High-Performance Flexible Organic Solar Cells exceeding 12% Enabled by High-Purity Transfer-Free Graphene Electrode produced via Direct Polyimide Integration

Abstract

The performance of organic solar cells (OSCs) has been steadily increasing, surpassing 15% power conversion efficiency (PCE). While most high-efficiency OSCs are fabricated based on a rigid platform, the device performance of flexible OSCs still falls behind that of their rigid counterparts. Herein, we introduce a highly flexible and durable transparent electrode with thermal stability achieved through direct integration of polyimide (PI) possessing dual functionalities on graphene. The PI-assisted graphene electrode exhibits an ultra-clean surface together with desirable optical transmittance, sheet resistance, and high thermal stability. Direct integration of PI on graphene sheet improved the durability of the graphene electrode by inhibiting delamination of the graphene film. Using the PI-assisted graphene as a transparent electrode, a high-efficiency flexible OSC with a PCE of 12.2% was obtained with outstanding mechanical robustness.