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Various approaches to the optical diagnostics of evolving polymer foams formed as a result of a decrease in the external pressure according to a given scenario in the “polymer-supercritical fluid” systems are considered. Formed polymer foams are considered as a material platform for the creation of scaffolds for biomedical applications. Diagnostics of the current state of the foam was carried out by statistical analysis of the spatiotemporal fluctuations of the probe laser radiation, multiple scattered in the volume of the evolving foam, or by analyzing the fluorescent response during foaming of the “polymer-fluorophore” mixture, pumped by laser radiation in the absorption band of the fluorophore. A relationship has been established between the average lifetime of dynamic speckles in scattered laser light and a generalized parameter characterizing the foam expansion dynamics. It was also found that the waveguide effect in the walls of the formed pores has a significant influence on the fluorescent response of the evolving foam, leading to an increase in the characteristic dwell time of fluorescence radiation in the walls and, accordingly, to an increase in the contribution of the induced component to the fluorescent response.

Carbon dots have attracted much attention due to the ease of synthetic methods and their stable photoluminescence with relatively high quantum yield. By the doping of carbon dot by heteroatoms the optical transitions can be tuned in a wide spectral range. In this work, the impact of heteroatoms on the optical properties of carbon dots has been investigated: the appearance of the luminescent states attributed to the CD surface states and the dependence of the photoluminescence lifetime versus emission wavelength have been revealed.

A green and efficient strategy was developed for one-step synthesis of sulfur and nitrogen co-doped carbon dots using urea, thiourea and thioacetamide as nitrogen and sulfur source and citric acid as carbon source. The influence of nitrogen and/or sulfur doping of the carbon dots on their optical transitions is investigated. The as synthesized carbon dots are demonstrated to possess redshifted photoluminescence with relatively high intensity. It is demonstrated that the presence of heteroatoms leads to the red shift of the photoluminescence band and increase of the crystalline phase inherent to amorphous carbon.

This work discloses routes of obtaining two-dimensional PbS nanostructures by chemical synthesis methods. Using the techniques of absorption and luminescence spectroscopy, their optical characteristics are revealed. Special attention is paid to the evolution of nanoplates in a colloidal solution. The processes of growth and degradation of the structure of nanoplatelets, as well as the corresponding changes in the optical properties of nanocrystals are considered.

Hybrid halide perovskites have emerged as one of the most promising type of materials for thin-film photovoltaic and light-emitting devices. Further boosting their performance is critically important for commercialization. Here we use femtosecond laser for post-processing of organo-metalic perovskite (MAPbI3) films. The high throughput laser approaches include both ablative silicon nanoparticles integration and laser-induced annealing. By using these techniques, we achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally 10-fold enhancement of absorbance in a perovskite layer with the silicon nanoparticles. Direct laser annealing allows for increasing of photoluminescence over 130%, and increase absorbance over 300% in near-IR range. We believe that the developed approaches pave the way to novel scalable and highly effective designs of perovskite based devices.

The analysis of the optical properties, including transient photoluminescence (PL), of CdSe quantum dots (QDs) self-assembled in supercrystals shows that supercrystals possess efficient QD PL. Although PL band is slightly broadened and blueshifted as compared with QD colloidal solution, PL kinetic is the same showing absence of induced channels of the energy dissipation. The data indicate the opportunity to create quantum dot solids with efficient PL.

The method of X-ray structural analysis (X-ray scattering at small angles) is used to show that the structures obtained by self-organization on a substrate of lead sulfide (PbS) quantum dots are ordered arrays. Self-organization of quantum dots occurs at slow evaporation of solvent from a cuvette. The cuvette is a thin layer of mica with teflon ring on it. The positions of peaks in SAXS pattern are used to calculate crystal lattice of obtained ordered structures. Such structures have a primitive orthorhombic crystal lattice. Calculated lattice parameters are: a = 21,1 (nm); b = 36,2 (nm); c = 62,5 (nm). Dimensions of structures are tens of micrometers. The spectral properties of PbS QDs superstructures and kinetic parameters of their luminescence are investigated. Absorption band of superstructures is broadened as compared to the absorption band of the quantum dots in solution; the luminescence band is slightly shifted to the red region of the spectrum, while its bandwidth is not changed much. Luminescence lifetime of obtained structures has been significantly decreased in comparison with the isolated quantum dots in solution, but remained the same for the lead sulfide quantum dots close-packed ensembles. Such superstructures can be used to produce solar cells with improved characteristics.

The paper deals with self-organization process of semiconductor lead sulfide nanoparticles with a luminescence in the range of 0.8–2 mkm. Corresponding diameters of nanoparticles determined by X-ray analysis lie in the range of 2.5–8 nm. Nanostructures are fabricated by evaporation of solvent on a glass substrate and by embedding in a porous matrix. The process of self-organization on the substrate and in the matrix is studied by means of X-ray structural analysis. It is shown that self-organized nanostructures are ordered structures consisted of close-packed nanoparticles. A formation of spatial regulation of nanoparticles leads to the appearance of specific maxima in the angular dependence of X-rays scattering, which position is determined by the period of the structure. It is found that the type of this regulation is independent of the size of nanoparticles, type of substrate and matrix. It is shown that a distance between nanoparticles centers in obtained structures depends linearly on its diameter, and the average value of the slope coefficient of size dependence is (1,2±0,1).

The dimensional dependence of the spectral and kinetic parameters of the PbS quantum dots luminescence has been investigated in a wide spectral range (0.8 - 2 microns). Registered lifetimes lie in the range of 0.25 - 2.7 ms, and decrease with the nanocrystal sizes growth. We consider a three-level model with the energy level in the forbidden zone to explain such long luminescence lifetimes. It is shown that the anomalous size dependence of the luminescence lifetimes can be related to the existence of transitions with both decreasing and increasing of energy at room temperature.