posted on 2024-03-01, 13:07authored byYi-Ting Tsai, Pei-Xuan Chen, Mikołaj Kamiński, Natalia Majewska, Sebastian Mahlik, Mu-Huai Fang
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)Al5xO8. 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.