Red-shifted delayed fluorescence at the expense of photoluminescence quantum efficiency – an intramolecular charge-transfer molecule based on a benzodithiophene-4,8-dione acceptor

Abstract

A donor–acceptor compound using a thiophene based quinone acceptor displays strongly red-shifted delayed emission but limited quantum efficiency.

Toward an understanding of electronic excitation energies beyond the molecular orbital picture

“…minimising the spatial overlap between the highest occupied MO (HOMO) and the lowest unoccupied MO (LUMO) for delayed fluorescence 1, 22 and to exploit diradical character in the ground state 26 or aromaticity in the triplet state 27 for singlet fission but a more comprehensive theoretical framework is not available and unwanted side-effects are hard to exclude. 28 More specific cases of the breakdown of the MO picture are concerned with exciton correlation in conjugated polymers. [29][30][31] A further long known, 32,33 but often neglected, problem is the differentiation between ionic and covalent states in hydrocarbons, which emerges in a valence-bond description but is hard to do within the MO picture.…”

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

“…This gives carbazole and its derivatives optical and electronic properties well suited for use in emissive devices based upon organic molecules. Carbazole has great synthetic versatility permitting systematic variations through substitution, interconversion and coupling reactions, allowing optimisation of the optoelectronic properties of carbazole derivatives for many applications [1–11] . Among the most important of these applications are their use as hole transport materials (HTMs), [12] or as host materials in the emissive layer (EML) of organic light emitting diodes (OLEDs) [13–17] .…”

Excited-state symmetry breaking in 9,10-dicyanoanthracene-based quadrupolar molecules: the effect of donor–acceptor branch length

“…[7][8][9] Donoracceptor-donor systems have also been introduced as promising chromophores for thermally activated delayed fluorescence providing low singlet-triplet gaps along with suitable emission strengths. 10,11 Additionally, these multi-branched dyes can be viewed as simple models of organic conjugated polymers and are particularly useful for understanding the electronic excited-state properties of these materials. Directly after optical excitation, the Franck-Condon excited state of these multi-branched dyes has a symmetric electronic structure with the excitation delocalized over the whole molecule.…”