Optical memory and anti-counterfeiting application based on luminescence reversible modification and color contrast of photochromic phosphor

Photochromism and photoluminescence are two interesting optical phenomena, and their combination in a single material can present some novel applications as multiple anti-counterfeiting and optical memory devices. However, a challenge exists in the exploitation of materials with both photochromism and photoluminescence upon double-light stimulation. Herein, the photochromic SrWO4:Yb3+,Er3+,Bi3+ phosphor was prepared with the help of a color center due to the formation of defects and photochromism reversal from white to dark yellow upon alternating 254-nm ultraviolet light and 473-nm laser irradiation. The reversible photoluminescence modification in SrWO4:Yb3+,Er3+,Bi3+ phosphor is demonstrated, explaining its photochromic reaction. The optical memory and anti-counterfeiting application of SrWO4: Yb3+,Er3+,Bi3+ phosphor was realized based on the associated color contrast and the luminescence intensity change. Flexible SrWO4:Yb3+,Er3+,Bi3+ film as a promising alternative can satisfy the diversified requirements and enhance practical application security, which is expected to encourage efforts toward photochromism-induced luminescence modulation.