Simple molecular structure design of iridium(III) complexes: Achieving highly efficient non-doped devices with low efficiency roll-off |
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| Affiliation: | 1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, PR China;2. State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun, Jilin 130012, PR China;1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China;2. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100190, China;1. Department of Applied Biology and Chemical Technology, Institute of Textile and Clothing, The Hong Kong Polytechnic University, Hong Kong, China;2. Clinical Division, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China;3. Institute of Molecular Functional Materials, Department of Chemistry and Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong, China;4. College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China;5. HKBU Institute of Research and Continuing Education, Shenzhen Virtual University Park, Shenzhen 518057, China;1. School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China;2. School of Elementary Education, Chongqing Normal University, Chongqing 400700, China;1. Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024, China;2. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China |
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| Abstract: | To construct efficient emitters suitable for non-doped devices and deeply understand the relationship between structures and performances, we designed and synthesized two heteroleptic iridium(III) complexes based on 1,2-diphenyl-1H-benzoimidazole (PBI) ligands whose substituents are varied simply from methyl (complex 2) to tert-butyl groups (complex 3). The parent complex 1 with non-substituent on PBI ligand has also been presented for a better comparison. Their photophysical, electrochemical and electroluminescent (EL) performances are investigated systematically. Despite their structural modification, all complexes exhibit almost identical emission and excited-state characters, which are rationalized by the quantum-chemical calculations. However, the obvious differences on device performances are found. Non-doped device employing 3 as emitting layer displays the highest EL performance with maximum current efficiency (ηc, max) of 18.6 cd A−1 and power efficiency (ηp, max) of 16.2 lm W−1 accompanied by low efficiency roll-off values, which is much higher than those of complexes 1 and 2. The obtained results herein suggest that introduction of the simple substituent into PBI ligand is an effective and feasible approach to develop highly efficient non-doped phosphors. |
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| Keywords: | Iridium(III) complex Simple molecular structure Non-doped device Improved efficiency Low roll-off DFT |
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