Strong Nd3+ NIR-II luminescence in LaZnAl11O19: Cr3+, Nd3+ via efficient energy transfer for multifunctional applications

Tuning the luminescence properties of efficient near-infrared (NIR) phosphors is critical to expanding their applications in NIR spectroscopy. In this paper, a series of novel Cr 3+ -doped LaZnAl 11 O 19 (LZAO: Cr 3+ ) phosphors are synthesized via a high-temperature solid-phase method. These phosphors exhibit NIR emission in the range of 650–900 nm, with the LZAO: 0.10Cr 3+ achieves an excellent internal quantum efficiency (IQE) of 89.9 %. Notably, it demonstrates excellent thermal stability, maintaining 97.2 % of the initial photoluminescence intensity at 513 K. Through co-doping with Nd 3+ , the NIR emission broadens across the 650–1100 nm range, and leads to a substantial enhancement in Nd 3+ emission intensity due to efficient Cr 3+ →Nd 3+ energy transfer. Remarkably, the optimum LZAO: Cr 3+ , Nd 3+ phosphor exhibits a high IQE (82 %) and an outstanding anti-thermal quenching behavior (118.0 % @ 513 K), with the underlying mechanism of its thermal stability further elucidated through defect level model. In addition, the synthesized phosphors show great promise for multifunctional applications in NIR phosphor-converted light emitting diodes, plant growth lighting, non-destructive testing, luminescence thermometry and solar cells.