Broadband near‐infrared emission enhancement in K₂Ga₂Sn₆O₁₆:Cr³⁺phosphor by electron‐lattice coupling regulation

Abstract

Cr3+‐doped phosphors have recently gained attention for their application in broadband near‐infrared phosphor‐converted light‐emitting diodes (pc‐LEDs), but generally exhibit low efficiency. In this work, K2Ga2Sn6O16:Cr3+ (KGSO:Cr) phosphor was designed and synthesized. The experimental results show that the Cr3+‐doped phosphor exhibited broadband emissivity in the range 650‐1300 nm, with a full width at half maximum (FWHM) of approximately 220‐230 nm excited by a wavelength of 450 nm. With the co‐doping of Gd3+ ions, the internal quantum efficiency (IQE) of the KGSO:Cr phosphor increased from 34% to 48%. The Gd3+ ions acted neither as activators nor sensitizers, but to justify the crystal field environment for efficient Cr3+ ions broad emission. The Huang‐Rhys factor decreased as the co‐doping of Gd3+ ions increased, demonstrating that the nonradiative transitions were suppressed. An efficient strategy for enhancing the luminescence properties of Cr3+ ions is proposed for the first time. The Gd3+–co‐doped KGSO:Cr phosphor is a promising candidate for broadband NIR pc‐LEDs.

Simultaneous Broadening and Enhancement of Cr3+Photoluminescence in LiIn2SbO6by Chemical Unit Cosubstitution: Night‐Vision and Near‐Infrared Spectroscopy Detection Applications

“…Meanwhile,the PL intensity and FWHM vary with increasing degree of cosubstitution (y), as shown in Figure 2d.O verall, the PL intensity is enhanced by forming asolid solution (y > 0.20), reaching am aximum at y = 0.50, which is 2.3 times higher than that of the initial LISO:Cr 3+ .E vidently,Z n 2+ incorporation can induce lattice distortion owing to the difference in radius.I th as been reported that proper lattice distortion can introduce an uneven symmetrical field that facilitates breaking of the forbidden transition of Cr 3+ , thereby realizing improved luminescence. [14] In addition, the reduced Stokes shift indicates less non-radiative transition, which also contributes to the enhanced NIR emission. The FWHM value varies in the range of 216-235 nm.…”

A General Ammonium Salt Assisted Synthesis Strategy for Cr3+‐Doped Hexafluorides with Highly Efficient Near Infrared Emissions

“…[ 21–23 ] Moreover, this type of emission can be realized by simply doping Cr 3+ ions into a weak octahedral crystal field environment. Therefore, several Cr 3+ activated phosphors for LEDs have been developed, [ 18,24–30 ] some of which exhibit high photoluminescence internal quantum efficiency (IQE) of >90%, such as Gd 3 Sc 2 Ga 3 O 12 :0.01Cr 3+ ,0.5Al 3+ (IQE = 98.6%), [ 31 ] Ca 3 Sc 2 Si 3 O 12 :0.06Cr 3+ (IQE = 92.3%), [ 32 ] and GdAl 3 (BO 3 ) 4 :0.01Cr 3+ (IQE = 91%). [ 33 ] However, the external quantum efficiency (EQE) of these phosphors is limited to 28%, owing to the relatively low absorption efficiency (AE) of Cr 3+ resulting from the parity‐forbidden 3d‐3d electronic transition.…”

Simultaneous Broadening and Enhancement of Cr3+Photoluminescence in LiIn2SbO6by Chemical Unit Cosubstitution: Night‐Vision and Near‐Infrared Spectroscopy Detection Applications

“…The cosubstitution of [Zn 2+ –Zn 2+ ] for [Li + –In 3+ ] causes contraction of the In−O bond (Figure S9), which increases the D q value according to the relationship of D q vs. 1/R 5 [16] . The nephelauxetic effect has a considerable effect on the Racah parameter, which is negatively related to the electronegativity of the ions [14a, 17] . The average cation electronegativity increases when Li + and In 3+ are substituted by Zn 2+ (Table S5), leading to a decreased B value.…”