Multiple optical thermometry and dynamic anti-counterfeiting based on multicolor emission in Y2GaSbO7:Bi3+,Er3+ phosphor

Abstract

Optical thermometric and anti-counterfeiting multifunctional materials hold great promise for practical applications, yet their development continues to encounter considerable challenges. Here, we successfully developed a new Bi³⁺,Er³⁺ co-doped Y₂GaSbO₇ powder with multicolor luminescence. Through adjusting the excitation wavelengths, emissions in violet, blue, green, and orange are achieved. The phosphor demonstrates remarkable thermochromism due to the distinct temperature-dependent luminescence of Bi³⁺ and Er³⁺, confirmed under irradiation at 312 or 980 nm. By reducing the power of 980 nm laser or increasing the laser-to-sample distance, the emitting color can be precisely tuned from gold‒yellow or yellow‒green to orange‒red. These diverse luminescent characteristics enable the creation of a multilevel anti-counterfeiting system. Moreover, a four-mode optical thermometry with an optimal relative sensitivity of 1.98% K⁻¹, a high thermal resolution of 0.15 K, and signal reversibility was established using fluorescence intensity ratio and fluorescence decay time. These results disclose that Y₂GaSbO₇:Bi³⁺,Er³⁺ phosphor is a promising candidate for temperature monitoring and dynamic anti-counterfeiting applications.