NOVELTY - Depositing (M1) a kesterite film comprising metal compound involves: contacting a source of hydrazine, source of copper, source of tin, source of at least one of sulfur and selenium, and source of zinc in an aqueous solvent forming an aqueous dispersion containing solid particles and dissolved components, applying the aqueous dispersion onto a substrate to form a thin layer and annealing at a temperature, pressure, and length of time sufficient to form the kesterite film.    USE - For depositing kesterite film of metal compound (I) which is used in composition, a photovoltaic device (d1) which is used in photovoltaic module (claimed).    ADVANTAGE - The method provides better control of the composition and ratio of solid and liquid components to achieve optimal rheological and film-forming characteristics required of the dispersion to obtain the necessary thickness of the films formed without crack-formation or de-lamination; provides improved safety and handling characteristics; uses water-based hydrazine-hydrate dispersions, especially in combination with ammonia, which has a vapor pressure three orders of magnitude higher than hydrazine-hydrate at room temperature, assures improved fire safety characteristics for large-scale photovoltaic manufacturing in comparison with prior art.    DETAILED DESCRIPTION - Depositing (M1) a kesterite film comprising metal compound of formula Cu2-xZn1+ySm(S1-zSe2)4+q (I) involves: either contacting a source of hydrazine, source of Cu, source of Sn, source of at least one of S and Se, and source of Zn in an aqueous solvent forming an aqueous dispersion containing solid particles and dissolved components, applying the aqueous dispersion onto a substrate to form a thin layer and annealing at a temperature, pressure, and length of time sufficient to form the kesterite film; or contacting hydrazine, source of Cu, and source of at least one of S and Se forming solution (A), contacting hydrazine, source of Sn, source of at least one of S and Se, and source of Zn forming dispersion (B'), mixing the solution (A) and the dispersion (B') under conditions sufficient to form a dispersion comprising Zn-containing solid particles, adding an aqueous solvent thus forming an aqueous dispersion containing solid particles and dissolved components, applying the dispersion onto a substrate to form a thin layer and annealing at a temperature, pressure, and length of time sufficient to form the kesterite film.    x,y=0-1;    z=less than 1 to greater than 1.    INDEPENDENT CLAIMS are included for the following:    (1) a composition, comprising: an aqueous dispersion of Zn-containing solid particles formed from hydrazine, source of Cu, source of Sn, source of Zn, and source of at least one of S and Se, which when annealed, forms the compound (I);    (2) a photovoltaic device (d1), comprising: a substrate having an electrically conductive surface; the kesterite film on the substrate formed by the method (M1); an n-type semiconducting layer; and top electrode having a transparent conductive material; and    (3) a photovoltaic module comprising several electrically interconnected photovoltaic devices (d1).