All-perovskite Indoor Tandem Solar Cells

Abstract

Lead halide perovskite solar cells are promising candidates for indoor photovoltaic (PV) applications, yet reported devices have relied exclusively on single-junction architectures. Here, we introduce new strategies for indoor PV by determining the theoretical efficiency limits of perovskite-based tandem and multi-junction devices under different indoor lighting spectra and identifying optimal bandgap combinations. We further demonstrate the first all-perovskite tandem solar cells (TSCs) for indoor use. Detailed-balance analysis indicates an indoor efficiency up to 60% for double-junction configurations. The tandem devices, fabricated by mechanically stacking a semitransparent wide-bandgap (2.30 eV) FAPbBr₃ top cell with a low-bandgap (1.68 eV) CsFAPb(IBr)₃ bottom cell, achieved efficiencies of 30.1% and 29.2% at 1000 lx, and 22.9% and 26.9% at 200 lx, under cold (6500 K) and warm (3000 K) WLED illumination, respectively. Importantly, the tandem device operated for over 640 h at the maximum power point under continuous indoor illumination (1000 lx) without showing any noticeable degradation in performance. These results establish tandem perovskite solar cells as efficient indoor PV candidates for powering next-generation smart and internet of things (IoT) technologies.