Fabrication And Study Of White Organic Light-Emitting Devices For The Backlight Of Liquid Crystal Display

As the backlight for the Liquid Crystal Display(LCD), it must have the following traits: high brightness, good luminescence uniformity, broad luminescent angle, lightness and thinness, low energy consumption, low cost, and even flat lighting source. Therefore, comparing with other backlight goods such as LED,tungsten lamp,ELD,CCF,CLL and metal tungsten lamp, organic light emitting devices(OLEDs) have many unique advantages of their high efficiency, flexible display, self light-emission, viewing angle, quick response, easy fabrication, low driving voltage, et al. and they are suitable to be used as the LCD backlight.In latest years, white OLED(WOLED) have been attracting much attention of researchers in this field due to their potential applications as the LCD backlight. But now the WOLED as backlights still have some shortages such as low luminescent efficiency, high heated, short life-time and so on. In order to improve the development of the WOLED as backlights, we have to overcome some problems by theirselves. In this paper our aim is how to enhance the efficiency and lifttime of WOLED as backlights, and we are engaged in study work as follow:Firstly, one type of WOLED devices based on Zn(BTZ)2 was fabricated and applied to LCD backlighting. Zn(BTZ)2 is a kind of organic material whose emission closes to white light. We made both a matrix light-emitting device and a full face light-emitting device for large area emission. And we discuss the feasibility of fabricated method of the two kinds of device in our study.Secondly, we made a single layer WOLED by using Zn(BTZ)2:Rubrene as light-emitting layer. The CIE coordinate of the best chroma of the devices is (0.34,0.35), and Rubrene is used as a dopant for rectify the emission color. Besides, we analyzed the reason which resulted in the maximal quantum efficiency value, the average brightness and its uniformization of devices decreased with the increasing active area of devices while the devices'current increased. As a result, we found the main reason is the limited conducting performance of ITO. We added the metallic assistant electrode for devices to improve performance at a certain extent. At last, all devices were matched LCD screen and satisfied the need of the LCD backlight.Then,we try to fabricate two kinds of WOLED for the LCD backlight. They both have good luminescent efficiency than single doping layer devices, but bad chroma than the latter. It is mainly attributed to the bad color purity of TBPe as a blue dopant. Otherwise, double doping layer devices because of their high doping concentration have simple facture process comparing with single doping layer ones. However, the single layer with two dopant OLEDs have better steady CIE coordinate of light emission.Last, encapsulation of the device can improve the lifetime of WOLED for the LCD backlight. In this letter, we discuss the technics for encapsulation and the solidifying of the encapsulation glue. Then, we measure the lifetime of the WOLED for the LCD backlight. At last, we design a project for the power supply to the WOLED for the LCD backlight.