Monolayer-Defined Flat Colloidal PbSe Quantum Dots in Extreme Confinement.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40717305.
- Also identified by DOI 10.1021/acs.nanolett.5c02957 and PMC identifier 12333419.
- 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
Colloidal 2D PbX (X = S, Se, Te) nanocrystals are innovative materials pushing the boundaries of quantum confinement by combining crystal thicknesses down to a monolayer with additional confinement in the lateral dimension. These flat PbSe quantum dots (fQDs) exhibit telecommunication band photoluminescence (1.43-0.83 eV), which is highly interesting for fiber optic information processing. With scanning tunneling microscopy/spectroscopy (STM/STS), we probe single-layer-defined fQD populations down to one monolayer, showing an in-gap state free QD-like density of states in excellent agreement with theoretical tight-binding (TB) calculations. Cryogenic ensemble spectra match STS/STM and TB calculations and exhibit the contribution of mono-, bi-, and trilayers to the photoluminescence. Comparing the electronic band gaps with the optical ones, we derive exciton binding energies as high as 600 meV for PbSe monolayers. Our results allow for a target-oriented synthesis of a <b>new class</b> of QDs with record binding energies and precisely tailored optical properties at technologically relevant wavelengths.