Alloying Bi-Doped Cs<sub>2</sub>Ag<sub>1-<i>x</i></sub>Na<sub><i>x</i></sub>InCl<sub>6</sub> Nanocrystals with K<sup>+</sup> Cations Modulates Surface Ligands Density and Photoluminescence Efficiency.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36288498.
- Also identified by DOI 10.1021/acs.nanolett.2c03112 and PMC identifier 9650775.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
We show how, in the synthesis of yellow-emissive Bi-doped Cs<sub>2</sub>Ag<sub>1-<i>x</i></sub>Na<sub><i>x</i></sub>InCl<sub>6</sub> double perovskite nanocrystals (NCs), preventing the transient formation of Ag<sup>0</sup> particles increases the photoluminescence quantum yield (PLQY) of the NCs from ∼30% to ∼60%. Calculations indicate that the presence of even a single Ag<sup>0</sup> species on the surface of a NC introduces deep trap states. The PL efficiency of these NCs is further increased to ∼70% by partial replacement of Na<sup>+</sup> with K<sup>+</sup> ions, up to a 7% K content, due to a lattice expansion that promotes a more favorable ligands packing on the NC surface, hence better surface passivation. A further increase in K<sup>+</sup> lowers the PLQY, due to both the activation of nonradiative quenching channels and a lower oscillator strength of the BiCl<sub>6</sub>→AgCl<sub>6</sub> transition (through which PL emission occurs). The work indicates how a deeper understanding of parameters influencing carrier trapping/relaxation can boost the PLQY of double perovskites NCs.