Novel Blue Fluorescent Dopants Based on Imidazole-Containing Compound for Organic Electroluminescent Devices

Aminul Islam; Chia-Chen Tsou; Hui-Ju  Hsu; Wen-Li  Shih; Charng-Hsing Liu; Chien-Hong Cheng

doi:10.6180/jase.2002.5.2.01

Novel Blue Fluorescent Dopants Based on Imidazole-Containing Compound for Organic Electroluminescent Devices

Aminul Islam¹ , Chia-Chen Tsou² , Hui-Ju Hsu² , Wen-Li Shih² , Charng-Hsing Liu² and Chien-Hong Cheng This email address is being protected from spambots. You need JavaScript enabled to view it.¹

¹Department of Chemistry Tsing Hua University Hsinchu, Taiwan 300, R.O.C.
²Department of Applied Chemistry Chia Nan University of Pharmacy and Science Tainan, Taiwan 717, R.O.C.

Received: April 1, 2002
Accepted: May 3, 2002
Publication Date: June 1, 2002

Download Citation: ||https://doi.org/10.6180/jase.2002.5.2.01

ABSTRACT

We report the synthesis of bis-imidazole derivatives [1,4-bis-(2-(4-benzoylphenyl)-5-R-1H-4-imidazolyl)benzene] BSIB-1 (R = phenyl) and BSIB-2 (R = p-tolyl) by a simple one-step reaction of the corresponding substituted tetraone, substituted benzaldehyde and ammonium acetate and the use of these organic compounds as dopant emitters in electroluminescent devices. The physical properties of BSIBs were thoroughly investigated. A general device structure of the devices is ITO/NPB (20 nm)/CBP (20 nm)/BSIB:TPBI (X%, Y nm)/TPBI (20 nm)/Mg:Ag (10:1; 55 nm)/Ag (100 nm), where NPB, CBP and TPBI stand for 4,4’-bis[N-(1-naphthyl)-N-phenyl-amino]- biphenyl, 4,4’-dicarbazolyl-1.1’-biphenyl and 2,2’,2’’-(1,3,5-phenylene) tris-[1-phenyl-1H-benzimidazole], respectively. Efficient blue-green to blue emission from the devices with luminance ranging from 2500-5000 cd/m2 was obtained. The efficiencies of the devices and the nature of the emitting color depended substantially on the concentration of the dopant and thickness of the emitting layer. The Förster mechanism is suggested to account for the transfer of energy from host TPBI to the dopant and emission from the dopant.

Keywords: Electroluminescent, Imidazole Derivatives, OLED, Blue-Light Emitting Dopants, Blue Light

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