Study Of White Organic Light-Emitting Devices Based On Novel Blue Emitting Material

Organic light-emitting devices (OLEDs) have been achieving much attention because of their ideal characteristics for industry, such as solid state display, active emitting, broad visual angle, high efficiency, availability for flexible and full color display, etc. Nowadays, white OLEDs can be used as backlights for liquid crystal displays, illumination light sources and even full color displays combined with color filters. In spite of having nice efficiency, many OLEDs are fabricated with complicated process. Thus, they are not adapted to the need of large-scale commercial manufacture. So in this paper we manage to study and produce the simple structure device with high efficiency.Firstly, we introduced the characteristic of TBPe, which is a new kind of blue material. Then we fabricated the single emitting layer OLED whose configuration is ITO/white emitting layer/BCP/Alq3/Mg:Ag. By adjusting the adulterated proportion and the configuration of the device properly, a white OLED with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.38) was generated. The CIE coordinate stayed virtually constant when the voltage increased from 8 to 16 V. The maximum brightness of the device was 553cd/m2, and the maximum external efficiency was 0.16%.In order to get higher efficient device using TBPe, we tried to make it as following structure: ITO/PVK:TBPe/Alq3:rubrene/Mg:Ag. Then the device had a white-light emission whose CIE coordinates was (0.26, 0.33). Furthermore, we attempted to use Zn(BTZ)2 instead of Alq3 as electron transport material. The device had a very low starting voltage at 6V. Bright white light, over 1300cd/ m2, was successfully obtained by controling the thickness of each emitting layer and the adulterated proportion of dopant accurately. The maximum exteral quantum efficiency reached 0.31% at 8V. The CIE coordinates of the white OLED was(0.32,0.36), which constantly located in the white-light region with changing voltage. In a word, the performance of the whole device was increased remarkably due to its suitable structure and dye material.At last, we chose another organic material—NPB as main blue light emitting component. The configuration of the device is ITO/PVK:MEH-PPV/NPB/BCP/Alq3/Mg:Ag, using BCP as hole blocking layer. After perfecting the device, the corresponding brightness and efficiency were 2320cd/m2 and 0.52%, respectively. The light emission, which is nearly to pure white, changed from (0.32,0.31) to (0.33,0.29) with the increasing driven voltage.In the whole paper, we tried to blend the polymer and small molecule organic material together as light emitting layer, which make up the shortcoming for each other. The efficiency of white light-emitting is improved only by designing the device structure and changing the electron transport material reasonably. We also discussed the emitting mechanisms of the material and the devices.