Issue 12, 2022

Triplet-to-singlet exciton transfer in hyperfluorescent OLED materials

Abstract

Hyperfluorescent organic light-emitting diodes combine two kinds of dopants to maximize device efficiency: one molecule exhibiting thermally activated delayed fluorescence (TADF) and another molecule with a high fluorescence rate and narrow emission spectrum. The postulated role of a TADF sensitizer is to enable up-conversion of triplet to singlet excitons through the reverse intersystem crossing mechanism, which is followed by a Förster energy transfer to the fluorescent emitter. However, a second mechanism based on the direct triplet-to-singlet exciton transfer between TADF molecules is a priori possible, but its role in hyperfluorescence has not been investigated. Here we employ first-principles electronic-structure and kinetic Monte Carlo simulations to study the hyperfluorescence mechanism in four pairs of TADF/fluorescent emitters. We demonstrate how the triplet-to-singlet energy transfer mechanism is, in some cases, the main driver for the quantum efficiency boost observed in hyperfluorescent devices.

Graphical abstract: Triplet-to-singlet exciton transfer in hyperfluorescent OLED materials

Supplementary files

Article information

Article type
Paper
Submitted
19 Nov. 2021
Accepted
17 Febr. 2022
First published
17 Febr. 2022

J. Mater. Chem. C, 2022,10, 4914-4922

Triplet-to-singlet exciton transfer in hyperfluorescent OLED materials

L. E. de Sousa, L. dos Santos Born, P. H. de Oliveira Neto and P. de Silva, J. Mater. Chem. C, 2022, 10, 4914 DOI: 10.1039/D1TC05596H

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