Development and application of composite emitter for organic light-emitting devices

• Main Authors: Chu, Miao-Tsai, 朱妙采
• Other Authors: Chen, Chin-Hsin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/34916891000151798193

碩士 === 國立交通大學 === 平面顯示技術碩士學位學程 === 98 === In this thesis, we introduce a concept of “composite emitter” for applying on organic light-emitting devices (OLEDs). The composite emitter is doping a carrier-transporting material into conventional host-guest emitter for promoting the transport of carriers from carrier-transporting layer into emitter to increase the efficiency and decrease the driving voltage of OLED. Especially, the composite emitter can apply to blue phosphorescent OLED which need to use a wide-bandgap host material; in additional to we also apply this concept to the green phosphorescent OLED, Green/Red yellow phosphorescent OLED and tandem white OLED. (1) Blue phosphorescent OLED A blue phosphorescent OLED with a current efficiency of 26.5 cd/A, a power efficiency of 19.9 lm/W, a driving voltage of 4.2V and CIEx,y of (0.17, 0.36) at a brightness of 1000 cd/m2 can be achieved by composite emitter which was composed a host material of PPT and a carrier-transporting material of TCTA. Under the composite emitter, the blue phosphorescent OLED was improved by a factor of 2.1 comparing to that of using conventional host-guest emitter. (2) Green phosphorescent OLED A green phosphorescent OLED with a current efficiency of 52.7 cd/A, a power efficiency of 47.7 lm/W, a driving voltage of 3.4V and CIEx,y of (0.33, 0.61) at a brightness of 1000 cd/m2 can be achieved by composite emitter which was composed a host material of CBP and a carrier-transporting material of TCTA. Under the composite emitter, the green phosphorescent OLED was improved by a factor of 1.2 comparing to that of using conventional host-guest emitter. (3) Green/Red yellow phosphorescent OLED A yellow phosphorescent OLED which was co-doping green and red phosphorescent dopant into composite emitter at the same time with a current efficiency of 44.1 cd/A, a power efficiency of 40.7 lm/W, a driving voltage of 3.4V and CIEx,y of (0.45, 0.52) at a brightness of 1000 cd/m2 can be achieved by composite emitter. Under the composite emitter, the yellow phosphorescent OLED was improved by a factor of 1.4 comparing to that of using conventional host-guest emitter. (4) Tandem white OLED Finally, under the concept of composite emitter, applying a blue phosphorescent OLED and a green/red yellow phosphorescent OLED to fabricate a tandem white OLED through a connecting layer which was constructed by n-doped/p-doped layers. A tandem white OLED with a current efficiency of 70.1 cd/A, a power efficiency of 27.5 lm/W, a driving voltage of 8V, CIEx,y of (0.33, 0.48) and a color rendering index (CRI) of 72 can be achieved. In order to improve the CRI for attaining a practical value of 80, using a blue fluorescent OLED with saturated color to instead of blue phosphorescent OLED. The tandem white OLED with a current efficiency of 44.2 cd/A, a power efficiency of 18.8 lm/W, a driving voltage of 7.4V, CIEx,y of (0.39, 0.45) and a color rendering index (CRI) of 84 can be achieved.