Bithieno[3,4‐c]pyrrole‐4,6‐dione‐Based Wide‐Bandgap Donor Polymers for Efficient Polymer Solar Cells

Abstract

AbstractThe polymer solar cells (PSCs) have garnered substantial interest owing to their lightweight, cost‐effectiveness, and flexibility, making them ideal for large‐scale roll‐to‐roll manufacturing. In this study, two wide‐bandgap (WBG) donor polymers, PFBiTPD and PClBiTPD, utilizing bithieno[3,4‐c]pyrrole‐4,6‐dione (BiTPD) as the electron‐accepting unit and fluorinated/chlorinated benzo[1,2‐b:4,5‐b']dithiophene (BDT) as the electron‐donating moiety are designed and synthesized. The polymers demonstrated large optical bandgaps (exceeding 1.80 eV) and are blended with ITIC‐4F to form the active layers in PSCs. The PFBiTPD‐based devices showed a well‐dispersed fibrillar network, facilitating efficient charge generation and transport. Thus, these devices attained a power conversion efficiency (PCE) of 8.60%, featuring a fill factor (FF) of 62.89%, an open‐circuit voltage (Voc) of 0.88 V and a short‐circuit current density (Jsc) of 15.54 mA cm−2. In contrast, PClBiTPD‐based devices displayed lower performance due to less favorable morphology. The study underscores the importance of polymer design and morphology control in optimizing the photovoltaic performance of PSCs.