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.

Core‐shell gallium nitride (GaN)‐based nanowires offer noteworthy opportunities for innovation in high‐frequency opto‐ and microelectronics. This work delves deeply into the physical properties of crystalline GaN nanowires with aluminum and hafnium oxide shells. Particular attention is paid to partial coverage of nanowires, resulting with exceptional properties. First, the crystal lattice relaxation is observed by X‐ray diffraction, photoluminescence, and Raman spectroscopy measurements. A high potential of partial coverage for optoelectronic applications is revealed with photo‐ and cathodoluminescence spectra along with an exploration of their temperature dependency. Next, the study focuses on understanding the mechanisms behind the observed enhancement of the luminescence efficiency. It is confirmed that nanowires are effectively protected against photoadsorption using partial coatings. This research advances the frontiers of nanotechnology, investigating the benefits of partial coverage, and shedding light on its complex interaction with cores.