Cr³⁺-Doped double perovskite antimonates: efficient and tunable phosphors from NIR-I to NIR-II

Abstract

Near-infrared (NIR) light devices have great potentials in non-destructive testing and biomedicine fields. However, the lack of stable and efficient long-wavelength NIR phosphors hinders its development. In this work, utilizing...

Broadband Short-Wave Infrared-Emitting MgGa2O4:Cr3+, Ni2+ Phosphor with Near-Unity Internal Quantum Efficiency and High Thermal Stability for Light-Emitting Diode Applications

“…There exist three different excitation bands peaking at 272, 420, and 572 nm, which are assigned to the Cr 3+ 4 A 2 → 4 T 1 ( 4 P), 4 A 2 → 4 T 1 ( 4 F), and 4 A 2 → 4 T 2 ( 4 F) transitions, respectively. 37 Under the excitation of blue light at 420 nm, the emission spectrum consists of a strong sharp line emission centered at ∼708 nm (Cr 3+ 2 E → 4 A 2 transition) and a broadband emission ranging from 800 to 1100 nm (Cr 3+ 4 T 2 → 4 A 2 transition). 59 Figure S2 shows the infrared luminescence spectra of the MgGa 2 O 4 :x% Cr 3+ (x = 0.5, 1, 2, and 3) phosphors under 420 nm blue light excitation.…”

“…32,33 In the case of Cr 3+ -doped phosphors, they can produce broadband SWIR emissions with a peak maximum centered above 900 nm when Cr 3+ ions are located in a very weak octahedral crystal field environment, such as LiSc-GeO 4 :Cr 3+ (peak wavelength: 1120 nm, FWHM = 300 nm), 34 InNbO 4 :Cr 3+ (peak wavelength: 1025 nm, FWHM = 231 nm), 35 Cs 2 AgInCl 6 :Cr 3+ (peak wavelength: 998 nm, FWHM = 193 nm), 36 and Ba 2 ScSbO 6 :Cr 3+ (peak wavelength: 1010 nm, FWHM ≈ 185 nm). 37 But these phosphors usually exhibit poor photoluminescence efficiencies of <30% due to the very large Stokes shifts when excited by blue light. Recently, several attempts on the blue LED chip-excitable broadband SWIR phosphors have been reported based on the efficient Cr 3+ → Yb 3+ energy transfer, represented by LiScP 2 O 7 :Cr 3+ , Yb 3+ , 38 Ca 2 LuZr 2 Al 3 O 1 2 :Cr 3 + , Yb 3 + , 3 9 Sr 9 Cr(PO 4 ) 7 :Yb 3 + , 4 0 Lu 2 CaMg 2 Ge 3 O 12 :Cr 3+ , Yb 3+ , 41 and Lu 0.2 Sc 0.8 BO 3 :Cr 3+ , Yb 3+ .…”

“…Generally, SWIR-emitting phosphors can be designed by doping trivalent lanthanide ions (Tm 3+ , Er 3+ , Nd 3+ , Pr 3+ , Yb 3+ , and Ho 3+ ) and transition-metal ions (Cr 3+ , Cr 4+ , and Ni 2+ ) into an appropriate inorganic matrix. ,− Among them, trivalent lanthanide ion-doped SWIR phosphors show weak absorption bands in the visible region and sharp-line emissions due to the electric dipole forbidden transitions, which inhibit the further development of these phosphors for light converters to realize that efficient luminescence in the SWIR. Cr 4+ -activated phosphors can emit broadband SWIR emissions, but they usually have wide and intense absorption bands in the red and infrared wavelength regions, which makes it hard for them to be efficiently excited by commercially available blue InGaN chips. , In the case of Cr 3+ -doped phosphors, they can produce broadband SWIR emissions with a peak maximum centered above 900 nm when Cr 3+ ions are located in a very weak octahedral crystal field environment, such as LiScGeO 4 :Cr 3+ (peak wavelength: 1120 nm, FWHM = 300 nm), InNbO 4 :Cr 3+ (peak wavelength: 1025 nm, FWHM = 231 nm), Cs 2 AgInCl 6 :Cr 3+ (peak wavelength: 998 nm, FWHM = 193 nm), and Ba 2 ScSbO 6 :Cr 3+ (peak wavelength: 1010 nm, FWHM ≈ 185 nm) . But these phosphors usually exhibit poor photoluminescence efficiencies of <30% due to the very large Stokes shifts when excited by blue light.…”

Broadband Near-Infrared Luminescence in Garnet Y3Ga3MgSiO12: Cr3+ Phosphors

“…Broadband near-infrared (NIR) light sources are playing an important role in brain imaging, palmprint identification, biological sensing, food composition analysis, etc., and are attracting increasing attention. − However, traditional infrared light sources (e.g., incandescent lamp and tungsten halogen lamp) suffer from the shortcomings of large size, low efficiency, and limited lifespan, which cannot meet the commercial application demands. − The newly developing NIR light-emitting diodes (LEDs) offer a long service life, high conversion efficiency, and small size, but the full width at half maximum (FWHM) of their emission bands is typically less than 50 nm, limiting their applications. , Inspired by white LEDs, NIR phosphor converted LEDs (NIR-pc-LEDs) provides a good solution to this problem, which possesses the advantages of compactness, low pollution, long lifetime, and competitive price. − Moreover, it can be combined with various NIR phosphors to satisfy the demands of potential fields. NIR phosphors act as an essential component of NIR-pc-LEDs.…”

Understanding the broadband near-infrared luminescence in a highly distorted garnet Ca4HfGe3O12:Cr3+ phosphor

“…[19][20][21][22][23][24][25] Cr 3+ has a specific 3d 3 electronic configuration, which makes its emission highly sensitive to the crystal field environment. [26][27][28][29][30] When introduced into a strong crystal field environment, it exhibits sharp line emission with a main peak near 700 nm generated by the forbidden transition 2 E -4 A 2 , while a broadband NIR emission of 650-1200 nm originated from spin allowed 4 T 2 -4 A 2 transition can be observed when located in a weak crystal field. 11,20,23,24,[31][32][33] To date, many Cr 3+ -doped NIR phosphors have been developed, among which the garnettype material with the formula of A 3 B 2 C 3 O 12 stands out due to its high luminescent efficiency and excellent thermal stability, such as Gd 3 Sc 2 Ga 3 O 12 :Cr 3+ (l em = 750 nm, FWHM = 110 nm, IQE = 91%, I 1501C = 86%), Ca 3 Sc 2 Si 3 O 12 :Cr 3+ (l em = 770 nm, FWHM = 110 nm, IQE = 97.4%, I 1501C = 92.3%) and Y 3 In 2 Ga 3 O 12 :Cr 3+ (l em = 760 nm, FWHM = 125 nm, IQE = 91.6%, I 1501 C = 100%).…”