High-Performance Ultra-Flexible Organic Solar Cells Enabled by Transfer-Free Polyimide/ITO Integrated Electrodes

Abstract

Ultra-flexible organic solar cells (OSCs) have recently garnered growing interest with remarkable advancements in power conversion efficiency (PCE), yet they still suffer from complicated transfer process and delicate device configuration design. Herein, we report an in-situ deposition strategy for ultra-thin (~5 μm) flexible transparent electrodes via direct integration of polyimide (PI) and indium tin oxide (ITO). The optimized ultra-flexible PI/ITO electrode achieves an excellent balance between transmittance and conductivity, featuring a low sheet resistance of 21 Ω/sq and a high optical transmittance of 90%. As a result, ultra-flexible PM6:Y6 OSCs fabricated with this PI/ITO electrode deliver a high PCE of 15.8%, which is comparable to that of their rigid counterparts. Furthermore, the PI-based ultra-flexible OSCs exhibit superior stability upon both thermal and bending stress, along with a significantly higher power density than their PET-based counterparts. This work provides a facile fabrication approach and useful guidelines for the development of high-performance ultra-flexible OSCs based on PI substrates.