Incorporation of electroluminescence and electrochemiluminescence in one organic light-emitting device

• Published in: Applied physics letters 2005-08, Vol.87 (9), p.093508-093508-3
• Main Authors: Zhen, Changgua, Chuai, Yutao, Lao, Chunfeng, Huang, Lan, Zou, Dechun, Lee, Do Nam, Kim, Byeong Hyo
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2012522

The incorporation of electroluminescence and electrochemiluminescence in one light-emitting device with the configuration of indium tin oxide (ITO)/ [ Ru ( bpy ) 2 ( dimbpy ) ] ( PF 6 ) 2 ∕ Alq 3 ( 30 nm ) ∕ NPB ( 45 nm ) ∕ Ag ( 60 nm ) is investigated. When the ITO and Ag electrodes are negatively and positively biased respectively, the color of the emission changes from green to light yellow-white within 100 s. So there is only one recombination zone in the bulk of the Alq 3 at the initial stage of the operation, followed by the formation of another recombination zone in the bulk of the [ Ru ( bpy ) 2 ( dimbpy ) ] ( PF 6 ) 2 . This directly indicates the existence of unipolar injection (electron injection) process in the ruthenium complex layer. The external quantum efficiency of the device is 1.4% compared with 0.45% of the ITO ∕ [ Ru ( bpy ) 2 ( dimbpy ) ] ( PF 6 ) 2 ∕ Ag device, improved by twofold. Furthermore, this hybrid device provides a feasible way to control the emission of a wide spectrum of colors including red, green, yellow, and white.