Dielectric and optical studies of CdSe nanoparticles: green synthesis

Nanoparticle of cadmium selenide (CdSe) was carried out through the green synthesis route method with the help of sodium selenite and cadmium nitrate. To control the size of nanoparticles, the capping agent utilized was starch. X-ray diffraction technique and transmission electron microscopy were used to calculate the grain size as well as the crystal structure of the particles was determined. The optical absorption spectra were studied by the UV–Visible spectroscopy. The morphology of prepared CdSe nanoparticles was studied by scanning electron microscope and TEM. The Fourier infrared spectroscopy (FTIR) was also carried out showing some dominant absorption peaks attributed to the characteristic absorption. The PL excitation spectra showed a single peak at 458 nm and broad PL emission band is visible at 677 nm in the emission spectra. Dielectric studies were carried out for the pelletized sample of CdSe nanoparticles in which the variation of the dielectric constant and dielectric loss were studied. This was done over the lower frequency range to higher frequency range at room temperature and other higher temperatures. The synthesized CdSe showed high dielectric constants at low frequency which rapidly decreases with the increase in the frequency. The dielectric loss also showed similar behavior with small difference. The semiconducting property of CdSe was confirmed, as with the increase of temperature the ac conductivity was also found to be increased.