Title: Smart Windows for Tomorrow: Nanoparticles Hybrid Coatings Merging Photochromic and Thermochromic Technologies
Research proposal No: 1.1.1.9/LZP/1/24/020
Duration: 01.03.2025.-29.02.2028.
Project Leader: Dr.chem. Tamara Tsebriienko
Total budget: 184 140 EUR
European Regional Development Fund (ERDF) funding: 156 519 EUR
ISSP UL budget: 9 207 EUR
Project description:
Chromogenic coating is the core technology for Smart Windows (SW), crucial for energy savings in future. In this project, we propose to combine chromogenic photochromic and thermochromic nanomaterials, creating a hybrid nanoparticles-based coating with enhanced visible transparency and high solar modulation. The primary goal is to achieve synergistic effects between the photochromic and thermochromic components, leading to a decreased transition temperature of the thermochromic material. This is accomplished by utilizing the additional energy absorbed from the solar spectrum and converted into thermal energy by the photochromic material. The aim is to achieve both high luminous transparency in the visible range and maintain high solar modulation in the NIR range, leveraging the paired chromogenic performance of the photochromic and thermochromic components. Furthermore, the NPs-based wet deposition technology allows for a significant reduction in fabrication costs compared to vacuum deposition, making SW more accessible for end-users. The key objective of this fundamental research project is to develop a cost-efficient and sustainable technology of high-performance hybrid chromogenic coatings for energy saving SW.
PROJECT PROGRESS
Time period: 01.07.2025. – 31.12.2025.
The study investigated the effect of rhenium doping on the structural, optical properties and phase transitions of VO₂ thin films obtained by DC magnetron sputtering as promising materials for use in smart windows.
High‑valence dopants such as W, Mo, and particularly Re increased the concentration of mobile charge carriers and introduced lattice distortions, which collectively reduced the metal–insulator transition temperature and enhanced the suitability of VO₂ for thermochromic applications.
Structural analysis confirmed the successful incorporation of Re into the VO₂ lattice.
X‑ray diffraction patterns of both undoped and Re‑doped VO₂ thin films displayed a distinct peak at 37.4°, characteristic of monoclinic VO₂, indicating that the crystal structure was preserved after doping.
Optical measurements demonstrated improved thermochromic performance at moderate Re concentrations.
Transmission spectra showed that Re‑doped VO₂ films achieved switching efficiencies of up to ~10% in the near‑infrared region.
Ellipsometry verified the first‑order semiconductor–metal transition and revealed dopant‑dependent behavior.
The hysteresis observed in Ψ and Δ during heating and cooling confirmed the first‑order nature of the transition.
Increasing Re concentration lowered the transition temperature and altered the hysteresis shape, reflecting modifications in optical constants and transition dynamics.
The simulations matched the experimental data well, validating the optical model.
An article is currently being prepared based on the obtained data.
Time period: 01.03.2025. – 30.06.2025.
During this project period, some progress has been made in the development of сhromogenic coating components, focusing on the synthesis and characterization of the materials.
It was developed a silver nanoparticle ink using eco-friendly terpineol and butylamine, achieving excellent inkjet compatibility and stable dispersion for over 85 days. The nanoparticles remained under 10 nm, ideal for precise, high-resolution printing.
Resulting Ag films were characterized by methods, including structural analysis by X-ray diffraction (XRD), morphological evaluation by scanning electron microscopy (SEM)
Thermal treatment at 400 °C boosted the silver film’s conductivity to 5.21 × 10⁷ S/m—about 81% of bulk silver—thanks to crystallite growth that improved electron flow and interparticle connections.
Silver is widely used in Low-E coatings that reflect infrared (IR) radiation — the part of sunlight responsible for heat — while allowing visible light to pass through. Silver inks can also serve as a functional base for chromogenic systems — as electrodes, interconnects, or even as part of hybrid multilayer structures.
It was published article “Novel Terpineol-Based Silver Nanoparticle Ink with High Stability for Inkjet Printing” in Nanomaterials journal (Q1) doi.org/10.3390/nano15130955
Participation in the international conference E-MRS 2025 Spring Meeting, which was held in Strasbourg, France, with poster presentation “New Thermochromic Films for Smart Windows Technology”.