Multiple resonance thermally activated delayed fluorescence enhanced by halogen atoms. Issue 33 (17th August 2022)

• Record Type: Journal Article
• Authors: Lee, Youngnam; Hong, Jong-In
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 33(2022)
• Page Start: 11855
• Page End: 11861
• Publication Date: 2022-08-17
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc02909j
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Halogenated multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters, Cl-MR and Br-MR, were developed to improve the reverse intersystem crossing rate constant of MR-TADF emitters. Abstract : We synthesized halogen-substituted multiple-resonance (MR) thermally activated delayed fluorescence emitters, namely 2, 12-dichloro- N, N, 5, 9-tetrakis(4-chlorophenyl)-5, 9-dihydro-5, 9-diaza-13 b -boranaphtho[3, 2, 1- de ]anthracen-7-amine (Cl-MR) and 2, 12-dibromo- N, N, 5, 9-tetrakis(4-bromophenyl)-5, 9-dihydro-5, 9-diaza-13 b -boranaphtho[3, 2, 1- de ]anthracen-7-amine (Br-MR). Cl-MR and Br-MR exhibited a decreased delayed fluorescence lifetime and an enhanced reverse intersystem crossing rate without any changes in Δ E ST and orbital distribution compared with a non-halogenated MR emitter. Cl-MR exhibited a high photoluminescence quantum yield (PLQY) of 85% and external quantum efficiency (EQE) of 17%; however, Br-MR did not exhibit any enhancement in the PLQY and EQE. The different performances of Cl-MR and Br-MR were rationalized by analysing the rate constants of the excited states and bond dissociation energies of the carbon–halogen bonds.