Designing Photochromic Materials La₂MgSnO₆:Er,Fe with Dynamic Luminescence Modulation for Dual‐mode Optical Information Reading

Abstract Inorganic photochromic luminescent materials hold immense promise as potential candidates for optical information storage applications. Unfortunately, static and single reading mode of photochromic luminescent materials in bright and dark environments pose a security threat to the stored information. Here, a novel material La₂MgSnO₆:Er³⁺,Fe³⁺ is developed, possessing both reversible photochromic and adjustable upconversion/downconversion photoluminescent (PL) properties. Upon exposure to 275 nm ultraviolet (UV) light, the sample changes in color from white to brown. And this transformation rapidly reverses when exposed to 365 nm UV light, resulting in a corresponding alteration in luminescence intensity. Notably, when combined with photochromic, the 980 nm excited upconversion PL maintains stable luminescence, while the 365 nm excited downconversion PL exhibits significant intensity changes. Inspired by this unique feature, a dark‐field selective dual‐mode reading is proposed that depends on the excitation wavelength, including static decrypt in long‐time cases and dynamic reading in time‐limited situations. These findings have the potential to revolutionize high‐security data storage applications and drive advancements in the field.