NOVELTY - Fabrication of ink containing intermixed nanoparticulate elements of groups IB and IIIA and optionally VIA, comprises forming elemental non-oxide metal nanoparticles containing elements from group IB; and forming elemental non-oxide metal nanoparticles from group IIIA; and optionally forming elemental non-oxide nanoparticles from group VIA. The elemental non-oxide nanoparticles from groups IB and IIIA, and optionally VIA are intermixed. Then, the particles are mixed to form a liquid that serves as an ink.    USE - Method of fabricating ink containing intermixed nanoparticulate elements of groups IB and IIIA and optionally VIA (claimed) used for forming copper indium gallium selenide (CIGS) photovoltaic cell active layer.    ADVANTAGE - The method provides an ink that avoids the need to expose the active material to hydrogen selenide gas during construction of a photovoltaic cell, allows more uniform melting during film annealing and more uniform intermixing of nanoparticles, and that can form higher quality absorber films. Hence, low-cost, high-volume production of large area photovoltaic devices can be achieved without having to undergo hazardous selenization or reduction of oxides in hydrogen. Further, the ink is compatible with roll-to-roll manufacturing of photovoltaic cells and modules that can be readily scaled up to high production volumes.    DETAILED DESCRIPTION - Fabrication of ink containing intermixed nanoparticulate elements of groups IB and IIIA and optionally VIA, comprises forming elemental non-oxide metal nanoparticles containing elements from group IB; and forming elemental non-oxide metal nanoparticles from group IIIA; and optionally forming elemental non-oxide nanoparticles from group VIA. The elemental non-oxide nanoparticles from groups IB and IIIA, and optionally VIA are intermixed. Then, the particles are mixed to form a liquid that serves as an ink. The particles have particle size diameter of 0.1-500. For each element metal, a majority of the mass of the elemental metal nanoparticles is no more than 40% above or below an average particle size, or if the average particle size is less than 5 nm, no more than 2 nm above or below the average particle size.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of a photovoltaic cell.    Base layer (202)    Base electrode (204)    IB-IIIA-VIA layer (206)    Window layer (208)    Transparent electrode (210)