Exciton dynamics related with phase transitions in CsPbCl3 single crystals

Characteristics of excitonic luminescence in CsPbCl3 single crystals have been investigated in a wide range of temperature. A blue luminescence band observed in the temperature range 4–300 K is due to radiative decay of free excitons. In addition to the blue band, a broad red band appears below ∼180 K. Temperature dependence of the steepness of the Urbach absorption tail suggests that a relaxation pathway of excitons into a self-trapped state gets opened below ∼180 K. The change in the excitonic luminescence as well as in the steepness of the absorption tail is ascribed to a phase transition at 176 K.