title: Donor polymer design enables efficient non-fullerene organic solar cells.
abstract: To achieve efficient organic solar cells, the design of suitable donor-acceptor couples is crucially important. State-of-the-art donor polymers used in fullerene cells may not perform well when they are combined with non-fullerene acceptors, thus new donor polymers need to be developed. Here we report non-fullerene organic solar cells with efficiencies up to 10.9%, enabled by a novel donor polymer that exhibits strong temperature-dependent aggregation but with intentionally reduced polymer crystallinity due to the introduction of a less symmetric monomer unit. Our comparative study shows that an analogue polymer with a C2 symmetric monomer unit yields highly crystalline polymer films but less efficient non-fullerene cells. Based on a monomer with a mirror symmetry, our best donor polymer exhibits reduced crystallinity, yet such a polymer matches better with small molecular acceptors. This study provides important insights to the design of donor polymers for non-fullerene organic solar cells.
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors: Zhengke
authors: Z
authors: Li
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.|HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st Road, Hi-tech Park, Nanshan, Shenzhen 518057, China.
authors: Kui
authors: K
authors: Jiang
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.|State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
authors: Guofang
authors: G
authors: Yang
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors: Joshua Yuk Lin
authors: 0000-0002-2196-0719
authors: JY
authors: Lai
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors: Tingxuan
authors: T
authors: Ma
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors: Jingbo
authors: 0000-0002-1143-482X
authors: J
authors: Zhao
authors: State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
authors: Wei
authors: 0000-0002-7239-2010
authors: W
authors: Ma
authors: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.|HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st Road, Hi-tech Park, Nanshan, Shenzhen 518057, China.|Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China.
authors: He
authors: H
authors: Yan