Influence of pH on the Properties of Chemically Prepared SnS and CdS Thin Films

The SnS and CdS thin films were chemically prepared from the bath solutions with different pH values of 9.8, 9.9, and 10, and 11.3, 11.4, and 11.5 respectively. The X-ray diffraction confirmed the formation of orthorhombic SnS with a preferred orientation along the 013 plane and cubic CdS along the 311 planes. Crystallite size and lattice strain were calculated from the Williamson-Hall plot, and it was found that the crystallite size increased as pH increased. Raman spectra showed the prominent peaks of SnS and CdS thin films. Optical studies revealed a decrease in the optical band gap of both samples with increasing pH values. SnS films showed needle-like morphology with agglomerates and CdS flake-like interconnected structures. From the EDS analysis, it was noticed that both the SnS and CdS thin films shifted to a metal-rich composition with the increase in the pH of the bath solution. Finally, a solar cell (ITO/SnS/CdS/Ag) was made, and it was found that cell structures formed with SnS and CdS that were deposited with pH valuesof 10 and 11.3 showed better performance.