Improving the visible transmittance of low-e titanium nitride based coatings for solar thermal applications

摘要

Low-emissivity (low-e) coatings on glass are nowadays extensively used for energy saving applications in architectural windows and on solar thermal collectors. In this work the feasibility of TiN-based layers as low-e coatings has been studied. TiN samples were deposited by reactive magnetron sputtering and, in order to improve their optical properties (transmission in the visible range, T and emissiv-ity, e), we have investigated the changes in optical response following three different approaches: (i) post-deposition annealing treatments up to 500℃, (ii) doping the TiN layers with aluminium (target composition: Ti/Al = 90/10,75/25 and 50/50) and (iii) deposition of antireflective coatings of TiO_2 in multilayers structures. The crystalline structure and chemical composition of the multilayers were studied by X-Ray Diffraction and Rutherford Backscattering Spectroscopy, respectively. Spectroscopic Ellipsom-etry, Fourier Transform Infrared Spectroscopy and direct emissivity measurements were employed to determine the optical properties Tand e. We have concluded that the most noticeable improvement has been obtained by the deposition of multilayers structures increasing in a 30% the original transmittance of the single TiN coatings.