Dual-phase inkjet printed electrochromic layers based on PTA and WOX/TiO2 nanoparticles for electrochromic applications

Thesis submitted in Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa for the degree of Master in Materials Engineering

The aim of the work was to develop flexible electrochromic windows via Inkjet Printing Technique based on amorphous Peroxotungstic Acid (PTA) and metal oxide nanocrystals. A unique selection of materials allows for a solution processed deposition of low temperature electrochromic layer which is compatible with flexible substrates such as PET, PEN and paper. The use of Inkjet Printing Technique was motivated by the fact that it is a cost efficient method (mass production) which has a reduced consumption of materials and energy. It is also a non-contact, digital, no mask and no vacuum patterning method which greatly simplifies the technological process. Developed devices were tested using optical, electrochemical, and structural characterization techniques, in order to find the optimum electrochromic layer composition which would guarantee desirable electrochromic behavior of the material. Laboratory studies were supported by statistical techniques such as Design of Experiment (DOE) and Multiple Regression which leads to a fitting of mathematical model of the optical and electrical responses. The dual-phase electrochromic layer consists in the combination of both amorphous and nanocrystalline phases significantly improve the electrochromic performance of the devices. The developed method of electrochromic windows manufacturing meets all the objectives at the beginning of the study.