Site-Selective Occupancy Control of Cr Ions toward Ultrabroad-Band Infrared Luminescence with a Spectral Width up to 419 nm

Abstract

Infrared-emitting phosphor-converted light-emitting diodes (LEDs) are desirable light sources for a very wide range of applications such as spectroscopy analysis, nondestructive monitoring, covert information identification, and night-vision surveillance. The most important aspect of infrared emitters for spectroscopy is to cover the widest possible wavelength range of emitted light. However, developing ultrabroad-band infrared emitters based on converter technology is still a challenging task due to the lack of suitable phosphor materials that emit in a wide wavelength range upon excitation from blue-emitting chips. Herein, this work demonstrates Cr3+-activated Mg2SiO4 infrared phosphors with a super wide infrared spectral range of 600 to 1400 nm and high internal quantum yield up to 80.4% upon 460 nm excitation. Site-selective occupancy of Cr3+ emitters in two different Mg sites in the Mg2SiO4 lattice results in two distinct broad emission bands peaking at 760 and 970 nm, both of which contribute to the ultrabroad-band infrared luminescence with a full width at half maximum (FWHM) of 419 nm. This is by far the broadest infrared emission to the best of our knowledge. On this basis, an ultrabroad-band infrared LED prototype has been fabricated by the combination of the Mg2SiO4:Cr3+ phosphor with a blue LED chip, which shows great potential for imaging and sensing applications. This work demonstrates that site-selective occupancy control of Cr ions is an effective strategy for developing ultrabroad-band Cr3+-doped phosphors.

Near-infrared luminescence and high thermal stability of Rb2NaScF6:Cr3+ phosphor for spectroscopy applications

“…All of them abide to a single exponential function, verifying Cr 3+ ion substitutes the single lattice site of Sc 3+ in RNSF matrix. 37 Increasing the x value from 0.005 to 0.07, the fitted lifetime descends from 372 to 68 μs (the lower part of Fig. 3c), which is attributable to the intensified non-radiation transition among Cr 3+ activators.…”

Valence state control of Cr4+-activated Li2SrGeO4for NIR-II light source to distinguish deuterium and non-deuterium reagents

“…3a. The energy of Cr 4+ in tetrahedron can be roughly estimated via eqn (S1) (ESI†), 39,43 from which the value of E[ 3 T 1 ( 3 P)] can be calculated from the energy 3 A 2 → 3 T 1 ( 3 P) of 460 nm, and the value of E[ 3 T 1 ( 3 F)] can be read as the average value of 650 nm, 671 nm, and 721 nm from the PLE spectrum of LSGO:0.5%Cr 4+ . Finally, the Dq / B value can be calculated to be 1.65, which is much less than the crossing point of 3 T 2 and 1 E levels in the Tanabe–Sugano energy level diagram of 3d 2 in the tetrahedral crystal field (Fig.…”

Near-infrared Sr7NaGa(PO4)6:Cr3+,Ln3+ (Ln = Nd, Er, and Yb) phosphors with different energy transfer paths: photoluminescence enhancement and versatility

“…[1][2][3][4] NIR phosphor-converted LEDs (NIR pc-LEDs) are expected to be the next generation NIR light source due to their small size, high conversion efficiency, long lifetime, and environmental friendliness. 5,6 The NIR pc-LEDs with broadband NIR emission can be employed in some areas such as nondestructive analysis and night vision. 7,8 And the NIR pc-LEDs in special ranges such as 720-740 nm and 650-950 nm (first biological window) can be used to facilitate plant growth, distinguish tumor tissues, and identify blood oxygen levels.…”