title: Thermally Activated Delayed Fluorescence and Aggregation Induced Emission with Through-Space Charge Transfer.
abstract: Emissive molecules comprising a donor and an acceptor bridged by 9,9-dimethylxanthene, were studied (XPT, XCT, and XtBuCT). The structures position the donor and acceptor with cofacial alignment at distances of 3.3-3.5 Å wherein efficient spatial charge transfer can occur. The quantum yields were enhanced by excluding molecular oxygen and thermally activated delayed fluorescence with lifetimes on the order of microseconds was observed. Although the molecules displayed low quantum yields in solution, higher quantum yields were observed in the solid state. Crystal structures revealed π-π intramolecular interactions between a donor and an acceptor, however, the dominant intermolecular interactions were C-H···π, which likely restrict the molecular dynamics to create aggregation-induced enhanced emission. Organic light emitting devices using XPT and XtBuCT as dopants displayed electroluminescence external quantum efficiencies as high as 10%.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsujimoto
authors.forename: Dong-Gwang
authors.initials: DG
authors.lastname: Ha
authors.forename: Georgios
authors.initials: G
authors.lastname: Markopoulos
authors.affiliation: Samsung Research America , 255 Main Street, Suite 702, Cambridge, Massachusetts 02142, United States.
authors.forename: Hyun Sik
authors.initials: HS
authors.lastname: Chae
authors.forename: Marc A
authors.initials: MA
authors.lastname: Baldo
authors.forename: Timothy M
authors.identifier: 0000-0002-3577-0510
authors.initials: TM
authors.lastname: Swager