Low driving voltage and efficient orange-red phosphorescent organic light-emitting devices based on a benzotriazole iridium complex

• Published in: Synthetic metals Vol. 159; no. 17-18; pp. 1782 - 1785
• Main Authors: Xia, Zhen-Yuan, Xiao, Xiao, Su, Jian-Hua, Chang, Chi-Sheng, Chen, Chin H., Li, Dan-Lin, Tian, He
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2009; Elsevier
• Subjects: Applied sciences; Benzotriazole derivative; Electronics; Exact sciences and technology; Iridium complex; Optoelectronic devices; Orange-red phosphorescent OLED; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Benzotriazole derivative; Iridium complex; Orange-red phosphorescent OLED; Benzotriazole derivatives; Driving voltage; Red light; Doped materials; Quantum yield; Quenching; Low voltage; Luminance; Biphenyl derivatives; Concentration effect; Organic light emitting diodes; Optoelectronic device; Acetylacetone derivatives; Phosphorescence; Organic electronics
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2009.05.026

Efficient orange-red phosphorescent organic light-emitting devices (PHOLED) with various doping concentrations of benzotriazole–iridium complex [(TBT)2Ir(acac)] (bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N1,C3] iridium acetylacetonate) in 4,4′-N,N′-di(carbazolyl) biphenyl (CBP) host were fabricated. The sterically hindered iridium ligands alleviate self-quenching of the phosphorescence at high doping levels. Under the optimal doping concentration of 20wt.%, the maximum external quantum efficiency (EQE), luminance and power yield reach 9.06%, 15.81cd/A and 13.8lm/W, respectively. Increasing the doping concentration from 5% to 30wt.% significantly decreases the driving voltage. The driving voltage of 30% (TBT)2Ir(acac) doped device is only 3.16V at 1mA/cm2 with power yield of 13.32lm/W.