Enhanced Photoluminescence of Double Perovskite CsSnI Nanocrystals Via Na Doping

Double perovskites without lead element have attracted great attention in recent years. Further increasing the photoluminescence quantum yield of lead-free double perovskites is necessary for their potential applications. In this work, Na doped CsSnI nanocrystals were synthesized by hot injection method. It was displayed that all the NCs have uniform hexagonal shape with good crystallization. Energy dispersing spectroscopy and X-ray photoelectron spectroscopy proves the Na ions were doped in the lattice of perovskite structure. The photoluminescence intensity of doped NCs is increased by 2.7-fold than that of pure NCs. A maximum photoluminescence quantum yield of 72% is obtained. The luminous mechanism was investigated by femtosecond transient absorption spectrum and a self-trap emission was proved by the observation of ground state bleaching and photo-induced absorption signals.