Simultaneous NIR photoluminescence and mechanoluminescence from Cr3+ activated MgGa2O4 phosphors with multifunctions for optical sensing

Light-emitting diodes (LEDs) combined with near-infrared (NIR) phosphors are rapidly becoming important light sources for food safety, anti-counterfeiting and biological imaging due to non-destructive and non-toxic advantages. Single-phase materials with multi-mode luminescence under different stimuli are crucial for the development and applications of smart NIR phosphors. Here, we have developed multifunctional Cr3+ activated MgGa2O4 (MGO:Cr3+) phosphors with simultaneous photoluminescence and mechanoluminescence for NIR sensing. Under 470 nm excitation, the phosphors can produce emission bands from 650 to 850 nm. Meanwhile, the flexible devices based on phosphors can exhibit strong emissions in response to mechanical deformation, such as shock and friction. In addition, optical manometers based on luminescence from phosphors can achieve pressure sensing from 7 to 64 KPa. More intriguingly, we combined the MGO:Cr3+ phosphor with a blue LED chip to fabricate an NIR phosphor-converted LED for anti-counterfeiting and biological tissue penetration. Our results suggest that the multifunctional NIR phosphors with simultaneous photoluminescence and mechanoluminescence have potential applications in various sensing devices.