Li Chenchen, Cai Mian, Bao Xichang, Liu Yanfang, Yang Renqiang, Wan Xiaobo
Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, School of Chemical & Environmental Engineering, Jianghan University Wuhan 430056 P. R. China
Qingdao Institute of Bioenergy & Bioprocess Technology, Chinese Academy of Sciences 189 Songling Road Qingdao 266101 People's Republic of China
RSC Adv. 2019 Apr 18;9(22):12310-12318. doi: 10.1039/c9ra01545k. eCollection 2019 Apr 17.
Lactam-containing acceptors, which could provide two potential alkylation positions (-alkylation and -alkylation), are important building blocks for polymeric donors in high performance polymer solar cells (PSCs). However, the influence of alkylation positions on the PSC performance has seldom been studied. Herein, we investigated the influence of -alkylation and -alkylation on a novel bislactam acceptor, namely dibenzonaphthyridinedione (DBND), on the physical properties of the corresponding polymers and hence their PSC performance. Besides -alkylated and -alkylated DBND, half--alkylated-half--alkylated DBND (,-DBND) was also prepared and copolymerized with stannyl bithiophene (2T). It was found that by varying the alkylation positions, the optical, crystalline and aggregation properties of the corresponding polymers were greatly altered. In comparison with P(-DBND-2T) and P(-DBND-2T), P(,-DBND-2T) shows both better solubility and shorter π-π stacking distance. By blending with PCBM, P(,-DBND-2T) forms better nano-fibrillar phase separation so that less charge recombination is observed, thus leading to a much better power conversion efficiency (PCE) around 5%, which is the highest value of the conjugated system based on ,-alkylated acceptors. The results show that the asymmetric ,-alkylation protocol is a promising way to adjust the properties of the bislactam-containing conjugated polymers.
含内酰胺的受体能够提供两个潜在的烷基化位点（-烷基化和-烷基化），是高性能聚合物太阳能电池（PSC）中聚合物供体的重要构建单元。然而，烷基化位点对PSC性能的影响鲜有研究。在此，我们研究了-烷基化和-烷基化对一种新型双内酰胺受体二苯并萘啶二酮（DBND）的影响，以及其对相应聚合物物理性质进而对PSC性能的影响。除了-烷基化和-烷基化的DBND，还制备了半-烷基化-半-烷基化的DBND（,-DBND），并将其与二丁基锡二噻吩（2T）共聚。研究发现，通过改变烷基化位点，相应聚合物的光学、结晶和聚集性质会发生很大变化。与P（-DBND-2T）和P（-DBND-2T）相比，P（,-DBND-2T）表现出更好的溶解性和更短的π-π堆积距离。通过与PCBM共混，P（,-DBND-2T）形成了更好的纳米纤维相分离，从而观察到更少的电荷复合，进而导致约5%的更高功率转换效率（PCE），这是基于,-烷基化受体的共轭体系的最高值。结果表明，不对称的,-烷基化方案是调节含双内酰胺共轭聚合物性质的一种有前景的方法。
