Within its activities, the ON2.4 group focuses on various research areas, these include:
- Nanopowders for biomedical applications
The focus of research in this area is the growth technology of metal oxide nanopowders (e.g. ZrO2, ZnO), including those doped with rare earth ions, and their detailed characterisation. In cooperation with the Faculty of Veterinary Medicine of the Warsaw University of Life Sciences, nanopowders are being investigated for their applications as innovative markers for the diagnosis and therapy of, among other things, cancer diseases, as tracers used for magnetic resonance imaging, but also as a medium for transporting drugs to selected organs of the body. The most recent direction of research is the use of nanopowders as additives, in inks, paints and varnishes giving them antibacterial properties. The results have been presented in many publications and are the subject of numerous patent applications, and have also been recognised at many innovation fairs through various awards.
- Biofunctional films for implantology
The subject of research in this area is ALD-deposited metal oxide-based films (e.g. ZnO, ZrO2). Such films have great potential for use in implantology as a protective coating against ion diffusion from the implant into the body. In addition, they also show antibacterial effects as well as supporting osteointegration. The subject of research is both the technology of film growth, their modification and characterisation by experimental physics methods, as well as their interaction with biomaterials.
- Studies on strongly correlated materials
Strongly correlated materials are condensed matter systems, in which the energy of electron-electron interactions are strong and comparable to electron kinetic energy. Strong electronic correlations result in unusually rich and complex physics. The examples of exotic phenomena, which have been discovered in such systems, are high temperature superconductivity in cuprate oxides, and, more recently, in iron-based pnictides and chalkogenides, or the colossal magnetoresistance in manganites. Competing interactions, involving charge, spin, orbital, and lattice degrees of freedom, produce complex phase diagrams, in which many phases with distinct ground electronic state coexist. These phases usually display different magnetic, electrical or thermal properties. The systems may be tuned between various phases either by doping, or by small variation of external parameters, such as temperature, magnetic field, or pressure. The ability of tuning of the physical properties promises applications of these materials in modern electronics. The research carried out by our group focuses on two important aspects of material studies: the growth of materials, and the experimental investigation of their physical properties. In particular, methods for the growth of epitaxial thin films of various oxides and superconductor/ferromagnetic structures are being explored, and research is being carried out into the mechanisms of superconductivity by means of doping, the study of vortex matter properties in superconductors, superconductor-insulator transitions and the microwave properties of the films.
- Oxide structures for photovoltaics
Members of the ON2.4 group have developed several important innovations targeted at the photovoltaic industry. One key area of research is the optimisation of ZnO films doped with aluminium as a transparent and conductive electrode, which can be used in different generations of photovoltaic cells (silicon, organic, perovskite). The team members also have developed a three-dimensional transparent electrode, which consists of ZnO nanorods (produced by a hydrothermal method) coated with ZnO:Mg and ZnO:Al films, which has a very rough surface, so that the amount of reflected light is even lower than in structured silicon cells. Based on this electrode, a simplified silicon cell has also been proposed, whose fabrication technology avoids high-temperature, costly and hazardous processes in production. These solutions are the subject of a whole series of publications and patents and have received numerous awards at innovation fairs.
- CuO films for electronic applications
As part of the team's work, an innovative method of growing copper(II) oxide films in aqueous solution has been developed. The technology is extremely simple, fast and does not require the use of sophisticated equipment. The obtained films are subject to intensive characterisation of their physical properties. They exhibit memristor properties and are therefore currently being investigated for use in electronic memory cells.
The ALD (Atomic Layer Deposition) method allows various oxide films to be obtained (including ZnO, Al2O3, ZrO2, MgO, Ga2O3, TiO2, HfO2 and multicomponent films). Within the scope of the work, team members have developed films with various functionalities, including antibacterial, hydrophobic, anti-corrosive, mechanical resistance enhancement or improving the thermal insulation properties of glass.
- ZnO nanorods obtained by a hydrothermal method
The developed technology for the growth of ZnO nanorods in aqueous solution is extremely simple, fast and does not require the use of any sophisticated equipment. It allows the growth of nanorods over large areas on almost any substrate, and the nanorods obtained are characterised by extremely high crystallographic quality. The application potential of such nanostructures has been demonstrated in silicon photovoltaic cells (the nanorods were an n-type partner and part of a three-dimensional electrode) and in the design of a resistive ultraviolet light detector characterised by much higher sensitivity than commercially used detectors. ZnO nanorods are still being studied, both to understand their properties and for further application work.
