Defect induced anti-thermal quenching of Cr3+ doped Zn1-xLi2xGa2O4 for plant growth LED

Abstract

Thermal stability improvement of the phosphors is significant to obtain high-efficiency and thermally stable emission in high power light emitting diodes (LEDs). Herein, an anti-thermal quenching deep-red phosphor (Zn, Li)Ga2O4:Cr3+ for plant growth LED is reported. The defects were introduced into ZnGa2O4 by doping with Li + ions with different valence state and the compounds Zn1-xLi2xGa2O4:Cr3+ were prepared. Optimized Zn0.9Li0.2Ga2O4:Cr3+ presents anti-thermal quenching and the emission from 580 to 680 nm increases as the temperature evaluates. The enhanced emission at around 630 nm is attributed to the increased defect VZn, at high temperature while the improved emission at around 670 nm arises from the new octahedral site for Cr3+. Both the emission of the optimized Zn0.9Li0.2Ga2O4:Cr3+ phosphor at room temperature and high temperature match well with the absorption spectra of the phytochrome PR and PFR. This simple strategy to introduce defects and obtain highly efficient and thermally stable emission provides a novel method to improve the thermal stability of the phosphors for high-power plant growth LEDs.