Sunlight-Activated Orange Persistent Luminescence from Bi-Doped SrBaZn₂Ga₂O₇ for Warm-Color Optical Applications

A warm persistent luminescence (PersL) material SrBaZn₂Ga₂O₇:Bi³⁺ was prepared using the conventional high-temperature solid-phase reaction method. We first investigated the PersL properties of SrBaZn₂Ga₂O₇:Bi³⁺ in detail via PersL spectra, PersL excitation spectrum, PersL decay curves, and thermoluminescence (TL) spectra. The highlight of this study is that in addition to the 254 nm light source, the low-energy light source of 365 nm and sunlight can effectively excite electrons and charge traps, resulting in preferable orange PersL performance. The PersL decay time of the representative sample can last for 960 s after excitation by a 365 nm light source and 900 s after excitation by simulated sunlight. Meanwhile, the PersL color can be regulated by changing the excitation wavelength. In order to explain the infrequent PersL phenomena after different light source excitations, we recorded a series of TL spectra as a function of different light sources, different charging times, and different decay times to reveal the distribution of traps in the material and the influence of trap distribution on trapping and detrapping processes. This novel sunlight-activated orange PersL material is expected to promote the development of sunlight-activated PersL materials and expand potential applications in solar energy utilization and anticounterfeit marking.