Study On The Organic Light Emitting Diodes With Organic Multiple Quantum Wells Structure

Organic electroluminescence has attracted a lot of attention due to its potential applications in large-area full-color flat-panel displays. To improve the emitting efficiency is one of the most important research aspects. There are many ways to improve the efficiency of organic light emitting diodes'(OLED). In this thesis we introduced a multiple hole-trapping layer to balance the hole and electron injection inthe emitting layer of the OLEDs.Detail of the research work is listed as following:1. An ultra thin Rubrene layer is used as emitting layer to detect the carrier's density due to Rubrene's hole and electron trap ability. The mechanism of carrier trapping effect of quantum well structure is revealed and the energy transform process is also discussed.2. The hole-blocking material Bathocuproine (BCP) is used with hole transporting material N,N'-diphenyl-N,N'-bis(1,1'-biphenyl)-4,4'-diamine (NPB) to form a multiple hole trapping structure to control the hole injection ability by verifying the number of multiple layer. Compared with conventional double layer device the efficiency is improved by over 3 times. Some quantum effect as color shifting is also presented.The result of the research work shows the multiple hole-trapping layer can control the hole mobility in hole transporting layer effectively and it is one of the useful ways to improve the efficiency of OLEDs due to the balance of hole and electron injection in emitting layer.