A research team led by Prof. HAN Keli from the
Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences synthesized undoped and Mn-doped lead-free double perovskite (DP) nanocrystals (NCs), and further revealed the photoluminescence mechanism. The study was published in
ACS Cent.Sci.
Lead-free halide DP NCs are expected to solve the issues of toxicity and instability of lead-based perovskite NCs. In recent years, the broadband and large red-shifted emission is the focus.
However, other specific wave-band emission and dopants emission are rarely studied in the visible region. Doping strategy can improve photophysical properties and stability in halide perovskite NCs.
In terms of Mn-doped NCs, dopant photoluminescence (PL) emission is often accompanied by free exciton emission or bright dark self-trapped exciton emission. Moreover, size effect and dynamics mechanism of doping lead-free DP have not been investigated.
The scientists synthesized a series of undoped and Mn-doped all-inorganic, lead-free, direct bandgap Na-based mixed In/Bi DP NCs. Undoped NCs exhibited band edge blue-light emission, while Mn-doped NCs showed bright pure Mn2+ PL with the best photoluminescence quantum efficiency of 44.6%.
Effect of Mn-doping on the emission spectra of lead-free double perovskite nanocrystals (Image by HAN Peigeng)
They proved that the process of dark self-trapped state assisted Mn2+ PL in DP NCs by ultrafast transient absorption techniques. In addition, size effect of Mn-doped Na-based DP was further studied.
This work emphasizes that the rational use of the advantages of sub-band states has important guiding significance for the design of high-performance semiconductor nanomaterials.
