Ultra-Broadband Phosphors Converted Near-Infrared Light Emitting Diode with Efficient Radiant Power for Spectroscopy Applications

Abstract

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 La 3 GaGe 5 O 16 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 Cr 3+ 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 Gd 3+ and Sn 4+ . The presence of multiple excited behavior states (multiple luminescent centers) of Cr 3+ 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.

Thermally Stable CaLu2Mg2Si3O12:Cr3+ Phosphors for NIR LEDs

“…If the 5.4% unmeasured part is taken into account, then the actual NIR optical power should be 65 mW@380 mA. In the same way, the total optical power of NIR light even reaches a high level of 62.9 mW@350 mA, which is much higher than the performance of most reported NIR phosphors (Table S7, Supporting Information), [ 14,21,25,30–33 ] such as CSSG:Cr 3+ in NIR pcLEDs (52 mW@350 mA). [ 30 ] The conversion efficiency from the input electric power to NIR light is only 4.7%@350 mA (Figure 4c) because of a low photoelectric efficiency of the used blue chip (26%@350 mA).…”

Cr3+‐Doped Sc‐Based Fluoride Enabling Highly Efficient Near Infrared Luminescence: A Case Study of K2NaScF6:Cr3+

“…Though the AlGaAs NIR light‐emitting diodes (LEDs) possess the advantages of small size, high efficiency, and long lifetime, their full width at half maximum (FWHM < 50 nm) is too narrow. [ 9–12 ] In this regard, the combination of blue InGaN chip and broadband NIR emitting phosphor will be an ideal approach to construct portable and smart NIR light source for its compact size and high efficiency as well as the low cost. [ 12 ] However, as the energy difference between the emissions of blue InGaN chip and NIR emitting phosphor is larger than that between the blue chip and yellow or red emitting phosphor, more heat will be inevitably produced in the NIR phosphor‐converted (pc) LEDs.…”

Advances in engineering near-infrared luminescent materials

“…Numerous Cr 3+ -based phosphors have been designed, usually used in conjugation with a blue LED for excitation, often with NIR photoluminescence yields of >65%, broadband emission over 700–1100 nm, and high thermal stability. Output powers in the 10s of mW make these LEDs suitable for a variety of near infrared spectroscopy applications ( Shao et al., 2018a , 2018b ; Xu et al., 2020 ; Rajendran et al., 2019 ). Basore et al.…”