Temperature-dependent Mn²⁺ emission in codoped CsPb₂ (BrCl)₅ perovskite nanocrystals

Abstract

We prepared codoped CsPb2(BrCl)5 nanocrystal (NC) films by varying the Cu/Mn molar ratio using a facile two-step solution method. The Mn2+ emission peak is studied in the temperature range of 80–300 K. Strong electron–optical-phonon coupling causes an anomalous blueshift and linewidth broadening of the Mn2+ emission peak with increasing temperature. The average optical-phonon energy is approximately 50 meV. The activation energy reaches 79.32 meV, indicating that the introduction of Cu2+ in Mn-doped CsPb2(BrCl)5 NCs greatly enhances the energy transfer (ET) from the perovskite NC host to Mn2+, increasing the Mn2+ emission intensity. A clear understanding of the optical mechanism of Mn2+ emission is of great significance for the widespread application of codoped CsPb2(BrCl)5 NCs in optoelectronic devices.