A Study Of Organic Light-emitting Diodes Devices Using Al/MoO₃as Composite Anode

Organic Light-Emitting Diodes （OLEDs） have extensive advantages fornext generation displays, such as self emission, full color, low powerconsumption, light weight, high flexibility, etc. Thus, they were sometimeshonored as the “Illusion Displays” or “Gorgeous Displays”. Because the OLEDscan he manufactured easily, many display factories and research groups areinvesting in their application areas. At present, the success of small for themarket of small LCD displays.In this thesis, we adopt bottom emitting OLED with micro-cavity structuretype. In this study of OLED with micro-cavity structure type, there are threemain elements to constitute microcavity OLED: first, two parallel cathode andanode with reflectivity. Second, a microcavity resonator between two electrodes,that is stack organic layers. Third, light source within microcavity OLED.We designed three types of OLED by the anode of Al/MoO₃,We willdescribe characters of the anode with analysis the performance of the entireOLEDs. The work includes three parts as follow:（1） The organic light-emitting diodes using alumina/molybdenum trioxideas composite anode were prepared. The structure of device wasAl/MoO₃/NPB/Alq₃:C545T（x%）/Alq₃/LiF/Al.We compared electroluminescentcharacteristics of the device which was doped different concentration of C545T.The results show the energy transfer is most efficient between subject and objectwhen the doped concentration is8%, meanwhile, the driving voltage offluorescent device is2.75V. The device exhibits maximum luminescence valueis27000cd/m²and luminous efficiency is6.97cd/A in the voltage of13V. Weanalyzed the performance of the OLED using Al/MoO₃as composite anodeaccording to the theory of Fowler-Nordheim tunnel effect and carrier injectionmechanism.（2） A microcavity organic light-emitting diodes device with Al as metalreflective film and metal semipermeable membrane is made. The structure is: Al/ MoO₃/NPB/ADN: TBPe: DCJTB/Alq₃/LiF/Al. The five different thickness ofthe metal anode semipermeable membrane device are designed and the thicknessof Al semipermeable film is as follow:12nm,13nm,14nm,15nm,16nm. Bychanging the thickness of anode Al semipermeable membrane and altering theoptical length of the micro-cavity, the results show that the luminous efficiencyand color purity both changed. So we research microcavity effect on theperformance of the device. When the thickness of Al semipermeable membraneis12nm, the devices attain the maximum brightness3381cd/m²in11V and thehighest efficiency is2.01CD/A, color coordinates is （0.33,0.39）. Therefore,using microcavity effect reasonable can improve the color purity of the devicewith Al anode and maintain a certain luminous efficiency.（3）We designed a configuration of Multilayers of OLEDs isAl/MoO₃/NPB/ADN:TBPe:DCJTB/Alq₃/LiF/Al. The results show that we canmodulated the response of microcavity by adjusting the thickness of NPB. Themicrocavity OLED could enhanced the strength of a certain spectrum lightingand changed chromaticity coordinate. The thickness of Hole injection layerNPB contributed to the performance of OLED is important. We could acquiredthe best performance of the device by properly adjusting the thickness of it.When the thickness of NPB is90nm, the devices attain the maximum luminanceefficiency and brightness, the luminance efficiency is6.32cd/A, and a maximumbrightness is12240cd/m².