Improved Near-Infrared Luminescence Properties of LiScSi₂O₆:Cr³⁺,Yb³⁺ Phosphors via Efficient Energy Transfer

Developing high-performance broadband near-infrared (NIR) phosphors for NIR phosphor-converted light-emitting diodes is still a challenge. Co-doping is an effective strategy for enhancing the performance of NIR phosphors. Herein, we explore a NIR phosphor by co-doping Yb³⁺ into LiScSi₂O₆:Cr³⁺ (LSS:Cr³⁺). Under 468 nm excitation, LSS:Cr³⁺,Yb³⁺ exhibits a broad NIR emission from 700 to 1100 nm. Due to the efficient energy transfer from Cr³⁺ to Yb³⁺, the maximum bandwidth of LSS:Cr³⁺,Yb³⁺ reaches 219 nm, broader than that of LSS:Cr³⁺ (170 nm). The addition of Yb³⁺ further suppresses the thermal quenching compared with that of the Cr³⁺ singly doped specimen. At 150 °C, LSS:Cr³⁺,Yb³⁺ retains 62% of the emission intensity at room temperature, while that of singly doped LSS:Cr³⁺ is only 40%. These results indicate that the construction of Cr³⁺ → Yb³⁺ energy transfer not only can broaden the emission spectrum but also can improve the thermal stability.