电致蓝光芴取代聚芴的合成与光谱稳定性

Synthesis and Spectral Stability of Blue Eletroluminescent Fluorene-Substituted Polyfluorenes

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24h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(40nm)/TPAFF-co-F或TPAFF-co-P(80nm)/Ba(4nm)/Al(120nm).在高电流密度下它们保持了良好的光谱稳定性,在547mA·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0.712cd·A-1.

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 maximum current efficiency of 0.712 cd·A^-1.