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Bright Green PhOLEDs Using Cyclometalated Diiridium(III) Complexes with Bridging Oxamidato Ligands as Phosphorescent Dopants

M’hamedi, Ahmed; Fox, Mark A.; Batsanov, Andrei S.; Al-Attar, Hameed A.; Monkman, Andrew P.; Bryce, Martin R.

Bright Green PhOLEDs Using Cyclometalated Diiridium(III) Complexes with Bridging Oxamidato Ligands as Phosphorescent Dopants Thumbnail


Authors

Ahmed M’hamedi

Andrei S. Batsanov

Hameed A. Al-Attar

Andrew P. Monkman



Abstract

In contrast to monoiridium complexes, the study of diiridium complexes as dopants in phosphorescent organic light-emitting devices (PhOLEDs) is largely unexplored. We now describe the syntheses, detailed NMR analyses, X-ray crystal structures and optoelectronic properties of the new cyclometalated diiridium complexes 5 and 6 in which the iridium centres are bridged by oxamidato ligands. These complexes contain diastereomers – the meso form (ΔΛ) and the racemic form consisting of two enantiomers (ΔΔ and ΛΛ) – with anti-oxamidato bridges. The precursor μ-dichloro-bridged complex 4 is very weakly emissive in solution, whereas the oxamidato bridged complexes 5 and 6 are highly emissive (ΦPL 73% and 63%) with short excited state lifetimes of τP 0.84 and 1.16 μs, respectively. Cyclic voltammetry studies demonstrate that the oxamidato bridging ligand plays a role in mediating intramolecular interactions between the iridium centres. Density functional theory (DFT) calculations and time dependent-DFT (TD-DFT) calculations provide further insights into the structural, electronic, and photophysical properties of the complexes in their ground and excited states. Phosphorescent organic light-emitting diodes (PhOLEDs) using complexes 5 and 6 as the emissive dopants in a simple architecture using a solution-processed active layer give bright green electroluminescence with remarkably high luminance (Lmax > 25[thin space (1/6-em)]000 cd m−2) for diiridium complexes.

Citation

M’hamedi, A., Fox, M. A., Batsanov, A. S., Al-Attar, H. A., Monkman, A. P., & Bryce, M. R. (2017). Bright Green PhOLEDs Using Cyclometalated Diiridium(III) Complexes with Bridging Oxamidato Ligands as Phosphorescent Dopants. Journal of Materials Chemistry C Materials for optical and electronic devices, 5(27), 6777-6789. https://doi.org/10.1039/c7tc00628d

Journal Article Type Article
Acceptance Date Jun 18, 2017
Online Publication Date Jun 28, 2017
Publication Date Jan 1, 2017
Deposit Date Jun 21, 2017
Publicly Available Date Jun 28, 2017
Journal Journal of Materials Chemistry C Materials for optical and electronic devices
Print ISSN 2050-7526
Electronic ISSN 2050-7534
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 5
Issue 27
Pages 6777-6789
DOI https://doi.org/10.1039/c7tc00628d

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Copyright Statement
This Open Access Article is licensed under a
Creative Commons Attribution 3.0 Unported Licence.






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