The Field Emission Electron Injection Organic Light-emitting Devices

In recent years, organic light-emitting diodes (OLED) have remarkably developed as novel flat panel devices. OLED have become a fascinating field in recent years for its excellent features such as high luminescent efficiency, low energy consumption, and quick response. However, there have still remained some problems unsolved, such as relatively lower luminescence efficiency, short life and so on. In this paper, jobs were done aim at improving luminescence efficiency, on the basis of the injection efficiency of carriers, including electrons and holes. A novel idea of combing Organic light-emitting with Field electrons emission is put forward, based on the theory of field electrons emission and organic electroluminescence. At the same time, the diamond microcrystalline-aggregate array as cathode was used to be a cathode of organic light-emitting device (OLED) in this paper.In order to enhance carrier injection the selection of efficiently electron-injecting cathode materials is of great importance. OLED has largely been confined to the application of low work function metals and their corresponding atmospherically stable alloys as cathodes. Field electrons emission has itself advantages of low work function, etc. Considering the priority of field electrons emission, the injection efficiency of electrons can be greatly improved in case that field emission cathode can be used as cathode in OLED structure.Firstly, the specific experimental conditions and preparation process of conventional OLED are explored, aimed at obtaining the optimal of thickness and experimental parameters of OLED. Organic light-emitting devices (OLEDs) with the structure of ITO/TPD/Alq₃/Al were fabricated .The threshold voltage of 6.5V, and the brightness of 4500cd/m² are obtained for the organic light-emitting device. The effect of the Joule heat on the degradation of OLEDs' lifetime, the stability of organic film, the transportation and the recombination of the carriers have been investigated in this paper.Secondly, top-emitting organic light-emitting devices based on silicon substrate are explored. According to the demand of device structure to anode layer, semi-transparent metal materials Ag and ITO, which has higher work function, are chosen as anode materials in this paper. Vacuum vaporization method is applied in preparing these metal Ag anodes. The thickness of metal thin film will have influence on the properties of optics and electrics of anodes. Therefore, it is imperative for us to study the transitivity and resistivity of metal Ag films with different thickness; Magnetic sputtering method is applied in preparing these ITO anodes under a low temperature. From the detailed discussion about this, the optimal of thickness and experimental parameters can be obtained. the diamond microcrystalline-aggregate array as cathode was used to be a cathode of OLED. Current-voltage characteristics and brightness-current characteristics are systematically studied. The diamond microcrystalline-aggregate array as cathode was used to be a cathode of organic light-emitting device (OLED). The electrons were emitted from the cathode directly to organic lay of Alq₃ in vacuum chamber. The luminescence emitted due to electrons injection was observed.Thirdly, the diamond microcrystalline-aggregate array as cathode was used to be a cathode of OLED. Current-voltage characteristics and brightness-current characteristics are systematically studied.The novelty in this paper can be depicted as follows: a novel device structure of OLED on silicon and carbon based thin films be used as cathodes of OLED are prepared, for improving the injection efficiency of electrons; An optimized experimental condition is discussed and used as preparation of anodes of OLED on silicon, for improving the injection efficiency of holes.