Light Emission Mechanism in Dimers of Carbene-Metal-Amide Complexes
Physical Chemistry Chemical Physics 2023
Armands Rudušs, Sergejs Beļakovs, Kitija Alise Štucere, Aivars Vembris, Kaspars Traskovskis

Recently an efficient dual electroluminescence from monomers and dimers was observed among the structural examples of the emerging emitter class of carbene–metal–amides (CMAs), allowing the preparation of simple design white organic light emitting diodes (wOLEDs). Here we investigate in detail the light emission mechanism in the dimeric species of CMA emitters on the basis of a copper(I) complex TCP bearing thiazoline carbene and 10H-phenothiazine 5,5-dioxide (Ptz) ligands. The X-ray structure for crystals with dimer-only emission was obtained, revealing that emissive aggregates consist of face-to-face stacked molecular pairs with an intermolecular distance of 3.673 Å. The close packing is aided by reduced sterical bulk at the carbene ligand, as well as by a torsional twist between the carbene and amide fragments. Experimental and computational data show that the emission mechanism in aggregates is related to the formation of a persistent dimer, not the excimer. Radiative relaxation proceeds through an intermolecular charge transfer process between the carbene and amide ligands of the neighbouring molecules. In comparison to the monomer, the thermally activated delayed fluorescence (TADF) process in the dimer is characterized with significantly higher energy gaps (ΔEST) between the lowest singlet (S1) and triplet (T1) excited states. At the same time the aggregated species exhibit a significantly increased phosphorescence rate (τ = 12 μs at 10 K temperature) due to the presence of two metal atoms, resulting in a sixfold increase in the spin–orbit coupling (SOC) matrix element in comparison to the monomer.


DOI
10.1039/D2CP05237G
Hipersaite
https://pubs.rsc.org/en/content/articlelanding/2023/cp/d2cp05237g/unauth#!divAbstract

Rudušs, A., Beļakovs, S., Štucere, K., Vembris, A., Traskovskis, K. Light Emission Mechanism in Dimers of Carbene-Metal-Amide Complexes. Physical Chemistry Chemical Physics, 2023, Vol. 25, No. 4, 3220.-3231.lpp. ISSN 1463-9076. e-ISSN 1463-9084. Pieejams: doi:10.1039/D2CP05237G

Publikācijas valoda
English (en)
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