All-inorganic lead halide perovskites of various compositions have emerged as a prospective family of materials for light-emitting devices and photonic applications. However, a comprehensive study of their structural and electronic properties is still missing. Moreover, thin film fabrication of these perovskites comprising heterohalide anions by wet chemistry approaches also remains challenging. Here we fabricate high-quality CsPbBr_3−xCl_x perovskite thin films using a wet chemical method accompanied by a chemical vapor anion exchange procedure, which allows rigorously studying their optical and structural properties at different compositions. Namely, we present both the numerical and experimental studies of the electronic properties of all-inorganic mixed-halide perovskites, showing their optical absorption, excitonic photoluminescence and exciton binding energy, phase, chemical composition, and band structure and the band gap evolution with a gradual change in x in CsPbBr_3−xCl_x. The results reveal that as Cl ions substitute for Br ones in the perovskite crystal lattice the room-temperature phase does not change its orthorhombic symmetry, whereas the energy of the direct electronic transition from the valence to conduction band at the Γ-point increases nonlinearly. By using the experimentally derived nonlinear dependence it is easy to accurately predict the band gap for any CsPbBr_3−xCl_x perovskite thin film consisting of grains with sizes beyond the quantum confinement regime.

Surface-enhanced Raman spectroscopy (SERS) is a promising optical method for analyzing molecular samples of various nature. Most SERS studies are of an applied nature, indicating a serious potential for their application in analytical practice. Dendritelike nanostructures have great potential for SERS, but the lack of a method for their predictable production significantly limits their implementation. In this paper, a method for controllably obtaining spatially separated, self-organized, and highly-branched silver dendrites via template synthesis in pores of SiO₂/Si is proposed. The dendritic branches have nanoscale roughness, creating many plasmon-active “hotspots” required for SERS. The first held 3D modeling of the external electromagnetic wave interaction with such a dendrite, as well as experimental data, confirms this theory. Using the example of a reference biological analyte, which is usually used as a label for other biological molecules, the dendrites’ SERS-sensitivity up to 10⁻¹⁵M was demonstrated with an enhancement factor of 10⁸. The comparison of simulation results with SERS experiments allows distinguishing the presence of electromagnetic and chemical contributions, which have a different effect at various analyte concentrations.

Thin nanocomposite films composed of ZnO and SnO₂ at 0.5–5 mol.% concentrations were synthesized by a new solid-phase low-temperature pyrolysis under the developed protocols. This hetero-oxide material was thoroughly studied by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques to be compared with electrical and gas-sensing properties. We have found that the films have a poly-nanocrystal structure of ZnO and SnO₂ crystals with characteristic grain sizes at 10–15 nm range. When comparing the chemiresistive response of the films with varied tin dioxide content, the sample of Sn:Zn optimum ratio taken as 1:99 yields 1.5-fold improvement upon to 5–50 ppm NO₂ exposure at 200 °C. We argue that these remarkable changes have matured from both a reducing the intergrain potential barrier down to 0.58 eV and increasing the concentration of anionic vacancies at this rational composite. The results demonstrate that solid-phase low-temperature pyrolysis is a powerful technique for adjusting the functional gas-sensing properties of hetero-oxide film via modifying the ratio of the oxide components.

Thin nanocomposite films based on zinc oxide (ZnO) added with cobalt oxide (Co₃O₄) were synthesized by solid-phase pyrolysis. According to XRD, the films consist of a ZnO wurtzite phase and a cubic structure of Co₃O₄ spinel. The crystallite sizes in the films increased from 18 nm to 24 nm with growing annealing temperature and Co₃O₄ concentration. Optical and X-ray photoelectron spectroscopy data revealed that enhancing the Co₃O₄ concentration leads to a change in the optical absorption spectrum and the appearance of allowed transitions in the material. Electrophysical measurements showed that Co₃O₄-ZnO films have a resistivity up to 3 × 10⁴ Ohm∙cm and a semiconductor conductivity close to intrinsic. With advancing the Co₃O₄ concentration, the mobility of the charge carriers was found to increase by almost four times. The photosensors based on the 10Co-90Zn film exhibited a maximum normalized photoresponse when exposed to radiation with wavelengths of 400 nm and 660 nm. It was found that the same film has a minimum response time of ca. 26.2 ms upon exposure to radiation of 660 nm wavelength. The photosensors based on the 3Co-97Zn film have a minimum response time of ca. 58.3 ms versus the radiation of 400 nm wavelength. Thus, the Co₃O₄ content was found to be an effective impurity to tune the photosensitivity of radiation sensors based on Co₃O₄-ZnO films in the wavelength range of 400–660 nm.

The modern development of nanotechnology requires the discovery of simple approaches that ensure the controlled formation of functional nanostructures with a predetermined morphology. One of the simplest approaches is the self-assembly of nanostructures. The widespread implementation of self-assembly is limited by the complexity of controlled processes in a large volume where, due to the temperature, ion concentration, and other thermodynamics factors, local changes in diffusion-limited processes may occur, leading to unexpected nanostructure growth. The easiest ways to control the diffusion-limited processes are spatial limitation and localized growth of nanostructures in a porous matrix. In this paper, we propose to apply the method of controlled self-assembly of gold nanostructures in a limited pore volume of a silicon oxide matrix with submicron pore sizes. A detailed study of achieved gold nanostructures’ morphology, microstructure, and surface composition at different formation stages is carried out to understand the peculiarities of realized nanostructures. Based on the obtained results, a mechanism for the growth of gold nanostructures in a limited volume, which can be used for the controlled formation of nanostructures with a predetermined geometry and composition, has been proposed. The results observed in the present study can be useful for the design of plasmonic-active surfaces for surface-enhanced Raman spectroscopy-based detection of ultra-low concentration of different chemical or biological analytes, where the size of the localized gold nanostructures is comparable with the spot area of the focused laser beam.