Efficient Red Organic Light Emitting Diodes of Nona Coordinate Europium Tris(β-Diketonato) Complexes Bearing 4'-Phenyl-2,2':6',2''-Terpyridine

Rashid Ilmi; Jingyu Wang; José D L Dutra; Liang Zhou; Wai-Yeung Wong; Paul R Raithby; Muhammad S Khan

doi:10.1002/chem.202300376

Efficient Red Organic Light Emitting Diodes of Nona Coordinate Europium Tris(β-Diketonato) Complexes Bearing 4'-Phenyl-2,2':6',2''-Terpyridine

Chemistry. 2023 Jul 3;29(37):e202300376. doi: 10.1002/chem.202300376. Epub 2023 May 9.

Authors

Rashid Ilmi¹, Jingyu Wang², José D L Dutra³, Liang Zhou², Wai-Yeung Wong⁴, Paul R Raithby⁵, Muhammad S Khan¹

Affiliations

¹ Department of Chemistry, Sultan Qaboos University, P. O. Box 36, Al, Khod 123, Oman.
² State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun, 130022, P. R. China.
³ Pople Computational Chemistry Laboratory, Department of Chemistry, UFS, 49100-000, São Cristóvão, Sergipe, Brazil.
⁴ Department of Applied Biology and, Chemical Technology and, Research Institute for Smart Energy, The Hong Kong Polytechnic University Hung Hom, Kowloon, Hong Kong, P. R. China.
⁵ Department of Chemistry, University of Bath Claverton Down, Bath, BA2 7AY, UK.

PMID: 37062705
DOI: 10.1002/chem.202300376

Abstract

Two novel nona-coordinated Eu(III) complexes [Eu(btfa)₃ (Ph-TerPyr)] (Eu-1) and [Eu(NTA)₃ (Ph-TerPyr)] (Eu-2) have been synthesized and characterized. The structure of the complexes was elucidated by density functional theory (DFT) methods. The experimental photophysical properties of the complexes were investigated and complemented with theoretical calculations. Effective energy transfer (ET) pathways for the sensitized red luminescence is discussed. The complexes were tested as emitting layers (EML) in organic light emitting diodes (OLEDs). At the optimum doping concentration of 4 wt.%, the double-EML OLEDs of Eu-1 exhibited red electroluminescence (EL) with an EQE of 4.0 % and maximum brightness (B)=1179 cd/m² , maximum current efficiency (η_c )=5.64 cd/A, and maximum power efficiency (η_p )=4.78 lm/W at the current density (J) of 10 mA/cm² . Interestingly, the double-EML OLEDs of Eu-2 at the optimum concentration of 3 wt.%, displayed an outstanding EL performance with EQE of 7.32 % and B=838 cd/m² , η_c =10.19 cd/A and η_p =10.33 lm/W at J=10 mA/cm² . The EL performance of this device is among the best reported for devices incorporating a europium complex as a red emitter.

Keywords: DFT calculations; Electroluminescence; Europium(III); Sensitized Luminescence; β-diketone.

Abstract

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