Simultaneously Possessing High Quantum Efficiency and Thermal Robustness in a Near‐Infrared Emitting ZnAlB_(1‐x)Ga_xO₄:Cr³⁺ Phosphor

Abstract

Near‐infrared (NIR) phosphors are a vital component of phosphor‐converted light‐emitting diodes (pc‐LEDs), with simultaneous high quantum efficiency and thermal stability being essential attributes for optimal performance. In this paper, a novel ZnAlB(1‐x)GaxO4:0.05Cr3+ system is designed by gradually substituting B with Ga. Surprisingly, a significant enhancement in photoluminescence performance is observed, reaching peak efficiency at x = 1. Further development led to a series of ZnAlGaO4:yCr3+ (ZAGO:yCr3+) phosphors, exhibiting variable full width at half maximum (FWHM) ranging from 32 to 163 nm with increasing Cr3+ content, attributed to energy transfer between two Cr3+ emission centers. Among these, ZAGO:0.05Cr3+ emerges as the optimal phosphor, boasting a high internal/external quantum efficiency of 80%/34% with a FWHM of 80 nm. Notably, this phosphor demonstrates anti‐thermal quenching behavior (125.53% @ 423 K), with its exceptional thermal stability elucidated through the defect level model. The fabricated NIR pc‐LEDs featuring ZAGO:Cr3+ phosphors show great prospect in multifunctional applications in plant cultivation, night vision, non‐destructive analysis and veins imaging.