Improved Organic Electroluminescent Device with Buffer Layers at the Anode

• Main Authors: Tiao-Hung Hsiao, 蕭調宏
• Other Authors: Meiso Yokoyama
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/80505532899683860506

碩士 === 國立成功大學 === 電機工程學系 === 89 === How to increase the brightness of organic electricluminescence (OEL) devices is an important topic. In this thesis, we will investigate the electrical and optical characteristics of the organic light emitting diode (OLED) devices using double buffer layer [ITO/CuPc/MTDATA]. At first, we investigate the characteristics of CuPc for ITO/CuPc/NPB/Alq3/AL and of MTDATA for ITO/MTDATA/NPB/Alq3/AL separately. Then, using the structure of ITO/CuPc/MTDATA/NPB/Alq3/AL, we investigate the electrical and optical characteristics of OLED and mechanism of double buffer layer [ITO/CuPc/MTDATA]. Finally, in reduction of thickness of the buffer layer, we change the percentage of thickness of CuPc and MTDATA to investigate the electrical and optical characteristics. Concerning to the study of the properties of CuPc and MTDATA, we observe the optimum optical characteristic with CuPc thickness of 10 nm and MTDATA thickness of 20 nm. Furthermore, by changing the percentage, we find that MTDATA suit for buffer layer and the double buffer layer is used to reduce the excess hole injection in order to increase recombination efficiency. In this research, the structure of ITO/CuPc(3.3nm)/MTDATA(6.7nm)/NPB(50nm)/Alq3(50nm)/Al(300nm) shows the highest brightness which is 778 cd/m2 at the current density of 120 mA/cm2. From the EL spectra, the OEL device using double buffer layer didn’t change the emitting wavelength. Therefore, it is useful to enhance the luminance of OEL devices by using double buffer layer structure.. The conclusion of this reveals that the structure of double buffer layer can be used to increasing recombination efficiency by reducing excess hole injection *The author **The advisor