An AIE-active acridine functionalized spiro[fluorene-9,9′-xanthene] luminophore with mechanoresponsive luminescence for anti-counterfeiting, information encryption and blue OLEDs

Abstract

Multifunctional aggregation induced emission (AIE)-active luminophores have drawn great interest in materials science. In this work, a new three-dimensional (3D) luminophore of 9,9′-dimethyl-9,10-dihydroacridine substituted spiro(fluorene-9,9′-xanthene) (SFX-Ad) was synthesized and characterized. The highly twisted 3D configuration endows SFX-Ad with typical AIE activity, which exhibits weak emission in dilute solution and enhanced emission in the H-aggregate state. More importantly, the weakly emissive herringbone packing of SFX-Ad in the solid state displays mechanoresponsive luminescence (MRL) turn-on behavior, and underwent a crystal-to-amorphous transition. Based on its unique MRL behavior, using the samples of SFX-Ad in distinct luminescent states as the codes, anti-counterfeiting and information-encryption applications were realized. Additionally, taking its suitable molecular orbital energy levels and bright emission together, a blue organic light emitting diode (λ_EL = 421 nm, CIE (0.15, 0.10)) based on an SFX-Ad emitter yields a maximum current efficiency, power efficiency, and external quantum efficiency of 3.22 cd A⁻¹, 2.30 lm W⁻¹, and 2.58%, respectively.