https://scholars.lib.ntu.edu.tw/handle/123456789/342712
標題: | Phosphorescent iridium(III) complexes with nonconjugated cyclometalated ligands | 作者: | Yun Chi, Yi-Hwa Chiu, Yuan-Chieh Chi, Cheng, Yi-Ming Lai, Cheng-Hsuan PI-TAI CHOU KEN-TSUNG WONG Tsai, Ming-Han CHUNG-CHIH WU |
關鍵字: | Conjugation; Cyclometalation; Energy transitions; Iridium; Phosphorescence | 公開日期: | 六月-2008 | 卷: | 14 | 期: | 18 | 起(迄)頁: | 5423-5434 | 來源出版物: | Chemistry-A European Journal | 摘要: | A series of blue phosphorescent iridium(III) complexes 1-4 with nonconjugated N-benzylpyrazole ligands were synthesized and their structural, electrochemical, and photophysical properties were investigated. Complexes 1-4 exhibit phosphorescence with yields of 5-45% in degassed CH2Cl 2. Of the compounds, 1 showed emission that was nearly true blue at 460 nm with a lack of vibronic progression. These photophysical data clearly demonstrate that the methylene spacer of the cyclometalated N-benzylpyrazole chelate effectively interrupts the π conjugation upon reacting with a third L∧X chelating chromophore. This gives a feasible synthesis for the blue phosphorescent complexes with a sufficiently large energy gap. In another approach, these complexes were investigated for their suitability for the host material in phosphorescent OLEDs. The device was synthesized by using 1 as the host for the green-emitting [Ir-(PPy)3] dopant, which exhibits an external quantum conversion efficiency (EQE) of up to 11.4% photons per electron (and 36.6 cd A-1), with 1931 Commission Internationale de L'E-clairage (CIE) coordinates of (0.30, 0.59), a peak power efficiency of 21.7 lmW-1, and a maximum brightness of 32000 cdm-2 at 14.5 V. At the practical brightness of 100 cdm-2, the efficiency remains above 11% and 18 lmW-1, demonstrating its great potential as the host material for phosphorescent organic light-emitting diodes. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA. |
URI: | http://scholars.lib.ntu.edu.tw/handle/123456789/342712 https://www.scopus.com/inward/record.uri?eid=2-s2.0-53849131360&doi=10.1002%2fchem.200800050&partnerID=40&md5=bd55c385822071ef440a9a8ec8362ece |
ISSN: | 09476539 | DOI: | 10.1002/chem.200800050 | SDG/關鍵字: | Electrochemical properties; Iridium; Ligands; Light emission; Luminescence; Phosphorescence; Conjugation; Cyclometalated ligands; Cyclometalation; Energy transitions; Iridium complexes; Nonconjugated; Photo-physical properties; Iridium compounds |
顯示於: | 電機工程學系 |
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