Monochrome Design And Preparation Of Organic Electroluminescent Devices

Organic light-emitting diodes(OLED) have become a shining star in the electronic display field since the end of 1980s.This technology exhibits bright prospect in photo electricity field due to its advantages of low DC drive voltage, active luminescence, excellent hue saturation, wide visual angle, etc. Nowadays, small-area OLED have been commercially produced in the area of mobile meters, screen of mobile phones and digital cameras, etc. However, some problems, especially on stability and lifetime, still need to be resolved. The design, fabrication and analyses of OLED device are discussed in this paper. In the first of the paper, the history and development of OLED are briefly introduced. Then the principle of OLED is summarized in the second chapter, as the theory fundamental of the whole paper. In the third chapter, the structure of OLED process system including two parts, organic chamber and metal chamber, and the whole fabrication process is introduced in detail. There are four steps in the process: surface treatment of ITO glass, deposition of organic layer, deposition of metal layer, encapsulation of device. In the fourth part the result of the experiment is tested and analyzed. Firstly, the electricity properties of two kinds of device are tested. The structure of the two devices are ITO/Alq3/LiF/Al and ITO/2-TNATA/NPB/Alq3:C545T/LiF/Al. It's proved that multilayer device is better than single layer device because of the better injection and transmits of carriers. The optimization of multilayer OLED is discussed in this paper, especially the optimization of the thickness of hole injection layer. The structure of multilayer OLED which is optimized is ITO/2-TNATA/NPB/Alq3:C545T/LiF/Al. The thickness of HIL is 25nm, 30nm, 35nm and 40nm. After the measurement of all the devices, it's found that the effective barrier between ITO and HTL cannot been decreased with thin hole injection layer and also the efficiency of the device cannot been increased with thick HIL due to the unbalance of hole and electron. In summary, the highest efficiency is obtained with 35nm HIL. In the end, the whole work is summarized.