Optimizing deposition parameters for CBD-grown CdS thin films: insights into morphology, optical, and electrical properties for optoelectronic applications

Abstract Cadmium sulfide (CdS) thin films are crucial in photovoltaic (PV) applications, particularly as window layers in heterojunction solar cells, due to their excellent optical and electrical properties. This study systematically investigates the impact of ammonia concentration and precursor molar ratios on the structural, morphological, optical, and electrical properties of CdS thin films synthesized via the chemical bath deposition method. Results indicate that increasing the ammonia concentration from 2 M to 14 M and using a 1:20 C d 2 + / S 2 − molar ratio produces films with superior surface uniformity, larger grain size, and enhanced crystallinity. Optical analysis reveals a direct bandgap increase from 2.20 eV to 2.36 eV, while transmittance decreases with increasing film thickness. Electrical characterization of the Mo/CZTS/CdS/Ag diode confirms the effective charge transport properties of the optimized CdS films, demonstrating their potential for efficient PV applications. The findings of this study contribute to advancing the fabrication of high-performance CdS-based solar cells and other optoelectronic devices.