In₂O₃:H-Based Hole-Transport-Layer-Free Tin/Lead Perovskite Solar Cells for Efficient Four-Terminal All-Perovskite Tandem Solar Cells

Narrow-band gap (NBG) Sn–Pb perovskites with band gaps of ?1.2 eV, which correspond to a broad photon absorption range up ?1033 nm, are highly promising candidates for bottom solar cells in all-perovskite tandem photovoltaics. To exploit their potential, avoiding optical losses the top layer stacks configuration is essential. This study addresses this challenge two ways (1) removing hole-transport (HTL) and (2) implementing transparent hydrogen-doped indium oxide In2O3:H (IO:H) electrodes instead commonly used tin (ITO). Removing HTL reduces parasitic loss shorter wavelengths without compromising photovoltaic performance. IO:H, an ultra-low near-infrared high charge carrier mobility, results remarkable increase photocurrent semitransparent (HTL-free) NBG perovskite when substituted ITO. As result, IO:H-based four-terminal cell (4T all-PTSCs) power conversion efficiency (PCE) as 24.8% demonstrated, outperforming ITO-based 4T all-PTSCs PCE 23.3%.