Highly efficient orange and warm white phosphorescent OLEDs based on a host material with a carbazole-fluorenyl hybrid.
A new carbazole-fluorenyl hybrid compound, 3,3'(2,7-di(naphthaline-2-yl)-9H-fluorene-9,9-diyl)bis(9-phenyl-9H-carbazole) (NFBC) was synthesized and characterized. The compound exhibits blue-violet emission both in solution and in film, with peaks centered at 404 and 420 nm. In addition to the application as a blue emitter, NFBC is demonstrated to be a good host for phosphorescent dopants. By doping Ir(2-phq)3 in NFBC, a highly efficient orange organic light-emitting diode (OLED) with a maximum efficiency of 32 cd A(-1) (26.5 Lm W(-1)) was obtained. Unlike most phosphorescent OLEDs, the device prepared in our study shows little efficiency roll-off at high brightness and maintains current efficiencies of 31.9 and 26.8 cd A(-1) at a luminance of 1000 and 10,000 cd m(-2), respectively. By using NFBC simultaneously as a blue fluorescence emitter and as a host for a phosphorescent dopant, a warm white OLED with a maximum efficiency of 22.9 Lm W(-1) (21.9 cd A(-1)) was also obtained.
School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China), Fax: (+86) 28-83201745; Center of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region (China), Fax: (+852) 27847826.
Xiaoyang
X
Du
Yun
Y
Huang
Silu
S
Tao
Xiaoxia
X
Yang
Chuan
C
Wu
Huaixin
H
Wei
Mei-Yee
MY
Chan
Vivian Wing-Wah
VW
Yam
Chun-Sing
CS
Lee
OLEDs; blue fluorescent host; doping; fluorescence; phosphorescence; warm white emission