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

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 MoO₃/Au/MoO₃ top electrode (59.9% transmittance). Incorporation of the bifunctional molecule 3-trifluoromethyl-1H-1,2,4-triazole, which coordinates with undercoordinated Pb²⁺ via ─CF₃ 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 cm² 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.