Uncovering the Effect of A-Site Cations on Localized Excitons Photoluminescence of Manganese-Doped Zinc Chloride Nanocrystals.

Elucidating the key factors that affect the localized excitons (LEs) photoluminescence (PL) in lead-free metal halide nanocrystals (NCs) is important for their optoelectronic applications. However, the effect of A-site cations on LEs based PL is not well understood. Herein, we varied the A-site cation ratio (Rb/Cs) to investigate the influence on LEs based PL in manganese-doped zinc chloride NCs. Through time-resolved photoluminescence (TR-PL) spectra and density functional theory (DFT) calculations, we discovered that Cl vacancy is energetically more favorable in Mn 2+ -doped Rb 3 ZnCl 5 NCs compared to Mn 2+ -doped Cs 3 ZnCl 5 NCs. The higher concentration of Cl vacancy increases the nonradiative recombination process in Rb 3 ZnCl 5 :Mn 2+ NCs, ultimately determining the PL efficiency. This research enhances the understanding of the A-site cation effect on LEs-based PL in lead-free metal halide NCs.