Compositional behaviour of Urbach absorption edge and exciton–phonon interaction parameters in Cu6PS5I1−xBrx superionic mixed crystals Original Research Article

Temperature behaviour of optical absorption edge in Cu6PS5I1−xBrx mixed crystals is studied in the interval 77–325 K. It is shown that the absorption edge has Urbach shape in the 215–325 K temperature interval. The influence of temperature and compositional disorder on the Urbach absorption edge parameters is presented. The mechanism of the Urbach bundle formation and the effect of I→Br anionic substitution on the exciton–phonon interaction parameters is elucidated.