| Summary: | 碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 98 === Highly-efficiency white phosphorescent organic light emitting diode (PHOLED) can be achieved by using thin double-emission layers and doping red phosphor on interface between two emission layers. In this study, we utilizes double emitting layers (D-EMLs) structure to enlarge exciton generation zone of devices for the purpose of reducing thickness of emitting layer (EML) and driving voltage for blue PHOLEDs. In experiment, TCTA and 26DCzPPY are used as host material of D-EMLs. Through utilizing the difference on hole mobility of materials in D-EMLs, in combination with doping concentration of FIrpic, recombination zone will be controlled to be at interface between TCTA and 26DCzPPY. In addition, a hole transport-type host material (TCTA) was inserted between HTL and EML as hole buffer layer. The balanced charge carrier can be achieved by adjusting thickness of TCTA to control the amount of hole due to the lower mobility of TCTA than that of hole transport layer (TAPC), and further increased the luminance efficiency. Experimental results had showed that for the blue OLED with brightness of 1000 cd/m2, the driving voltage was 4.4 V, luminance efficiency 35 cd/A, and power efficiency reached 25 lm/W. Finally, the orange-red-emitting phosphor (Os(fptz)2 (PPh2Me)2) was doped at the interface of two emission layers. By using the ability of hole trapping in Os(fptz)2(PPh2Me)2, the holes were trapped in the interface of the double-emission layers, avoided the color-shift of the white OLED device. Experimental results had showed that for the white OLED with brightness of 1000 cd/m2, the driving voltage was 4.9 V, luminance efficiency 35 cd/A, and power efficiency reached 22 lm/W.
|
|---|
