Energy transfer realizes efficient NIR emitting Ca2ScTaO6:Cr3+, Yb3+ perovskite-structured phosphors

Stable and efficient broadband near-infrared (NIR) emitting phosphors are vital for the next-generation NIR sources. However, it still remains challenging to construct such phosphors, particularly those with a NIR-II window. In this work, using the Cr3+-Yb3+ energy transfer (ET) strategy, the as-synthesized Ca2ScTaO6:Cr3+, Yb3+ phosphor retains 86.2% of the initial luminescence intensity of Yb3+ at 373 K with characteristic emissions of both activators ranging from 700 nm to 1200 nm. The occupation of Cr3+ into both Ta5+ and Sc3+ sites is confirmed by X-ray diffraction, time-resolved emission spectrum, and crystal structure. The efficient ET from Cr3+ to Yb3+ is revealed by the diffuse reflection spectrum, steady-state and transient fluorescence. As a result, it contributes to the excellent performance of the phosphor. Based on the optimized phosphor, a NIR light-emitting diode is fabricated and demonstrated its advantage in imaging and potential application in information encryption. The result highlights ET as a robust strategy to construct efficient NIR phosphor.