Highly Robust Anode Interlayer for Water-Proof and Stretchable Organic Solar Cells
Organic solar cells (OSCs) offer unique advantages for wearable electronics due to their light weight and mechanical flexibility. However, achieving both high optoelectronic performance and mechanical robustness in organic semiconductors remains challenging, compromising the efficiency and durability of stretchable OSCs. Here, we report a cross-linked conjugated polyelectrolyte (CPE)-polyoxometalate (POM) anode interlayer (AIL), PTN-POM, constructed via strong electrostatic interactions between ammonium groups and POM. The PTN-POM film exhibits an electrical conductivity of 3.30×10−3 S/m and high stretchability, significantly outperforming the classic PEDOT:PSS AIL in mechanical strength. Binary OSCs modified with PTN-POM achieve a power conversion efficiency (PCE) of 19.59%, the highest reported for OSCs using a cross-linked AIL. Notably, PTN-POM enables fabrication of water-proof OSCs that show no performance degradation after underwater storage for 42 days. Furthermore, stretchable OSCs incorporating PTN-POM demonstrate enhanced mechanical robustness, retaining 81% of initial PCE under a large tensile strain of 50%. This work significantly enhances the photovoltaic, waterproof, and mechanical properties of OSCs, advancing their potential for wearable photovoltaics.