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8.78% Efficient All‐Polymer Solar Cells Enabled by Polymer Acceptors Based on a B←N Embedded Electron‐Deficient Unit
Author(s) -
Li Yongchun,
Meng Huifeng,
Liu Tao,
Xiao Yiqun,
Tang Zhonghai,
Pang Bo,
Li Yuqing,
Xiang Ying,
Zhang Guangye,
Lu Xinhui,
Yu Gui,
Yan He,
Zhan Chuanlang,
Huang Jianhua,
Yao Jiannian
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201904585
Subject(s) - materials science , polymer , thiophene , conjugated system , acceptor , electron acceptor , ambipolar diffusion , polymer solar cell , band gap , imide , absorption spectroscopy , solar cell , absorption (acoustics) , optoelectronics , photochemistry , electron , polymer chemistry , organic chemistry , chemistry , optics , composite material , physics , quantum mechanics , condensed matter physics
In the field of all‐polymer solar cells (all‐PSCs), all efficient polymer acceptors that exhibit efficiencies beyond 8% are based on either imide or dicyanoethylene. To boost the development of this promising solar cell type, creating novel electron‐deficient units to build high‐performance polymer acceptors is critical. A novel electron‐deficient unit containing B←N bonds, namely, BNIDT, is synthesized. Systematic investigation of BNIDT reveals desirable properties including good coplanarity, favorable single‐crystal structure, narrowed bandgap and downshifted energy levels, and extended absorption profiles. By copolymerizing BNIDT with thiophene and 3,4‐difluorothiophene, two novel conjugated polymers named BN‐T and BN‐2fT are developed, respectively. It is shown that these polymers possess wide absorption spectra covering 350–800 nm, low‐lying energy levels, and ambipolar film‐transistor characteristics. Using PBDB‐T as the donor and BN‐2fT as the acceptor, all‐PSCs afford an encouraging efficiency of 8.78%, which is the highest for all‐PSCs excluding the devices based on imide and dicyanoethylene‐type acceptors. Considering that the structure of BNIDT is totally different from these classical units, this work opens up a new class of electron‐deficient unit for constructing efficient polymer acceptors that can realize efficiencies beyond 8% for the first time.