Electroluminescent (EL) the devices based on organic materials have the potential to realize the full-color flat-panel display. Some materials have now demonstrated adequate efficiency and durability for practical applications. However, the factors that govern the efficiency and durability are poorly understood. In this report, we provide a brief review of the organic EL devices on the basis of the information obtained from literatures and the results of our study. Firstly, the basic mechanism of light emission and a relationship between the device structure and the emission efficiency are reviewed. Secondly, the developments of materials such as hole transport materials, electron transport materials and emission materials are shown, and the stability, emission color and efficiency of EL devices using such materials are then discussed considering molecular structures of the organic materials. The electrode materials for high injection of electron and hole are also shown. Finally, the recent progress in the practical applications is shown and the future prospects are discussed.
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