Nanostructured WO3 electrochromic film: synthesis, characterization and functionalization

Author(s)

José de Ribamar Martins Neto

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2015-09-25

Examining board members

Susana Ines Cordoba de Torresi; Wendel Andrade Alves; Mauro Bertotti; Claudia Longo; Thiago Regis Longo Cesar da Paixão

• Advisor: Susana Ines Cordoba de Torresi

Abstract

The present work describes the synthesis and characterization of WO3 nanoplates in a non-aqueous solvent using ultrasonic irradiation process. This method presents some advantages such as the small amount of reactants and time consumed. WO3 nanoplates have been characterized by TEM and SEM microscopies, Raman and Infrared spectroscopies, thermogravimetric analysis and X-ray diffraction. The nanostructured nanoplates were immobilized by electrostatic layer by layer and Electrophoretic Deposition (EPD) processes onto ITO substrates. Spectroelectrochemical experiments were carried out showing electrochromic performance of the WO3 films such as optical density, response time and chromatic efficiency in a typical way for nanostructured films of WO3. The results using a protic ionic liquid (PIL) as electrolyte, instead of H2SO4, showed improvement in cyclic durability. Cyclic voltammograms were combined with transmittance measurements for all films that undergo typical reversible electrochromic reaction. In order to modulate and improve the colorimetric changes, viologen molecules were prepared with an anchoring group for modifying the surface by the chemisorption of a monolayer. WO3 films with viologen monolayer were investigated using Spectroelectrochemical and color coordinates analysis. A virtual colorimeter was applied for the accurate calculation of CIE 1931 xy color coordinates investigation during the electrochromic reaction of modified films. (AU)

• FAPESP's process: 10/08043-2 - Synthese, characterization of functionalized WO3 nanoparticles modified electrodes for high performence electrochromic devices
• Grantee: José de Ribamar Martins Neto
• Support Opportunities: Scholarships in Brazil - Doctorate