新型Silole与窄带隙单体的交替共聚物的合成、荧光光谱及光伏性能

Novel Alternating Copolymers Based on Silole and Narrow Band Gap Monomers: Synthesis, Photoluminescence and Photovoltaic Behaviour

采用Pd催化偶联的方法合成了1,1-二乙炔基-2,3,4,5-四苯基S ilole,并分别与2,1,3-苯并噻二唑(BT)和4,7-二(2-噻基)-2,1,3-苯并噻二唑(DBT)组成两种交替共聚物PS-BT和PS-DBT,并研究了两种共聚物的紫外吸收光谱、光致发光及光伏电池性能。PS-DBT具有更宽的可见光吸收范围和更强的吸收。两种共聚物溶液的光致发光光谱的最大发射波长均随着溶液浓度的增大逐步红移。光伏电池器件结构为ITO/PE-DOT/copolym ers∶PCBM(1∶4)/Ba/A l。PS-BT和PS-DBT的开路电压分别为0.50,0.40 V,填充因子(FF)分别为24%和33%,在模拟太阳光(AM1.5)照射下的能量转化效率(ECE)分别为0.009%和0.032%。

During the last decade, conjugated polymers have attracted much attention because of their important applications in polymeric light-emitting diodes, photovoltaic cells, and field-effect transistors. Siloles are conjugated organometallic molecules that possess low-lying LUMO associated with the σ^＊-π^＊ conjugation arising from the interaction between the σ^＊ orbital of two exocyclic or-bonds on the ring silicon and the π^＊ orbital of butadiene moiety. As a result, siloles exhibit high electron acceptability and fast electron mobility. So far siloles have been utilized as efficient electron-transport materials and light-emitting materials in the construction of electroluminescence devices, and increasing interests have been paid to silole-base polymers. Benzothiadiazole and its derivatives are excellently narrow band-gap comonomers for modifications of known conjugated polymers, which can tune emission color of copolymers with enhanced emissive efficiency due to efficiently intramolecular and intermolecular energy transfer. Up to now, to the best of our knowledge, there is no report of a copolymer derived from a silole and benzothiadiazole or its derivative, and applications of a silole-based polymer in photovoltaic cells have not been investigated. Two novel alternating copolymers PS-BT and PS-DBT derived from 1,1-diethynyl-2,3,4,5-tetraphenylsilole and 2,1,3-benzothiadiazole （BT） or 4,7-bis（2-thienyl） -2,1,3-benzothiadiazole （DBT） were prepared by palladium-catalyzed coupling reactions. UV-Vis absorption, photoluminescence （PL） and photovohaic behaviour of the copolymers were also investigated. PS-DBT showed wider and stronger absorption in the visible light region, compared with PS-BT. Along with the increasing of solution concentration, red-shifting of the peak positions of PL spectra were found for the two copolymers. Photovohaic cells were fabricated with a configuration of ITO/PEDOT/copolymers： PCBM （1：4）/Ba/Al. The open-circuit voltages for PS-BT and PS-DBT were 0.50 and 0.40 V, respectively. The fill factors for PS-BT and PS-DBT were 24% and 33%, respectively. Under the illumination of an AM1.5 solar light simulator, the energy conversion efficiencies for PS-BT and PS-DBT were 0.009% and 0.032% , respectively.