Temperature behavior of the near band edge luminescence in CsPbBr3 single crystal and nanoparticle ensemble

The temperature dependences of the luminescence spectra for CsPbBr3 single crystal and nanoparticle ensemble are presented. The emission bands of single crystal are interpreted in terms of the direct and indirect exciton transitions. An attempt to estimate the contribution of the direct and indirect transitions for wide luminescence band inherent for CsPbBr3 nanoparticles is made. The temperature dependence of the luminescence band position is analyzed by the taking into account the thermal expansion and exciton-phonon interaction. For both the single crystal and the ensemble of nanoparticles, main contribution to the shift of the luminescence bands of the direct and indirect excitons to the low-energy region was revealed to be caused by the interaction with optical phonons. This interaction is predominant for the indirect excitons and can be used as a sign of Rashba nature of the exciton.