New ultra-violet and near-infrared blocking filters for energy saving applications: fabrication of tantalum metal atom cluster-based nanocomposite thin films by electrophoretic deposition

Abstract

This study reports the first integration of inorganic tantalum octahedral metal atom clusters into multifunctional nanocomposite coating materials and devices for window technology and energy saving applications. [Ta₆Brⁱ₁₂]ⁿ⁺ (n = 2, 3 or 4) cluster-based high visible transparency UV and NIR filters are realized. Green and brown colored films are fabricated by coating on an indium-doped tin oxide glass substrate by electrophoretic deposition, an industrialized solution process. The efficiency in energy saving of the new UV-NIR filters was estimated by the determination of different figure of merit (FOM) values, such as T_vis, T_sol and T_vis/T_sol (T_sol = solar transmittance and T_vis = visible transmittance), and the color coordinates (x, y, z and L*a*b). The T_vis/T_sol ratio is equal to 1.25 for the best films. Such values are evidence of a higher energy saving efficiency than most of the inorganic composites reported in the literature. These promising results pave the way for the use of transition metal clusters as a new class of nanocoatings in energy saving window-based applications.