Stable Semitransparent All-Polymer Solar Cells with Color-Tunable Reflection and Neutral Transmission

Enhancing the stability and optical tailorability of semitransparent organic solar cells (ST-OSCs) is crucial for building-integrated photovoltaics. In this work, we propose a smart design for realizing stable and color-tunable all-polymer ST-OSCs through integrating a self-assembled MeO-2PACZ layer capped in conjunction with an optically engineered coupling structure (dielectric layer/metal/dielectric layer). Owing to the effective blocking of interfacial diffusion of metal ions, the devices with MeO-2PACZ receive considerable gains of stability, as manifested by the retention of 90% of the initial efficiency after 4000 h under storage and a retention of 82% after 600 h at maximum power point tracking. The optical coupling layer enables independent modulation of reflective properties while maintaining a high transmittance neutrality. This results in colorful ST-OSCs with a wide reflective chrominance range and a peak light utilization efficiency of 3.62%, among the best for all-polymer ST-OSCs. This strategy advances next-generation, sustainable photovoltaic windows.