Solution processing of CIGS absorber layers using a hydrazine-based approach

A simple solution-based approach has been developed for CIGS absorber layer deposition, employing hydrazine as the solvent for all metal chalcogenide components. Advantages of the technique include the molecular (rather than nano or microparticle) nature of the precursor solutions, which enables intimate mixing of the various CIGS components before the final heat treatment, the absence of carbon, oxygen and other common contaminants from the solution, and the lack of need for a post deposition selenization treatment to achieve highquality CIGS films. Relatively smooth and compact films, with up to μm-scaled thicknesses and grain sizes, have been achieved by spin coating. Gallium and sulfur have been successfully incorporated into the Cu1−zIn1−xGaxSe2−ySy layers for x≪0.5, y≪0.6 and z≪0.15. Preliminary PV devices based on a glass/Mo/CIGS/CdS/i-ZnO/ITO structure and employing the solution-processed CIGS films have yielded efficiencies of up to 10% (AM 1.5 illumination).