An Extra‐Broadband VIS‐NIR Emitting Phosphor toward Multifunctional LED Applications

Abstract

The development of extra-broadband emitting phosphors is challenging but meaningful work. So far, however, phosphors that can be effectively excited by GaN-based blue light-emitting diode (LED) chips and emit from visible (VIS) to near-infrared (NIR) regions are still rare. Herein, this study designs an extrabroadband VIS-NIR emitting phosphor with emission band ranging from 460 nm to 880 nm (bandwidth >400 nm) upon 450 nm excitation, owing to an efficient energy transfer from Ce 3+ to the red and NIR emitting Mn 2+ ions in Lu 2 BaAl 4 SiO 12 (LBAS) host. By the analysis of extended X-ray absorption fine structure (EXAFS) spectra and fluorescence lifetimes, it is demonstrated that the NIR emission most probably originates from those Mn 2+ occupying the dodecahedral sites with high symmetry rather than the exchange-coupled Mn 2+ -Mn 2+ pairs. Furthermore, two single-phase phosphor-converted LEDs are fabricated by combining blue LEDs with LBAS:Ce 3+ ,Mn 2+ phosphors, and thanks to the extra-broadband emission, the resultant devices may realize multifunctional applications, such as in high-quality general lighting, NIR spectroscopy, and plant growth lighting.

Glass‐Crystallized Luminescence Translucent Ceramics toward High‐Performance Broadband NIR LEDs

“…The NIR photoelectric efficiency is as high as 30.5% at 10 mA (2.66 V) for the pc‐LED device based on YCAS:0.04Cr 3+ ceramics (Figure 4b ), which is about 2.5 times higher than that of its PiS counterpart (12.4%@10mA); an NIR output power of 62.6 mW can be also obtained at 100 mA (3 V) with the efficiency decreased to 21.2% due to the “efficiency droop” of the LED chip (Figure S13 , Supporting Information); these electroluminescence properties are much better than those of the previously reported ones (Table S8 , Supporting Information). [ 9 , 10 , 14 ] Notably, the NIR output power of the all‐inorganic pc‐LEDs increases monotonously with the input current within the rated current (350 mA) of blue LED chips (Figure 4b and Figure S14 , Supporting Information), whereas the saturation can be clearly observed in the case of YCAS:0.08Cr 3+ powders (Figure S15 , Supporting Information).…”

“…Trivalent chromium ion (Cr 3+ ) [ 9 ] has shown its superiority to other activator ions [ 10 ] in emitting far‐red/NIR light of 650–1100 nm upon blue light excitation. For example, high IQE (>90%) was achieved through cation substitution [ 9c,d ] and optimizing synthesis strategy; [ 11 ] single‐phase extra‐broadband emission with FWHM > 200 nm was also realized by exploring host crystals allowing multiple‐site occupation of Cr 3+ .…”

Tunable broadband photoluminescence from bismuth‐doped calcium aluminum germanate glasses prepared in oxidizing atmosphere

“…Materials that exhibit tunable and broadband photoluminescence (PL) are of great interest for customized visible-to-infrared light sources and spectral converters, for example, for highly sensitive temperature sensing, highdensity optical communication, photodynamic therapy, or photochemical energy conversion. [1][2][3][4][5][6] Such converter materials rely on the combination of a robust matrix phase with one or more suitable activator species. When glasses are used for this purpose, the activator can be homogeneously incorporated into the material, which avoids light scattering at particle-matrix interfaces.…”

Efficient, Stable, and Ultra‐Broadband Near‐Infrared Garnet Phosphors for Miniaturized Optical Applications

“…[3] However, the spectral properties and optical output power of NIR pc-LEDs are still far from practical application for the lack of satisfactory NIR phosphors.Phosphors play a key role in the conversion of narrowband blue light from LED chips to the desired broadband NIR one. Over the past few years significant effort has been devoted to exploiting a variety of ions including Cr 3+ , [4][5][6][7] Mn 2+ , [8] and Eu 2+[9] as the broadband NIR emitters, but only Cr 3+ has hitherto exhibited high internal quantum efficiency (IQE) and good photoluminescence (PL) thermal stability in a handful of host crystals, such as Gd 3 Sc 1.…”