Research Of White Organic Light-emitting Devices

With qualities of low-voltage drive, initiative light-emitting, high-brightness, high efficiency, wide viewing angle, rapid response, Shock and vibration-resistant characteristics, white organic light-emitting diode (WOLED) has broad application prospects in the display and lighting area. The paper reviewed the history of the development of OLED devices, presented it's present situation and problems. The application and realization of the white is mentioned, and the paper briefly accounted the structure of the OLED, organic luminous material nature and principles.In order to find good blue light-emitting material, we studied a new type of 9,9 '-bianthracene (BA), produced a OLED with structure ITO / PVK: TPD / BA/ Alq₃/ Al. As Alq₃ is made in different thickness, the device is different from the EL spectrum. When Alq₃ is 330 nm thick, El spectrum has only one peak of 530 nm, the device itself emits green light. When Alq₃ is 50 nm thick, EL spectrum also has only one peak of 450 nm, the device itself emits blue light. And when the thickness of electronic transmission is between 50 nm and 350 nm, the device has two El spectrum peaks, which at 530 nm and 450 nm and the device emits green light. A device which Alq₃ is 50 nm thick working voltage is 10 V; When the applied voltage above 10 V, the device becomes brighter rapidly as the voltage increases, it can reach 1042 cd/m² when voltage at 20V.Doping yellow light-emitting material rubrene by spin-coating, we got WOLED with structure of ITO / PVK : TPD / 9,9'-bianthracene: rubrene / Alq₃/ Al. When the doping ration is 0.9 percent, emitting light of the devices is nearly white, its color coordinates is (0.308, 0.347) and its driving voltage is 8 V. When the applied voltage increases to 25 V, the brightness reaches 3120 cd/m².