TY - JOUR
T1 - Fluorobenzotriazole (FTAZ)-Based Polymer Donor Enables Organic Solar Cells Exceeding 12% Efficiency
AU - Liao, Zhihui
AU - Xie, Yuanpeng
AU - Chen, Lie
AU - Tan, Yun
AU - Huang, Shaorong
AU - An, Yongkang
AU - Ryu, Hwa Sook
AU - Meng, Xiangchuan
AU - Liao, Xunfan
AU - Huang, Bin
AU - Xie, Qian
AU - Woo, Han Young
AU - Sun, Yanming
AU - Chen, Yiwang
N1 - Funding Information:
Z.L. and Y.X. contributed equally to this work. L.C. thanks for the support from the National Natural Science Foundation of China (NSFC) (Nos. 51673092, 21762029, 51473075, and 21674007). Y.C. thanks for support from the National Science Fund for Distinguished Young Scholars (No. 51425304), and the National Natural Science Foundation of China (NSFC) (No. 51833004). H.Y.W. acknowledges the financial support from the National Research Foundation (NRF) of Korea (2015M1A2A2057506).
PY - 2019/3/7
Y1 - 2019/3/7
N2 - The fluorobenzotriazole (FTAZ)-based copolymer donors are promising candidates for nonfullerene polymer solar cells (PSCs), but suffer from relatively low photovoltaic performance due to their unsuitable energy levels and unfavorable morphology. Herein, three polymer donors, L24, L68, and L810, based on a chlorinated-thienyl benzodithiophene (BDT-2Cl) unit and FTAZ with different branched alkyl side chain, are synthesized. Incorporation of a chlorine (Cl) atom into the BDT unit is found to distinctly optimize the molecular planarity, energy levels, and improve the polymerization activity. Impressively, subtle side chain length of FTAZ realizes a dramatic improvement in all the device parameters, as revealed by the short-current density (J sc ) improved from 7.41 to 20.76 mA cm −2 , fill-factor from 36.3 to 73.5%, and even the open-circuit voltage (V oc ) from 0.495 to 0.790 V. The best power conversion efficiency (PCE) of 12.1% is obtained from the L810-based device, which is one of the highest values reported for FTAZ-based PSCs so far. Notably, the corresponding external quantum efficiency curve keeps a very prominent value up to 80% from 500 to 800 nm. The notable performance is discovered from the reduced energy loss, improved molecular face-on orientation, the down-shifted energy levels, and optimized absorption coefficient regulated by side-chain engineering.
AB - The fluorobenzotriazole (FTAZ)-based copolymer donors are promising candidates for nonfullerene polymer solar cells (PSCs), but suffer from relatively low photovoltaic performance due to their unsuitable energy levels and unfavorable morphology. Herein, three polymer donors, L24, L68, and L810, based on a chlorinated-thienyl benzodithiophene (BDT-2Cl) unit and FTAZ with different branched alkyl side chain, are synthesized. Incorporation of a chlorine (Cl) atom into the BDT unit is found to distinctly optimize the molecular planarity, energy levels, and improve the polymerization activity. Impressively, subtle side chain length of FTAZ realizes a dramatic improvement in all the device parameters, as revealed by the short-current density (J sc ) improved from 7.41 to 20.76 mA cm −2 , fill-factor from 36.3 to 73.5%, and even the open-circuit voltage (V oc ) from 0.495 to 0.790 V. The best power conversion efficiency (PCE) of 12.1% is obtained from the L810-based device, which is one of the highest values reported for FTAZ-based PSCs so far. Notably, the corresponding external quantum efficiency curve keeps a very prominent value up to 80% from 500 to 800 nm. The notable performance is discovered from the reduced energy loss, improved molecular face-on orientation, the down-shifted energy levels, and optimized absorption coefficient regulated by side-chain engineering.
KW - absorption coefficient
KW - fluorobenzotriazole
KW - quantum efficiency
KW - side chain
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U2 - 10.1002/adfm.201808828
DO - 10.1002/adfm.201808828
M3 - Article
AN - SCOPUS:85060240701
VL - 29
JO - Advanced Functional Materials
JF - Advanced Functional Materials
SN - 1616-301X
IS - 10
M1 - 1808828
ER -
