Thin Layer Of Blue Phosphorescent Oled Devices And Encapsulation Technology Was Studied

Since OLED was found by C. W. Tang in1979, after33years of development, now it has been the hottest point in display and lighting industry. However, there is a long way to go. The research of blue phosphorescent device has been in a relatively backward state, needed to improve the efficiency and chroma. So, high-performance blue phosphor martial and reasonable device structure have become the primary task for the development of blue phosphorescent OLED. As for the device lifetime, the existing technology, encapsulating OLED, can not meet with application. Especially, TFE (the thin film encapsulation) is at the beginning, which needs more attention and technology investment, such as developing the packaging equipment and structure. In view of above problems, lots of experiments on the structure and packaging method of blue phosphorescent device are introduced in this paper, as follows:1. Device structure optimization, doping electron block layer and hole block layer blue in phosphorescent devices.Hole-transporting material TAPC was chosen as electron block layer. With optimized thickness of TAPC, the device of ITO/NPB(45nm)/TAPC(5nm)/mCP: FIrpic(8%,25nm)/Bphen(35nm)/Mg:Ag was fabricated. When the luminance was1000cd/m2, the operating voltage was7V, and the power efficiency could be2.491m/W.Phosphorescent host material UGH2was chosen as hole block layer, With optimized thickness of UGH2, the device of ITO/NPB(45nm)/TAPC(5nm)/mCP: FIrpic(8%,25nm)/UGH2(5nm)/Bphen(35nm)/Mg:Ag was fabricated. When the current density was100mA/cm2and voltage was10.6V, the power efficiency could be8.82lm/W.2. Interesting in features of ultra-thin quantum well structure, we used this structure as light-emitting layer in blue phosphorescent device, and exploring on the structure of dual-band white phosphorescent device. Concretely include:We selected the commonly used phosphor materials, mCP and FIrpic, to compose the "host-guest-host" quantum well structure as the emitting layer. After the thickness of guest materials optimization, we got a blue phosphor OLED with stable performance and high light-emitting efficiency with the structrure of ITO/NPB(55nm)/TAPC(5nm)/mCP(2nm)/FIrpic(0.2nm)/mCP(2nm)/Bphen(50nm)/Mg:Ag(10:1,100nm). The turn-on voltage of the device was7.8V, of which the broadband emission peak was at466nm, and the maximum luminous power efficiency reached9.54lm/W at8.1V.We chose multi-quantum well structure as emitting layer, and prepared5blue phosphorescent devices based on FIrpic. And we found that devices with4quantum-wells had the best performance. The turn-on voltage is only2.5V, and when the current density became100mA/cm2at6V, the power efficiency became5.72lm/W. Compared to FIrpic, its spectrum peak shifted to blue by9nm, entering the range of pure blue light.We prepared2devices using additive color method, with Firpic and Ir(2-phq)2(acac) chose as guests, of which emitting layer had a5quantum-wells structure. By comparing their performance, we obtain the better structure of emitting layer,(mCP(2.5nm)/FIrpic(0.3nm)/mCP(2.5nm))2/Ir(2-phq)2(acac)(0.3nm)/UGH2(2.5nm)/Ir(2-phq)2(acac)(0.3nm)/UGH2(2.5nm))2. When the operating voltage turned to8V, the device reached the highest power efficiency,3.381m/W, and its CIEx,y was (0.33,0.34).3. Based on the improvement of cap encapsulation and the exploration of thin film encapsulation, we improved the encapsulation method of OLED.Based on traditional glove box encapsulation, we introduced encapsulated condition of vacuum chamber, metal gasket, and pure N2, and then proposed a new method of vacuum encapsulation. As a result, the lifetime of device increased to12970hrs,18.20%more than the one, which was encapsulate by traditional technology.To make the device thinner and lighter, thin film encapsulation was selected, in which Monomer and Al2O3alternately make up a package unit. We encapsulated the red device by2package units, and found the half-life of the device reached2830hrs.In summary, this thesis research work will focus on influence of electron block layer and hole block layer on blue phosphorescent device, parameters optimization of blue non-doped phosphorescent device with ultra-thin quantum-well as emitting layer, fabrication of dual-band white device, improvement of cap encapsulation equipment, and exploring Barix thin-film encapsulation technology. To some extent, the whole research work would prompt the development of high-efficiency and long-lifetime device.