Probing Electron Excitation Characters of Carboline-Based Bis-Tridentate Ir(III) Complexes |
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Authors: | Jie Yan Ze-Lin Zhu Chun-Sing Lee Shih-Hung Liu Pi-Tai Chou Yun Chi |
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Affiliation: | 1.Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR, China;2.Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China;3.Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan; |
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Abstract: | In this work, we report a series of bis-tridentate Ir(III) metal complexes, comprising a dianionic pyrazole-pyridine-phenyl tridentate chelate and a monoanionic chelate bearing a peripheral carbene and carboline coordination fragment that is linked to the central phenyl group. All these Ir(III) complexes were synthesized with an efficient one-pot and two-step method, and their emission hue was fine-tuned by variation of the substituent at the central coordination entity (i.e., pyridinyl and phenyl group) of each of the tridentate chelates. Their photophysical and electrochemical properties, thermal stabilities and electroluminescence performances are examined and discussed comprehensively. The doped devices based on [Ir(cbF)(phyz1)] (Cb1) and [Ir(cbB)(phyz1)] (Cb4) give a maximum external quantum efficiency (current efficiency) of 16.6% (55.2 cd/A) and 13.9% (43.8 cd/A), respectively. The relatively high electroluminescence efficiencies indicate that bis-tridentate Ir(III) complexes are promising candidates for OLED applications. |
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Keywords: | bis-tridentate Ir(III) complex carboline carbene OLED substituent effect |
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