Altinolcek, N., Battal, A., Tavasli, M., Cameron, J. , Peveler, W. J. , Yu, H. A. and Skabara, P. J. (2020) Yellowish-orange and red emitting quinoline-based iridium(III) complexes: synthesis, thermal, optical and electrochemical properties and OLED application. Synthetic Metals, 268, 116504. (doi: 10.1016/j.synthmet.2020.116504)
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Abstract
Two novel heteroleptic iridium(III) acetylacetonate (acac) complexes K3a and K3b were synthesised from cyclometallating ligands of 2-(4′-formylphenyl)quinoline 11a and 2-(5′-formylphenyl)quinoline 11b. Complexes K3a and K3b were fully characterised by NMR spectroscopy, mass spectrometry and FT-IR. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) indicate that both complexes were amorphous solids, stable up to 303 °C and 313 °C, respectively. Complexes K3a and K3b showed strong, high-energy absorption bands (<400 nm) due to ligand-centred (1LC) transitions and weaker, low-energy absorption bands (400−600 nm) arising from a mixture of metal-to-ligand charge transfer (1MLCT/3MLCT) and ligand-centred (3LC) transitions. In degassed dichloromethane solutions, complexes K3a and K3b gave yellowish-orange and red phosphorescent emissions at 579 nm and 630 nm, with quantum efficiencies of 99.3 % and 79.3 %, respectively. At positive potential, complexes K3a and K3b exhibited a one-electron reversible oxidation (Eox1/2) peak at 0.69 V and a quasi-reversible oxidation (Eox1/2) peak at 0.60 V, respectively, which were assigned to the Ir(III)/Ir(IV) couple. At negative potentials, complexes K3a and K3b exhibited a one-electron irreversible reduction peak at -1.79 V and -1.94 V, respectively. Phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated with a device configuration of ITO/PEDOT:PSS/EML/TPBi/LiF/Al, in which K3a and K3b gave yellowish-orange and red electroluminescence (EL) at 572 nm and 628 nm, respectively. Complex K3a gave the highest luminance of 2773 cd/m2, current efficiency of 3.3 cd/A, external quantum efficiency of 1.2 % and maximum power efficiency of 1.05 lm/W with a turn-on voltage of 5.0 V (Device A).
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Peveler, Dr William and Cameron, Dr Joseph and Skabara, Professor Peter and Yu, Dr Holly |
| Creator Roles: | Cameron, J.Project administration Peveler, W. J.Resources, Writing – review and editing Yu, H. A.Investigation Skabara, P. J.Resources, Writing – review and editing, Supervision |
| Authors: | Altinolcek, N., Battal, A., Tavasli, M., Cameron, J., Peveler, W. J., Yu, H. A., and Skabara, P. J. |
| College/School: | College of Science and Engineering > School of Chemistry |
| Journal Name: | Synthetic Metals |
| Publisher: | Elsevier |
| ISSN: | 0379-6779 |
| ISSN (Online): | 1879-3290 |
| Published Online: | 11 July 2020 |
| Copyright Holders: | Copyright © 2020 Elsevier B.V. |
| First Published: | First published in Synthetic Metals 268: 116504 |
| Publisher Policy: | Reproduced in accordance with the publisher copyright policy |
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