Super Broadband Emission Across NIR‐I and NIR‐II Under Blue Light Excitation of Cr³⁺, Ni²⁺ Co‐Doped Sr₂GaTaO₆ Phosphor Achieved by Two‐Site Occupation and Effective Energy Transfer

Abstract

The performance of the near‐infrared phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) mainly depends on the NIR emitting phosphors used. Cr3+ doped materials can be excited by blue light chips, but their emission is located in the NIR‐I region (650–1000 nm). Ni2+ doped materials are mainly located in the NIR‐II region (1000–1700 nm), but they cannot be effectively excited by blue light chips. Herein, Cr3+, Ni2+ mono‐doped, and co‐doped Sr2GaTaO6 NIR emitting phosphors are prepared and investigated. Cr3+ and Ni2+ ions occupy two octahedral sites of Ga3+ and Ta5+. The co‐doping of Cr3+ ions has achieved two breakthroughs. One is to shift the optimal excitation wavelength from violet light to blue light due to the energy transfer (efficiency up to 70%) from Cr3+ to Ni2+. The other is to achieve the broadband and continuous emission across NIR‐I and NIR‐II regions (650–1700 nm, with a full width at half maximum (FWHM) of 410 nm (173 nm + 237 nm)). The prepared Sr2GaTaO6: 0.02Cr3+, 0.01Ni2+ phosphor is combined with a commercial 460 nm blue chip to realize its application in organic compounds identification, night vision, and biological imaging. This work points out a direction for the future development of efficient super broadband NIR‐emitting phosphors.

Blue light-excited broadband NIR-II-emitting Li2ZnSn3O8:Cr3+,Ni2+ phosphor for multifunctional optical applications

“…44 This phenomenon also occurs in Sr 2 GaTaO 6 :Cr 3+ ,Ni 2+ and other ET systems of Cr 3+ → Yb 3+ , Ce 3+ /Eu 2+ → Mn 2+ . [44][45][46] The ET process from Cr 3+ to Ni 2+ is shown in Fig. 2f.…”