Understanding photoluminescence of Cs2ZrCl6 doped with post-transition-metal ions using first-principles calculations

Doped lead-free halide perovskites have been widely reported for impressive photoluminescence properties. Herein we study the mechanisms of photoluminescence in Se4+-, Te4+-, Sb3+-, and Bi3+-doped Cs2ZrCl6 and also in this undoped host via first-principles calculations with hybrid density functionals. The results show that the main photoluminescence in the host, as well as isovalent and aliovalent dopants, can be attributed to highly localized self-trapped excitons composed of an electron on Zr and a V-k center (molecular-like Cl-2(-)), MCl6 (M = Se4+, Te4+), and MCl5 (M = Bi3+, Sb3+) complexes, respectively. The systematic underestimation of the emission energies is discussed and is attributed to the over-relaxation of the excited-state geometric structures. Our results illustrate the photoluminescence processes and excited-state dynamics in host and aliovalent dopant of Cs2ZrCl6, which may inspire further revelations of the mechanisms of photoluminescence of other materials in the tetravalent halide perovskite family.

Automated summary

This study reveals the mechanisms of photoluminescence in doped lead-free halide perovskites through theoretical calculations, showing that the main photoluminescence can be attributed to highly localized self-trapped excitons. The research may inspire further understanding of the photoluminescence mechanisms in other materials.