Microwave-assisted synthesis of Pr doped ZnS QDs like nanoparticles for optoelectronic applications.

Pr-doped ZnS nanoparticles were synthesised using a low-cost microwave assisted technique and investigations on their structure, morphology, optical properties, Raman resonance, dielectric properties and luminescence were conducted. Broad XRD peaks suggested the formation of low-dimensional Pr-doped ZnS nanoparticles with a cubic structure which was validated by TEM/HRTEM analysis. The energy gaps were identified using diffuse reflectance spectroscopy and it was found that the values varied between 3.54 and 3.61 for different samples. Vibrational experiments on Pr doped ZnS nanoparticles revealed significant Raman modes at ~ 270 and ~350 cm -1 associated to TO and LO modes that are shifted to lower wavenumbers, indicating phonon confinement in the synthesised products. The PL spectra of all samples demonstrate that the pure and Pr doped ZnS nanoparticles are three level laser active materials. EDX and mapping study confirms the homogeneous presence of Pr in ZnS. TEM study shows that the particles are of very small size and cubic phase. The samples have high dielectric constant values between 13 and 24 and low loss values, according to the dielectric analysis. With an increase in frequency and a change in the Pr content of ZnS, an intense peak can be seen in the PL spectra at a wavelength of 360 nm, and some other peaks observed correspond to the transition of Pr 3+ . The produced NPs are appropriate for optoelectronic applications due to their short dimension, high energy gap, high dielectric constant and low loss values.