Impact of molecular solvophobicity vs. solvophilicity on device performances of dimeric perylene diimide based solution-processed non-fullerene organic solar cells.
Impact of molecular solvophobicity vs. solvophilicity on device performances of dimeric perylene diimide based solution-processed non-fullerene organic solar cells.
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DOI：
10.1039/c3cp51475g
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发表时间：
2013-06
期刊：
影响因子：
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通讯作者：
Zhenhuan Lu;Xin Zhang;C. Zhan;B. Jiang;Xinliang Zhang;Lili Chen;J. Yao
中科院分区：
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作者：
Zhenhuan Lu;Xin Zhang;C. Zhan;B. Jiang;Xinliang Zhang;Lili Chen;J. Yao
由于其优异的分子光电性能，二萘嵌苯二酰亚胺（PDI）是常用的PCBM的有前途的替代品。然而，PDIs过强的聚集能力、差的溶液加工性和相容性严重限制了其光伏应用。我们转而借用两亲物的概念来改善这些超分子性质。实际上，我们通过改变噻吩基桥接的二聚体PDI骨架的湾区中的弱疏溶剂2-甲氧基乙氧基（EG）基团的数目，相对于分子亲溶剂性（例如F（疏溶剂体/亲溶剂体））微调分子疏溶剂性，形成Bis-PDI-T（0 EG）、Bis-PDI-T-EG（2 EG）和Bis-PDI-T-di-EG（4 EG）的三种PDI二聚体（方案1）。通过ITO/PEDOT：PSS/P3HT：PDI dimer/Ca/Al的器件结构研究了这些二聚体作为溶液处理的非富勒烯电子受体和P3HT作为电子供体的光伏性能。Bis-PDI-T表现出过强的聚集能力和非常差的溶液加工性，这严重限制了相容性，得到非常差的功率转换效率（PCE）为0.007%。当两个EG基团连接在1，1 ′-位上时，所得的Bis-PDI-T-EG显示出显著降低的聚集能力，改善的溶液加工性，相容性和适当的相分离。小尺寸相（~20 nm）在活性层中占主导地位，并且最佳PCE增加到0.39%。当引入四个疏溶剂EG官能团时，提供了具有优异超分子性质的Bis-PDI-T-di-EG，特别是相分离的改善，相尺寸增加到2-4 nm，电子和空穴迁移率相对于Bis-PDI-T-EG提高了2 - 4倍。最佳PCE进一步提高到0.88%。在使用1-氯萘作为1，2-二氯苯的共溶剂以进一步改善相容性之后，PCE进一步提高至Bis-PDI-T的0.41%、Bis-PDI-T-EG的0.76%和Bis-PDI-T-di-EG的1.54%。
Because of their outstanding molecular optoelectronic properties, perylene diimides (PDIs) are promising alternatives to the commonly used PCBM. However, the overly strong aggregation ability, poor solution-processability and compatibility of PDIs severely limit their photovoltaic applications. We turned to borrowing the amphiphile concept to improve these supramolecular properties. Practically, we fine-tuned the molecular solvophobicity with respect to the molecular solvophilicity, e.g. F(solvophob/solvophil), by changing the number of the weakly solvophobic 2-methoxyethoxyl (EG) groups in the bay-region of the thienyl-bridged dimeric PDI backbone, forming three PDI dimers of Bis-PDI-T (0 EG), Bis-PDI-T-EG (2 EG) and Bis-PDI-T-di-EG (4 EG) (Scheme 1). The photovoltaic properties using these dimers as the solution-processed non-fullerene electron-acceptor and P3HT as the electron-donor were investigated via the device configuration of ITO/PEDOT:PSS/P3HT:PDI dimer/Ca/Al. Bis-PDI-T exhibited overly strong aggregation ability and very poor solution-processability, which severely limited compatibility, giving a very poor power conversion efficiency (PCE) of 0.007%. When two EG groups were attached at the 1,1'-positions, the resulted Bis-PDI-T-EG showed dramatically reduced aggregation ability, improved solution-processability, compatibility and proper phase separation. Small sized phases (∼20 nm) dominated in the active layer and the best PCE was increased to 0.39%. When four solvophobic EG functions were introduced, affording Bis-PDI-T-di-EG with excellent supramolecular properties, particularly, the improvement of the phase separation with an increased phase size of 24 nm and the enhanced electron and hole mobilities, by 2-4 times, with respect to that of Bis-PDI-T-EG. The best PCE was further enhanced to 0.88%. After using 1-chloronaphthalene as the co-solvent of 1,2-dichlorobenzene to further improve the compatibility, the PCE was improved further up to 0.41% for Bis-PDI-T, 0.76% for Bis-PDI-T-EG and 1.54% for Bis-PDI-T-di-EG.