Toward scalable semitransparent organic photovoltaics: Slot-die-coated 210-cm2 modules with visible transmission of up to 50% and LUE up to 4%

State-of-the-art devices often fail to combine compatibility with large-scale fabrication, such as sputtering, slot-die coating using non-halogenated solvents, and laser structuring. Here, fully slot-die-coated large-area semitransparent organic photovoltaic (STOPV) modules (aperture area 210.25 cm²) incorporating a near-infrared reflecting back electrode and a metal-free top electrode are presented, with a power conversion efficiency (PCE) of up to 9.26%, an average visible transmittance (AVT) of 43.2%, and a light utilization efficiency (LUE = AVT × PCE) of up to 4.0%. Current-voltage measurements at various illumination intensities and illuminated lock-in thermography provide insight into the module's loss mechanisms. Stability tests under continuous illumination for 1,000 h show promising operational durability, while the observed losses in fill factor can almost entirely be assigned to decreased conductivity of the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) top electrode. Flexible STOPV modules retaining 100% of their initial PCE after 1,274 bending cycles over a 15-mm diameter rod were fabricated, thus demonstrating their mechanical robustness.