Multilayer Coatings for temperature management through glass windows of buildings

• Autor(a) principal: Barbosa, Margarida Rosado
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/147268
• topic: Infrared; Sputtering; TCO; Metal; Electrospray; Chalcogenides; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Infrared (IR) blocking windows are considered to have an important role in reducing the building’s energy consumption by providing better insulation due to their transparency to visible light and ability to block heat. This work reports on visible light transmitting IR filters formed by a metallic layer between transparent conductive oxides (TCO). GZO as TCO and Cu as the metal layer were the focus of this work. Copper‐based low‐emissivity coatings are being considered as an alternative to that of Ag due to their lower cost and durability for heat reflectors. The TCOs were deposited by sputtering and the metallic layer by resistive thermal evaporation. Depending on the TCO required thickness (from 20 to 269 nm), different deposition times and powers were used and their influence on the optical properties studied. Results showed that the GZO (20 nm)/Metal/GZO (20 nm) multilayers obtained a transmittance at 550 nm of about 78.1% and 63.1% and a NIR reflection of 80.1% and 72.7% for the Ag (11 nm) and Cu (5 nm), respectively. The best performance was accomplished with the GZO (20 nm)/Ag (11 nm)/GZO (20 nm) film. CuS or Ag2S nanoparticles have been added to the coatings as an attempt to absorb NIR radiation and achieve IR‐shielding. These have been synthetized by microwave‐assisted synthesis (MW) and Ag2S also via ultrasonic irradiation (UI). Their optical characteristics were obtained before and after deposition on GZO substrates and GZO‐metal structures by electrospray. The optical properties revealed that adding those nanoparticles causes the metal films to lose their IR reflective properties and some visible transmission.