Perovskite nanocrystals (NCs) are currently one of the most efficient optical materials in the visible spectral range. Much attention is paid to extending their efficiency to the near-infrared (NIR) spectral region, which will significantly benefit their applications in optoelectronics, photonics, and biomedicine. To further promote this effort, we developed a novel synthetic approach to dual-band emitting Yb3+-doped perovskite NCs, whose stoichiometry and hence the position of the visible photoluminescence can be tuned independently of the Yb3+-precursor. The intensity of the NIR emission from Yb3+ ions shows a notable nonlinear dependence on the excitation power. To describe the corresponding redistribution of the photoluminescence intensities between the emissive channels, we developed a theoretical description of the relaxation dynamics in the doped NCs, including both the energy transfer and quantum cutting processes. Finally, we showed that the dual-band photoluminescence in the doped NCs can be excited via two-photon absorption. Our findings thus pave the way for new nanomaterials that can be operated entirely in the NIR spectral range.

In this work, chitosan-TiO2 nanocomposites (NСs CS-TiO2) were developed for the photocatalytic degradation of some representatives of polycyclic aromatic hydrocarbons (PAHs). TiO2 nanoparticles (NPs) were synthesized by laser ablation method and their sizes were determined by dynamic laser light scattering (DLLS). Anthracene and pyrene in micellar solution were used as representatives of PAHs. The effect of TiO2 in the composition of prepared nanocomposites on the photodegradation of PAHs in model environments under UV irradiation was studied. The method of solid-phase luminescence (SPL) was used to estimate the decrease in PAHs concentrations. Based on the results of the studies carried out, pseudo-first order photodegradation kinetics were plotted. The efficiency of using the nanocomposites for the photocatalytic degradation of anthracene and pyrene was proved.

Lead halide perovskite nanoplatelets (NPls) attract significant attention due to their exceptional and tunable optical properties. Doping is a versatile strategy for modifying and improving the optical properties of colloidal nanostructures. However, the protocols for B-site doping have been rarely reported for 2D perovskite NPls. In this work, we investigated the post-synthetic treatment of CsPbBr3 NPls with different Cd2+ sources. We show that the interplay between Cd2+ precursor, NPl concentrations, and ligands determines the kinetics of the doping process. Optimization of the treatment allows for the boosting of linear and nonlinear optical properties of CsPbBr3 NPls via doping or/and surface passivation. At a moderate doping level, both the photoluminescence quantum yield and two-photon absorption cross section increase dramatically. The developed protocols of post-synthetic treatment with Cd2+ facilitate further utilization of perovskite NPls in nonlinear optics, photonics, and lightning.

Currently, lead halide perovskite nanostructures are an essential platform for designing new optical materials with required functionalities. Photoluminescence (PL) wavelength tuning is an important tool for targeted applications of optical...

The preparation method of modified chitosan films for adsorption of pyrene from solution is described. Solid-phase luminescence of samples was studied, degree of extraction and index of polarity of microenvironment of pyrene molecules was determined. It has been proven possible to carry out luminescent analysis of substances for pyrene content using made films. The observed results demonstrate an ability for the using method of solid-phase luminescence (SPL) to increase the range of optical transparency and avoid pre-extraction and concentration of the test samples.