物理化学学报 >> 2019, Vol. 35 >> Issue (3): 275-283.doi: 10.3866/PKU.WHXB201804231

所属专题: 非富勒烯有机太阳能电池

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第三组份端基对有机太阳能电池性能的影响

薛佩瑶1,张俊祥2,辛景明3,RECHJeromy4,李腾飞1,孟凯鑫1,王嘉宇1,马伟3,尤为4,MARDER Seth R.2,韩平畴1,*(),占肖卫1,*()   

  1. 1 北京大学工学院材料科学与工程系,教育部高分子化学与物理重点实验室,北京 100871
    2 美国佐治亚理工大学化学与生物化学学院,有机光电中心,亚特兰大,佐治亚州 30332-0400,美国
    3 西安交通大学金属材料强度国家重点实验室,西安 710049
    4 美国北卡罗来纳大学教堂山分校化学系,教堂山,北卡罗来纳州27599-3290,美国
  • 收稿日期:2018-03-29 发布日期:2018-08-28
  • 通讯作者: 韩平畴,占肖卫 E-mail:ray-han@pku.edu.cn;xwzhan@pku.edu.cn
  • 基金资助:
    国家自然科学基金(21734001);国家自然科学基金(51761165023);国家自然科学基金(21504066);国家自然科学基金(21534003);美国海军部(N00014-14-1-0580);美国海军部(N00014-16-1-2520);中国科学技术部(2016YFA0200700);美国自然科学基金(DMR-1507249);美国自然科学基金(CBET-1639429)

Effects of Terminal Groups in Third Components on Performance of Organic Solar Cells

Peiyao XUE1,Junxiang ZHANG2,Jingming XIN3,Jeromy RECH4,Tengfei LI1,Kaixin MENG1,Jiayu WANG1,Wei MA3,Wei YOU4,Seth R. MARDER2,Ray P. S. HAN1,*(),Xiaowei ZHAN1,*()   

  1. 1 Department of Materials Science and Engineering, College of Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing 100871, P. R. China
    2 Center for Organic Photonics and Electronics, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
    3 State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    4 Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
  • Received:2018-03-29 Published:2018-08-28
  • Contact: Ray P. S. HAN,Xiaowei ZHAN E-mail:ray-han@pku.edu.cn;xwzhan@pku.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21734001);the National Natural Science Foundation of China(51761165023);the National Natural Science Foundation of China(21504066);the National Natural Science Foundation of China(21534003);the Department of the Navy, U.S.(N00014-14-1-0580);the Department of the Navy, U.S.(N00014-16-1-2520);the Ministry of Science and Technology, China(2016YFA0200700);the Natural Science Foundation, U.S.(DMR-1507249);the Natural Science Foundation, U.S.(CBET-1639429)

摘要:

我们用宽带隙聚合物FTAZ (苯并二噻吩-二氟苯并氮三唑共聚物)作为给体,窄带隙稠环电子受体FOIC (六噻吩稠环-氟代腈基茚酮类化合物)作为受体,中带隙稠环电子受体IDT-IC (引达醒-腈基茚酮类化合物)和IDT-NC (引达醒-腈基苯并茚酮类化合物)分别作为第三组分,制备了三元共混有机太阳能电池,研究了第三组分端基对器件性能的影响。IDT-IC和IDT-NC具有相似的化学结构,仅端基不同;IDT-IC端基是苯环,而IDT-NC端基是萘环。与IDT-IC相比,IDT-NC吸收光谱红移40 nm,LUMO能级下移0.11 eV,电子迁移率提高50%。基于FTAZ:FOIC,FTAZ:IDT-IC,FTAZ:IDT-NC二元共混体系的有机太阳能电池效率分别为9.73%,7.48%,7.68%。FTAZ:FOIC:IDT-IC和FTAZ:FOIC:IDT-NC三元共混器件的效率分别提升到11.2%和10.4%。对于FTAZ:FOIC:IDT-IC三元共混器件,由于IDT-IC比FOIC具有更高的LUMO能级,开路电压(VOC)随着IDT-IC含量的增多而增加。由于IDT-IC与FOIC吸收光谱高度互补,短路电流(JSC)也显著提高。第三组份IDT-IC的加入改善了薄膜形貌和载流子传输,填充因子(FF)有所提高。对于FTAZ:FOIC:IDT-NC三元共混器件,由于IDT-NC比FOIC具有更高的LUMO能级,VOC随着IDT-NC含量的增多而增加;但由于IDT-NC的LUMO能级比IDT-IC的LUMO能级低,其VOC比FTAZ:FOIC:IDT-IC体系低。由于FOIC和IDT-NC吸收光谱高度重叠,JSC降低。第三组份IDT-NC的加入改善了薄膜形貌和载流子传输,FF提高,甚至比FTAZ:FOIC:IDT-IC体系有更好的载流子传输和FF。

