Hybrid Nanophotochromic oxidized yttrium hydride films

The project aims to develop yttrium oxyhydride-based hybrid/composite photochromic films. The YHO powders have been synthesized by two methods: reactive magnetron sputtering and by hydrogenating yttrium particles with subsequent oxidation. The particles have been characterized systematically and incorporated into polymers by scalable methods. Inc was developed from the hybrid/composite particles and thin films were printed out by inkjet printing machine. The thus obtained inkjet printed film exhibits photochromic properties. Preliminary research has been performed on toxicity of the YHO nanoparticles. We found that the YHO nanoparticles are not toxic. Theoretical and experimental study of sensitivity of YHO to different gases have been performed. We showed that the YHO films and powders are sensitive to humidity. The project was the platform for implementing the exciting research plan described in the project, to get very interesting results that have been documented as two patents and several journal articles. Three PhD student have defended thesis, the work was related to the FRINATEK project. Also, the project created the fundament for future collaboration with partners and applying projects to National and HEU funding Institutions.

Achieved outcomes 1. Low-cost deposition method of photochromic YHO powders has been developed. It is based on hydrogenation of metallic Y particles that will subsequently be oxidized (to be patented). 2. The photochromic powders have potential to be used in photochromic contact lenses. Collaboration has been established with stakeholder VSY Biotechnology producing contact lenses. After testing of safety of the YHO photochromic powders, the company can provide report about safety of YHO films and powders. 3. Method of preparing photochromic YHO-based ink has been developed by mixing the YHO particles with different polymers that can be used for inkjet printing or spraying on already installed window (to be patented). 4. We found sensitivity of YHO to humidity that has led us to developing the method of preventing it (patented). 5. By DFT modelling sensitity of YHO to gases has been studied. We found that YHO can be used as CO2 catalyst. Also, absorption energy of humidity is found to be very high. Using encapsulating materials is recommended. Potential outcomes 1. We found possibility of other applications of the YHO films: ophthalmology (contact lenses and goggles), automobile industry, gas sensors, and blood transport through microchannels. 2. A project about understanding degradation can be submitted by IFE jointly with industry-academic collaborators. 3. A new research topic has been formulated about whether the photochromic YHO nanoparticles and films are toxic or not.

The Nanochromatics project aims to demonstrate a hybrid nanophotochromic material based on oxidized yttrium hydride (Y-H-O) nanoparticles incorporated into a polymer. It has potential for a number of applications such as glass coatings for buildings and transportation to control the sunlight and heat transfer through glass. Alternative applications are in the medical industry and environmental technology (as emitting and sensing devices) and in military - as coatings to reduce visibility to IR viewers. The hybrid films are expected to have numerous advantages over the organic counterparts by enhanced durability, stability to UV radiation and sensitivity to humidity, and over the inorganic counterparts by independence on angle of incidence of sunlight, by enhanced transparency in the clear state and colorfulness, by faster kinetics of color change. The interest to Y-H-O is originates from its efficient photochromism, which does not form midgap states blocking the visible light. However, for realization of the materials potential the following challenges must be addressed: (i) understanding oxidation of the YHx films, establishing the link between transparency in the clear state, colorfulness, and kinetics of color change as a function of concentration of O and H; (ii) Interaction with gases and synthesis of hybrid films, stability with respect to thermal processing, UV light, and humidity; (iii)synthesis through chemical methods . Dissemination, high impact publication, business opportunities and training of young researchers is also expected. The later will deliver a good balance between young and experienced scientists and and assist in achievement of the gender balance. It is multidisciplinary and combines complementary expertise of participants through national and international collaboration. The network has state-of-the-art infrastructure, strong expertise on the topic, and trained manpower to do the work.