The correlation between phase transition and photoluminescence properties of CsPbX3 (X = Cl, Br, I) perovskite nanocrystals

Abstract

We report a correlation between the structural phase transition of CsPbX₃ (X = Cl, Br, I) nanocrystals (NCs) and their temperature-dependent steady-state photoluminescence (PL) and time-resolved PL (TRPL). In contrast to CsPbBr₃ and CsPbI₃ NCs which exhibited a continuous blue-shift in their band gap with increasing temperature, the CsPbCl₃ exhibited a blue shift until ∼193 K, followed by a red shift until room temperature. We attribute this change from a blue to a red shift to a structural phase transition in CsPbCl₃, which also manifested in the temperature dependent TRPL. This pronounced phase transition in CsPbCl₃ NCs is probably due to the condensation of its vibrational modes at low temperature, and the presence of the weak quantum confinement effect. Notably, the exciton recombination lifetimes showed a similar reverse trend due to the phase transition in CsPbCl₃, which has not been reported previously.