新型稠环苯并呋喃类宽带隙聚合物材料的合成及性能研究

The key component in a polymer solar cell is the photovoltaic material. According to the optical bandgap, polymer donors can be divided into three major types: wide-bandgap (WBG), moderate-bandgap (MBG) and low-bandgap (LBG) copolymers. In terms of the development of donor-acceptor (D–A) conjugated polymers, the emphasis has been on MBG and LBG polymers. However, the design and synthesis of high-performance WBG polymers still remains a challenge. Solar cells based on WBG polymers tend to have high open-circuit voltage (Voc), but relatively low short-circuit current (Jsc), resulting in moderate power conversion efficiencies (PCEs). Benzo[1,2-b:4,5-b′]difuran (BDF) has recently attracted attention due to its symmetric and planar conjugated structure. Moreover, furan is an abundant product, which can be made from renewable resources, such as vegetable waste in agriculture and food industry and can lower the production cost of the materials. In comparison with the well-studied benzo[1,2-b:4,5-b′]thiophene (BDT) unit, BDF has received far less attention. The PCEs of BDF-based copolymers are relatively lower. Exploration of high-performance WBG polymers is of crucial importance for multi-junction organic solar cells. In this project, the applicant will focus on the development of high-performance BDF-based wide-bandgap polymer donors. On the one hand, the applicant will design and synthesize high-performance WBG polymer donors by enlarging π-conjugated system with fused aromatic rings along the polymer backbone to increase the carrier mobility. On the other hand, the applicant will systematically study the influence of the conjugated side chains on the performance of the materials. Finally, organic solar cells have been fabricated with these high-performance WBG conjugated polymers.

聚合物光伏材料是聚合物有机太阳能电池的核心组成部分，根据其带隙大小，可分为宽带隙、中宽带隙和窄带隙三类。其中，宽带隙聚合物材料的发展滞后且性能较低。最近苯并二呋喃单元（BDF）引起了科研人员的广泛关注，主要因为BDF单元为刚性共轭结构且结构对称，另外构成BDF的结构单元-呋喃是可再生以及可生物降解的，从而可以大幅度降低原料成本，减少环境污染。虽具有上述优点，但目前基于BDF的宽带隙聚合物材料种类匮乏，光伏性能有待提高。所以从材料角度考虑，开发高性能的宽带隙聚合物材料是促进有机太阳能电池发展的有效途径之一。申请人将重点设计合成具有高迁移率的大π共轭平面结构的BDF类宽带隙聚合物材料：系统研究BDF分子中不同侧链对宽带隙聚合物材料性能的影响，从中揭示结构-性能之间的关系；同时通过构筑太阳能电池器件来筛选出高性能的宽带隙聚合物光伏材料。

有机太阳能电池因其成本低、制作容易以及可制成柔性大面积器件等优点，已经成为太阳能电池中最热门的研究领域之一。聚合物光伏材料是聚合物有机太阳能电池的核心组成部分，根据其带隙大小，可分为宽带隙、中宽带隙和窄带隙三类。其中，宽带隙聚合物材料的发展滞后且性能较低。最近苯并二呋喃单元（BDF）引起了科研人员的广泛关注，主要因为BDF单元为刚性共轭结构且结构对称，另外构成BDF的结构单元-呋喃是可再生以及可生物降解的，因此可以大幅度降低原料成本，减少环境污染。虽具有上述优点，但目前基于BDF的宽带隙聚合物材料种类匮乏，光伏性能有待提高。所以从材料角度考虑，开发高性能的宽带隙聚合物材料是促进有机太阳能电池发展的有效途径之一。申请人系统研究了苯环、噻吩氯和萘基等共轭侧链对BDF单元的影响，与苯并三氮唑受体单元或者苯并二噻吩二酮受体单元共聚，合成了几种高性能聚合物给体材料，设计合成出了几种低HOMO能级、宽带隙和高迁移率的BDF聚合物光伏材料；系统研究了不同取代基的BDF单元对聚合物聚集态结构的影响，发现在薄膜状态下能形成纤维结构的BDF聚合物，具有较高的结晶性和迁移率；与不同的稠环电子受体材料共混，制备了效率近16%的有机光伏器件，系统研究了活性层形貌对电荷传输和光伏性能之间的关系。此外，申请人还在设计与合成稠环电子受体材料、三元有机光伏器件以及电压能量损失方面也做了系列研究工作。所取得的研究成功相继发表在Nat.Commun.，Adv. Mater.，Angew. Chem. Int. Ed., Adv. Energy Mater., Adv. Funct. Mater, Acs Energy Mater.和Chem. Mater.等国际著名杂志上。申请人基于BDF的系列研究工作，拓展了聚合物给体材料体系，推动了有机太阳能电池领域的发展。