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Hydrogen‐Bonding Strategy to Optimize Charge Distribution of PC 71 BM and Enable a High Efficiency of 12.45% for Organic Solar Cells
Author(s) -
Du Xiaoyang,
Tao Silu,
Li Lijuan,
Wang Wei,
Zheng Caijun,
Lin Hui,
Zhang Xiujuan,
Zhang Xiaohong
Publication year - 2018
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201800038
Subject(s) - ternary operation , materials science , organic solar cell , stacking , dopant , energy conversion efficiency , hydrogen bond , analytical chemistry (journal) , optoelectronics , doping , chemistry , organic chemistry , molecule , composite material , computer science , programming language , polymer
Short‐circuit current density ( J SC ), fill factor (FF), and open‐circuit voltage ( V OC ) are the determining factors on organic solar cells (OSCs) performance. For ternary blend devices, the V OC generally shows a smaller change compared to their binary blend counterpart. Therefore, increase in the J SC and FF of ternary OSCs is the dominating approach to improve device performance. Here, we report a new strategy to enhance OSCs performance via hydrogen‐bonding between PC 71 BM and dopant coumarin7 (C7) in a PTB7‐Th:C7:PC 71 BM ternary system. The formation of hydrogen bonds between PC 71 BM and C7 was predicted by Vienna ab initio simulations (VASP) and verified by Fourier‐transform infrared spectroscopy (FT‐IR). Hydrogen‐bonding induces charge accumulation on the surface of PC 71 BM, which facilitates electron withdrawal of PC 71 BM and π‐π stacking between donor and acceptor, resulting in enhanced J SC values of OSCs. Besides, hydrogen bond interaction improves the morphology of C7‐containing OSCs via formation of an interpenetrating network nanofiber structure, as revealed by transmission electron microscopy (TEM). The combination of the above benefits yields a ternary blend OSC consisting of PTB7‐Th:10%C7:PC 71 BM to have an average power conversion efficiency (PCE) of 12.23% (maximum PCE of 12.45%) at a J SC of 22.26 mA cm −2 and a FF of 70.71%, which represents 31.89% enhancement above the best PCE of the control OSC (9.44%). These results demonstrate a new strategy to improve OSCs efficiency.