芴与噻吩发光共聚物的合成及其电致发光性能

采用Suzuki偶合方法合成出了一系列新型的 9,9 二辛基芴 (DOF)和噻吩 (Th)的共聚物 .其中 ,DOF与Th的投料比 (摩尔比 )分别为 95∶5 (PTF5 )、90∶1 0 (PTF1 0 )、85∶1 5 (PTF1 5 )、70∶3 0 (PTF3 0 )、5 0∶5 0 (PTF5 0 ) .所有的聚合物均可溶于常用的有机溶剂 ,如THF,CHCl3等 ,其分子量在 60 0 0～ 5 3 0 0 0之间 .当在聚芴主链中引入噻吩后 ,其发光波长发生了红移 ,最大发光波长由PTF5时的 490nm红移到PTF5 0时的 5 41nm .随着聚芴主链中噻吩含量的增加 ,最大电致发光和光致发光效率都逐渐降低 由这些聚合物所制得的器件 ,最大电致发光效率为PTF5和PTF1 0的 0 45 %.由此表明 ,在聚芴主链中引入少量的低带隙单体噻吩可以调节聚芴的发光颜色及发光效率

SYNTHESIS AND ELECTROLUMINESCENT PROPERTIES OF COPOLYMER OF FLUORENE AND THIOPHENE

The emission color of polyfluorenes can be turned over entire visible region by incorporating comonomer into polyfluorene backbone.In this paper,we demonstrate color tuning in polyfluorene derivatives by incorporating thiophene into the polyfluorene main chain.High molecular weight ( M n=6000～53000),readily soluable copolymers of different compositions were prepared from 2,7 dibromo 9,9 dioctylfluorene (DOF),2,7 bis(4,4,5,5 tetramethyl 1,3,2 dioxaborolan 2 yl) 9,9 dioctylfluorene and a narrow band gap comonomer 2,5 dibromothiophene using palladium catalyzed Suzuki coupling methods.The comonomer feed ratios of DOF to thiophene were 95:5,90:10,85:15,70:30 and 50:50 respectively.The resulting copolymers are soluble in common organic solvents,such as THF and CHCl-3.The actual molar ratios of DOF to thiophene in the copolymers were estimated by means of elemental analysis.The results indicate that the actual ratio of DOF to thiophene in the copolymer is very close to the feed ratio.The electrochemical,optical,photoluminescent (PL) and electroluminescent (EL) properties of the copolymers were studied.Cyclic voltammogram (CV) indicates that the LUMO level of the copolymers is close to that of the PF homopolymer, and it keeps almost constant for copolymers with different thiophene content. The HOMO level slightly decreases with increasing the thiophene content in the copolymer.PL and EL peaks are red shifting with increasing the thiophene content.The maximal EL emission wavelength of the copolymers is red shifted from 490?nm to 541?nm, when the thiophene content increases from 5% to 50%.Both PL and EL efficiencies decrease with increasing the thiophene content.The highest external EL quantum efficiency 0 45% was obtained from the device at the thiophene ratio of 5% and 10%, respectively.The results indicate that the use of conjugated polyfluorene as wide band gap segment with a small amount (1%～5%) of narrow band gap dopant in the molecular level could provide a new way to combine high quantum efficiency along with color turning ability.