NOVELTY - Emulsion (I) comprises droplets of metal liquid, a solvent and a surfactant, where the metal is indium, gallium or alloys of the metals and the solvent is alkanethiol compound (I), alkanethiol ester compound (II) or propionic alkanethiol ether compound (III).    USE - (I) is useful for: fabricating a photovoltaic device comprising a photovoltaic battery, a photovoltaic panel, or a photovoltaic cell; and depositing a film of a metal comprising iridium, gallium and its alloys, on the surface of at least one substrate (all claimed).    ADVANTAGE - (I) is stable. The method: provides good conversion efficiencies, desired stoichiometry and minimizes or even eliminates the use of a metal salt and can be implemented in the ambient atmosphere (in air).    DETAILED DESCRIPTION - Emulsion (I) comprises droplets of metal liquid, a solvent and a surfactant, where the metal is indium, gallium or alloys of the metals and the solvent is alkanethiol compound of formula (CH3-(CH2)n-SH) (I), alkanethiol ester compound of formula (CH3-(CH2)n-S-C(=O)-R) (II) or propionic alkanethiol ether compound of formula (CH3-(CH2)n-S-C(=S)-R) (III).    R = CH3 or ethyl; and    n = 5-19.    INDEPENDENT CLAIMS are included for:    (1) preparing (I) comprising: (a) introducing a metal comprising indium, gallium and their metal alloys, in the solvent; (b) heating the suspension obtained in step (a) at a temperature greater than the melting temperature of the metal and lower than the temperature of solvent; (c) adding the surfactant; (d) applying ultrasound for 15 minutes while maintaining the same temperature as in steps (b) and (c), with a probe of 20 kHz, 75% amplitude; (e) cooling the emulsion obtained in step (d) by natural cooling; and (f) applying ultrasound for 15 minutes with a probe 20 kHz, 20% amplitude, at room temperature;    (2) process of depositing a film made of the metal, optionally with copper comprising: depositing (I) of the desired metal on at least one surface of a substrate; and heat treatment of at least one surface; and    (3) fabricating an active layer of a photovoltaic device, comprising depositing a film of copper-indium-gallium-sulfur or copper-indium-gallium-selenium on at least one surface of a substrate by the process.