A High Efficiency Trivalent Chromium-Doped Near-Infrared-Emitting Phosphor and Its NIR Spectroscopy Application

The wearable biosensing and food safety monitoring equipment requires high-brightness and thermally stable near-infrared (NIR) phosphor-converted light emitting diodes (pc-LEDs), and the performance of these pc-LEDs is highly dependent on the properties of the NIR phosphors. This work reports an ultrawide near-infrared emission phosphor Ca3Sc2Si3O12: Cr3+. Under 460 nm excitation, Ca3Sc2Si3O12: Cr3+ presents an ultrawide emission range from 650 to 900 nm. The weak absorption capacity of Cr3+ is the main factor causing its undesirable luminous efficiency. Ce3+ was introduced into the matrix as a role of sensitizer to contribute to the improvement of the absorption of Cr3+. An efficient process for energy transfer from Ce3+ to Cr3+ can be observed within the Ca3Sc2Si3O12 codoped substance with Ce3+ and Cr3+. The sample with the best doping concentration has demonstrated excellent thermal stability. At a particular temperature at 150 °C, the phenomenon of the near-infrared emission intensity is maintained at 82% at room temperature. The output power of the NIR-pc-LED based on the Ca3Sc2Si3O12: Ce3+, Cr3+ and 450 nm chip reached 21.65 mW@350 mA. The excellent performance of penetrating human tissues demonstrated by the near-infrared pc-LED was observed.