Change of optical properties of inorganic perovskite nanocrystals of CsPbCl$_x$Br$_{3-x}$, alloyed with Yb$^{3+}$ ions, when carrying out an anion exchange reaction

Alloying of perovskites nanocrystals by lanthanoids makes it possible to produce materials that luminesce effectively in both visible and near infrared spectra. In the present work, the influence of the width of the forbidden zone on the optical properties of the inorganic perovskites nanocrystals CsPbCl$_x$Br$_{3-x}$ alloyed by ions Yb$^{3+}$ is investigated. For changing the chemical composition of nanocrystals, an anionic exchange method is used by adding bromide dodecyltrimethylammonium. As a result of the gradual substitution of chlorine ions with bromine ions, the forbidden area of nanocrystals is narrowed, resulting in a change in the spectral position of the optical transitions, the quantum output of photoluminescence in the near and infrared spectral ranges and the attenuation of photoluminescence. When the width of the forbidden area reaches 2.54 eV, the total quantum output of photoluminescence reaches 72%.