stability, and structural characteristics of the perovskite-based luminescent solar cells.