title: Solution-Processable Hyperbranched Conjugated Polymer Nanoparticles Based on C3h-Symmetric Benzotrithiophene for Polymer Solar Cells.
abstract: The development of photovoltaic polymers based on C3h-symmetric benzotrithiophene (C3h-BTT), an analogue of the well-known benzodithiophene (BDT) donor unit, has been severely limited due to difficult processability. Here the authors report the preparation of solution-processable C3h-BTT-based hyperbranched conjugated polymer nanoparticles (BTT-HCPNs) with tunable particle sizes via Stille miniemulsion polymerization. Compared with the corresponding star-shaped small molecule (C3h-BTT core with three diketopyrrolopyrrole arms, BTT-3DPP) with a wide bandgap (1.83 eV), both BTT-HCPNs show strong aggregation even in dilute solutions, leading to much-extended absorption (up to ≈1000 nm) and lower bandgaps (1.38 eV). The larger BTT-HCPN particle exhibits stronger aggregation and more extended absorption than the smaller one. As a result, solar cells fabricated from BTT-HCPNs/PC71BM solutions show a power conversion efficiency up to 1.51% after DIO additive treatment, much higher than that of BTT-3DPP (0.31%).
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
authors.forename: Xiaofu
authors.initials: X
authors.lastname: Wu
authors.affiliation: University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Hang
authors.affiliation: University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Tong
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
authors.forename: Lixiang
authors.initials: L
authors.lastname: Wang
mesh_terms: D053758:Nanoparticles / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D012993:Solar Energy; D013472:Sunlight
chemical_list: D011108:Polymers
keywords: Stille polymerization in miniemulsions; benzotrithiophene; hyperbranched conjugated polymer nanoparticles; polymer solar cells; solution-processability