Improved Activation Treatment for CdTe Solar Cells

A series of CdTe thin film solar cells were prepared on CSS-deposited CdS-/CdTe-substrates (100 × 100 mm2) by partly applying a standard reference process and partly introducing an additional thermal annealing step at 250 °C or 300 °C for 20/40 min at ambient conditions after the activation treatment. The remaining process steps for the generation of solar cells have not been varied and activation-temperature and -duration were kept constant with 400 °C/25 min. The back contact comprised an etching step with a nitric-/phosphoric-acid solution followed by deposition of 150 nm of gold. In contrast to standard processed solar cells, the cells gained from additional thermal annealing treatment gave significantly improved performance with better current-voltage values; quantumefficiencies - however - remained well comparable to standard processed cells.