近红外聚合物受体的设计合成及其在全聚合物太阳电池中的应用

All-polymer solar cells (all-PSCs) are of great industrial prospect and market value due to their advantages of easy adjustment of optoelectronic properties, good optical/thermal stability and outstanding mechanical properties. However, one of the critical issues to limit all-PSCs from labs to practical applications is the relatively lower photovoltaic efficiencies. In particular, the current high-performance all-PSCs have poor absorptions in the solar spectrum, including the lower absorption coefficients and lacks of the near-infrared region, which is among the important restrictions of the advance of the device efficiencies. Therefore, the applicant intends to use 3-(dicyanomethylidene)indan-1-one (IC) as parent moieties, which is commonly used end-capping groups in the design of excellent small molecular acceptors, to construct the polymerizable electron-deficient units. By fusing and then modifying two IC moieties, the monomer fused IC (f-IC) unit can be obtained, and then it will be used to design novel polymer acceptors with strong near-infrared absorption. In the project, two methods, for example, tuning the structure of electron-donating units in the copolymer main chain and the fusing position of f-IC, will be used for adjusting the copolymer acceptors’ optoelectronic properties and physicochemical properties. Then the combined stratergy of the polymer donors selection and optimization of processing devices will be used to fabricate high-performance all-PSCs. Besides, how the highly efficient polymer acceptors are matched with polymer donors and the material structure-property relationship will be studied. On the basis, ternary all-PSCs will also be tried to made for the better photovoltaic efficiencies. The project will provide material alternatives and design rules for the realization of high-performance all-PSCs, and it will also speed up the commercialization of this photovoltaic technology.

全聚合物太阳电池（all-PSCs）由于具有光电性能易于调节、光/热稳定性好、机械性能突出的优势极具产业化前景和市场应用价值。然而, all-PSCs从实验室走向实际应用仍面临“光伏效率偏低”的问题。针对当前高效全聚合物活性层中吸光区域吸收系数低、吸光范围窄的局限，申请人拟以高效小分子受体中广泛使用的缺电子单元-氰基茚酮（IC）作为母体，将两个IC单元稠合和修饰构筑可聚合用的缺电子单元，并以此设计合成新型近红外共聚物受体材料。通过改变共聚物中共聚单元类型和缺电子单元并环方式，调节其基本光电性能和物理化学特性，并通过选用合适的聚合物给体优化工艺条件，实现高效的all-PSCs；此外，研究该类高效聚合物给、受体间的匹配规律以及材料的构效关系；以此为基础，探索材料在三元all-PSCs中的应用以提升器件性能。本项目的实施为高效all-PSCs提供了材料备选和设计思路，并推进了该技术的应用化进程。

围绕“全聚合物太阳电池(all-PSCs)近红外区域吸光弱”这一关键问题，本项目通过设计合成新型近红外聚合物受体材料构筑高效的all-PSCs。首先，通过设计引达省四酮（ITO）单元的聚合物受体材料实现了7.60%的光伏效率，进一步作为第三组份制备器件实现了16.08%的光伏性能。由于ITO类聚合物受体近红外区域太阳光吸收能力仍不充足，因此，我们设计了其他类型的高效聚合物电子受体材料。通过分离受体端基设计合成了溴位置异构的小分子受体单体和相应的聚合物电子受体。该部分研究揭示了取代位置和主链键接方式对材料光伏性能的影响，5-位键接的聚合物受体能够显著提升材料的光伏性能，实现超过16%的光伏效率，超过当时文献报道的最高值。这一高效的器件性能显然离不开受体聚合物近红外区强的吸光能力。此外，项目中也包含了非稠合近红外聚合物电子受体的研究。尽管设计的受体材料未实现高效的光伏器件，但是展现了其在钙钛矿太阳电池中的应用潜力。理论上，如果共轭单元选择合适，烷基链长短调控得当，这类材料仍然有巨大的提升空间。这类聚合物受体材料的开发有望为高效聚合物光伏材料低成本地制备提供可能。此外，本研究中仍然存在一些不足需要完善。基于非稠合近红外聚合物受体材料探索还不够详细深入，材料结构的优化设计、器件工艺、共混膜形貌和器件物理过程研究不足，需要后续更进一步的研究。