| Organic light-emitting diode (OLED) has many advantages, such as low DC drive voltage, high luminescence and high efficiency, active luminescence, wide visual angle, fast response, etc. Because of the above advantages, in recent years, it has shown enormous appealing in display technology fields. However, due to the confinement of materials and device structures of OLED, there have still remained some problems unsolved, such as relatively lower luminescence efficiency, short life and so on. In this paper, jobs 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, a new type of OLED on silicon (OLEDoS) is sketched in this paper.Optimizing the performance of electrodes of OLED can be regarded as an important approach on the way of improving the injection efficiency of electrons and holes. Field electrons emission has itself advantages of large current density, high density of electrons emission spots, etc. At the present time, field emission display (FED) takes up a large share in display field. 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. Moreover, due to the well-rounded technics and compatibility of silicon, devices on silicon are playing more and more important role in morden industry. Therefore, carbon based thin films on silicon substrates will be used as cathodes in this novel OLED structure. Improving the injection efficiency of holes is also an important task in this paper. Considering both the device structure and confinement of organic materials, as for anode, higher demands should be satisfied including transitivity and conductivity properties, higher work function, as well as little damage to organic materials during the process of deposition.Firstly, the specific experimental conditions and preparation process of carbon based cathodes are explored, aimed at obtaining the thin film cathode with excellent field emission properties, such as follows:(1) the preparation of nano-graphite thin films:The experimental methods and parameters of preparing nano-graphite films are detailed explored. Field emission properties of these films are measured and the better parameters can be concluded according to the measurements. At the same time, a deeply field emission mechanism regarding to the prepared nano-graphite thin film is discussed. From the results of measurements and discussion, conclusion can be drawn that if the prepared nano-graphite thin films are used as cathodes in OLEDoS, the injection efficiency of electrons of devices can be greatly improved.(2) the preparation of diamond thin film and diamond coated with metal layer:The preparation parameters and experimental process for high quality diamond films are schematically discussed in this section. Then field emission properties of diamond film are measured under certain conditions, which show relatively wore performance. To improve the field emission properties of diamond films, a thin metal coating is deposited on the surface of diamond film. The effect of different metal coatings and different metal films thickness on the field emission properties of diamond film is schematically investigated. Based on the energy band structure of diamond, characteristic of interface of diamond-metal contact is analyzed, which will contribute to the analysis of the reason about the improvement on the field emission properties due to the existence of metal coating on the surface of diamond film. A valued result can be obtained from the discussion. The structure of diamond-metal and its field emission properties can satisfy with the demands as cathode of OLED device.Another part of jobs done is the preparation of anode. According to the demand of device structure to anode layer, semi-transparent metal materials, such as Ag and Al, which has higher work function, are chosen as anode materials in this paper. Vacuum vaporization method is applied in preparing these metal anodes. The thickness of metal thin film will have influence on the properties of optics and elctrics of anodes (mainly including transitivity and electricity). Therefore, it is imperative for us to study the transitivity and resistivity of metal films with different thickness. From the detailed discussion about this, the optimium of thickness and experimental parameters can beobtained. From the comparison of Ag and Al, Ag metal used as OLEDoS anode will show certain superiority over Al.The novelty in this paper can be depicted as follows: a novel device structure of OLEDoS is put forward; carbon based thin films with better field emission properties are prepared and will be used as cathodes of OLEDoS, for improving the injection efficiency of electrons; An optimized experimental condition is discussed and used as preparation of anodes of OLEDoS, for improving the injection efficiency of holes. |
