Solid Additive Dual‐Regulates Spectral Response Enabling High‐Performance Semitransparent Organic Solar Cells

Abstract Semi‐transparent organic solar cells (ST‐OSCs) possess significant potential for applications in vehicles and buildings due to their distinctive visual transparency. Conventional device engineering strategies are typically used to optimize photon selection and utilization at the expense of power conversion efficiency (PCE); moreover, the fixed spectral utilization range always imposes an unsatisfactory upper limit to its light utilization efficiency (LUE). Herein, a novel solid additive named 1,3‐diphenoxybenzene (DB) is employed to dual‐regulate donor/acceptor molecular aggregation and crystallinity, which effectively broadens the spectral response of ST‐OSCs in near‐infrared region. Besides, more visible light is allowed to pass through the devices, which enables ST‐OSCs to possess satisfactory photocurrent and high average visible transmittance (AVT) simultaneously. Consequently, the optimal ST‐OSC based on PP2+DB/BTP‐eC9+DB achieves a superior LUE of 4.77%, representing the highest value within AVT range of 40–50%, which also correlates with the formation of multi‐scale phase‐separated morphology. Such results indicate that the ST‐OSCs can simultaneously meet the requirements for minimum commercial efficiency and plant photosynthesis when integrated with the roofs of agricultural greenhouses. This work emphasizes the significance of additives to tune the spectral response in ST‐OSCs, and charts the way for organic photovoltaics in economically sustainable agricultural development.