Studies On Green Organic Light-emitting Device (OLED)

Since the multi-layer and high efficient organic light emitting device (OLED) was reported by Tang in 1987. Compared with the CRT, LCD, LED, and PDP, The OLED possesses many advantages, such as high brightness, high luminescence efficiency, wide view-angle, self-emission, full solid device, super-thin thickness, light weight, simple fabrication technologies and low cost, fast response, applications in full color organic displays, can make into different figures because of their good ma-chine processing capability etc. So During the last three decades, the OLED has attracted much attention and investigation, and it has been considered as the most ideal and potential display technology for next generation flat panel display after PDP and LCD. At the present time, the OLED obtains considerable development, but there are many questions, if we want to become it as a real commodity. For example, single luminescent materials, lower life-time and lower stability etc. Nowa-days, the primary aims of our research are Exploiting the organic light-emitting and the carries transporting materials with high Electroluminescence efficiency and stable physical characteristic, searching for new film fabrication, and optimizing the configuration of device. In this dissertation, we have made some meaningful works relating to the improving efficiency, enhancing brightness and decreasing the turn-on voltage of OLED.Opening chapter reviews the development history of OLED:Including the re-search status of domestic and foreign; and compared with other flat panel display, the advantages and the disadvantages of OLED.Briefly describes the fundamental knowledge of OLED:Including the lumi-nescent mechanism light principle of OLED, Some typical structure, fabrication method(Organic small molecule device and Polymer device), and the parameters are used to evaluated the performance of the device, and then how to improved the luminous efficiency of OLED.Consideration from the structure of the device, organic light-emitting materials can be divided into electrode materials, carrier transport material, luminescent ma-terials and the buffer materials. at the same time, Organic light-emitting materials might contain organic small molecule materials, polymers and metal chelates, and Phosphorescence Materials. Focuses on the luminescence properties of the organic small molecules, From Electro-phosphorescence luminescent principle of and Elec-troluminescence mechanism of phosphorescence starting, the several phosphorescent materials were studied.Annealing treatment impacts on the performance of OLED, Mainly from the following three aspects discussed:Firstly, after ITO glass was annealed at different annealing temperatures, the XRD, SEM and sheet resistance were tested, and study the annealing effect for the ITO films; Secondly, we fabricated the same structure of the OLED on the annealing ITO glass at the different annealing temperature, The structure of the device is ITO/TPD:PVK/Alq3/LiF/Al, and I—V and L—V char-acteristics are tested, Discuss the impact of heat treatment for the performance of the device; Finally, The same structure of the device, hole transport layer(TPD:PVK) was annealed at the different temperature, and find that annealing improve the performance of the device, when the organic layer was annealed at the appropriate temperature.The devices were prepared by vacuum thermal evaporation method, the struc-ture of OLED is ITO(150 nm)/2T-NATA:F4-TCNQ(x%)(30 nm)/Alq3(70nm)/LiF (1 nm)/Al(200 nm), and F4-TCNQ is used as p-type oxidation, and discussed the different doping concentration how to impact on the performance of the device, When the doping concentration of F4-TCNQ(mass percentage) is 8% in the HTL (at the drive voltage of 22 V), the brightness of the OLED as high as 4256 cd/m2; at the same this voltage, compared with the undoped, the maximum electrolumi-nescence efficiency from the 2.9 cd/A increased to 3.4 cd/A.Finally, we fabricated three structures green OLED by Vacuum thermal evap-oration, and I—V and L—V characteristics were tested. The results showed that the device containing the two Al/Alq3 layers had a higher brightness and electrolu-minescent efficiency than the device without this layer.