Mo Daize, Chen Hui, Zhu Yulin, Huang Hsin-Hsiang, Chao Pengjie, He Feng
Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China.
School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong 529020, China.
ACS Appl Mater Interfaces. 2021 Feb 10;13(5):6147-6155. doi: 10.1021/acsami.0c17598. Epub 2021 Jan 27.
The end groups' halogenations among the nonfullerene acceptors (NFAs) were a very useful method to fabricate high-performance NFAs-based organic solar cells (OSCs). We report three high-performance NFAs, , , and . They all have a fused benzothiadiazole as the core unit and different dihalogenated end groups (IC-2F, IC-2Cl, and IC-2Br) as the terminal unit. Thanks to the improved intramolecular charge-transfer ability of the brominated NFAs, bromination is more effective than fluorination and chlorination in lowering the energy levels and red-shifting the absorption spectra of the resulting NFAs. When compared with the chlorinated and fluorinated counterparts, the blend films exhibit lower roughness, better phase separation size, and stronger face-on stacking. When blended with poly{[4,8-bis[5-(2-ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-:4,5-']-dithiophene-2,6-diyl]--[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4,8-benzo[1,2-:4,5-']dithiophene-1,3-diyl]]} (PBDB-TF) as the polymer donor material, the -based OSCs exhibit the highest power conversion efficiency (12.41%), with a higher current density and a higher open-circuit voltage than the -based OSCs (11.29%) and -based OSCs (10.64%). These results show that the bromination of the NFAs' electron-withdrawing end groups can also be very effective in constructing high-performance photovoltaic materials.
在非富勒烯受体（NFAs）中，端基卤化是制备高性能基于NFAs的有机太阳能电池（OSCs）的一种非常有用的方法。我们报道了三种高性能的NFAs， 、 和 。它们都以稠合苯并噻二唑作为核心单元，并以不同的二卤化端基（IC - 2F、IC - 2Cl和IC - 2Br）作为末端单元。由于溴化NFAs的分子内电荷转移能力得到改善，溴化在降低所得NFAs的能级和使吸收光谱红移方面比氟化和氯化更有效。与氯化和氟化的对应物相比， 共混膜表现出更低的粗糙度、更好的相分离尺寸和更强的面内堆积。当与聚{[4,8 - 双[5 - (2 - 乙基己基)-4 - 氟 - 2 - 噻吩基]苯并[1,2 - :4,5 - ']-二噻吩 - 2,6 - 二基] - - [2,5 - 噻吩二基[5,7 - 双(2 - 乙基己基)-4,8 - 二氧代 - 4,8 - 苯并[1,2 - :4,5 - ']二噻吩 - 1,3 - 二基]]}（PBDB - TF）作为聚合物供体材料共混时，基于 的OSCs表现出最高的功率转换效率（12.41%），与基于 的OSCs（11.29%）和基于 的OSCs（10.64%）相比，具有更高的电流密度和更高的开路电压。这些结果表明，NFAs吸电子端基的溴化在构建高性能光伏材料方面也可能非常有效。
