Enhanced and Broadened NIR Emission of CaZnGe₂O₆:Cr³⁺ by Yb³⁺ Codoping for NIR Applications

Abstract

Compact and portable near-infrared (NIR) light sources have been widely used in the fields of NIR spectroscopy, night vision lighting, medical measurement, etc. Although Cr 3+ -activated phosphors have been widely reported, achieving broadband and high-efficiency near-infrared emission remains of great significance. In this work, CaZnGe 2 O 6 :Cr 3+ with highly efficient and ultrabroadband NIR emission was synthesized by a solid reaction method, and Yb 3+ -codoping not only enhanced the NIR emission efficiency but also broadened its emission band. As the absorption efficiency was greatly improved due to Yb 3+ doping, CaZnGe 2 O 6 :Cr 3+ ,Yb 3+ presented excellent NIR emission properties with a fwhm of 295 nm, an internal quantum efficiency (IQE) of 98.4, an external quantum efficiency (EQE) of 31.1%, and an effective emission band for NIR spectroscopy over 350 nm. A pc-LED was prepared by packaging the CaZn-Ge 2 O6:Cr 3+ ,Yb 3+ phosphor with a 460 nm LED chip, and its NIR electro-optical conversion efficiency and output power reached 12.9%@100 mA and 249.3 mW@300 mA, respectively. This pc-LED can illuminate a pattern clearly on wall 15 m away and demonstrated application in NIR spectroscopy through the measurement of the glucose solution concentration. Our results indicate that the CaZnGe 2 O 6 :Cr 3+ ,Yb 3+ ultrabroadband NIR phosphor is a high-performance light source material for portable compact NIR devices.

Enhancing the inherent NIR photoluminescence in SrLaLiTeO6 through Cr3+–Yb3+ co-substitution for high performance pc-LEDs

“…The energy barrier between the lowest excited state 4 T 2 and the conduction band can be empirically determined using the equation, . Δ E P for SLLT:3%Cr 3+ is 0.52 K. Thermal activation energies of the phosphors above room temperature were calculated using the Arrhenius equation given by 23,24,29 …”

“…2 F 5/2 → 2 F 7/2 emission transitions of Yb 3+ serve as an effective means to circumvent nonradiative transitions between different energy levels, consequently enhancing the thermal stability of the phosphors. [22][23][24][25][26][27][28][29] Cr 3+ and Yb 3+ co-doped NIR phosphors have been recently studied as spectral converters for solar cell applications since Yb 3+ emission matches well with the spectral response of Sisolar cells. 30 Inspired by this, the combination of Cr 3+ and Yb 3+ has been utilized by many researchers to develop NIR pc-LEDs.…”

“…26 The phosphor shows an emission spanning from 700 to 1200 nm. Some other examples using Cr 3+ [22][23][24]27,29 The pursuit of developing broadband-emitting NIR phosphors underscores the importance of exploring new materials in this field. Double perovskites are known for their various physical properties resulting from their unique crystal structure with distinct sites that can accommodate almost all the elements in the periodic table.…”

“…Some other examples using Cr 3+ –Yb 3+ energy transfer are CaZnGe 2 O 6 :Cr 3+ ,Yb 3+ , LiScSi 2 O 6 :Cr 3+ ,Yb 3+ , KYbP 2 O 7 :Cr 3+ ,Yb 3+ , LiGaP 2 O 7 :Cr 3+ ,Yb 3+ , and Ca 4 ZrGe 3 O 12 :Cr 3+ ,Yb 3+ . 22–24,27,29 The pursuit of developing broadband-emitting NIR phosphors underscores the importance of exploring new materials in this field.…”

Dynamic Luminescence of Lead-Doped Calcium Zinc Germanate Clinopyroxene for Multimode Anticounterfeiting

“…One such material is CaZnGe 2 O 6 [calcium zinc germanate (CZGO)], which is a clinopyroxene material utilized in long persistent luminescence phosphors. 33−36 The dopants used in CZGO clinopyroxene include chromium (Cr); 35,37 manganese (Mn); 33,38 bismuth (Bi); 33,39 dysprosium (Dy); 36 terbium (Tb), 34 and lead (Pb). 17 In particular, Dong et al recently reported the synthesis and application of leaddoped CZGO (CZGO: Pb) with dynamic fluorescence and photochromic properties.…”