Humidity Control and Method for Thin Film Photovoltaic Materials

A method for processing a thin film photovoltaic module, the method comprising:

• providing a substrate having a first electrode layer and an overlying absorber layer composed of copper indium gallium selenide (CIGS) or copper indium selenide (CIS) material, the absorber material comprising a plurality of sodium bearing species, the sodium bearing species having a concentration of at least about 5×1018 atoms per cm3;
• maintaining the substrate in a controlled environment after formation of at least the absorber layer, the controlled environment including a water vapor with high chemical activity and having a relative humidity of less than 10% and a temperature ranging from about 10 degrees Celsius to about 40 degrees Celsius;
• subjecting the substrate to a liquid comprising water at a temperature from about 10 degrees Celsius to about 80 degrees Celsius to process the plurality of substrates after formation of the absorber layer;
• subjecting the substrate having the absorber layer to an environment having a relative humidity of greater than about 10% to a time period of less then four hours;
• and
• performing a lamination process on at least the substrate to form a solar module, the solar module being characterized by an efficiency parameter at a first efficiency level before the lamination process and a second efficiency level after the lamination process.