Halide perovskites have been studied very intensively by researchers during the last decade. Development of these materials has improved their unique optoelectrical properties reaching even higher standards, making them promising candidates for photovoltaic applications. It should be noted that most inorganic halide perovskites obtained to date have been synthesized using organic solvents in the form of nanosized colloids. Here, a low‐temperature synthesis protocol for the preparation of microcrystalline CsPbBr₃ perovskite powder doped with Yb³⁺ ions is proposed. The structural and photoluminescence features of the studied material are thoroughly investigated and described. It turns out that the excitation of the CsPbBr₃:Yb³⁺ perovskite with a 375 nm wavelength leads to spontaneous luminescence of excitons and Yb³⁺ ions. Hence, the use of CsPbBr₃:Yb³⁺ as a luminescent thermometer or an additional absorbing layer on a solar cell surface is possible. The latter application may result in an increase in the conversion efficiency of the cell. In order to verify this, such a layer is prepared and installed on a commercial silicon solar cell. Its photovoltaic properties are investigated by measurements of the current–voltage characteristics with 1‐sun illumination and the spectral characteristics of the external quantum efficiency.

The synthesis and investigation of the physicochemical properties of a novel one-dimensional (1D) hybrid organic-inorganic perovskitoid templated by the 1,1,1-trimethylhydrazinium (Me(3)Hy(+)) cation are reported. (Me(3)Hy)[PbI3] crystallizes in the hexagonal P6(3)/m symmetry and undergoes two phase transitions (PTs) during heating (cooling) at 322 (320) and 207 (202) K. Xray diffraction data and temperature-dependent vibrational studies show that the second-order PT to the high-temperature hexagonal P6(3)/mmc phase is associated with a weak change in entropy and is related to weak structural changes and different confinement of cations in the available space. The second PT to the lowtemperature orthorhombic Pbca phase that corresponds to the high change in entropy and dielectric switching is associated with an ordering of the trimethylhydrazinium cations, re-arrangement and strengthening of hydrogen bonds, and slightly shifted lead-iodide octahedral chains. The high-pressure Raman data revealed two additional PTs, one between 2.8 and 3.2 GPa, related to the symmetry decrease, ordering of the cations, and inorganic chain distortion, and the other in the 6.4-6.8 GPa range related to the partial and reversible amorphization. Optical studies revealed that (Me(3)Hy)[PbI3] has a wide band gap (3.20 eV) and emits reddishorange excitonic emission at low temperatures with an activation energy of 65 meV.

Mono-substituted cage-like silsesquioxanes of the T₈-type can play the role of potential ligands in the coordination chemistry. In this paper, we report on imine derivatives as ligands for samarium, terbium, and erbium cations and discuss their efficient synthesis, crystal structures, and magnetic and optical properties. X-ray analysis of the lanthanide coordination entities [MCl₃(POSS)₃]·2THF [M = Er³⁺ (3), Tb³⁺ (4), Sm³⁺ (5)] showed that all three compounds crystallize in the same space group with similar lattice parameters. All compounds contain an octahedrally coordinated metal atom, and additionally, 3 and 5 structures are strictly isomorphous. However, surprisingly, there are two different molecules in the crystal structure of the terbium coordination entity 4, monomer (sof 65%) and dimer (sof 35%), with one and two metal centers. Absorption measurements of the investigated materials recorded at 300 K showed that regardless of the lanthanide involved, their energy band gap equals 2.7 eV. Moreover, the analogues containing Tb³⁺ and Sm³⁺ exhibit luminescence typical of these rare earth ions in the visible and infrared spectral range, while the compound with Er³⁺ does not generate any emission. Direct current variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3-5 were performed between 1.8 and 300 K. The magnetic properties of 3 and 4 are dominated by the crystal field effect on the Er³⁺ and Tb³⁺ ions, respectively, hiding the magnetic influence between the magnetic cations of adjacent molecules. Complex 5 exhibits a nature typical for the paramagnetism of the samarium(III) cation.

An increase of graphene concentration in Sr ₂ CeO ₄ nanocomposites reduces the quality of Stokes emission and improves LIWE properties.

The levels of Nd³⁺ in CsPbCl₃ lie below the top of the host's VB. Consequently, Nd³⁺ luminescence is not observed.

Graphene nanoplatelets (GNPs) were prepared using the electrolytic exfoliation method on graphite foil in an ammonium sulfate solution. A series of experiments were conducted in order to optimize the production of the flakes by varying the pH of the solution, applied voltage and current, duration of electrolysis, temperature in the electrolytic system, and type and duration of the ultrasound interaction. The quality of the produced graphene nanoplatelets was analyzed using X-ray diffraction, Raman and IR spectroscopy, and TEM.