Reliability of low-cost CdS/Cu 2 S solar cells

Accelerated life tests show that CdS/Cu2S solar-cell lifetimes increase with lower temperature, cyclic light and a nitrogen-gas ambient. A normal Arrhenius type of temperature dependence was found. Extrapolated lifetime for cells kept below 50°C in nitrogen gas with earth deployment exceeded twenty years. The probable decay mechanisms are thermal diffusion, formation of recombination centres and voltage-induced decomposition.