聚噻吩的后修饰与光电性质

Photoelectric Properties of Polythiophene Modified by Post-Polymerization Strategy

为了解决Kumada催化剂转移缩聚(Kumada catalyst transfer polycondensation,KCTP)反应构建的聚噻吩材料结构单一、能级较高等问题,通过KCTP法成功实现了含有4个噻吩单元与硫醚侧链单体的聚合,构建了含有硫代烷基侧链的新型聚噻吩材料(PtTSBO),并通过控制氧化剂间氯过氧苯甲酸(m-CPBA)的用量和反应温度,将侧链上的硫醚选择性地氧化为亚砜或砜基,制备了含有亚砜或砜基的PtTSBO(PtTSOBO或PtTSOOBO)。通过核磁共振氢(1H-NMR)谱、元素分析(EA)、紫外-可见分光(UV-Vis)光谱和电化学(CV)曲线对聚合物的结构、吸光和电学性能进行了表征,并对所制备的光伏器件进行了光电性质研究。结果表明,这种后修饰策略有效地将硫醚官能团转变为强吸电子基团,相比于PtTSBO,聚合物PtTSOBO和PtTSOOBO的能级显著降低,相应光伏器件的开路电压(Voc)得到了提升。

To optimize the structure and energy levels of polythiophene,a new type polymer namely of PtTSBO with thioalkyl side chains is successfully synthesized by Kumada catalyst transfer polycondensation(KCTP)with the monomer containing four thiophene units and thioalkyl sidechains,which broadens the scope of KTCP application.A post-polymerization strategy is also developed to functionally modify the side chains of PtTSBO.Polymers PtTSOBO and PtTSOOBO are prepared by controlling the amount of 3-chloroperbenzoic acid(m-CPBA)and the reaction temperature so that the sulfide in the side chains of PtTSBO can be efficiently and selectively oxidized to sulfoxide and sulfone.The chemical structure,light absorption and electrical properties are characterized by 1H-NMR,elemental analysis(EA),UV-Vis absorption spectroscopy and cyclic voltammetry(CV),and corresponding photovoltaic devices.After the post-polymerization modification,the HOMO energy levels of PtTSOBO and PtTSOOBO are significantly lower than that of PtTSBO,thus increasing the open-circuit voltage(Voc)of the corresponding photovoltaic devices.However,by introducing sulfoxide or sulfone groups, the planarity of the backbone in polythiophene is reduced, which is not conducive to their solid- state aggregation, consequently deteriorating the overall performance of photovoltaic devices fabricated. The photovoltaic devices based on PtTSOBO and PtTSOOBO need to be further studied and optimized, such as meticulous selection of acceptor materials with more suitable energy levels and miscibility. Meanwhile, the downshift energy levels of PtTSOBO and PtTSOOBO suggest they might be available for the application as electron-acceptor. This post-polymerization method paves a new way for modifying polythiophenes and promoting the low-cost production of functionalized polythiophenes.