Gradient defects mediate negative thermal quenching in phosphors

Luminescent materials often suffer from thermal quenching (TQ), limiting the continuation of their applications under high temperatures up to 473 K. The formation defect levels could suppress TQ, but rational synthesis and deep understanding multiple defects-regulated luminescent working in such a wide temperature range still remain challenging. Here, we prepare negative (NTQ) phosphor LiTaO3 : Tb3 + by introducing gradient defects VTa5−, TbLi2+, ( VTaTbLi)3 − as identified advanced experimental theoretical studies. Its photoluminescence significantly becomes intense with rising then slowly increases at 373 mechanism studies reveal that varied trapping depths act energy buffer layers effectively capture carriers. Under disturbance, stored carriers successively migrate activators consecutive zones, compensating for TQ enhance luminescence emission. This study initiates multi-defect NTQ phosphors temperature-dependent applications.