NOVELTY - Forming a dense film (110) on a substrate (102) involves formulating an ink of particles in which at least 50% of the particles are flakes (e.g. nanoflakes and/or microflakes), where each flake has a non-spherical, planar shape and contains at least one element from group IB, IIIA and/or VIA; coating a substrate with the ink to form a precursor layer; and processing the precursor layer in an atmosphere to form a dense film. The overall amounts of the elements from group IB, IIIA and/or VIA contained in the ink are such that the ink has a desired stoichiometric ratio of the elements.    USE - For forming a dense film useful in formation of a semiconductor absorber for a photovoltaic device (claimed), and useful in the formation of precursor layers for thin film solar cells; useful for providing high-throughput printing of semiconductor precursor layer; and useful in manufacture of photovoltaic devices and solar cells.    ADVANTAGE - The planar shape of the nanoflakes creates greater surface area contact between adjacent nanoflakes, thus forming the dense film at a lower temperature and in a shorter time as compared to a film made from a precursor layer using an ink of spherical nanoparticles having similar material composition as the ink used in the dense film formation method. The planar shape of nanoflakes can form the dense film at an annealing temperature, at least 50degreesC less as compared to a film made from a precursor layer using an ink of spherical nanoparticles having similar material composition as the ink used in the method. The planar shape of the nanoflakes creates greater surface area contact between adjacent nanoflakes relative to adjacent spherical nanoparticles and thus promotes increased atomic intermixing; and creates a higher packing density (e.g. at least 95% packing density) in the precursor layer that forms the dense film, as compared to a film made from a precursor layer made from an ink of spherical nanoparticles having similar material composition as the ink used in the method. The planar shape of the flakes results in grain sizes of at least 0.5 microns in at least one dimension in the semiconductor absorber of the photovoltaic device. The planar shape of nanoflakes provides the nanoflakes with a material property to avoid rapid and/or preferential settling of the particles or nanoflakes with different material compositions or different particle sizes, when forming the precursor layer; and provides the nanoflakes with a material property to avoid grouping of nanoflakes, and particularly undesired grouping of nanoflakes of a particular class such as nanoflakes of specific material composition, in the ink, thus enabling a finely and evenly dispersed solution of nanoflake resulting in the formation of a good coating; provides nanoflakes with a material property that reduces surface tension of nanoflakes with the ink to improve dispersion quality; and provides the nanoflakes with a material property that enables a more even distribution of group IIIA material throughout in the dense film as compared to a film made from a precursor layer made from an ink of spherical nanoparticles having similar material composition as the ink used in the method. The ink can be formulated by using low molecular weight dispersing agent due to favorable interaction of the dispersing agent with the planar shape of the nanoflakes. The ink can be formulated using a carrier liquid and without a dispersant. The substrate can be at different temperatures than the precursor layer during processing, thus enabling the substrate to use materials that melt or become unstable at the processing temperature of precursor layer. The method provides more efficient and simplified creation of dispersion of microflakes and its resulting coating to form the dense film. The method provides high-throughput printing of semiconductor precursor layer.    DETAILED DESCRIPTION - Forming a dense film (110) on a substrate (102) involves formulating an ink of particles in which at least 50% of the particles are flakes (e.g. nanoflakes and/or microflakes), where each flake has a non-spherical, planar shape and contains at least one element from group IB, IIIA and/or VIA; coating a substrate with the ink to form a precursor layer; and processing the precursor layer in an atmosphere to form a dense film. The overall amounts of the elements from group IB, IIIA and/or VIA contained in the ink are such that the ink has a desired stoichiometric ratio of the elements. The processing step is preferably accelerated via thermal processing techniques using pulsed thermal processing, laser beams and/or heating by infrared (IR) lamps.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional diagram illustrating fabrication of a film.    substrate (102)    dense film. (110)