NOVELTY - A precursor composition (C1) comprises: a liquid-based solvent containing a primary amine; and a solute containing copper and selenium. The precursor composition is free of oxygen containing compounds and devoid of a precipitate comprising copper selenide.    USE - For making thin film (claimed) useful for semi-conductor applications such as for the preparation of absorber layers for solar cells.    ADVANTAGE - The precursor composition is free of oxygen containing compounds and devoid of a precipitate comprising copper selenide (Cu2Se). The process produces a liquid based material that can be used in deposition techniques that are easier, less expensive, and more efficient to use than solid based deposition techniques such as vacuum deposition. The precursor compositions allow for deposition by such techniques such as drop coating, dip coating, spin coating, spraying, brushing, air brushing, stamping, printing, including ink jet printing, pouring, wiping, smearing and other methods of applying liquids to the surface of a substrate. The precursor compositions can be used to produce thin films with additional advantageous properties i.e. having no oxygen or oxygen containing compounds (as oxygen-containing compounds (e.g. CuO), which can lead to defects in the copper selenide film leading to defects in the absorber layer (e.g. copper-indium-selenide (CIS) or copper-indium/gallium-diselenide (CIGS)) which can adversely affect the energy conversion efficiency of a solar panel.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a liquid-based preliminary precursor composition (C2) comprising: solvent containing primary amine; and solute containing copper and selenium where the preliminary precursor composition is free of oxygen-containing compounds;    (2) a thin film comprising the precursor composition (C1) heated to a temperature to remove the solvent;    (3) making the liquid-based preliminary precursor composition (C2) involving: combining the solvent and the solute to form a solution; and agitating the solution until a non-soluble product is formed;    (4) making (M1) the liquid-based precursor composition (C1) involving: combining the solvent and the solute to form preliminary precursor composition; agitating the preliminary precursor composition to form a non-soluble product; and removing the non-soluble product to form the liquid-based precursor composition; and    (5) making (M2) a thin film involving: depositing the precursor composition (C1) on a substrate, and heating the precursor composition to remove the solvent.