Synthesis of sphere-like-crystal CdS powder and thin films using chemical residue in chemical bath deposition (CBD) for thin film solar cell application

CdS microcrystal, with sphere like morphology, was synthesised from the residue obtained after the chemical bath deposition (CBD) of CdS thin layers usually deposited for CdTe and/or CIGS thin film solar cells, specifically by recycling the chemical waste. The residue was collected and reused to deposit cadmium sulphide (CdS) thin films on glass substrate by thermal evaporation. The films were subsequently annealed in vacuum at 250 °C, 350 °C and 420 °C for 40 min. The structural and optical properties were characterized by XRD, SEM, and UV-Vis spectrometry. All the films were found to exhibit high transmittance (over 70 to 90%). The optical band gap energy was found to be in the range of 2.28-2.37 eV, which is very suitable to be used as buffer or window for CdTe or CIGS thin film solar cells.