电致蓝光芴取代聚芴的合成与光谱稳定性

为了筛选高效稳定的聚合物电致蓝光材料, 设计合成了三苯胺和芴取代的二芳基芴单体, 并通过Suzuki缩聚合成了交替共聚物TPAFF-co-F和TPAFF-co-P. 将二辛基芴引入聚芴的9位可以增加其溶解度, 同时具有屏蔽主链和减少主链芴9位被氧化的作用, 三苯胺基团将有利于提高空穴在阳极界面的注入能力. 200 ℃下空气中退火24 h实验表明, 在相同条件下, 绿光指数(Igreen/Iblue)顺序为聚(9,9-二辛基芴)(1.07)>TPAFF-co-F(0.65)>TPAFF-co-P (0.47), 证明了烷基芴引入减少了主链氧化的几率. 还制作了发光二极管器件, 其结构为ITO/PEDOT:PSS(40 nm)/TPAFF-co-F或TPAFF-co-P(80 nm)/Ba(4 nm)/Al(120 nm). 在高电流密度下它们保持了良好的光谱稳定性, 在547 mA·cm-2电流密度下, TPAFF-co-F的CIE(国际发光照明委员会)坐标为(0.22, 0.24), TPAFF-co-P的CIE坐标为(0.24, 0.26), 后者的电流效率为0.712 cd·A-1.

Synthesis and Spectral Stability of Blue Eletroluminescent Fluorene-Substituted Polyfluorenes

A monomer of diarylfluorene containing triphenylamine and dialkylfluorene groups at the 9-position and its copolymers, TPAFF-co-F and TPAFF-co-P, were successfully synthesized by a Suzuki cross-coupling polycondensation to obtain stable and highly efficient blue light-emitting polymers. The dialkylfluorenes on the polyfluorene chain served as an antioxidant function as well as a shielding effect. Triphenylamine groups are favorable for hole-injection at the ITO/emitting-layer interface. The combination impart good thermal, morphological and spectral stabilities. Annealing experiments for 24 h in air at 200 ℃show that the sequence of green indexes (Igreen/Iblue) decreases as follows: poly(9,9-dioctylfluorene) (1.07)>TPAFF-co-F(0.65) >TPAFF-co-P (0.47). These results indicate that dialkylfluorene plays a role in the antioxidant function. Devices were fabricated with the following configuration: ITO/PEDOT:PSS(40 nm)/TPAFF-co-F or TPAFF-co-P(80 nm)/Ba(4 nm)/Al (120 nm). Preliminary results confirmed that they have stable electroluminescent spectra with Commission Internationale d'Eclairage (CIE) coordinates of (0.22, 0.24) at a current density of 547 mA·cm-2 for TPAFF-co-F and a CIE of (0.24, 0.26) for TPAFF-co-P with a maximumcurrent efficiency of 0.712 cd·A-1.