Luminance and charge transport mechanisms for phosphorescent organic light-emitting devices fabricated utilizing a tris(2-phenylpyridine)iridium-doped N,N′-dicarbazolyl-3,5-benzene emitting layer

• Published in: Thin solid films Vol. 519; no. 15; pp. 5253 - 5256
• Main Authors: Choo, Dong Chul, Ko, Yo Seop, Kim, Tae Whan, Seo, Ji Hyun, Kim, Young Kwan
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 31.05.2011; Elsevier
• Subjects: Applied sciences; Charge transport; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Current density; Devices; Electroluminescence; Electronics; Emittance; Exact sciences and technology; Luminance; Luminance efficiency enhancement; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optoelectronic devices; Other luminescence and radiative recombination; Phosphorescent organic light-emitting diode; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin films; Triplet exciton; Voltage; Triplet exciton; Luminance efficiency enhancement; Phosphorescent organic light-emitting diode; Molecular orbital; Electronic conductivity; Doping; Electron injection; Electroluminescence; Charge transport; Nitrogen addition; Light emitting diode; Benzene; Organic light emitting diodes; Phenanthrolines; Iridium; Current density
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.01.170

The luminance and the charge transport mechanisms for phosphorescent organic light-emitting devices (PHOLEDs) fabricated utilizing a tris(2-phenylpyridine)iridium (Ir(ppy) 3)-doped N,N′-dicarbazolyl-3,5-benzene (mCP) emitting layer (EML) were investigated to improve the luminance efficiency of PHOLEDs. When Ir(ppy) 3 molecules existed on the electron transport layer (ETL) side of the EML, the current density of the PHOLED with an mCP EML containing an Ir(ppy) 3-doped thin layer increased. The Ir(ppy) 3-related electroluminescence (EL) intensity of the PHOLEDs with an Ir(ppy) 3-doped EML increased with increasing operating voltage. The increase in the current density was due to the lowest unoccupied molecular orbital levels of the Ir(ppy) 3 and the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ETL being identical, and the increase in the EL intensity could be attributed to a movement of the recombination zone to the center of the EML due to an increase in the electron injection from the ETL into the EML at high voltages.