Effect of iodine impurity on the absorption spectrum and phase transitions in CsPbCl₃ thin films

Abstract

The absorption spectra of thin films of solid solutions CsPb(Cl₁₋xIx)₃ 0≤x≤1 were studied. It has been found that at low concentrations x≤0.2, excitonic spectra of a amalgamation type (according to the classification of Onodera-Tojazawa) are formed. The concentration shift of the exciton bands with increasing x at x = 0.3 indicates the formation of the exciton spectrum of a persistence type in the interval 0.3≤x < 1. The iodine impurity leads to an insignificant increase of the phase ransition temperatures in the orthorhombic (Tc₃) and cubic (Tc₁) phases of CsPbCl₃.