A study of the effects of varying cadmium chloride treatment on the luminescent properties of CdTe/CdS thin film solar cells

Photoluminescence (PL) and electroluminescence (EL) spectroscopy have been used on a series of chemically bevelled CdTe/CdS thin film solar cells to study the effects of different CdCl sub(2) annealing times. An anneal time of 10 min was found to produce the most efficient (8.4%) cells. Evidence was found for the CdCl sub(2) anneal promoting the formation of a CdS sub(x)Te sub(1-x) alloy near the interface. Emission at the back surface of the cells was identified as being due to the `Y' luminescence band and a donor-acceptor pair (DAP) recombination involving cadmium vacancies and chlorine donors. Sulphur diffusion into the CdTe was estimated based on changes to the energy gap obtained from the PL data.