Effect of organic additives on the morphological and electrochromic properties of WO3 films

The WO3 film is the most important material for electrochromic (EC) layer especially in electrochromic display (ECD). In this project WO3 films were deposited on indium thin oxide (ITO) glass substrates. For this propose peroxotungstic acid derivative (APTA) was synthesized by sol-gel method and was used as a precursor solution for depositing by dip coating technique. Whereas many properties of the films, including some of the EC properties, they were dependent on microstructure of the films, were found to be modified by the addition of small amount of oxalic acid dihydrate which is an organic compound, ranging from 0% to 10% by weight in PTA solution. In this report, The morphology of the film structure, and EC response were investigated. Heat treatment of APTA and transparency of layer were carried out in different temperatures and concentrations. The findings showed that the addition of oxalic acid to the precursor solution on the films resulted in excellent EC properties without micro cracks.