Synthesis of SrZnOSe Crystals with Low Phonon Energy for Enhancing Near-Infrared Mechanoluminescence

Near-infrared (NIR) light is promising for bioimaging and information technology due to its high penetration ability and resistance to interference with environmental radiation. Here, a new class of lanthanide-doped SrZnOSe crystals are developed for the self-sustainable generation of NIR emissions under mechanical excitation. It is shown that the SrZnOSe crystals render ≈5-fold stronger NIR emissions than the well-established CaZnOS due to the low phonon energies of the selenide host, as confirmed by Raman spectroscopy. The potential utility of the crystals is demonstrated by integration with a mouthguard, which can generate bright NIR emissions by bite force to transmit encrypted optical signals through thick tissues (up to 8 mm) in ambient environments. The findings provide a powerful addition to the toolbox of self-recovery mechanoluminescent materials and open new possibilities for applied research.