Development of cross-linked donor polymers for polymer solar cells with improved efficiency and thermal stability

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-10, Vol.497, p.154496, Article 154496
• Main Authors: Wang, Shaoqiang, Wang, Fei, Yu, Junting, Yuan, Bin, Zhu, Weiguo, Tan, Hua
• Format: Article
• Language: English
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.154496

•A series of cross-linked donor polymers P1 and P2 have been developed for PSCs with non fullerene receptor Y6, where photovoltaic performance and thermal stability can be significantly improved.•The P1 based PSC achieved an excellent power conversion efficiency (PCE) of 17.29%, exceeding the 9% of the PM6 based PSC.•The P1 based PSCs exhibit better thermal stability with a 17 % efficiency loss under continuous 60 °C for 210 h. Due to low glass-transition temperature and high diffusion coefficient of small molecule acceptors (SMAs), the bi-continuous interpenetrating morphology of SMA-based polymer solar cells (PSCs) are metastable and therefore most SMA-based PSCs exhibit poor operational and thermal stability. Cross-linked donor polymers have been proposed because the cross-linked behavior can “freeze” the initial morphology and avoid its further evolution. In this work, two new cross-linked donor polymers P1 and P2 were designed for application in PSCs with a non-fullerene acceptor Y6, in which the photovoltaic performance and thermal stability of PSCs were significantly improved. The P1-based PSCs achieved a superior power conversion efficiency (PCE) of 17.29 % with a Jsc of 25.99 mA cm−2, a Voc of 0.860 V and a FF of 77.35 %, which surpassed 9 % for PM6-based PSCs (15.86 %). Furthermore, the P1-based PSCs exhibited better thermal stability with a 17 % efficiency loss under continuous 60 °C for 210 h due to the fixation of active layer morphology, while PM6-based PSCs suffered from a serve PCE reduction of over 26 %. These results demonstrate that cross-linked donor polymer has a great application prospect to improve the PCE and thermal stability of PSCs.