CdS Thin Films Deposited by the CBD Method

In solar cells based on mined layers, there is a problem of electron–hole pair recombination losses between the window layer and the absorber layer. For this reason, the CdS layers have been studied as tampon layers. Thin layers of CdS have been deposited on glass substrates by chemical bath deposition for photovoltaic applications. CdS thin films were synthesized by a chemical bath (CBD) with different deposition protocols to optimize deposition parameters such as temperature, deposition time, ion concentrations and pH. The surface morphology and optical and chemical composition properties of CdS thin films were studied by SEM, XRD, AFM and spectrophotometer. The transmission is 80% in the visible region 300–1000 nm, and the gape energy is around 2.7 eV. The structure is hexagonal wurtzite, and the surface morphologies are formed by flower-shaped nanoparticles with the cluster. The images show that the film is uniform and that the surface is covered with the nanoparticle, and the AFM images show that all the CdS samples present well-defined nanometric grains. The roughness of the films is small. This in turn increases the transmittance of incident light and prevents recombination from generating more pairs of holes in the absorbing layer. The roughness values Ra are 3.88 and Rq are 5.01; this result favors the application of these films in solar cells as a buffer layer.