Bright Green Frequency Upconversion in Catechin Based Yb³⁺/Er³⁺ Codoped LaVO₄ Nanorods upon 980 nm Excitation

A series of Yb³⁺–Er³⁺ codoped LaVO₄ phosphors using catechin as a chelating agent and phase director have been prepared by the low temperature hydrothermal synthesis technique. The sample exists in two different crystalline phases, i.e., monoclinic and tetragonal, depending on the concentration of dopants. Structural, optical, and thermal characterizations have been done by using X-ray diffraction, EDX, FE-SEM, UV–vis diffuse reflectance, FTIR, and TGA analysis. Upconversion emission (UC) based imaging and drug delivery systems have been proposed to overcome some significant drawbacks of existing systems. Though fluorides are better hosts for UC, their harmful character has forced researchers to look at alternatives including oxides. The frequency upconversion emission (UC) study upon excitation at 980 nm has been performed in this particular host (m-LaVO₄) which is not an ideal upconverting host. The sample emits bright green color upconversion emission, along with relatively weak emissions in the blue, red, and NIR regions. The nanorod shape of the developed samples has been confirmed by FE-SEM image analysis. The purity of the green color emission has been confirmed by CIE chromaticity diagram which supports its utility in the fabrication of green upconverters.