Control of Singlet Emission Energy in a Diphenyloxadiazole Containing Fluorophore Leading To Thermally Activated Delayed Fluorescence

Matthew W Cooper; Xiaoqing Zhang; Yadong Zhang; Canek Fuentes-Hernandez; Stephen Barlow; Bernard Kippelen; Seth R Marder

doi:10.1021/acsomega.8b01979

Control of Singlet Emission Energy in a Diphenyloxadiazole Containing Fluorophore Leading To Thermally Activated Delayed Fluorescence

ACS Omega. 2018 Nov 6;3(11):14918-14923. doi: 10.1021/acsomega.8b01979. eCollection 2018 Nov 30.

Authors

Matthew W Cooper¹, Xiaoqing Zhang¹, Yadong Zhang¹, Canek Fuentes-Hernandez¹, Stephen Barlow¹, Bernard Kippelen¹, Seth R Marder¹

Affiliation

¹ School of Chemistry and Biochemistry, School of Electrical and Computer Engineering, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.

Abstract

2-(4-(9,9-Dimethylacridin-10(9H)-yl)phenyl)-5-phenyl-1,3,4-oxadiazole has an energy difference between the lowest excited singlet and triplet states (ΔE _ST) of ca. 0.24 eV. Introduction of two electronegative fluorine atoms onto the acceptor portion of the molecule to give 2-(4-(9,9-dimethylacridin-10(9H)-yl)-3,5-difluorophenyl)-5-phenyl-1,3,4-oxadiazole lowers the energy of the singlet emission with a negligible effect on the corresponding triplet energy, leading to a donor-acceptor compound with decreased ΔE _ST of ca. 0.13 eV that displays thermally activated delayed fluorescence. Organic light-emitting diodes fabricated using the latter compound display high EQE_max of 21.9% at a luminance of 10 cd/m² and sky-blue emission, however, they suffer from a large efficiency roll-off at increased luminance.