Molecular design of cost-effective donor polymers with high visible transmission for eco-friendly and efficient semitransparent organic solar cells

Photoactive layer materials that overcome the trade-off between power conversion efficiency (PCE) and average visible transmittance (AVT) are required to prepare successful high-performance semitransparent organic solar cells (ST-OSCs). Among 12 novel cost-effective D–π=A polymers with high visible light transmission, P(3IN = 0.3)(3IN2F = 0.5)(BDD = 0.2) achieved a PCE of 14.0% and high stability in an eco-friendly solvent-processed OSC with BTP-eC9. This blend film exhibited an AVT of 62.1% and a color rendering index of 95.0, demonstrating the high potential for ST-OSCs. The ternary OSC with PM6 greatly enhances the PCE to 17.3%. Binary and ternary ST-OSCs achieve light utilization efficiencies (LUEs) of 4.38% and 4.04%, respectively, demonstrating the potential of the D–π=A structure. Under a 3000 K light-emitting diode light at 958 lx low illuminance, PCEs of 12.4% and 15.7% are obtained for binary and ternary ST-OSCs, respectively, and the indoor LUEs (LUIEs) of ST-OSCs are greatly enhanced to 5.52% and 5.48%, respectively. Air-processed eco-friendly ternary ST-OSC module (4.7 cm2) achieves not only a PCE of 12.1% and LUIE of 3.90% under 958 lx, but also color coordinates of (0.290, 0.323) and an infrared radiation rejection rate of 87.5%, meeting the civil engineering specifications for windows. This ST-OSC module can be a substitute power source of the thermo-hygrometer in real time, even operate at 195 lx, which paved the way towards zero-energy indoor and outdoor electrical devices as well as windows for buildings and vehicles.