Synthesis and investigation of properties of CdS/PVA nanocomposite prepared by CBD method

In this work, CdS quantum dots embedded in polyvinyl alcohol (PVA) polymer were prepared in colloidal form using the chemical bath deposition (CBD) method. Three different compounds were used in the chemical bath to prepare CdS quantum dots. In the first case, the ratio of Cd2+ ions was higher than that of S2- ions. In the second case, the ratio of Cd2+ ions was lower than that of S2- ions, and in the third case, the ratio of Cd2+ ions was equal to that of S2- ions. Optical properties including energy gap, and absorption and emission spectra were studied. According to the XRD spectrum, it can be said that the phase formed for CdS nanoparticles is a combination of hexagonal and zinc blende cubic structures. From the results of atomic force microscopy (AFM), it can be seen that CdS nanoparticles are embedded in the polymer matrix, and the sample prepared from Solution 2 has a more uniform distribution of particle size than the samples from the other two solutions. The TEM images showed that CdS particles are nearly spherical, and with increasing concentration of Cd2+ ions in the solution, the particle size increases. The energy gap of the samples was found to be in the range of 2.45 eV to 2.84 eV, which is larger than the energy gap of CdS bulk, i.e., 2.42 eV.