High-Efficiency Red Phosphorescent Iridium Dendrimers with Charge- Transporting Dendrons: Synthesis and Electroluminescent Properties

Authors

  • B. Liang,

    1. Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640, P.R. China
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  • L. Wang,

    1. Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640, P.R. China
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  • Y. H. Xu,

    1. Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640, P.R. China
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  • H. H. Shi,

    1. Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640, P.R. China
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  • Y. Cao

    1. Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640, P.R. China
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  • The authors are deeply grateful to the National Natural Science Foundation of China (Project No. 50433030) and the MOST National Research Project (No. 2002CB613403) for their financial support. Supporting Information is available online from Wiley InterScience or from the author.

Abstract

A series of 1-phenylisoquinoline derivatives encapsulated with peripheral arylamines as dendrons are synthesized by using the Ullmann reaction and palladium-catalyzed aromatic carbon–carbon Suzuki-coupling reactions. Red-emitting dendritic iridium complexes (called G1-1, G1-2, and G2) are synthesized using the following derivatives: N,N-diphenyl-3′-isoquinolin-4-biphenylaniline, N,N-di(9,9-dimethylfluorenyl-3′-isoquinolin-4-biphenylaniline, N,N-di(4′-di(2′-(9′,9′-dimethylfluorenyl)amine)biphenyl-3′-isoquinolin-4-biphenylaniline as the first ligands and 5-methyl-3-(pyridin-2′-yl)-1H-1,2,4-triazole as an ancillary ligand. The obtained dendrimers are soluble in common organic solvents, and uniform thin films can be spin-coated from such solutions. Devices fabricated from dendritic iridium complexes G1-2 and G2 with a small molecule host are fabricated by spin-coating from chloroform solution in different device configurations. G1-2 and G2 show similar device performances with maximum external quantum efficiencies (EQEs) of 12.8 % and 11.8 % (photons/electron) and luminous efficiency of 9.2 cd A–1 and 8.5 cd A–1 at 0.1 mA cm–2, respectively. Devices based on polymer host poly(9,9-dioctylfluorene)(PFO) (30 % PBD (2-(4-biphenyl)-5-(4-tert-butylphenyl-1,3,4-oxadiazole)) show a slightly higher efficiency for G1-2, with a maximum EQE of 13.9 % at a much higher current density of 6.4 mA cm–2 and luminance of 601 cd m–2.

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