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Bright green PhOLEDs using cyclometalated diiridium( iii ) complexes with bridging oxamidato ligands as phosphorescent dopants

DOI: 10.1039/C7TC00628D DOI Help

Authors: Ahmed M’hamedi (University of Abdelhamid Ibn Badis) , Mark A. Fox (Durham University) , Andrei S. Batsanov (Durham University) , Hameed A. Al-attar (Durham University) , Andrew P. Monkman (Durham University) , Martin R. Bryce (Durham University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: J. Mater. Chem. C , VOL 5 , PAGES 6777-6789

State: Published (Approved)
Published: June 2017
Diamond Proposal Number(s): 11145

Open Access Open Access

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.

Subject Areas: Chemistry


Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 13/07/2017 10:40

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