Electronic structure study of luminiscent monometallic and bimetallic copper(I) complexes

Luminiscent materials have become an important subject of interdisciplinary research in the fields of physics, chemistry and material sciences, due to their potential applications in optolectronic devices. One example of compounds widely studied are luminescent copper(I) complexes, which can emit photons through fluorescence, phosphorescence or thermally activated delayed fluorescence (TADF). TADF allows to harvest both singlet and triplet excitons generated in electroluminescent devices such as OLEDs, being the most promising luminescence mechanism for such applications. [1,2] 

Understanding how to control the luminescence mechanism and its efficiency of a copper(I) complex requires to know the influence of variables such as molecular geometry, electronic properties of ligands and nuclearity over the electronic structure of the molecule. In this way, quantum chemical based modelling of the ground and excited states of a molecule is a useful tool to rationalize structure-property relationships.

In this work, we present the study of the electronic structure of a series of monometallic and bimetallic copper(I) complexes with prototypical ligands used in luminescent compounds, by means of electronic structure calculations (Time Dependent Density Functional Theory). These results show the complexity of the excited state dynamics in these systems, involving excited states with different orbital configuration that mediates forbidden process as direct or reverse intersystem crossing and phosforescence.

[1] H. Yersin et al, Chemistry of Materials, 2019, 31, 12, 4392-4404.
[2] M. J. Leitl, V. A. Krylova, P. I. Djurovich, M. E. Thompson and H. Yersin, Journal of the American Chemical Society, 2014, 136, 16032–16038.