Hetero-valent substitution induced luminescence enhancement of Zn1-xGa2+xO4+:Cr3+near infrared phosphors for plant cultivation

Cr3+ doped near infrared (NIR) phosphors have remained exploding in the area of bioimaging, food detection and plant cultivation. Herein, the spinel ZnGa2O4:Cr3+ NIR phosphor was prepared and the defect was intro-duced into the matrix via substituting the bivalent Zn2+ with the trivalent Ga3+. Structure variation and the microstructure of the phosphors were investigated and the state of the elements was confirmed. The existence of the defect in the lattice was verified by X-ray photoelectron spectroscopy and thermoluminescence. By substituting Zn2+ with Ga3+ both the emission intensity and the thermal stability were improved. Thermal stability improvement was explored as the result of the defect level in the lattice. The emission intensity of the optimized Zn0.98Ga2.02O4+delta:Cr3+ kept 77.3% at 423 K than that at room temperature. This work provides a strategy to enhance the luminescence efficiency and thermal stability simultaneously of Cr3+ doped NIR phosphors.