SODIUM DOPED THIN FILM CIGS/CIGSS ABSORBER FOR HIGH EFFICIENCY PHOTOVOLTAIC DEVICES AND RELATED METHODS

A method of processing a thin-film absorber material with enhanced photovoltaic efficiency. The method includes providing a soda-lime glass substrate having a surface region and forming a barrier material overlying the surface region, followed by formation of a stack structure including a first thickness of a first precursor, a second thickness of a second precursor, and a third thickness of a third precursor. The first thickness of the first precursor is sputtered with a first target device including a first mixture of copper, gallium, and a first sodium species. The method further includes subjecting the soda-lime glass substrate having the stack structure in a thermal treatment process with at least H2Se gas species at a temperature above 400° C. to cause formation of an absorber material. Moreover, the method includes transferring a second sodium species from a portion of the soda-lime glass substrate via gas-phase diffusion during the thermal treatment process.