Through-space charge transfer blue polymers containing acridan donor and oxygen-bridged triphenylboron acceptor for highly efficient solution-processed organic light-emitting diodes

Three kinds of through-space charge transfer(TSCT)blue polymers containing non-conjugated polystyrene backbone together with spatially-separated acridan donor and oxygen-bridged triphenylboron acceptors having different substituents of tert-butyl,hydrogen and fluorine are designed and synthesized.The designed TSCT blue polymers possess photoluminescence quantum yields up to 70%in solid-state film,single-triplet energy splitting below 0.1 eV,and typical thermally activated delayed fluorescence(TADF)effect.Meanwhile,the resulting polymers exhibit aggregation-induced emission(AIE)effect with emission intensity increased by up to^27 folds from solution to aggregation state.By changing the substituent of acceptors to tune the charge transfer strength,blue emission with peaks from 444 to 480 nm can be realized for the resulting polymers.Solution-processed organic light-emitting diodes based on the polymers exhibit excellent device performance with Commission Internationale de L’Eclairage(CIE)coordinates of(0.16,0.27),together with the maximum luminous efficiency of 30.7 cd A-1 and maximum external quantum efficiency of 15.0%,which is the best device efficiency for blue TADF polymers.

三苯基硼的合成

以氯苯、金属钠和硼酸三异丙酯为原料,以甲苯为溶剂合成三苯基硼,考察了反应温度、物料配比、反应时间和加料方式对三苯基硼合成过程及其收率的影响。研究结果表明,以甲苯为溶剂,反应可在常压下进行,降低了对设备和操作的要求;采用逐滴加料的方式,可降低反应体系中氯苯和硼酸三异丙酯的浓度,减少副产物联苯和偏硼酸钠的生成。当温度较高时,钠砂的聚并速率较快,导致钠砂的比表面积下降,使产物收率降低;但温度过低又会降低主反应的选择性,导致产物收率下降。适宜的工艺条件为:反应温度65℃,反应时间4 h,n(钠)∶n(氯苯)∶n(硼酸三异丙酯)=7.00∶3.50∶1.00。在该条件下,产物三苯基硼的收率为85.04%。