Highly Efficient Broadband Near-Infrared Luminescence with Zero-Thermal-Quenching in Garnet Y₃In₂Ga₃O₁₂:Cr³⁺ Phosphors

Abstract

Broadband near-infrared (NIR) light source based on phosphor-converted light-emitting-diode (pc-LED) is crucial for applications in medical diagnosis, food quality analysis, and night vision fields, motivating the development of highly efficient and thermal robust NIR phosphor materials. Herein, a novel Cr 3+ -doped garnet phosphor Y 3 In 2 Ga 3 O 12 :Cr 3+ emerges from a fundamental study of the Ln 3 In 2 Ga 3 O 12 (Ln = La, Gd, Y, and Lu) family. Upon 450 nm excitation, this material presents a broadband NIR emission covering 650−1100 nm with a peak located at 760 nm and a full width at half maximum of 125 nm. This material also possesses an ultrahigh internal quantum efficiency (IQE = 91.6%) and absorption efficiency (AE = 46.6%), resulting in an external quantum efficiency as high as 42.7%. Moreover, the emission intensity of this material at 150 °C maintains 100% of the initial intensity, showing a rare zero-thermalquenching property. Fabricating an NIR pc-LED device by using this material, an excellent NIR output power of 68.4 mW with a photoelectric efficiency of 15.9% under 150 mA driving current can be obtained, which exhibits much better performance than the devices fabricated by using some reported efficient NIR materials. Therefore, this work not only provides an ultraefficient and thermally robust broadband NIR material for spectroscopy application but also contributes to the foundation of design rules of NIR materials with high performance.

Efficient and Thermally Robust Broadband Near‐Infrared Emission in a Garnet Ca3MgHfGe3O12:Cr3+ Phosphor

“…The red‐shift of emission spectra is caused crystal field weakening derived from gradual lattice expansion as an increase of temperature; while the broadening of emission spectra should be ascribed to the increased vibration amplitude of excited electrons induced by the enhanced electron‐lattice interaction with increasing temperature. [ 34,51,52 ] The integral intensity at 423 K (Figure 4c) of this material maintains 84.5% of the initial intensity at 298 K. This value is lower than the garnets Ca 3 Mg 0.99 Zr 0.99 Ge 3 O 12 :0.02Cr 3+ (87.9%) and Ca 3 Mg 0.99 Sn 0.99 Ge 3 O 12 :0.02Cr 3+ (89.8%) in this family, but much higher than the Cr 3+ ‐activated garnet materials with long‐wavelength (λ em ≥ 800 nm) emission (as listed in Table 2 ).…”

Blue-light-excitable pure and efficient short-wave infrared luminescenceviaCr3+→ Yb3+energy transfer in a KYbP2O7:Cr3+phosphor

“…62 With the increase of the temperature, the excited electrons prefer to reach the intersection of the 4 T 2 and 4 A 2 energy levels of Cr 3+ and then return to the ground state by non-radiative transition rather than light emission due to the EPC effect. 59,63 The increase of temperature will intensify the EPC effect, leading to a reduction of energy transferred from Cr 3+ to Yb 3+ , resulting in the decrease of the Yb 3+ SWIR luminescence. Significantly, it can be found that the integrated SWIR emission intensity of the KYbP 2 O 7 :0.01Cr 3+ phosphor at 120 °C retains 55.6% of the room temperature SWIR luminescence intensity, which is better than those of most of the other AMP 2 O 7 compounds (for example, ∼30%@120 °C in LiScP 2 O 7 :Cr 3+ , 51%@100 °C in LiGaP 2 O 7 :Cr 3+ , 47.5%@100 °C in NaInP 2 O 7 :Cr 3+ , and 47%@100 °C in LiInP 2 O 7 :Cr 3+ ), 38,64–66 suggesting that the phosphor has a fairly good luminescence thermal stability.…”

“…With the further increase of the Cr 3+ doping content from 0.03 to 0.1, the lifetimes decrease rapidly from 0.43 to 0.21 ms, evidencing the enhanced nonradiative transition with higher Cr 3+ concentration. 59,60 With the increase of doping concentration, the curve slightly deviates from the single exponential function owing to the inequivalent Cr 3+ sites distributed in the octahedrons. 61 The internal and external quantum efficiencies of the KYbP 2 O 7 :0.01Cr 3+ phosphor are also measured to evaluate its SWIR photoluminescence performances as shown in Fig.…”

[Zn2+–Ge4+] co-substitutes [Ga3+–Ga3+] to coordinately broaden the near-infrared emission of Cr3+ in Ga2O3 phosphors

“…The IQE, l max and FWHM of this phosphor and some recently studied NIR phosphors are compared in Table 2. 4,6,12,17,31,[42][43][44][45][46][47]…”