Iridium(III) complexes with 6-pentafluorophenyl-2, 4-diphenylquinolines for red OLEDs
- Authors
- Park, Gui Youn; Seo, Ji Hyun; Kim, Young Kwan; Kim, Young Sik
- Issue Date
- 2007
- Publisher
- TAYLOR & FRANCIS LTD
- Keywords
- DFT; 2,4-diphenylquinoline ligand; iridium complex; OLED; phosphorescence; red
- Citation
- MOLECULAR CRYSTALS AND LIQUID CRYSTALS, v.471, pp.293 - 303
- Journal Title
- MOLECULAR CRYSTALS AND LIQUID CRYSTALS
- Volume
- 471
- Start Page
- 293
- End Page
- 303
- URI
- https://scholarworks.bwise.kr/hongik/handle/2020.sw.hongik/24305
- DOI
- 10.1080/15421400701548530
- ISSN
- 1542-1406
- Abstract
- Novel red electrophosphorescent devices were fabricated by doping perfluorophenyl substituted iridium( III) complex, bis[ 1-( 6- Pentafluorophenyl- 2,4- diphenyl) quinolinato-N, C-2'] iridium( III) ( acetylacetonate) [ Ir( PF- dpq)(2)( acac)] for the application in organic light- emitting diodes ( OLEDs). The maximum electroluminescent ( EL) wavelengths of Ir( dpq)(2)( acac) and Ir( PF- dpq)(2)( acac) have shown at 614nm and 620 nm, respectively. The device using Ir( PF- dpq) 2( acac) showed red emission with 1931 CIE chromaticity coordinates ( x= 0.640, y= 0.342) at 12 V. The perfluorophenyl substituent on the quinoline ring as electron withdrawing group decreased the lowest unoccupied molecular orbital ( LOMO). As a result, the energy gap is reduced, leading to red- shift the emission wavelength. The ab initio calculation using the time- dependent density function theory ( DFT) showed in agreement with the experimental results. However, the iridium complex of PF- dpq underwent a weak MLCT transition because of the weak coupling between the 5d- orbital of the iridium atom and HOMO of the substituted ligand. Thus, the luminous efficiency of the device using Ir( dpq)(2)( acac) and Ir( PF- dpq)(2)( acac) are 4.36 cd/A and 3.13 cd/A, respectively, at the current density of 3.38mA= cm(2) and 1.11mA/cm(2).
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Collections - College of Engineering > Department of Science > 1. Journal Articles
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