Highly Emitting Neutral Dinuclear Rhenium Complexes as Phosphorescent Dopants for Electroluminescent Devices

Authors

  • Matteo Mauro,

    1. Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy)
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  • Elsa Quartapelle Procopio,

    1. Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy)
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  • Yinghui Sun,

    1. Westfälische Wilhelms Universität Münster Physikalisches Institut Mendelstrasse, 7 48149 Münster, Germany and Center for Nanotechnology (CeNTech) 48149 Münster (Germany)
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  • Chen-Han Chien,

    1. Department of Applied Chemistry National Chiao Tung University Hsinchu, 30056 (Taiwan)
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  • Daniela Donghi,

    1. Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy)
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  • Monica Panigati,

    1. Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy)
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  • Pierluigi Mercandelli,

    Corresponding author
    1. Dipartimento di Chimica Strutturale e Stereochimica Inorganica Universitá degli Studi di Milano Via Venezian 21, 20133 Milano (Italy)
    • Dipartimento di Chimica Strutturale e Stereochimica Inorganica Universitá degli Studi di Milano Via Venezian 21, 20133 Milano (Italy).
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  • Patrizia Mussini,

    1. Dipartimento di Chimica Fisica ed Elettrochimica Universitá degli Studi di Milano Via Golgi 19, 20133 Milano (Italy)
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  • Giuseppe D'Alfonso,

    Corresponding author
    1. Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy)
    • Dipartimento di Chimica Inorganica Universitá degli Studi di Milano Metallorganica e Analitica “L. Malatesta” Via Venezian 21, 20133 Milano (Italy).
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  • Luisa De Cola

    Corresponding author
    1. Westfälische Wilhelms Universität Münster Physikalisches Institut Mendelstrasse, 7 48149 Münster, Germany and Center for Nanotechnology (CeNTech) 48149 Münster (Germany)
    • Westfälische Wilhelms Universität Münster Physikalisches Institut Mendelstrasse, 7 48149 Münster, Germany and Center for Nanotechnology (CeNTech) 48149 Münster (Germany).
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Abstract

A series of neutral, dinuclear, luminescent rhenium(I) complexes suitable for phosphorescent organic light emitting devices (OLEDs) is reported. These compounds, of general formula [Re2(µ-Cl)2(CO)6(µ-1,2-diazine)], contain diazines bearing alkyl groups in one or in both the β positions. Their electrochemical and photophysical properties are presented, as well as a combined density functional and time-dependent density functional study of their geometry, relative stability and electronic structure. The complexes show intense green/yellow emissions in toluene solution and in the solid state and some of the complexes possess high emission quantum yields (ϕ = 0.18–0.22 for the derivatives with disubstituted diazines). In butyronitrile glass, at 77 K, due to the charge transfer character of the lowest (emitting) excited state, strong blue shift of the emission is observed, accompanied by a strong increase in the lifetime values. The highest-performing emitting complex, containing cyclopentapyridazine as ligand, is tested in a polymer-based light-emitting device, with poly(9-vinylcarbazole) as matrix, as well as in a device obtained by vacuum sublimation of the complex in the 2,7-bis(diphenylphosphine oxide)-9-(9-phenylcarbazol-3-yl)-9-phenylfluorene (PCF) matrix. This represents the first example of devices obtained with a rhenium complex which can be sublimed and is solution processable. Furthermore, the emission is the bluest ever reported for electrogenerated luminescence for rhenium complexes.

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