Efficient Reverse Intersystem Crossing in Carbene-Copper-Amide TADF Emitters via an Intermediate Triplet State

Author(s)

J. Patrick Zobel, Anna M. Wernbacher, Leticia González

Abstract

The mechanism behind reverse intersystem crossing (rISC) in metal-based TADF emitters is still under debate. Thermal rISC necessitates small singlet/triplet energy gaps as realized in donor-acceptor systems with charge-transfer excited states. However, their associated spin-orbit couplings are too small to account for effective rISC. Here, we report the first nonadiabatic dynamics simulation of the rISC process in a carbene-copper(I)-carbazolyl TADF emitter. Efficient rISC on a picosecond time scale is demonstrated for an initial triplet minimum geometry that exhibits a perpendicular orientation of the ligands. The dynamics involves an intermediate higher-lying triplet state of metal-to-ligand charge transfer character (³MLCT), which enables large spin-orbit couplings with the lowest singlet charge transfer state. The mechanism is completed in the S₁ state, where the complex can return to a co-planar coordination geometry that presents high fluorescence efficiency.

Organisation(s)

Department of Theoretical Chemistry, Research Platform Accelerating Photoreaction Discovery

Journal

Angewandte Chemie - International Edition

Volume

62

ISSN

1433-7851

DOI

https://doi.org/10.1002/anie.202217620

Publication date

04-2023

Peer reviewed

Yes

Austrian Fields of Science 2012

104022 Theoretical chemistry, 103006 Chemical physics

Keywords

ASJC Scopus subject areas

Catalysis, Chemistry(all)

Portal url

https://ucris.univie.ac.at/portal/en/publications/efficient-reverse-intersystem-crossing-in-carbenecopperamide-tadf-emitters-via-an-intermediate-triplet-state(87d130e3-b862-4afd-abc6-ed93038de6df).html