PVK∶NPB复合空穴传输层对有机电致发光器件的影响

Influence of PVK:NPB hole transporting layer on organic light-emitting devices characteristics

采用poly(N-vinylcarbazole)(PVK):N,N′-bis-(1-naphthyl)-N,N′-biphenyl-1,1′-biphenyl-4,4′-diamine(NPB)掺杂体系作为复合空穴传输层,通过调节该体系的组分,制备了结构为indium-tin oxide(ITO)/PVK:NPB/8-hydroxyquinoline aluminum(Alq3)/Mg:Ag的双层有机电致发光器件(OLED),研究了具有不同掺杂质量比的OLED器件的电致发光特性,并对掺杂薄膜的表面形貌进行了表征。结果表明,将NPB掺杂到PVK中会提高空穴传输能力,改善器件的发光亮度和效率,并调节载流子复合区域的位置,光谱谱峰从509nm移动到530nm;但随着NPB质量比例提高,掺杂薄膜表面的平均粗糙度由3nm上升为10nm,电流密度和亮度先升高后降低。当PVK和NPB的掺杂质量比为1∶3时,器件具有最优性能,发光亮度达到7852cd/m2,功率效率为1.75lm/W。

Organic light-emitting devices （OLEDs） with a structure of indium-tin oxide （ITO）/poly（N-vinylcarbazole） （PVK） ：N,N＇-bis-（1-naphthyl）-N,N＇ biphenyl-1,l＇-biphenyl-4,4＇-diamine （NPB）/＆hydroxyquinoline aluminum （Alq3）/Mg：Ag are fabricated. A doping system consisting of small-molecular hole transporting material NPB and polymer materiaI PVK is employed as the composite hole transporting layer （CHTL）. By adjusting the component ratio of doping system, a series of devices with different concentration proportion of PVK： NPB are constructed. The electroluminescent characteristics of the devices are investigate and the AFM images of surface morphology of PVK： NPB thin film with different component ratios are compared. The result shows that the doping concentration of NPB enhances the competence of hoIe transporting ability,and modifies the recombination region of charge carriers as welI as affects the surface morphology of PVK：NPB thin film. Optimum device with a maximum brightness of 7 852 cd/m^2 and a luminance efficiency of 1.75 lm/W can be obtained by choosing the best concentration proportion of PVK：NPB at 1 ： 3.