title: Kinetics of thermal-assisted delayed fluorescence in blue organic emitters with large singlet-triplet energy gap.
abstract: The kinetics of thermally activated delayed fluorescence (TADF) is investigated in dilute solutions of organic materials with application in blue light-emitting diodes (OLEDs). A method to accurately determine the energy barrier (ΔE(a)) and the rate of reverse intersystem crossing (kRisc) in TADF emitters is developed, and applied to investigate the triplet-harvesting mechanism in blue-emitting materials with large singlet-triplet energy gap (ΔE(ST)). In these materials, triplet-triplet annihilation (TTA) is the dominant mechanism for triplet harvesting; however, above a threshold temperature TADF is able to compete with TTA and give enhanced delayed fluorescence. Evidence is obtained for the interplay between the TTA and the TADF mechanisms in these materials.
authors.affiliation: Department of Physics, University of Durham, Durham DH1 3LE, UK f.m.b.dias@durham.ac.uk.
authors.forename: Fernando B
authors.identifier: http://orcid.org/0000-0001-9841-863X
authors.initials: FB
authors.lastname: Dias
keywords: delayed fluorescence; organic light-emitting diodes; reverse intersystem crossing; thermally activated delayed fluorescence; triplet–triplet annihilation