Visible to Near-Infrared Persistent Luminescence and Mechanoluminescence from Pr3+-Doped LiGa5O8 for Energy Storage and Bioimaging

Here, a novel multifunctional phosphor of Li1-xGa5O8:xPr(3+) is reported. The crystal structure, mechanoluminescence (ML), persistent luminescence (PersL), photoluminescence (PL) and photoluminescence excitation (PLE) are systematically studied. LiGa5O8 emits blue PersL peaked at 437 nm after irradiation by a 254 nm lamp for 10 s, and corresponding PersL can be observed for 30 min by naked eyes. In the same case, the PersL from Li0.995Ga5O8:0.005Pr(3+) covers visible to near-infrared lights (400-1000 nm) which can persist for 120 min. Thermoluminescence analysis shows Pr3+ doping not only increases the shallower trap (0.73 eV) concentration by at least 20 times but also helps the formation of deeper trap centers (0.87 eV). The differences between ML and PersL spectra reveal the selective effects of mechanical stimuli on the transitions of Pr3+ ions. In the end, the fabrication of an intelligent PersL quick response code (QR-code) permits optical information write-in after irradiation by a 254 nm lamp and then cryptical information of SCUT can be read out by thermal stimulation which shows the potential in information storage. Moreover, the biological tissues penetration experiments and cytotoxicity tests are carried out to display the potential of PersL in bioimaging.