Nonlinear Optical Response of La-Doped VTe₂ Nanomaterials for Optical Limiter

Vanadium ditelluride (VTe2) is a promising material for various optoelectronic applications due to its intriguing optical and electronic properties. In this study, VTe2 and La-doped VTe2 (LVT) nanostructures were synthesized by using a hydrothermal method for their potential optoelectronic applications. The presence of a monoclinic phase of VTe2 in all samples was confirmed through a structural study, while Raman spectroscopy identified characteristic vibrational modes associated with it. The pristine VTe2 primarily exhibited a nanorod-like structure, whereas the incorporation of La led to a mixed nanorod and nanosheet morphology. X-ray photoelectron spectroscopy analysis revealed the chemical states of V, Te, and La in the La-doped VTe2 sample, with a noticeable shift in the XPS peaks toward higher binding energies, indicating changes in the electronic environment due to La doping. Optical absorption analysis revealed a blue shift of the absorption edge for La-doped samples, increasing their optical band gap from 1.45 to 1.53 eV. But, for the 0.25 mmol (higher), La-doped VTe2 decreased to 1.39 eV. The nonlinear optical studies carried out by an open-aperture Z-scan indicate that both pristine VTe2 (1.45 eV) and 0.25 mmol La-doped VTe2 (1.39 eV) samples demonstrate reverse saturable absorption (RSA) behavior, making them suitable for optical limiter applications. These findings highlight the potential of La-doped VTe2 nanostructures for advanced optoelectronic applications, particularly in nonlinear optical devices.