基于苯并噻二唑的小分子光伏材料设计合成与性质研究

摘要

通过 Suzuki偶联反应成功合成了两种新型的小分子光伏给体材料 BT-1和 BT-2,其以5,6-正辛氧基苯并噻二唑为中心吸电子单元,分别以9-苯基-9H-咔唑或 N,N-二甲基苯胺为末端给电子单元,以联二噻吩或噻吩为桥键.利用核磁和高分辨质谱对其进行了结构表征.通过紫外-可见吸收光谱和电化学循环伏安法及密度泛函和含时密度泛函理论对其性质进行了研究.结果表明,BT-1和BT-2在常规有机溶剂中具有良好的溶解性;具有较宽的紫外-可见光谱吸收范围;具有与受体材料 PC61BM相匹配的 HOMO 和 LUMO 能级.其中,弱给电子单元9-苯基-9 H-咔唑的引入有效降低了BT-1的 HOMO能级,有助于获得较高的开路电压;强给电子单元 N,N-二甲基苯胺的引入降低了BT-2的禁带宽度,有利于获得较大的短路电流.%Two novel small molecule photovoltaic donor materials of BT-2 and BT-1 are designed and synthesized by Suzuki coupling reaction,consisting of 5,6-bis-(octyloxy)benzo [c][1,2,5] thiadiazole as acceptor core,9-phenyl-9 H-carbazole or N,N-dimethylaniline donor unit as different ending groups,and bithiophene or thiophene as π bridge-bond,respectively.The structures of two small molecules are characterized by NMR and HRMS,and the properties of the materials are studied by UV-visible absorption spectra,cyclic voltammetry and DFT as well as TD-DFT computation.The results show that the compounds BT-1 and BT-2 all have good solubility in common organic solvent, and exhibit a broad absorption range covering the whole visible spectral region and keep the appropriate HOMO and LUMO energy levels matched with acceptor material PC61BM.BT-1 with 9-phenyl-9 H-carbazole as donor unit shows more deeper HOMO energy level which is beneficial for increasing the open-circuit voltage.BT-2 with N,N-dimethylaniline donor unit achieves relatively narrow bandgap which is beneficial for getting higher short circuit current.