Defect induced anti-thermal quenching of Cr3+ doped Zn1-Li2Ga2O4 for plant growth LED

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)Ga 2 O 4 :Cr 3+ for plant growth LED is reported. The defects were introduced into ZnGa 2 O 4 by doping with Li + ions with different valence state and the compounds Zn 1- x Li 2 x Ga 2 O 4 :Cr 3+ were prepared. Optimized Zn 0.9 Li 0.2 Ga 2 O 4 :Cr 3+ 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 V Zn , at high temperature while the improved emission at around 670 nm arises from the new octahedral site for Cr 3+ . Both the emission of the optimized Zn 0.9 Li 0.2 Ga 2 O 4 :Cr 3+ phosphor at room temperature and high temperature match well with the absorption spectra of the phytochrome P R and P FR . 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.