Remarkable role of B site regulation on a highly heat-resistant double-perovskite phosphor with versatile NIR utilizations

Abstract

Double-perovskite-type near-infrared (NIR) phosphors have emerged as a desirable research hotspot, benefiting from the B/B’O₆ coordinations suitable for Cr³⁺ luminescence. However, NIR efficiency and thermostability maintain challenging. Meanwhile, the precise identification of the Cr³⁺ occupancy appears to be particularly important due to the abundant cation sites in double-perovskite structure. Herein, this research reported a Cr³⁺-activated A₂BB’O₆ (Ca₂AlTaO₆) NIR phosphor with high luminescence heat-resistance (94 %@423 K). Under 444 nm excitation, Ca₂AlTaO₆:1.2 %Cr³⁺ exhibits sharp emission originating from the ²E_g→⁴A₂ transition of Cr³⁺. The visualized proof provided by aberration-corrected transmission electron microscopy and spectral analysis confirm that Cr³⁺ simultaneously occupies [BO₆] and [B’O₆] sites. Moreover, the B site regulation by Ga³⁺ boosts luminescent efficiency 1.5 times. The Ca₂Al_0.8Ga_0.2TaO₆:1.2 %Cr³⁺-converted NIR LED device demonstrates stable photoelectric performance under high current over an extended period. Subsequently, the fascinating material is successfully demonstrated via the multifunctional applications in non-destructive detection, night vision, and plant growth lighting. This work provides valuable insights for constructing better double-perovskite-type NIR-emitting materials.