Structure Optimization of Hole Injection and Emitting Layer Using Solution-Based Processing and Stamping for Organic Light Emitting Diodes

• Main Authors: Tran Van Huong, 陳文向
• Other Authors: 謝傑任
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/uhemde

碩士 === 國立虎尾科技大學 === 機械與機電工程研究所 === 102 === In this thesis, a blue small- molecular organic light- emitting diodes (SM- OLEDs) based on a solution-process and stamping transfer method were first investigated. The structure of OLEDs device is described as follows: ITO/PEDOT: PSS/26DCzPPy: FIrpic/TPBi/LiF/Al. Therein, PEDOT: PSS as a hole injection layer is formed onto ITO-glass via spin-coating; emitting layer consists of host material 26DCzPPy with high triplet energy and blue dopant FIrpic are mixed and dissolved in chlorobenzene to form onto PEDOT: PSS layer by spin-coating. A specialized fabrication process-stamping method is utilized to transfer the TPBi film that plays an important role as electron transporting layer and also a hole blocking layer, from PDMS surface onto the 26DCzPPy: FIrpic. LiF/Al is thermally evaporated as a cathode electrode. The external pressure applied during for stamping TPBi was kept at 0.5 kg/cm2 and the heating temperature was carried out at 1200C for 100 seconds. A blue small- molecular organic light emitting diodes with CIE (0.16, 0.30) and the highest 3.5 cd/A of current efficiency at current density 20 mA/cm2 was obtained with entire solution-based process with stamping. Design of experiment (DOE) with response surface methodology (RSM) was applied to optimize the current efficiency of OLED devices. In this case, TPBi was fabricated via vacuum-deposition with thickness of 30 nm. The thickness of the hole injection layer (PEDOT: PSS) and the emitting layer (26DCzPPy: FIrpic) are chosen as two main input factors of processes. 13 OLED devices with different parameters were conducted following by an initial setting of Design Expert Software version V8.0.6. The optimum process parameters are forecasted by verifying the factors of output quality characteristics via analysis of variance (ANOVA). Finally, an impressive result 8.75 cd/A of current efficiency at 20 mA/ cm2, and a low 6.1 volt of driving voltage at 100 cd/m2 of luminance was reached by DOE with RSM.