Donor N-substitution as design principle for fast and blue luminescence in carbene-metal-amides

Reponen, Antti-Pekka M., Chotard, Florian, Lempelto, Aku, Shekhovtsev, Vitalii, Credgington, Dan, Bochmann, Manfred, Linnolahti, Mikko, Greenham, Neil C. and Romanov, Alexander S. (2022) Donor N-substitution as design principle for fast and blue luminescence in carbene-metal-amides. Advanced Optical Materials, 10. ISSN 2195-1071

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Abstract

A series of gold-centered carbene-metal-amide (CMA) complexes are synthesized with the carbazole donor ligand modified by substitution with nitrogen atoms in varying positions. The luminescence of new aza-CMA complexes shows a significant blueshift depending on the position of the N atom, to provide bright blue-green (500 nm), sky-blue (478 nm), blue (450 nm) and deep-blue (419 nm) light-emitters. The impact of the electron-withdrawing aza-group on the nature of the luminescence and the excited state energies of the locally excited (LE) or charge transfer (CT) states have been interpreted with the help of transient absorption, in-depth photoluminescence experiments and theoretical calculations. By considering the orbital characters of the lowest CT and LE states, we develop a new concept for simultaneous energy tuning for both of these states with a single aza-substitution, allowing for fast and blue CT emission. This concept allows the interference of 3LE phosphorescence to be avoided at room temperature. The approach is extended to two N substitutions at the optimal location in the 3- and 6-positions of the carbazole skeleton. These results suggest a practical molecular design towards the development of bright and deep-blue emitting CMA materials to tackle the stability problem of energy-efficient deep-blue OLEDs.

Item Type: Article
Additional Information: Acknowledgements: This work was supported by the European Research Council, the Royal Society and the Academy of Finland. A.S.R. acknowledges support from the Royal Society (Grant nos. URF\R1\180288 and RGF\EA\181008) and Engineering and Physical Sciences Research Council (EPSRC grant EP/K039547/1). M.B. is an ERC Advanced Investigator Award holder (Grant no. 338944-GOCAT). M.L. acknowledges the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN), decision 320166. (TD) DFT computations were made possible by use of the Finnish Grid and Cloud Infrastructure resources (urn:nbn:fi:research-infras-2016072533). A.-P.M.R. acknowledges support from the Royal Society (Grant no. RGF\EA\180041) and the Osk. Huttunen Foundation.
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: LivePure Connector
Date Deposited: 30 May 2022 09:30
Last Modified: 22 Jun 2022 00:26
URI: https://ueaeprints.uea.ac.uk/id/eprint/85220
DOI: 10.1002/adom.202200312

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