新型芴类发光共聚物

Novel Fluorene-based Light-emitting Copolymers

采用Suzuki偶合方法合成了芴与低带隙单体噻吩 (Th)及其衍生物乙烯基二氧噻吩 (EDT )、4 ,7_二噻吩_2 ,1,3_苯并噻二唑 (DBT )、4 ,7_二噻吩_2 ,1,3_苯并硒二唑(BTSe)的二元无规共聚物 ,实现了聚芴颜色的调节 ,得到了发蓝绿光到黄光 (峰值波长在4 90～ 5 6 0nm之间 )以及饱和红光 (峰值波长在 6 2 8～ 718nm )的聚合物 ,所得到的共聚物的光荧光和电荧光量子效率都比文献中所报道的交替共聚物要高得多 .芴与噻吩共聚物的最大电致发光 (EL)外量子效率为 0 .4 5 % ,芴与EDT共聚物的最大EL外量子效率为1.8% ,芴与DBT共聚物的最大EL外量子效率为 1.4 % ,均比文献中所报道的相应聚合物高得多 .芴与BTSe共聚物的最大EL外量子效率为 0 .5 % ,这是首次报道含BTSe的发光聚合物 .实验中还观察到了由于激子在低带隙单体DBT和BTSe位置的捕获而产生的有效的能量转移 。

A series of novel random copolymers based on 9,9_dioctylfluorene (DOF) and thiophene or its derivatives (ethylenedioxythiophene(EDT), 4,7_dithien_2_yl_2,1,3_benzo thiadiazole (DBT),4,7_dithien_2_yl_2,1,3_benzoselenadiazole(BTSe)) were synthesized by the palladium_catalyzed Suzuki coupling method. The successful color tuning from green (490～560 nm) to red (628～718 nm) was obtained. The PL and EL quantum efficiencies of these random copolymers are higher than those of alternating copolymers reported by other researchers. The maximal EL quantum efficiency is 0.45% for copolymer of fluorene and thiophene, 1.8% for copolymer of fluorene and EDT, 1.4% for copolymer of fluorene and DBT and 0.5% for copolymers of fluorene and BTSe. This is the highest EL external efficiency reported so far for the same fluorene_based copolymers. The efficient energy transfer due to exciton trapping on the narrow band_gap BTSe or DBT sites has been observed. The results indicate that the use of conjugated polyfluorene as wide band_gap segment with a small amount of narrow band_gap dopant in the polymer main chain could provide a new way to combine high quantum efficiency along with color tuning ability.