Design of a New Small‐Molecule Electron Acceptor Enables Efficient Polymer Solar Cells with High Fill Factor,Advanced Materials

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Design of a New Small‐Molecule Electron Acceptor Enables Efficient Polymer Solar Cells with High Fill Factor
Advanced Materials ( IF 27.4 ) Pub Date : 2017-10-23 , DOI: 10.1002/adma.201704051
Sunsun Li _{1,

2} , Long Ye ₃ , Wenchao Zhao _{1,

2} , Xiaoyu Liu ₁ , Jie Zhu ₁ , Harald Ade ₃ , Jianhui Hou _{1,

2}

Affiliation

Improving the fill factor (FF) is known as a challenging issue in organic solar cells (OSCs). Herein, a strategy of extending the conjugated area of end‐group is proposed for the molecular design of acceptor–donor–acceptor (A–D–A)‐type small molecule acceptor (SMA), and an indaceno[1,2‐b:5,6‐b′]dithiophene‐based SMA, namely IDTN, by end‐capping with the naphthyl fused 2‐(3‐oxocyclopentylidene)malononitrile is synthesized. Benefiting from the π‐conjugation extension by fusing two phenyls, IDTN shows stronger molecular aggregation, more ordered packing structure, thus over one order of magnitude higher electron mobility relative to its counterpart. By utilizing the fluorinated polymer (PBDB‐TF) as the electron donor, the corresponding device exhibits a high efficiency of 12.2% with a record‐high FF of 0.78, which is approaching the theoretical limit of OSCs. Compared with the reference molecule, such a high FF in the IDTN system can be mainly attributed to the more ordered π–π packing of acceptor aggregates, higher domain purity and symmetric carrier transport in the blend. Hence, enlarging the conjugated area of the terminal‐group in these A–D–A‐type SMAs is a promising approach not only for enhancing the electron mobility, but also for improving the blend morphology, and both of them are conducive to the fill‐factor breakthrough.

中文翻译：

新型小分子电子受体的设计可实现具有高填充因子的高效聚合物太阳能电池

在有机太阳能电池（OSC）中，提高填充因子（FF）是一个具有挑战性的问题。本文中，针对受体-供体-受体（A-D-A）型小分子受体（SMA）和indaceno [1,2-b]的分子设计，提出了扩展端基共轭面积的策略。：5,6-b']二噻吩基SMA，即IDTN，通过将萘基稠合的2-（3-氧代环戊基）丙二腈进行封端合成。得益于通过融合两个苯基进行的π共轭扩展，IDTN表现出更强的分子聚集性，更有序的堆积结构，因此相对于其对应物而言，电子迁移率高出一个数量级。通过使用氟化聚合物（PBDB-TF）作为电子供体，相应的器件具有12.2％的高效率和0.78的创纪录高FF，这已接近OSC的理论极限。与参考分子相比，IDTN系统中如此高的FF主要归因于受体聚集体的π-π堆积更有序，共混物中更高的域纯度和对称的载流子传输。因此，在这些A–D–A型SMA中扩大末端基团的共轭面积是一种有前途的方法，不仅可以增强电子迁移率，而且可以改善共混物的形貌，并且两者都有利于填充。因素突破。

更新日期：2017-10-23

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