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

Abstract

The wearable biosensing and food safety monitoring equipment requires high-brightness and thermally stable nearinfrared (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 Ca 3 Sc 2 Si 3 O 12 : Cr 3+ . Under 460 nm excitation, Ca 3 Sc 2 Si 3 O 12 : Cr 3+ presents an ultrawide emission range from 650 to 900 nm. The weak absorption capacity of Cr 3+ is the main factor causing its undesirable luminous efficiency. Ce 3+ was introduced into the matrix as a role of sensitizer to contribute to the improvement of the absorption of Cr 3+ . An efficient process for energy transfer from Ce 3+ to Cr 3+ can be observed within the Ca 3 Sc 2 Si 3 O 12 codoped substance with Ce 3+ and Cr 3+ . 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 Ca 3 Sc 2 Si 3 O 12 : Ce 3+ , Cr 3+ 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.

A General Ammonium Salt Assisted Synthesis Strategy for Cr3+‐Doped Hexafluorides with Highly Efficient Near Infrared Emissions

“…[ 33 ] However, the external quantum efficiency (EQE) of these phosphors is limited to 28%, owing to the relatively low absorption efficiency (AE) of Cr 3+ resulting from the parity‐forbidden 3d‐3d electronic transition. [ 34 ] Increasing the doping concentration of Cr 3+ can effectively improve the AE; however, the optimal concentration of Cr 3+ in these phosphors is typically lower than 15%, with higher Cr 3+ concentrations inducing concentration quenching. [ 15 ] In addition, in the case of Cr 3+ ‐doped oxide phosphors synthesized by a high temperature solid‐state reaction method, the issues of avoiding mixed Cr valence states (Cr 3+ /Cr 4+ ) or the formation of the Cr 3+ –Cr 3+ pairs should be considered.…”

Abnormal Self-Reduction Phenomenon of Europium-Doped Borate and Its Luminescence Properties

“…For specific experimental steps, one can refer to our previous work. 35 2.2. Measurements and Characterization.…”

Crystal‐Field Engineering Control of an Ultraviolet–Visible‐Responsive Near‐Infrared‐Emitting Phosphor and Its Applications in Plant Growth, Night Vision, and NIR Spectroscopy Detection

“…However, in the case of weak crystal field emission, the emission transition appears as a broad emission peak ( 4 T 2 – 4 A 2 ), and is easier to red‐shift or blue‐shift in response to changes in the crystal field. [ 6,10 ] Additionally, there was a broad peak that represented the weak crystal field emission of Cr 3+ ( 2 T 1 – 4 T 1 ) in a four‐coordinate tetrahedral crystal field (Figure S4, Supporting Information), and the emission peak tended to occur at a relatively longer wavelength. [ 23 ] Based on these results, there are three possible lattice occupancy situations of Cr 3+ in BaMgAl 10 O 17 :0.01Cr 3+ , as shown in Figure 2e.…”