Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (9): 20230163.doi: 10.7503/cjcu20230163

• Article • Previous Articles     Next Articles

Simple Modulation of Side-chains of Near-infrared Absorbing Non-fullerene Acceptor for Higher Short-circuit Current Density

WANG Jiacheng1, CAI Guilong3, ZHANG Yajing1, WANG Jiayu2, LU Xinhui3, ZHAN Xiaowei2(), CHEN Xingguo1()   

  1. 1.Hubei Key Laboratory on Organic and Polymeric Opto?electronic Materials,College of Chemistry and Molecular Sciences,Wuhan University,Wuhan 430072,China
    2.School of Materials Science and Engineering,Peking University,Beijing 100871,China
    3.Department of Physics,Chinese University of Hong Kong,Hong Kong 999077,China
  • Received:2023-04-01 Online:2023-09-10 Published:2023-06-05
  • Contact: CHEN Xingguo E-mail:xwzhan@pku.edu.cn;xgchen@whu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51973163)

Abstract:

A long flexible side-chain of n-octyl group has been simultaneously introduced at indacenodithieno[3,2-b]thiophene(IDT) central core and (1,1-dicyanomethylene)rhodanine end-group to build a new “A-π-D-π-A” type non-fullerene acceptor(NFA)(JC11) with thiophene-fused benzothiadiazole(BTT) unit as a π-bridge, which has been proposed to investigate the influence of different side-chains at different sites of the same conjugated backbone on the properties. Compared with the previous reported acceptors A2 and JC1, the introduction of a suitable long alkyl side-chain of octyl groups at central core and terminal group not only endows JC11 to show more favorable intermolecular stacking, thus exhibiting more red-shifted absorption and better improved crystallinity than A1 with a more rigid and steric hexylphenyl group at central core, but also ensures its better solubility to avoid the poor phase-separation morphology in the blend film with PTB7-Th than JC1 with a short ethyl side-chain at end-group. Moreover, JC11 owns a higher molar extinction coefficient of up to 1.14×105 L∙mol-1∙cm-1 and a higher electron mobility of 1.01×10-3 cm2∙V-1∙s-1 as well as more balanced electron/hole mobilities(μe/μh=2.72) in the D/A blend film than A2 and JC1. Therefore, the optimized PTB7-Th∶JC11 based device achieves a more promising power conversion efficiency(PCE) of 10.09% with a much higher short circuit current density(JSC) value of 24.20 mA/cm2, which greatly surpass the PCE of 8.20% and 8.16% with relatively low JSC values of less than 20 mA/cm2 for the optimized devices based on PTB7-Th∶A2 and PTB7-Th∶JC1, respectively. This work indicates that the regulation of side-chains is a simple but very effective strategy to improve the absorption and crystallization properties of the NFAs, thus resulting in higher JSC and PCE for bulk heterojunction organic solar cells.

Key words: A-π-D-π-A structure, Non-fullerene acceptors(NFAs), Side-chain engineering, Organic solar cell

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