Enhanced electroluminescent performance by doping organic conjugated ionic compound into graphene oxide hole-injecting layer

Organic conjugated ionic compound 10,10 '-dimethyl-9,9 '-biacridinum bis(monomethyl terephthalate) (MMT) is doped into graphene oxide (GO) hole-injecting layer to enhance the electroluminescent performance of organic light-emitting diodes (OLEDs). The composite films are characterized in detail by FTIR, SEM, XPS, and UPS. The XPS result indicates the evident pi-pi stacking interaction between the conjugated structures of GO and MMT. The UPS result shows the decrease in ionization potential of GO due to MMT-doping. As a result, at the optimal doping ratio of 4wt%, the maximum luminous efficiency of OLEDs is increased to 15.46cd/A, which is 3.4 times as 4.55cd/A of the control device. Besides, the luminance is also enhanced to 19950cd/m(2), while the turn-on voltage is decreased to 2.5V. Doping organic conjugated ionic compound into the GO hole-injecting layer is a facile and efficient approach to improve the electroluminescent performance of OLEDs.