Peripheral carbazole units-decorated MR emitter containing B-N covalent bond for highly efficient green OLEDs with low roll-offOACSTPCDEI

Boron-nitrogen doped multiple resonance(BN-MR)emitters,characterized by B-N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B-N]N,through a one-pot borylation reac-tion directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-t-butylcarbazole(tCz)units into a B-N covalent bond doped BN-MR parent molecule via para-C-π-D and para-N-π-D conjuga-tions.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Conse-quently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd∙m-2,the device maintains a high EQE value of 24.6%.