TCTA在外电场下的双分子发光现象

Bimolecular Emission of TCTA Under External Electric Field

制备了三苯胺化合物4,4′,4″-三(咔唑-9-基)三苯胺(TCTA)的单层器件ITO/MoO3/TCTA/LiF/Al和TCTA/TPBi双层异质结器件ITO/NPB/TCTA/TPBi/Bphen/LiF/Al,研究了TCTA的双分子发光现象。通过测试器件的光电性能和薄膜的稳态光谱,得出以下结论:(1)单层器件的电致发光光谱有425 nm和600 nm两个发光峰。与TCTA薄膜的光致发光光谱对比,可知425 nm附近的蓝色发光峰来源于TCTA单体发光,而600 nm附近的橙色发光应为TCTA二聚体electromer的发光。蓝色和橙色发光混合,使单层器件发光颜色表现为白色,对应色坐标为(0.381,0.343)。(2)TCTA/TPBi双层异质结器件的电致发光光谱为440 nm的单峰,器件的最大发光亮度为930 cd/m2,发光性能明显优于单层器件。结合薄膜TCTA、TPBi和TCTA/TPBi的光致发光光谱和紫外-可见光吸收光谱,可知双层器件的发光来自TCTA+TPBi-电致激基复合物。双层器件表现出良好的色稳定性,电压在6~11 V范围,CIE色坐标为(0.18±0.01,0.14±0.01)。

In order to investigate bimolecular excited state emission of 4,4,4-tris(N-carbazolyl)triphenylamine(TCTA),a single-layer device(ITO/MoO3/TCTA/LiF/Al)and a bilayer heterojunction device(ITO/NPB/TCTA/TPBi/Bphen/LiF/Al)were fabricated,respectively.Optical and electrical characteristics of devices and steady-state spectra of films were measured.The following conclusions are drawn.(1)Electroluminescent(EL)spectra of single layer devices demonstrate two emission peaks:425 nm and 600 nm.The peak at 425 nm is originated from the emission of TCTA monomer according to photoluminescent(PL)spectrum of TCTA film,and the peak centered at 600 nm is attributed to the emission from electromer.White color with 1931 CIE values of(0.381,0.343)was obtained for the single layer devices because of the superposition of blue emission peaked at 425 nm and orange emission centered at 600 nm.(2)TCTA/TPBi bilayer device exhibited EL spectra peaked at 440 nm,which is belonged to the emission of TCTA+TPBi-electroplex according to the PL and UV-Vis absorption spectra of TCTA,TPBi and TCTA/TPBi films.Meanwhile,better properties were shown in the bilayer device than those of single devices.The maximum brightness was 930 cd/m2 and CIE coordinates were(0.18±0.01,0.14±0.01)for applied voltages varying from 6 V to 11 V.