Narrowband deep blue thermally activated delayed fluorescent (TADF) materials have attracted significant attention. Herein, four asymmetrical structured TADF emitters based on diphenylsulfone (DPS) acceptor and 9,9-dimethyl-9,10-dihydroacridine (DMAC) donor with progressive performances were developed. The tert-butyloxy auxiliary electron-donor was adopted to restrict the intramolecular rotations and provide efficient steric hindrance. Regioisomerization by altering the substitution position of DMAC on DPS unit further enhanced the intra- and inter-molecular interactions. The accompanying effects yielded increased energy level, minimized reorganization energy, and inhibited non-radiative transitions in the crystals of tBuO-SOmAD, which achieved narrowband deep-blue emission peaking at 424 nm (FWHM=64 nm, ΦF =33.6 %) through aggregation-induced, blue-shifted emission (AIBSE). In addition, deep-blue organic light emitting diodes (OLEDs) based on tBuO-SOmAD realized the electroluminescence (EL) spectrum peaking located at 435 nm and CIE coordination of (0.12, 0.09).
Keywords: TADF; aggregation-induced hypochromism; deep blue; narrowband emission.
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