Exciton absorption spectra of KPb₂Br₅ thin films

Abstract

Absorption spectra of KPb2Br5 thin films of tetragonal (I) and monoclinic (II) structures were investigated in the spectral region of 2-6 eV and the temperature range of 90-440 K. It was found that KPb₂Br₅(I) of the tetragonal structure irreversibly transferred in KPb₂Br₅(II) of the monoclinic structure when T = 293 K. It was found that low-frequency exciton excitations of KPb₂Br₅(I,II) were localized in the sublattice, which contained Pb²⁺ ions and were two-dimensional nature.