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

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 Cr(3+)/Ni(2+) energy transfer in LiGa(5(1-x))Al(5x) O(8). High-resolution X-ray diffraction revealed the typical solid solution and distortion occurring in Al(3+) octahedral sites. In addition, the X-ray absorption spectrum illustrates that Cr(3+) and Ni(2+) have different coordination environments, showing the possibility that they occupy different positions or that the coordinated environment of Ni(2+) is distorted due to charge imbalance. Temperature-dependent studies provide insights into the energy transfer dynamics between Cr(3+)/Ni(2+), from the (2)E level of Cr(3+) (sharp band) to the (3)T(1) level of Ni(2+) (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 (3)T(1) level above the (2)E level of Cr(3+) 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.