基于三苯胺和螺(芴-9,9＇-氧杂蒽)的星射形蓝光寡聚材料的合成与光电性质

Synthesis and Optoelectronic Properties of Blue-Emitting Star-Burst Oligomers Based on Triphenylamine and Spiro(fluorene-9,9'-xanthene)

通过Sonogashira反应合成了基于三苯胺、螺(芴-9,9 -氧杂蒽)及芴的星射形寡聚物. 三种寡聚物(TPA-F、TPA-SFX和TPA-SFXCz)都具有很高的热分解温度,分别为417、439和425℃.差示扫描量热(DSC)分析研究表明,它们也具有高的玻璃化转变温度(Tg), 都在100℃以上,其中两种螺芴取代的寡聚物(TPA-SFX和TPA-SFXCz)的Tg分别达到141和127℃.光物理的研究发现, 在薄膜中,TPA-F具有很宽的双发射峰, 峰值为424和455nm;而TPA-SFX和TPA-SFXCz仍保持单一蓝光发射, 发射峰分别为434和442nm.这表明将三苯胺非平面结构和螺形取代基团相结合,能有效抑制在薄膜中聚集和激基缔合物的产生.电化学的研究表明,由于引入富电子的三苯胺核心结构,三者都具有-5.4 eV左右的较高的HOMO能级.通过旋涂法制备了结构为ITO(氧化铟锡)/PEDOT:PSS(聚3,4-乙撑二氧噻吩:聚苯乙烯磺酸盐)/寡聚物/TPBI(1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯)/LiF/Al电致发光器件.器件测试结果表明,TPA-SFX的器件具有最好的光电性能. 以它为发光层,获得最大亮度为2680 cd·m-2、最大电流效率为0.35 cd·A-1、色坐标为(0.17, 0.13)的蓝光器件.

Three star-burst conjugated oligomers based on triphenylamine （TPA）, fluorene and spiro （fluorene-9,9＇-xanthene） （SFX） have been synthesized via the Sonogashira cross-coupling reaction. These well-defined oligomers possess high decomposition temperatures （Td） at 417, 439, and 425 °C, respectively. Differential scanning calorimetry （DSC） demonstrates two oligomers which incorporate the SFX unit, TPA-SFX and TPA-SFXCz, possess higher glass transition temperatures （Tg） at 141 and 127 ° C, respectively, compared with 101 °C for TPA-F. The investigation of their optical properties shows TPA-SFX and TPA-SFXCz exhibit a single blue emission in film with emission peaks at 434 and 442 nm, respectively, whereas TPA-F shows a broad double-peak emission located at 424 and 455 nm, which implies the nonplanar TPA and spiro SFX moieties can effectively restrict the formation of aggregates or excimers. Electrochemical investigations show that these oligomers have relatively high HOMO levels at around -5.4 eV due to incorporation of the electron-rich TPA core. Electroluminescence （EL） devices with a configuration of ITO （indium tin oxide）/PEDOT：PSS （poly（3,4-ethylenedioxythiophene）： poly （styrenesulfonate））/ oligomer/TPBI （1,3,5-tris（1-phenyl-1H -benzimidazol-2-yl）benzene）/LiF/Al were constructed using these oligomers as the emitter by spin-coating, with TPBI as the electron-transporting and hole-blocking layer. The device using TPA-SFX as the emitting layer exhibits bright blue emission with the maximum brightness and maximum current efficiency of 2680 cd·A-2 and 0.35 cd·A-1, and CIE color coordination of （0.17, 0.13）.