Influence of Covalent and Noncovalent Backbone Rigidification Strategies on the Aggregation Structures of a Wide-Band-Gap Polymer for Photovoltaic Cells,Chemistry of Materials

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Influence of Covalent and Noncovalent Backbone Rigidification Strategies on the Aggregation Structures of a Wide-Band-Gap Polymer for Photovoltaic Cells
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-02-20 , DOI: 10.1021/acs.chemmater.9b04971
Sunsun Li ₁ , Wenchao Zhao ₁ , Jianqi Zhang ₂ , Xiaoyu Liu ₁ , Zhong Zheng ₁ , Chang He ₁ , Bowei Xu ₁ , Zhixiang Wei _{2,

3} , Jianhui Hou _{1,

3}

Affiliation

With the purpose of improving the backbone planarity and thus the charge transport property of the wide-band-gap ester-modified polymer, the covalent and noncovalent (F···S conformational lock) backbone rigidification strategies are, respectively, employed to design two new benzodithiophene and ester-modified oligothiophene-based copolymers (PBDE-TT and PBDE-DFDT). Although thieno[3,2-b]thiophene (TT) and difluorinated 2,2′-bithiophene (DFDT) possess planar conformations with similar conjugation length, polymer PBDE-DFDT shows much stronger aggregation effects in diluted solution and more compact and ordered π–π stacking in thin film compared to the polymer PBDE-TT, which are associated with the existence of several nontraditional hydrogen-bonding interactions for the DFDT-based oligothiophene unit. Thus, the hole mobility of polymer PBDE-DFDT is over two times higher than that of its counterpart. The photovoltaic device based on PBDE-DFDT:IT-4F blend achieves a distinctly higher power-conversion efficiency of 14.16%, which is mainly attributed to the higher ordering of aggregates and more symmetric charge transport in the blend film. The results reveal that optimizing the aggregation structures via the modulation of intermolecular interactions is of great importance for enhancing the charge mobility and photovoltaic performance of materials, which shall be considered for further designing high-performance donor polymers with simple chemical structures.

中文翻译：

共价和非共价主链刚性化策略对光伏电池宽带隙聚合物聚集结构的影响

为了改善主链平面性并因此改善宽带隙酯改性聚合物的电荷传输性能，分别采用共价和非共价（F···S构象锁）主链刚性化策略来设计两种新的苯并二噻吩和酯改性的低聚噻吩基共聚物（PBDE-TT和PBDE-DFDT）。虽然thieno [3,2- b]噻吩（TT）和二氟2,2'-联噻吩（DFDT）具有类似的共轭长度的平面构象，与稀释后的溶液相比，聚合物PBDE-DFDT在稀释溶液中显示出更强的聚集效应，并且在薄膜中具有更紧密和有序的π-π堆积聚合物PBDE-TT，与基于DFDT的低聚噻吩单元存在几种非传统的氢键相互作用有关。因此，聚合物PBDE-DFDT的空穴迁移率是其对应物的空穴迁移率的两倍以上。基于PBDE-DFDT：IT-4F共混物的光伏器件实现了14.16％的明显更高的功率转换效率，这主要归因于共混膜中聚集体的更高排序和更对称的电荷传输。

更新日期：2020-02-20

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