微腔有机发光器件中的电致发光光谱

设计了结构为Glass/DBR/ITO/TPD/Alq3/Ag的微腔有机发光器件。从理论上详细地研究了腔内各层结构对器件电致发光谱性能的影响。结果表明:随着腔长厚度的增加,器件的归一化电致发光谱强度不断减小;在可见光区,器件的EL谱随发光层厚度的增加出现振荡变化。空穴传输层和发光层的界面位置对器件电致发光谱的影响也很大。最后得到,在设计微腔时发光层厚度要尽量窄,并且中心发光区域应位于谐振腔中电场的峰值位置。

Electroluminescence Spectra in Microcavity Organic Light-emitting Devices

Microcavity structure consisting of distributed Bragg reflector and metal silver mirror is designed. The structure is glass/DBR/ITO/TPD/Alq3/Ag. The tris(8-hydroxyquinoline) aluminum( Alq3 ) is the electron transport layer and the emissive layer, and the N,N'-diphenyl-N,N'-bis(3-methyl-phenyl)-1,1 'biphenyl- 4,4'diamine(TPD)is the hole-transport layer. Compared to the electroluminescence(EL) spectra of non-cavity OLEDs, the linewidth of the MOLEDs is narrower, and the emission peak is enhanced. So the microcavity effect is very observable. In this work, the matrix method was adopted. The dependence of the electroluminescence(EL) spectra on the cavity length,the emitting layer thickness, the position of the interface between EML and HTL and the position of the emission region was analysed detailedly. In all calculation, the thickness and refraction of ITO and the thickness of the metalsilver were kept constant. The results show: 1. with increasing the thickness of cavity, the normalized electroluminescence (EL) intensity decreased continually; 2. with increasing the thickness of the emitting layer, the normalized EL intensity discontinuously changed; 3. because the electron mobility in Alq3 is different from the hole mobility in TPD,the emitted radiation was strongly dependent on the position of the emissive layer inside the cavity. Finally, the emission region should be narrow at the center of the electric field in the resonant cavity to optimize MOLED.