Multimodal Strategy for Efficient Semi‐Transparent Perovskite Solar Cells and Modules with Record Indoor Performance

ABSTRACT Balancing transparency and efficiency remains a key challenge for semi‐transparent perovskite solar cells (ST‐PSCs), restricting their application in building‐integrated photovoltaics and indoor electronics. Here, we present a multimodal strategy combining optical modelling, transparent electrode engineering, and molecular passivation to overcome this transparency‐efficiency trade‐off. Guided by transfer matrix simulations, a 1.7 eV FAMA‐based perovskite layer with a thickness of ∼185 nm was integrated with an optimized MoO 3 /Au/MoO 3 top electrode (59.9% transmittance). Incorporation of the bifunctional molecule 3‐trifluoromethyl‐1H‐1,2,4‐triazole, which coordinates with undercoordinated Pb 2+ via ─CF 3 group and forms N…H interactions with FA + /halide species, effectively suppresses trap‐assisted recombination and stabilizes the lattice. Consequently, the champion ST‐PSC delivers 13.78% power conversion efficiency (PCE), 31.1% average visible transmittance (AVT), and a high light utilization efficiency (LUE) of 4.29%. Notably, this study demonstrates for the first time efficient indoor operation of ST‐PSCs, achieving 22.41% indoor PCE (iPCE) under 1000 lux LED illumination, and further realizes the first scalable 30 × 30 cm 2 semi‐transparent module retaining 8.2% (7.4%) PCE under 1 sun (0.2 sun). The unencapsulated ST‐PSCs retain 79.6% of initial PCE after 268 h of continuous standard light soaking. This integrated framework provides a universal route toward efficient, scalable, transparent photovoltaics for next‐generation indoor and building‐integrated energy harvesting.