Intrinsically Stretchable, Highly Efficient Organic Solar Cells Enabled by Polymer Donors Featuring Hydrogen‐Bonding Spacers

• Published in: Advanced materials (Weinheim) Vol. 34; no. 50; pp. e2207544 - n/a
• Main Authors: Lee, Jin‐Woo, Seo, Soodeok, Lee, Sun‐Woo, Kim, Geon‐U, Han, Seungseok, Phan, Tan Ngoc‐Lan, Lee, Seungjin, Li, Sheng, Kim, Taek‐Soo, Lee, Jung‐Yong, Kim, Bumjoon J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.12.2022
• Subjects: Electrical properties; Energy conversion efficiency; flexible spacers; Hydrogen bonding; Hydrogen embrittlement; intrinsically stretchable organic solar cells; Materials science; mechanical robustness; Molecular structure; Optical properties; Photovoltaic cells; Polymers; Power sources; Solar cells; Stretchability; hydrogen bonding; intrinsically stretchable organic solar cells; flexible spacers; mechanical robustness; stretchability
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202207544

Intrinsically stretchable organic solar cells (IS‐OSCs), consisting of all stretchable layers, are attracting significant attention as a future power source for wearable electronics. However, most of the efficient active layers for OSCs are mechanically brittle due to their rigid molecular structures designed for high electrical and optical properties. Here, a series of new polymer donors (PDs, PhAmX) featuring phenyl amide (N1,N3‐bis((5‐bromothiophen‐2‐yl)methyl)isophthalamide, PhAm)‐based flexible spacer (FS) inducing hydrogen‐bonding (H‐bonding) interactions is developed. These PDs enable IS‐OSCs with a high power conversion efficiency (PCE) of 12.73% and excellent stretchability (PCE retention of >80% of the initial value at 32% strain), representing the best performances among the reported IS‐OSCs to date. The incorporation of PhAm‐based FS enhances the molecular ordering of PDs as well as their interactions with a Y7 acceptor, enhancing the mechanical stretchability and electrical properties simultaneously. It is also found that in rigid OSCs, the PhAm5:Y7 blend achieves a much higher PCE of 17.5% compared to that of the reference PM6:Y7 blend. The impact of the PhAm‐FS linker on the mechanical and photovoltaic properties of OSCs is thoroughly investigated. Efficient, intrinsically stretchable organic solar cells (IS‐OSCs) are developed by designing a new series of polymer donors (PDs, PhAm) featuring hydrogen‐bonding‐capable flexible spacers. High power conversion efficiency (PCE = 12.7%) and stretchability (PCE retention of > 80% at 32% strain) are demonstrated, which represent the best performances in terms of both PCE and stretchability among the IS‐OSCs reported to date.