High efficiency and color saturated blue electroluminescence by using 4,4′-bis[ N-(1-naphthyl)- N-phenylamino]biphenyl as the thinner host and hole-transporter

• Published in: Solid-state electronics 2008, Vol.52 (1), p.121-125
• Main Authors: Li, Mingtao, Li, Wenlian, Su, Wenming, Zang, Faxin, Chu, Bei, Xin, Qi, Bi, Defeng, Li, Bin, Yu, Tianzhi
• Format: Article
• Language: English
• Subjects: Applied sciences; Blue OLED; Carrier recombination; Electronics; Exact sciences and technology; NPB host; Optoelectronic devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2007.07.030

A traditional hole-transporting (HT) material, 4,4′-bis[ N-(1-naphthyl)- N-phenylamino]biphenyl (NPB) was used as the host to fabricate a blue organic light-emitting diode (OLED) in which the blue dopant emitter is 2,5,8,11-tetra- t-butyl-perylene (TBP) and the another NPB layer adjusted to thinner host was also used as the HT-layer. The blue electroluminescent (EL) was proved to be originated from the narrower doped layer and the adjacent NPB HT-layer. Compared with the previous blue EL devices based on TBP dopant, the performances of the blue OLED were improved by using a thinner NPB host layer. The blue OLED shows higher efficiency and better blue color saturation, such as the device behaving a maximum efficiency of 4.6 cd/A, CIE color coordinates of x = 0.136 and y = 0.173 at a bias of 5 V, and a peak luminance of 11,500 cd/m 2 at a bias of 20 V. The operation mechanism of the blue device was also discussed.