to its figure of merit, zT, defined as zT = (S 2 •σ)•κ −1 •T, an ideal thermoelectric material must exhibit high electrical conductivity (σ), high Seebeck coefficient (S), and low thermal conductivity (κ), simultaneously, to maximize its efficiency for the desired temperature range. In this context, there has been a significant increase of reports in the literature on Cu 2−x Se as a p-type material with high power factor (PF) [3] (being the PF = S 2 • σ). [1,3,4] Therefore, copper selenides have become a hot topic in the TE field, with reported figures of merit as high as zT ≈ 1.6 @ 727 °C. [5] Moreover, Cu 2−x Se has a crystallographic phase transition at T ≈ 130 °C, and it has been shown that around this transition temperature zT can reach values as high as 2.3. [6] Thermoelectric thin films occupy an industrial niche for microfabricated multielement planar devices on flexible substrates as low-current voltage generators for room temperature (RT) applications. In this range of temperatures, the highest zT reported value for bulk crystalline material is 0.28 (Liu et al. [5]). Cu 2−x Se films are typically p-type, highly conducting, semitransparent, and with a bandgap varying between 1.1 and 1.4 eV. Numerous methods have been reported for the deposition of Cu 2−x Se films at low substrate temperatures, such as a chemical bath deposition, [7-9] galvanic synthesis, [10] solution growth, [11] hydrothermal method, [12] or electrochemical deposition. [10,13] Other methods, such as adsorption/diffusion (selenization), [14-16] SILAR method, [17] and pulsed laser deposition [18,19] require high-temperature post growth treatments to improve and stabilize the thermoelectric properties. In any case, those different manufacturing film methods have not been able to surpass the thermoelectric efficiencies at room temperature of the Cu 2−x Se bulk samples prepared by solid-state reaction. [20,21] In the case of bulk samples other methods, such as spark plasma sintering, [4,5,22-28] ball milling followed by hot pressing, [24,29] and quenched bulk [30] have also been reported. In all these cases, high temperatures and long manufacturing times (even weeks) are necessary. In this work, we have developed a fabrication approach namely pulsed hybrid reactive magnetron sputtering (PHRMS) based on reactive sputtering, a vacuum technique that is widely used in industry as particularly suitable for thin film devices