Optimisation of cadmium chloride solution processing of close space sublimated thin film CdTe solar cells

In this paper, we describe the optimisation process for the Cadmium Chloride (CdCl2) wet chemical treatment of cadmium telluride (CdTe) photovoltaics (PV). Various experiments were performed on Close Spaced Sublimated (CSS) CdTe cells, including optimisation of the cadmium chloride deposition process and optimisation of the annealing process. The treatment consisted of dipping the sample for various time periods in a methanol solution containing CdCl2 using different concentrations and different temperatures. The samples were subsequently annealed in an oven at different temperatures and times. The optimum conditions were found to be: dipping for 15 minutes in a solution of 1%wt CdCl2 in methanol heated to 50°C and annealing for 15 min at 370°C in a pre-heated furnace.