Sharp-to-Broad Band Energy Transfer in Lithium Aluminate and Gallate Phosphors for SWIR LED

ACS Appl Opt Mater. 2024 Mar 1;2(12):2401-2408. doi: 10.1021/acsaom.3c00464. eCollection 2024 Dec 27.

Abstract

Short-wave infrared (SWIR) phosphor-converted light-emitting diode (LED) technology holds promise for advancing broadband light sources. Despite the potential, limited research has delved into the energy transfer mechanism from sharp-line to broadband emission in SWIR phosphors, which remains underexplored. Herein, we demonstrate bright SWIR phosphors achieved through Cr3+/Ni2+ energy transfer in LiGa5(1-x)Al5x O8. High-resolution X-ray diffraction revealed the typical solid solution and distortion occurring in Al3+ octahedral sites. In addition, the X-ray absorption spectrum illustrates that Cr3+ and Ni2+ have different coordination environments, showing the possibility that they occupy different positions or that the coordinated environment of Ni2+ is distorted due to charge imbalance. Temperature-dependent studies provide insights into the energy transfer dynamics between Cr3+/Ni2+, from the 2E level of Cr3+ (sharp band) to the 3T1 level of Ni2+ (broadband). The increased emission intensity at lower temperatures in the x = 0.6 and x = 1.0 samples can be explained by the positioning of the 3T1 level above the 2E level of Cr3+ ions. Finally, we established a mechanism involving a sharp line to broadband energy transfer showcasing a high-power SWIR LED with a radiant power of 21.45 mW.

Publication types

  • Review