High efficiency and luminance of near white fluorescent-phosphorescent organic light emitting diodes by multi-emission layer structure

• Main Authors: Wen-Jie Wu, 吳文傑
• Other Authors: Su-Hua Yang
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/09983455331306226990

碩士 === 國立高雄應用科技大學 === 電子工程系碩士班 === 101 === In this theme, a High efficiency and luminance of near white fluorescent-phosphorescent organic light emitting diodes was successfully fabricated using the structure of ITO/NPB (30 nm)/CBP:BCzVB (10 nm, 8 wt%)/CBP (2 nm)/CBP:Ir(piq)3:Ir(ppy)3 (10 nm, 2 wt%, 5 wt%)/CBP:Ir(ppy)3 (10 nm, 5 wt%)/CBP (2 nm)/CBP:BCzVB (10 nm, 8 wt%)/BPhen (50 nm)/LiF(1 nm)/Al (200 nm). At first, NPB and Bphen were selected as hole transport layer and electron transport layer materials, respectively. Moreover, LiF played an important role of OLEDs, that improved the injection of electrons. CBP was selected as host material because the triplet energy of CBP is higher than that of guests. In the meanwhile, CBP shows a favored characteristic for hole transfer. Hence, it can not only balance the carriers in the emission layer (EML) but also reduce the h+ polaron effect. The structure of EML contains several subjects, including: the blue fluorescent EML placed in the center of emission layer, the right side of EML was green phosphorescent EML, the left side of EML was red phosphorescent EML, and a CBP spacer was inserted between the fluorescence EML and phosphorescence EML. Furthermore, the green and red EMLs moved to the center of EML to achieve pure white-light emission. Moreover, phosphorescent sensitizer was added to the red EML to enhance the efficiency of the device.