Study On Effect Of Heat Treatments On The Luminescent Performance Of Organic Light-Emitting Diodes

Organic light-emitting diode (OLED) is a kind of promising flat panel display because of its many advantages. But some luminescent performance of it, such as lifetime, efficiency etc, is not ideal which restrict its further development All factors which affect the luminescence performance of OLED were analysised in this paper and we considered that the characteristics of the interface between the organic layer and the cathode and the device structure are the crucial factors. In the light of the above analysis, the luminescence performance of different types of OLED devices were promoted by adopting heat treatment. In the end of this paper , we studied a new type of organic electroluminescent material.1. Heat treatment at low vacuum on MEH-PPV OLED with single-layer structure and blend-layer structure at different temperature and time conditions were performed in the third chapter. After heat treatment, the luminescence performance of the above devices is improved obviously. Our experiments indicated that the optimum heat treatment condition for the MEH-PPV devices is 180℃,1 hour. We analysised the reason of this phenomenon.2. LPPP OLED devices with single-layer structure and blend-layer structure were fabricated in the forth chapter and heat treatment was applied to enhance the luminescence performance of the above blue-emitting OLED for the first time。170℃,1 hour is the optimum heat treatment condition for the above devices. The reason of the enhancement of the above blue-emitting OLED by adopting heat treatment may be similar with that of MEH-PPV devices.3. In the fifth chapter, we fabricated a type of polymer blend-layer white light OLED using MEH-PPV,PVK,PMMMA,OXD-7 and demonstrated the heat treatment utilized to control the intensity of spectral peaks of the devices for the first time. The spectrum of the white light OLED using heat treatment is quite similar to that of it producted by Japanese Nichia Corporation whose white light inorganic LED product is the best.4. The primary content of the sixth chapter is some pilot study of a new type of organic electroluminescent material. We found that this new type of material can used not only as the electroluminescent material but also as the electro transporting material and the hole transporting material, which provides a new type of material for the development of the OLED technology.