Liu Zixian, Tang Haoran, Feng Hexiang, Tan Ching-Hong, Liang Youcai, Hu Zhicheng, Zhang Kai, Huang Fei, Cao Yong
Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China.
Macromol Rapid Commun. 2022 Nov;43(22):e2200190. doi: 10.1002/marc.202200190. Epub 2022 May 15.
In organic solar cells, interfacial materials play essential roles in charge extraction, transportation, and collection. Currently, highly efficient and thickness-insensitive interfacial materials are urgently needed in printable large area module devices. Herein, water/alcohol-soluble conjugated polyelectrolyte PFNBT-Br, with medium bandgap based on benzothiadiazole, are doped by two alkali metal sodium salts, NaH PO , Na C O with different counter anions, to pursue high efficiency and thickness-insensitive electron-transport layers. Results show that the doping of electron-transport material can effectively promote the performance of the devices. Moreover, electron-transport layers doped by these salts with different counter anions show different behaviors in performances. Among which, the salt with oxalate anion C O (also named Ox ) shows much better device performance than the salt with hypophosphite anion (H PO ), especially under the thick film condition (e.g., 50 nm). The greatly enhanced performances of interfacial material doped by Ox are due to reduced series resistance between the active layer material and the electrode, reduced dark-current, improved charge transport, and extraction efficiency, and decreased charge recombination for the devices at thick-film condition. These results demonstrated that n-doping could be a great potential strategy for making thickness-insensitive interfacial layers, besides, the performances can be further improved by carefully selecting salts.
在有机太阳能电池中，界面材料在电荷提取、传输和收集方面起着至关重要的作用。目前，可印刷大面积模块器件迫切需要高效且对厚度不敏感的界面材料。在此，基于苯并噻二唑的具有中等带隙的水/醇溶性共轭聚电解质PFNBT-Br，被两种具有不同抗衡阴离子的碱金属钠盐NaH₂PO₂、Na₂C₂O₄掺杂，以寻求高效且对厚度不敏感的电子传输层。结果表明，电子传输材料的掺杂能有效提升器件性能。此外，由这些具有不同抗衡阴离子的盐掺杂的电子传输层在性能上表现出不同的行为。其中，具有草酸根阴离子C₂O₄²⁻（也称为Ox²⁻）的盐比具有次磷酸根阴离子（H₂PO₂⁻）的盐表现出更好的器件性能，尤其是在厚膜条件下（例如50纳米）。由Ox²⁻掺杂的界面材料性能大幅提升是由于活性层材料与电极之间的串联电阻降低、暗电流减小、电荷传输和提取效率提高，以及厚膜条件下器件的电荷复合减少。这些结果表明除了仔细选择盐可以进一步提高性能外，n型掺杂可能是制备对厚度不敏感的界面层的一种极具潜力的策略。
