High‐Performance Ternary Polymer Solar Cells Enabled by a New Narrow Bandgap Nonfullerene Small Molecule Acceptor with a Higher LUMO Level,Macromolecular Rapid Communications

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High‐Performance Ternary Polymer Solar Cells Enabled by a New Narrow Bandgap Nonfullerene Small Molecule Acceptor with a Higher LUMO Level
Macromolecular Rapid Communications ( IF 4.2 ) Pub Date : 2020-10-21 , DOI: 10.1002/marc.202000393
Dan Su ₁ , Kun Li ₂ , Wanru Liu ₁ , Weichao Zhang ₃ , Xiaofang Li ₁ , Yishi Wu ₂ , Fugang Shen ₁ , Shuying Huo ₁ , Hongbing Fu ₂ , Chuanlang Zhan ₃

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Obtaining a large open‐circuit voltage (V_OC) and high short‐circuit current density (J_SC) simultaneously is important in improving power conversion efficiency (PCE) of organic photovoltaics. The ternary strategy with using a higher lowest unoccupied molecular orbital (LUMO) level nonfullerene acceptor (NFA) guest can achieve increased V_OC, yet J_SC is decreased or maintained, so it's still a challenge to offer increased V_OC and J_SC values concurrently via the newly presented V_OC‐increased ternary strategy. To overcome this issue, a new narrow bandgap NFA TT‐S‐4F is reported by introducing 3,6‐dimethoxylthieno[3,2‐b]thiophene (TT) as π‐spacers to connect electron‐rich core with terminal groups, so as to upshift the LUMO level and extend π‐system. When adding 10% TT‐S‐4F into binary system based on PTB7‐Th:IEICO‐4F, the higher‐LUMO‐level of TT‐S‐4F, the increased charge mobilities, the reduced trap‐assisted combination loss, and a finer nanofiber structure and increased phase separation size are obtained, which simultaneously promotes J_SC, V_OC, and fill factor (FF), thus obtaining an optimal PCE (12.5% vs 11.5%). This work illustrates that an extending conjugated backbone with large π‐spacers and inclusion of alkylthiophenyl side‐chains is a concept to synthesize NFA guests for use on the V_OC‐increased ternary strategy that enables to realize simultaneously increased J_SC, V_OC, and FF.

中文翻译：

新型窄带隙非富勒烯小分子受体具有更高的LUMO含量，可实现高性能三元聚合物太阳能电池

同时获得较大的开路电压（V _OC）和较高的短路电流密度（J _SC）对于提高有机光伏的功率转换效率（PCE）非常重要。使用较高的最低未占用分子轨道（LUMO）水平的非富勒烯受体（NFA）客体的三元策略可以实现增加的V _OC，但是J _SC降低或维持，因此同时提供增加的V _OC和J _SC值仍然是一个挑战通过新推出的V _OC增加三元策略。为了克服这个问题，报道了一种新的窄带隙NFA TT-S-4F，它通过引入3,6-二甲氧基噻吩并[3,2-b]噻吩（TT）作为π间隔基来连接富电子核心和末端基团，因此以提高LUMO水平并扩展π系统。当将10％TT‐S‐4F添加到基于PTB7‐Th：IEICO‐4F的二进制系统中时，TT‐S‐4F的LUMO级别更高，电荷迁移率提高，陷阱辅助的组合损耗降低以及获得了更细的纳米纤维结构和更大的相分离尺寸，同时促进了J _SC，V _OC，以及填充因子（FF），从而获得最佳PCE（12.5％对11.5％）。这项工作说明具有大π间隔基并包含烷基硫代苯基侧链的扩展共轭主链是合成NFA客体以用于V _OC增加的三元策略的概念，该策略能够同时实现J _SC，V _OC和FF。

更新日期：2020-12-07

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