Highly Efficient and Robust Ternary All‐Polymer Solar Cells Achieved by Electro‐Active Polymer Compatibilizers

• Published in: Advanced energy materials 2023-10, Vol.13 (39)
• Main Authors: Kim, Geon‐U, Choi, Changeun, Jeong, Dahyun, Kim, Dong Jun, Phan, Tan Ngoc‐Lan, Song, Seunghoon, Park, Jinseok, Kim, Taek‐Soo, Kim, Yun‐Hi, Kim, Bumjoon J.
• Format: Article
• Language: English
• Subjects: Compatibility; Compatibilizers; Energy conversion efficiency; Mechanical properties; Morphology; Photovoltaic cells; Polymer blends; Polymers; Solar cells; Stretchability; Thermal stability
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202302125

All‐polymer solar cells (all‐PSCs), using polymerized non‐fullerene acceptors (PNFAs), have shown promise in improving device stabilities compared to small‐molecular acceptor‐based PSCs. However, low mixing entropy between polymer donors ( P D s) and PNFAs hampers the development of optimized blend morphology. Herein, this study develops efficient conjugated polymers that serve as interfacial compatibilizers between host P D and PNFA. Ternary all‐polymer blends containing the compatibilizer demonstrate improved blend morphology with strengthened interfaces, resulting in better photovoltaic properties and thermal/mechanical stabilities. In detail, the power conversion efficiency (PCE) increases from 15.4 to 17.1% upon the addition of the compatibilizer. Moreover, the devices based on the ternary blend enable good thermal stability, retaining 90% of the initial PCE after 96 h at 125 °C. Additionally, the mechanical properties are improved; the cohesive fracture energy ( G c ) of 2.6 J m −2 and crack onset strain (COS) of 20.4% of the ternary blend outperform those of the binary blend ( G c = 1.1 J m −2 and COS = 16.5%). Resultingly, the stretchable PSCs based on the ternary blend exhibit an excellent PCE of 13.7% and stretchability with a strain at PCE 80% of 35%.