Self‐Doped Alcohol‐Soluble Quinacridone Polymer as a Cathode Interfacial Layer for Enhanced Performance in Organic Solar Cells

ABSTRACT As a key component of organic solar cells, the cathode interface layer (CIL) plays a crucial supporting role in enhancing the power conversion efficiency (PCE) and stability of the device. In this study, a nitrogen‐containing polar side chain was introduced onto the electron‐deficient group QA, which was then polymerized with fluorene units bearing alkyl side chains to obtain the material PQAN‐F. After being integrated into the device, PQAN‐F can generate interfacial dipoles at the cathode interface, which lowers the work function of the cathode material. Additionally, this material exhibits a strong self‐doping capability, which significantly improves the electron transport capacity of the device while endowing it with excellent electrical conductivity. When the concentration is 0.50 mg mL −1 , with a short‐circuit current density ( J SC ) of 16.01 mA cm −2 and a fill factor (FF) as high as 71.12%, the optimal PCE of 9.04% is achieved. This PCE represents a 40% enhancement compared to the device of w/o. The obtained results provide significant insights for the development of efficient cathode interface materials, while also offering an expanded basis to guide the design strategies employed in OSC interface engineering.