Solution‐Processed Semi‐Transparent Organic Photovoltaics Achieving 5% Light Utilization Efficiency through Synergistic Active Layer and Electrode Design †

Comprehensive Summary Semi‐transparent organic photovoltaics (ST‐OPVs) suffer from an inherent trade‐off between power conversion efficiency (PCE) and average visible transmittance (AVT). Here, we report a synergistic solution‐processed strategy that concurrently optimizes the active layer composition and transparent electrode architecture to achieve a record solution‐processed light utilization efficiency (LUE). Reducing the donor content in bulk heterojunctions represents an effective strategy to enhance the AVT, yet inevitably incurs severe efficiency penalties arising from disrupted charge transport and enhanced recombination. By incorporating a tert ‐butyl‐functionalized 4‐PACz derivative (tB‐4P) into a donor‐diluted bulk heterojunction, we suppress trap‐assisted recombination and rebalance charge transport, recovering both the fill factor and short‐circuit current density. Complementarily, a sandwich‐structured ZnO/AgNW/ZnO composite electrode—employing optimized long aspect‐ratio silver nanowires—is integrated with a solution‐processed PMMA optical coupling layer and an anti‐reflection coating to enhance photon harvesting and transparency. The resulting donor‐diluted ST‐OPV device delivers a PCE of 10.41% and an AVT of 48.0%, yielding a record LUE of 5.00% among solution‐processed ST‐OPVs reported to date. This work establishes a scalable pathway toward high‐performance photovoltaic windows and building‐integrated photovoltaics.