Effect of Mn2+ doping on exciton recombination and carrier trapping in the Cs2CdCl4 metal halide

Abstract

The lattice defects that occur in material preparation processes are closely related to carrier migration. The carrier migration can be regulated by artificially modulating the defects to improve the luminescence performance, which is important for the development and application of luminescent materials. Here, we achieved a 3.29-fold increase in the high-temperature luminescence intensity by introducing Mn²⁺ to generate Cl vacancy defects in Cs₂CdCl₄. Due to thermally induced electron de-trapping, Cs₂CdCl₄:Mn²⁺ also displays anti-thermal quenching (ATQ) behavior and good thermal quenching resistance (329% at 175 °C). The increase in the photoionization effect and de-trapping of the captured electrons from shallow trap states were appropriately attributed to this exceptional phenomenon, based on thermoluminescence (TL) analysis. Based on comprehensive optical characterization, thermoluminescence and temperature-dependent X-ray diffraction (XRD), we reveal that the Cl vacancy trap state generated by Mn doping is the reason for the enhanced PL in air. The discovery of these materials helps to better understand the optical properties of all-inorganic perovskites.