Improved near infrared emission of Li2MgZrO4:Cr3+ induced by Ga3+ doping

Abstract

Near-infrared pc-LEDs are a promising light source for various applications including bio-imaging, night vision monitoring, environmental surveillance and plant cultivation, offering advantages such as low cost, wide emission spectra and compact design. The development of high-performance NIR phosphors is of great significance to the advancement of NIR pc-LEDs. In this work, the luminescence properties of NIR phosphor Li₂MgZrO₄:0.01Cr³⁺ have been effectively improved by Ga³⁺ doping. Under excitation of 445 nm blue light, the emission intensity of the Li₂MgZr_0.75O₄:0.01Cr³⁺,0.25Ga³⁺ phosphor is 2.61 times that of its Ga³⁺ free counterpart. The internal quantum efficiency (IQE) increases from 28.8% to 35.3%, and the external quantum efficiency (EQE) increases from 6.2% to 12.7%. The temperature stability of the Li₂MgZr_0.75O₄:0.01Cr³⁺,0.25Ga³⁺ phosphor is also improved. The increased structural rigidity and crystal field strength of Cr³⁺ induced by doped Ga³⁺ ions are responsible for the better luminescence properties. The improved phosphor has the potential for use in NIR light sources.