Ultra-Broadband Phosphors Converted Near-Infrared Light Emitting Diode with Efficient Radiant Power for Spectroscopy Applications
Copyright © 2019 American Chemical Society. Narrowing the size of near-infrared (NIR) spectrometers has gained substantial interest among researchers in both scientific and nonscientific communities due to the inherent usage in the nondestructive investigations, especially for foodstuff evaluation and human health monitoring. The immense size and deteriorating accessibility of traditional NIR light sources make the phosphor-converted NIR light-emitting diode (pc-NIR LED) with high radiant flux an alternative growing light source. In this work, the crystal structure of La3GaGe5O16 is solved for the actual crystallographic sites through a joint Rietveld refinement tool (X-ray diffraction and high-resolution neutron powder diffraction) and reporting for the ultrabroadband NIR luminescence (650-1050 nm) by doping with Cr3+ with the hyper-radiant power of 43.1 mW. It is noteworthy that the possible benchmarking radiant power of 65.2 mW is achieved by the chemical substitution of Gd3+ and Sn4+. The presence of multiple excited behavior states (multiple luminescent centers) of Cr3+ due to its intermediate crystal field resulted in broadening of the emission spectrum along with increased intensity. The nonexponential decay character of the R-line and broadband luminescence further confirms the observation of the multiple excited state. The findings of this work are discussed based on structural characterization and spectroscopic studies at different measurement environments, and the potentials of the phosphors are also demonstrated by the prototype pc-NIR LED packaging.