This dissertation is devoted to the development of a material science basis for controlling the structure-sensitive characteristics of nanoparticles (NPs) and films of CuO, ZnO:Al, and SnS compounds obtained by printing methods, in particular, droplet 3D printing and sputtering of nanoinks on glass and flexible substrates under various physical and technological conditions. Special attention was paid to optimizing the characteristics of these materials by post-growth thermal annealing of single- and two-layer structures based on them. Consequently, n-ZnO/p-CuO heterojunction films and prototype device structures were created, which could be further used in solar energy, sensors, and flexible electronics. The results of this study can contribute to improving the technological processes of applying films of oxide and chalcogenide compounds and to the expansion of the applications of these materials in modern energy and electronic devices.
To achieve the goal of this work, laboratory synthesis methods were developed, and precursors were selected to obtain single-phase NPs of metal oxides and sulfides with specific characteristics (composition, phase, shape, and structure). Then, using the synthesized particles, nanoinks with the required density and viscosity were obtained for applying films by scalable, energy-efficient, vacuum-free printing methods. The films were subjected to a post-growth heat treatment to remove organic impurities from the composition, which were used during the synthesis of NPs and in the creation of inks. Annealing also makes it possible to reduce the number of defects in the thin layer structure, increase the crystalline quality of the material, and improve its electronic and optical properties, which are important for ensuring the stability and efficiency of the films in their further use in various technological and industrial applications.
Considering the above aspects, the optimal conditions for synthesizing the NP compounds, CuO, ZnO:Al, and SnS, were determined. In particular, the polyol-colloid method was used to synthesize CuO and ZnO:Al NPs, which allows precise control over the morphology and size of the particles. Five syntheses were carried out to obtain the NP compounds SnSx-polyol-colloidal with precursors CS(NH2)2, Na2S, and CH3C(S)NH2 at a temperature of 483 K, and synthesis in an aqueous ammonium solution with precursors CH3C(S)NH2 and Na2S at a temperature of 293 K. It was shown that NPs synthesized in triethanolamine at 293 K with the precipitant Na2S had the stoichiometry closest to that of the SnS compound, while synthesis in diethylene glycol at 483 K with the precipitant CH3C(S)NH2 made it possible to obtain particles of the SnS2 compound.
The resulting NPs were dispersed in environmentally safe and non-toxic solvents, such as water-alcohol-glycol-PVP, to create inks with controlled characteristics. These solvents stabilize the particles in suspension, allowing for the fine-tuning of nanoink properties such as flowability, viscosity, and adhesion to the substrate.
A 3D printer previously assembled in the laboratory was used to apply continuous films of CuO compounds via drop printing. However, a standard extruder is unsuitable for printing with nano-inks because of the specific requirements for the viscosity and uniformity of the nano-ink supply. Therefore, the standard extruder was replaced with a specially developed extruder for printing liquid or semi-liquid materials. The new extruder was equipped with a dosing system that precisely controlled nano-ink delivery in droplets. ZnO, ZnO:Al, and SnS films were applied by ink spraying. An airbrush with a nozzle diameter of 0.2 mm was used for this. The methods used made it possible to obtain samples with reproducible characteristics, which ensured high stability and reliability of the results.
This dissertation is devoted to the development of a material science basis for controlling the structure-sensitive characteristics of nanoparticles (NPs) and films of CuO, ZnO:Al, and SnS compounds obtained by printing methods, in particular, droplet 3D printing and sputtering of nanoinks on glass and flexible substrates under various physical and technological conditions. Special attention was paid to optimizing the characteristics of these materials by post-growth thermal annealing of single- and two-layer structures based on them. Consequently, n-ZnO/p-CuO heterojunction films and prototype device structures were created, which could be further used in solar energy, sensors, and flexible electronics. The results of this study can contribute to improving the technological processes of applying films of oxide and chalcogenide compounds and to the expansion of the applications of these materials in modern energy and electronic devices.
