Electrochromic thin-films for optical attenuation and sensing applications

The optical properties of electrochromic layers change upon oxidation/reduction of an element in the material. Electrochromic devices exploit the redox dependent optical properties of electrochromic materials to control the optical transmission, absorption, reflectance and emittance of light. These devices have a broad range of applications, from smart windows and displays to sensor application. While the technology has existed for a long time, the commercialization is still limited in scope. During the Ph.D. research, you will synthesize thin-film electrochromic materials and develop mechanistic understanding into the electrochromism of these films. 

You will study electrochromism in different binary oxide thin-films, such as In2O3, SnO2, Nb2O5 and MoO3. First you will develop methods to synthesize conformal films with well controlled composition, density, and morphology. Different techniques can be used to deposit these films, such as PVD, CVD, or ECD. You will build on the decade long expertise on thin-film deposition and characterization in the Electrochemical Storage and Conversion group in imec. 

In the second phase, mechanistic understanding of the reduction reaction in the presence of small molecules, for instance H+, Li+, K+, Na+, Mg2+,,... will be pursued. Different mechanisms, such as conversion reactions (forming metal nanoparticles) or intercalation processes can take place. During ion insertion, the shape, morphology and size of the binary oxide thin-film will be altered, which in turn will affect the material’s optical properties. The changes in these material properties will be investigated by combining a variety of physical characterization techniques (ESPM, ERD, XPS,...) with thorough electrochemical analyses.  

In the final phase, the redox induced modifications of the optical properties will be linked to the intrinsic electrochromism of the film (i.e. the material oxidation state) and physical changes of the film shape and morphology. Insights into in size effects of the thin-films will enable engineering and optimization of the electrochromic layers towards specific optical attenuation and sensing applications. Further modification of the electrochromic properties can be achieved by stacking multiple layers to achieve unique electrochromic device stacks. During the Ph.D. you will work in the state-of-the-art facilities of imec Leuven. You will be working in a team together with other Ph.D. students, researchers, and engineers, while collaborating with several different universities, research institutes, and companies.