Inline Rubidium Fluoride Treatment of (A)CIGS Absorbers Deposited onto Flexible Substrates in a Production-Scale Process Tool

The record CIGS solar cell device efficiency has increased recently due to the use of heavier alkalis in the post-deposition treatment after absorber growth. Applying this knowledge to the production lines will be key to realizing record thin film solar cell module efficiencies. In this study, Global Solar Energy investigated the replacement of potassium with rubidium in an established Roll-to-Roll manufacturing process. Implementing the inline deposition of rubidium fluoride resulted in an average absolute efficiency gain of 0.5% for small-area devices made from representative CIGS samples. A rubidium treatment step was also integrated into a silver-containing ACIGS growth process, which has yielded device efficiencies that are greater than 18%.