Non-vacuum processing of CIGS solar cells

A promising pathway to minimizing cost per watt and maximizing return on investment is the use of nonvacuum techniques for depositing PV thin films. Nonvacuum techniques based on nanoparticulate materials are particularly useful for forming both CuIn_1-xGa_xSe₂ (CIGS) absorber films and metal oxide transparent conductor (TC) coatings. Spraying and printing techniques have been used for depositing layers of particulate precursor materials that are subsequently sintered into CIGS films. Printing is faster than pneumatic spraying, and printed layers are more planar and better packed than sprayed layers. Non-vacuum processes have also been used to deposit TC coatings. TC coatings have been deposited using organic reactants, nanoparticulate precursor materials, and conducting polymers. Further work is required to achieve adequate sheet conductances at low processing temperatures.