Phototunable full-color emission of dynamic luminescent materials

Abstract

A dynamic luminescent material that can change its color upon exposure to different photo-stimuli is significantly important and always desirable in color-on-demand applications such as anticounterfeiting and encryption. Herein, a facile approach for the fabrication of full-color dynamic luminescent materials based on trichromacy and dynamical afterglow was reported. Trichromic (green, blue, and red) luminescent materials (SrAl₂O₄:Eu²⁺,Dy³⁺, CaAl₂O₄:Eu²⁺,Nd³⁺ and Ca_0.25SrS_0.75:Eu²⁺) were synthesized by a high temperature solid state method. After simply blending them together, a dynamic full range of afterglow was observed after ultraviolet-visible (UV-vis) lamp irradiation. The afterglow intensity of mixtures revealed the existence of an interaction impact and energy transfer between components. The emissive colors were tunable in the full-color region simply by adjusting the blending ratio or excitation wavelengths. Moreover, the mixtures revealed the photo-stimuli responsive properties from different excitation sources. Ultimately, a luminescent three-dimensional (3D) code that could be read out by using a smartphone was prepared through this blended trichromic material. As a result, the pattern could only be read out after UV-vis lamp irradiation and could be converted to other information. These results indicate a facile, simple, and effective method for information encryption, conversion, and dynamic anticounterfeiting.