Non-vacuum method for fabrication of a photovoltaic absorber layer

A method for fabricating a thin film photovoltaic absorber layer comprising the steps of:

• a) providing nanoparticles comprising a combination of either Cu and one or more group IIIA elements, and optionally one or more group VIA elements or a combination of Cu and one or more group IIB and one or more group IVA elements, and optionally one or more group VIA elements of the periodic table, wherein further comprises forming the nanoparticles by a physical breakdown of a bulk material and wherein the nanoparticles have an identical atomic ratio between the elements as the bulk material;
• b) preparing a colloidal suspension of a mixture of the nanoparticles in a liquid medium, wherein the atomic ratio between Cu and group IIIA and optional group VIA elements and between Cu and group IIB and group IVA elements and optional group VIA elements are predetermined;
• and
• c) submerging a substrate and a counter electrode into the colloidal suspension and depositing the mixture of nanoparticles onto the substrate to form a thin film photovoltaic absorber layer by electrophoretic deposition, wherein the predetermined atomic ratio between Cu and group IIIA and optional group VIA elements or between Cu and (group IIB plus group IVA elements) and optional group VIA elements is 25%:25%:50% plus or minus 15%.