High-Performance Semi-Transparent Organic Photovoltaic Devices via Improving Absorbing Selectivity

Semi-transparent organic photovoltaics (ST-OPVs) are promising solar windows for building integration. Improving the light-absorbing selectivity, that is, transmitting the visible photons while absorbing the invisible ones, is a key step toward high-performance ST-OPV. To achieve this goal, the optical properties of the active layer, transparent electrode, and capping layer are comprehensively tailored, and a highly efficient ST-OPV with good absorbing selectivity is demonstrated. First, a numerical method is established to quantify the absorbing selectivity of materials and devices, based on which, an infrared absorbing non-fullerene acceptor, that is, H3, is selected among a large pool of photo-active materials. Second, an ultra-smooth transparent thin Ag layer with small granule size is developed via polyethylenimine wetting, which alleviates light scattering and improves the electric properties for ST-OPV. Finally, as guided by optical simulation, a TeO₂ capping layer is deposited on top of the ultra-thin Ag to further improve the light-absorbing selectivity. As a result, the light utilization efficiency is significantly improved to 3.95 ± 0.02% (best ≈4.06%), with a good color rendering index of 76.85. These results make it one of the best among color-neutral ST-OPVs. This work stresses the importance of manipulating the light-absorbing selectivity for high-performance ST-OPVs.