关键词: 稠环电子受体, 非富勒烯受体, 有机太阳能电池, 端基效应, 三元共混

Abstract:

Ternary blends have been considered as an effective approach to improve power conversion efficiency (PCE) of organic solar cells (OSCs). Among them, the fullerene-containing ternary OSCs have been studied extensively, and their PCEs are as high as over 14%. However, all non-fullerene acceptor ternary OSCs are still limited by their relatively lower PCEs. In this work, we used wide-bandgap benzodithiophene-difluorobenzotriazole copolymer FTAZ as the donor, low-bandgap fused-ring electron acceptor (FREA), fused tris(thieno- thiophene) end-capped by fluorinated 1, 1-dicyanomethylene-3-indanone (FOIC) as acceptor, and two medium-bandgap FREAs, indaceno-dithiophene end- capped by 1, 1-dicyanomethylene-3-indanone (IDT-IC) and indacenodithiophene end-capped by 1, 1-dicyanomethylene-3-benzoindanone (IDT-NC), as the third components to fabricate the ternary blends FTAZ:FOIC:IDT-IC and FTAZ:FOIC:IDT-NC, and investigated the effects of the third components on the performance of ternary OSCs. Both IDT-IC and IDT-NC are based on the same indacenodithiophene core but contain different terminal groups (phenyl and naphthyl). Relative to IDT-IC with phenyl terminal groups, IDT-NC with naphthyl terminal groups has extended π-conjugation, down-shifted lowest unoccupied molecular orbital (LUMO), red-shifted absorption and higher electron mobility. The binary devices based on the FTAZ:FOIC, FTAZ:IDT-IC and FTAZ:IDT-NC blends exhibit PCEs of 9.73%, 7.48% and 7.68%, respectively. Compared with corresponding binary devices, both ternary devices based on FTAZ:FOIC:IDT-IC and FTAZ:FOIC:IDT-NC exhibit better photovoltaic performances. When the IDT-IC weight ratio in acceptors is 50%, the FTAZ:FOIC:IDT-IC ternary devices exhibit the best PCE of 11.2%. The ternary-blend OSCs yield simultaneously improved open-circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) compared with the binary devices based on FTAZ:FOIC. The higher VOC is attributed to the higher LUMO energy level of IDT-IC compared with FOIC. The improved JSC is attributed to the complementary absorption of FOIC and IDT-IC. The introduction of IDT-IC improves blend morphology and charge transport, leading to higher FF. The FTAZ:FOIC:IDT-NC system yields a higher PCE of 10.4% relative to the binary devices based on FTAZ:FOIC as the active layer. However, the PCE of the FTAZ:FOIC:IDT-NC-based ternary devices is lower than that of the FTAZ:FOIC:IDT-IC-based ternary devices. Compared with the binary devices based on FTAZ:FOIC, in FTAZ:FOIC:IDT-NC-based ternary devices, as the ratio of the third component increases, the VOC increases due to the higher LUMO energy level of IDT-NC, the FF increases due to optimized morphology and improved charge transport, while the JSC decreases due to the overlapped absorption of FOIC and IDT-NC. The terminal groups in the third components affect the performance of the ternary OSCs. The lower LUMO. energy level of IDT-NC is responsible for the lower VOC of the FTAZ:FOIC:IDT-NC devices. The red-shifted absorption of IDT-NC leads to the overlapping of the absorption spectra of IDT-NC and FOIC and lower JSC. On the other hand, replacing the phenyl terminal groups by the naphthyl terminal groups influences the π-π packing and charge transport. The FTAZ:FOIC:IDT-NC blend exhibits higher electron mobility and more balanced charge transport than FTAZ:FOIC:IDT-IC, leading to a higher FF.

Key words: Fused-ring electron acceptor, Non-fullerene acceptor, Organic solar cell, Terminal-group effect, Ternary blend

MSC2000: 

  • O649