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.