Tb3+-Doped Ca3Ga4O9 Phosphors with Color-Tunable Photoluminescence and Non-Pre-Irradiation Mechanoluminescence for Multimodal Applications

Abstract

Materials that can emit light under optical/mechanical stimulation are usually called photoluminescent/mechanoluminescent (PL/ML) materials. PL materials are used in diverse fields for half a century. While, ML materials have burst out in the last two decades, and now are showing great application potential in the fields of anti-counterfeiting, information storage, and stress imaging. It is of great significance to explore new luminescent materials with PL and ML dual response. In this study, Tb3+-doped Ca3Ga4O9 phosphors with color-tunable PL and non-pre-irradiation ML properties are reported. Ca3Ga4O9 exhibits a broadband blue emission centering at 425 nm, which originates from the 4T2-4A2 transition of electrons in d orbits of Ga3+. Due to the energy transfer from host to Tb3+, color-tunable emission from blue to cyan, and ultimately to green can be realized by increasing the concentration of Tb3+. Particularly, ML is seen from Ca3Ga4O9:Tb3+ under grinding and from the Ca3Ga4O9:Tb3+/PDMS film under bending or stretching originated from the triboelectric mechanism. The non-pre-irradiation ML behavior is evidenced by the contrast thermoluminescence (TL) experiments. This study not only provides a new candidate toward multi-purpose luminescent applications, but also demonstrates a good case in which the triboelectric effect can efficiently trigger the non-pre-irradiation ML behavior.