Near-Infrared LuCa₂ScZrGa₂GeO₁₂:Cr³⁺ Garnet Phosphor with Ultra-broadband Emission for NIR LED Applications

Abstract

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs), as a new generation of NIR lighting sources, have wide prospects in the areas of food analysis and biological and night vision imaging. Nevertheless, NIR phosphors are still limited by short-wave and narrowband emissions as well as low efficiency. Herein, a series of NIR phosphors, LuCa2ScZrGa2GeO12:Cr3+ (LCSZGG:Cr3+), with broadband emissions have been developed and first reported. At 456 nm excitation, the optimized LCSZGG:0.005Cr3+ phosphor represents an ultra-broadband emission within the range of 650–1100 nm, peaking near 815 nm with a full width at half maximum of 166 nm. Furthermore, the LCSZGG:0.005Cr3+ phosphor possesses good internal quantum efficiency of 68.75%, and its integrated emission intensity at 423 K still retains about 64.17% of that at room temperature. By combining the optimized sample with a blue chip, a NIR pc-LED device is fabricated, which has an excellent NIR output power of 37.88 mW with an NIR photoelectric conversion efficiency of 12.44% under a 100 mA driving current. The aforementioned results demonstrate that these LCSZGG:Cr3+ broadband NIR phosphors are expected as NIR light sources.

Rational design for broad near-infrared emission from a two-sited Rb2LiAlF6:Cr3+ phosphor with high efficiency and thermal stability for spectroscopic applications

“…According to the slope of the line, the hω and S values were determined to be 14.9 meV and 2.64, respectively, which indicated that Cr 3+ activators experienced a weak EPC effect in RLAF host. 46 This was also assumed to be the reason for the remarkable PL thermal stability of RLAF:Cr. Moreover, the QE of RLAF:0.02Cr upon excitation with a wavelength of 450 nm was found to be 77.7%.…”

Developing the Na2CaZr2Ge3O12:Cr3+ Garnet Phosphor for Advanced NIR pc-LEDs in Night Vision and Bioimaging

“…Nevertheless, the maximum value of IQE is higher than those of most NIR materials when the emission peak is centered above 800 nm. This includes LuCa 2 ScZrGa 2 GeO 12 :Cr 3+ (λ em = 815 nm, IQE = 68.8%), La 2 MgZrO 6 :Cr 3+ (λ em = 825 nm, IQE = 58%), and LiScSi 2 O 6 :Cr 3+ (λ em = 845 nm, IQE = 64.4%). − The AE and EQE values also increase with increasing Cr 3+ concentration. This can be attributed to the improved absorption of the incident excitation energy by the phosphor.…”

“…Room-temperature photoluminescence decay curves of Na 2 CaZr 2– x Ge 3 O 12 : x Cr 3+ ( x = 0.01, 0.02, 0.04, 0.06, 0.08, and 0.10) are presented in Figure d upon excitation with 460 nm light. All of the decay curves are described by a single-exponential function as presented in eq , I t = I 0 + A nobreak0em0.1em⁡ exp ( − t τ ) where I 0 stands for the offset, I t represents intensity at time t , A represents the fitting constant, and τ is the lifetime. The obtained lifetime gradually decreases from 54.8 to 40.2 μs with increasing Cr 3+ concentration, stemming from the gradually enhanced interactions between Cr 3+ ions, which lead to energy loss in nonradiative transitions.…”

An efficient and thermally stable Cr3+-activated Y2GdSc2Al2GaO12 garnet phosphor for NIR spectroscopy applications

“…In addition, the thermal stability is also a crucial factor for evaluating the potential of phosphors in practical applications. 55 The temperature-dependent PL spectra of the YGSAG:0.08Cr 3+ sample from 303 to 483 K with an interval of 30 K were collected, as depicted in Fig. 5a.…”