Thin-film solar cells

In 2002, the highest reported efficiency for thin film solar cells based on CdTe is 18%, which was achieved by research at Sheffield Hallam University, although this has not been confirmed by an external test laboratory.
The US national renewable energy research facility NREL achieved an efficiency of 19.9% for the solar cells based on copper indium gallium selenide thin films, also known as CIGS .
NREL has since developed a robot that builds and analyzes the efficiency of thin-film solar cells with the goal of increasing the efficiency by testing the cells in different situations.
These CIGS films have been grown by
physical vapour deposition in a three-stage co-evaporation process. In this process In, Ga and Se are evaporated in the first step; in the second step it is followed by Cu and Se co-evaporation and in the last step terminated by In, Ga and Se evaporation again.
Thin film solar has approximately 15% marketshare; the other 85% is crystalline silicon. Most of the commercial production of thin film solar is CdTe with an efficiency of 11%.
As of 28 April 2010, ZSW in Stuttgart have released a statement claiming they have created CIGS-based cells with a new record 20.1% efficiency.