物理化学学报 >> 2019, Vol. 35 >> Issue (4): 394-400.doi: 10.3866/PKU.WHXB201805091

所属专题: 非富勒烯有机太阳能电池

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骨架非稠合的电子受体在聚合物太阳能电池中的应用

章中强1,张书华1,刘志玺1,张志国2,李永舫2,李昌治1,*(),陈红征1,*()   

  1. 1 浙江大学高分子科学与工程学系,硅材料国家重点实验室,高分子合成与功能构造教育部重点实验室,杭州 310027
    2 中国科学院化学研究所,北京 100190
  • 收稿日期:2018-04-10 发布日期:2018-09-13
  • 通讯作者: 李昌治,陈红征 E-mail:czli@zju.edu.cn;hzchen@zju.edu.cn
  • 基金资助:
    国家自然科学基金(21734008);国家自然科学基金(61721005);国家自然科学基金(21674093);国家自然科学基金(51473142);浙江省科技计划(2018C01047)

A Simple Electron Acceptor with Unfused Backbone for Polymer Solar Cells

Zhongqiang ZHANG1,Shuhua ZHANG1,Zhixi LIU1,Zhiguo ZHANG2,Yongfang LI2,Changzhi LI1,*(),Hongzheng CHEN1,*()   

  1. 1 MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
    2 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2018-04-10 Published:2018-09-13
  • Contact: Changzhi LI,Hongzheng CHEN E-mail:czli@zju.edu.cn;hzchen@zju.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21734008);the National Natural Science Foundation of China(61721005);the National Natural Science Foundation of China(21674093);the National Natural Science Foundation of China(51473142);the Zhejiang Province Science and Technology Plan, China(2018C01047)

摘要:

非富勒烯电子受体由于其吸收强,能级可调,稳定性好等优点,近年来受到研究者的广泛关注,并且光电转换效率已突破14%。在本研究中,我们设计并合成了一种结构简单,易于合成的非稠环结构的非富勒烯电子受体ICTP。通过合理的结构设计,利用分子内的非共价作用力,实现了高的空间平面性。其在长波长区域宽且强的吸收和合适的能级水平,使得ICTP适合与许多聚合物给体材料搭配,制备太阳能电池。基于PBDB-T:ICTP的聚合物太阳能电池取得了4.43%的光电转换效率和0.97 V的开路电压。

关键词: 聚合物太阳能电池, 非富勒烯受体, 非共价作用力, 光电转换效率, 结构平面性

Abstract:

Non-fullerene electron acceptors have attracted enormous attention of the research community owing to their advantages of optoelectronic and chemical tunabilities for promoting high-performance polymer solar cells (PSCs). Among them, fused-ring electron acceptors (FREAs) are the most popular ones with the good structural planarity and rigidity, which successfully boost the power conversion efficiencies (PCEs) of PSCs to over 14%. In considering the cost-control of future scale-up applications, it is also worthwhile to explore novel structures that are easy to synthesize and still maintain the advantages of FREAs. In this work, we design and synthesize a new electron acceptor with an unfused backbone, 5, 5'-((2, 5-bis((2-hexyldecyl)oxy)-1, 4-phenylene)bis(thiophene-2-yl))bis(methanylylidene)) bis(3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene))dimal-ononitrile (ICTP), which contains two thiophenes and one alkoxy benzene as the core and 2-(3-oxo-2, 3-dihydroinden-1-ylidene) malononitrile (IC) as the terminal groups. The synthetic route to ICTP involves only three steps, with high yields. Density functional theory calculations indicate that the non-covalent interactions, O…H and O…S, help reinforce the space conformation between the central core and the terminals. ICTP shows broad and strong absorption in the long-wavelength range between 500 and 760 nm. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of ICTP were measured to be -5.56 and -3.84 eV by cyclic voltammetry. The suitable absorption and energy levels make ICTP a good acceptor candidate for medium bandgap polymer donors. The best devices based on PBDB-T:ICTP showed a PCE of 4.43%, with an open circuit voltage (VOC) of 0.97 V, a short circuit current density (JSC) of 8.29 mA∙cm-2, and a fill factor (FF) of 0.55, after adding 1% 1, 8-diiodooctane (DIO) as the solvent additive. Atomic force microscopy revealed that DIO could ameliorate the strong aggregation in the blended film and lead to a smoother film surface. The hole and electron mobilities of the optimized device were measured to be 9.64 and 2.03 × 10-5 cm2∙V-1∙s-1, respectively, by the space-charge-limited current method. The relatively low mobilities might be responsible for the moderate PCE. Further studies can be performed to enlarge the conjugation length by including more aromatic rings. This study provides a simple strategy to design non-fullerene acceptors and a valuable reference for the future development of PSCs.

Key words: Polymer solar cell, Non-fullerene acceptor, Non-covalent interaction, Power conversion efficiency, Structure planarity

MSC2000: 

  • O646