Study On Organic Electron-transporting Materials

Organic light-emitting devices based on organic thin layers are one of the most promising next-generation flat panel display systems. These devices can be made into large-area, extremely thin full color display that can be operated by batteries with high luminance. The structure of the device is simple, having organic thin layers sandwiched between two electrodes. Because organic layer can be formed by vacuum evaporation or solution casting, the cost of fabrication could be less than that of the liquid crystal displays, which are the most widely used flat panel displays. They can be used as white light sources replacing traditional fluorescent lamp, which has significant impact on energy-saving and environmental protection. OLED's core technologies and the property right are monopolized by America and Japan. In the application of OLED, Japan is in the lead followed by South Korean and Chinese Taiwan. The number of units in domestic engaged in the OLED research increases gradually. Many enterprises have joined into the OLED display device's industrialization process.In the OLED's research, the material was very important. Organic electroluminescent materials were composed of emission materials, hole-transporting materials and electron-transporting materials. A number of emission materials and hole-transporting materials were reported. In contrast, materials for electron-transporting materials were relatively few. Representative electron-transporting materials such as tris(8-quiolinolato) aluminum(III)(Alq) reduced OLED's lifetime obviously because of the existence of oxygen atom. Therefore, the development of novel effective electron-transporting materials have became the key which the organic electroluminescent device further develops.The purpose of this paper was designing and synthesizing novel non-oxygen heterocyclic compounds, including nitrogen heterocyclic ring groups (pyridine ring, quinoxaline ring), which overcame the weakness of that oxygen atom influence device's lifetime. Through the configuration of molecular structure and the performance evaluation of device, novel electron-transporting materials with high performance were synthesized and studied to satisfy the need of organic electroluminescent display technology.The non-oxygen heterocyclic compounds were synthesized and characterized, such as TMCD macrocyclic compounds, pyridine-containing hydrazine compounds and quinoxaline compounds. The FT-IR, UV-visible absorption spectrum, thermal performances, electrochemical property and ionization potential (I_p) of these compounds were determined. Organic electroluminescent devices using these compounds as electron-transporting layers were fabricated and determined by the EL spectrum, current density-voltage characteristics and luminance-voltage characteristics. Green luminance from Alq layer of all the devices was observed, which demonstrated these compounds could be used in organic electroluminescent devices as electron-transporting materials with high performance.