LAUSR

Thermochromic fluorescence materials (TFMs) characterized by noticeable emission color variation with temperature have attracted pervasive attention for their frontier application in stimulus-response and optical encryption technologies. However, existing TFMs typically suffer from weak PL reversibility as well as limited mild operating temperature and severe temperature PL quenching. PL switching under extreme conditions such as high temperature will undoubtedly improve the encryption security while it is still challenging for present TFMs. In this work, high temperature thermochromic fluorescence up to 473 K and robust structural and optical reversibility of 80 cycles are observed in Rb2 MnBr4 (H2 O)2 and related crystals, which is seldom reported for PL change at such a high temperature. Temperature driven nonluminous, red and green light emission states can be achieved at specific temperatures and the modulation mechanism is verified by in-situ optical and structural measurements and single particle transition. By virtue of this unique feature, a multi-color anti-counterfeiting label based on a broad temperature gradient and multi-dimension information encryption applications are demonstrated. This work opens a window for the design of inorganic materials with multi-PL change and the development of advanced encryption strategy with extreme stimuli source. This article is protected by copyright. All rights reserved.