Inorganic Surface Passivation of PbS Nanocrystals resulting in Strong Photoluminescent Emission

TL;DR

This paper demonstrates that inorganic surface passivation of PbS nanocrystals with CdS precursors significantly enhances their photoluminescent emission across the visible spectrum, with lifetimes indicative of exciton recombination.

Contribution

It introduces a novel inorganic surface passivation method using CdS precursors to improve PbS nanocrystal photoluminescence.

Findings

Enhanced visible emission from PbS nanocrystals after passivation

Emission peaks near 1.95 eV with nanosecond lifetimes

Emission involves relaxation from higher excited states

Abstract

Strong photoluminescent emission has been obtained from 3 nm PbS nanocrystals in aqueous colloidal solution, following treatment with CdS precursors. The observed emission can extend across the entire visible spectrum and usually includes a peak near 1.95 eV. We show that much of the visible emission results from absorption by higher-lying excited states above 3.0 eV with subsequent relaxation to and emission from states lying above the observed band-edge of the PbS nanocrystals. The fluorescent lifetimes for this emission are in the nanosecond regime, characteristic of exciton recombination.