Substitution effect on solid parking motif and luminescence of diphenylfuro[2,3-b]quinoxaline isomers

Abstract

The organic molecules combining light-emitting and charge-transporting property are highly expected. We designed and synthesized a pair of isomers, 2,6-diphenylfuro[2,3-b]quinoxaline (26dPFQ) and 2,7-diphenylfuro[2,3-b]quinoxaline (27dPFQ), and investigated effect of changing substituent position on molecule packing motif, conducting and luminescence feature of resulting materials. In CH2Cl2 solution, both isomers, 26dPFQ and 27dPFQ, emit deep blue light with a wavelength of 422 nm and shows photoluminance quantum yield (PLQY) of 58.9% and 48.7%, respectively. In crystal, the 26dPFQ employs H-type packing motif and retains blue florescent emission with low PLQY (10.0%) while 27dPFQ adopts J-aggregated packing motif and shows enhanced green fluorescent emission with a PLQY of 55.0%. The organic light-emitting devices for both emitters show deep blue emission, the EL peak at 410 nm for 26dPFQ and 424 nm for 27dPFQ, and respectively presents the maximum EQE of 1.2% and 1.0%. The 26dPFQ shows better charge transport capability over 27dPFQ. Our results suggested 2,6-substitution on furo[2,3-b]quinoxaline core are expected to afford such dual functional materials.