Organic Thin Film Electroluminescent Light Emitting Device (oled) Research And Development

Organic light-emitting diodes (OLED) have become a shining star in the electronic display field since the end of the 1980s. This technology exhibits bright prospect in photoelectricity 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, screens of mobile phones and digital cameras, etc. However, some problems, especially on stability and lifetime, still need to resolve.In respect of the excellent stability of polymer, the OLED using polymer doped with small molecular materials is fabricated. The anode is fabricated by direct current (DC) reaction sputtering method. The cathode is fabricated by DC sputtering method or vacuum vaporization method. The organic films are deposited by spin-casting method. Finally, the relatively stable OLED with maximum luminance of 18.8cd/m2 emitting green color resulting from 8-tris-hydroxyquino-line aluminum (A1Q) is obtained.Firstly, the effect of the ratio of poly-(N-vinylcarbazole) (PVK):A1Q: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-l,3,4-oxadiazole (PBD) in emitting layer (EML) and PVK content in hole transport layer (HTL) on dual OLED property is discussed at the relatively invariable spin speed. The optimized contents of different organic materials are confirmed by comparing the observational luminance and stability of OLED with each other.Then the effect of the Al cathode thickness and the ITO anode surface procession on OLED property is explored. The result shows that the optimized thickness of Al cathode can result in better luminance and stability, while the excessively thin or thick Al film will degenerate the property of OLED.Next, the effect of the device structure on the property of OLED is discussed. The results show that the optimized dual-layer structure device is superior to the single-layer one, while inferior to the optimized three-layer one. The optimization of three-layer structure device is also discussed.The effect of different deposition methods of Al cathode is also studied novelly. Itshows that the optimized dual-layer device with Al cathode deposited by the vacuum vaporization method has lower dark electric current and luminescence turn-on voltage than that deposited by DC magnetron sputtering method. The mechanism of these phenomena is discussed in detail.