Influence of cadmium ion doping on luminescence of CsPbBr3 single crystals

Abstract

The effect of impurity doping with cadmium ions on the luminescent properties of CsPbBr3 perovskite single crystals has been investigated. The luminescence spectra of pure and Cd-activated CsPbBr3 crystals, obtained upon excitation with synchrotron radiation, reveal characteristic excitonic bands, which are interpreted as the emission of free and bound excitons in the vicinity of the crystal absorption edge, a broadband luminescence at 556.3 nm, and additional luminescence bands at 920 nm. The introduction of Cd is shown to result in an increase in the intensity of the excitonic luminescence, the emergence of supplementary emission bands due to the scattering of excitons on quasilocal lattice vibrations, and a shift of the near-edge luminescence bands toward the high-energy region. Cadmium doping is proposed to improve the tolerance factor of the perovskite structure, reduce the concentration of bromine vacancies, and increase the formation energy of anionic vacancies in Cd–Br pairs, thereby limiting halogen diffusion. These modifications lead to a reduction in non-radiative relaxation channels and enhance the efficiency of near-edge luminescence by a factor of 4. The luminescence band at 920 nm is attributed to the emission of radiation-induced defects. The results obtained highlight the potential of CsPbBr3–Cd single crystals for the development of fast scintillators with improved light output.