Device modeling and performance analysis of lead-free perovskite solar cells for indoor and outdoor illumination using SCAPS-1D

Lead free Organic inorganic halide perovskites (OIHPs) as indoor photovoltaics cells with higher power conversion efficiency (PCE) • High Indoor Efficiency : FASnI 3 achieves 45% simulated efficiency under LED warm light at 1000 nm thickness. • Multijunction Advantage : FAPbI 3 –FASnI 3 tandem reaches 33% (AM1.5G) and 41% (LED warm), showing strong bandgap synergy. • Voc–Jsc Trade-off : Pb-based perovskites offer higher Voc; Sn-based deliver higher Jsc. Tandems balance both. • Spectral Sensitivity : MAPbI 3 and MASnI 3 show reduced efficiency under incandescent light due to spectral mismatch. • Thickness Matters : Optimal absorber thicknesses (500 nm) yield 22% (MAPbI 3 ) and 27% (MASnI 3 ) under AM1.5G. Indoor photovoltaic (IPV) systems are increasingly critical for powering low-energy devices in smart homes and IoT applications, where conventional solar technologies underperform due to low light intensity and narrow spectral ranges. Despite the promise of organic–inorganic halide perovskites (OIHPs), current designs lack optimization for indoor conditions, particularly for lead-free compositions and multijunction architectures. In this work, we employ SCAPS-1D device modeling for systematic evaluation of single-junction and tandem OIHP solar cells under diverse indoor spectra and AM1.5G illumination. Our simulations reveal a strong dependence of power conversion efficiency (PCE) on absorber thickness and spectral compatibility. Optimal thicknesses of 500 nm for MAPbI 3 and MASnI 3 yield efficiencies of 22% and 27% under AM1.5G, while performance drops sharply under incandescent light due to spectral mismatch. Remarkably, the lead-free FASnI 3 achieves a simulated PCE of 45% under LED warm light at 1000 nm thickness, and the FAPbI 3 –FASnI 3 tandem reaches 41% under the same conditions. In Indoors, we quantify how spectral matching and interface‑limited open-circuit voltage govern device operation, and we delineate reporting practices (irradiance‑based metrics and power density at Maximum Power Point (MPP)) for fair benchmarking. These findings establish design guidelines for high-efficiency, environmentally friendly IPV cells and highlight the potential of Sn-based and multijunction perovskites to advance indoor energy harvesting.