Photon Correlations in Colloidal Quantum Dot Molecules Controlled by the Neck Barrier
arXiv:2306.14614 · doi:10.1016/j.matt.2022.07.032
Abstract
We investigate the charge re-distribution upon optical excitation of various necked homodimer CQDMs using single particle emission spectroscopy. By tuning the hybridization of the electron wavefunction at a fixed center-to-center distance through controlling the neck girth, we reveal two coupling limits. On one hand a connected-but-confined situation where neighbouring CQDs are weakly fused to each other manifesting a weak coupling regime, and on the other hand, a connected-and-delocalized situation, where the neck is filled beyond the facet size leading to a rod-like architecture manifesting strong-coupling. Either coupling regimes entrust distinct optical signatures clearly resolved at room temperature in terms of photoluminescence quantum yield, intensity time traces, lifetimes, and spectra of the neutral-exciton, charged-exciton, and biexciton states. The interplay between the radiative and non-radiative Auger decays of these states, turns emitted photons from the CQDMs in the weak-coupling regime highly bunched unlike CQD monomers, while the antibunching is regained at the strong-coupling regime. This behavior correlates with the hybridization energy being smaller than the thermal energy (kT approx. 25meV) at the weak-coupling limit (delta E approax.5-10meV), leading to exciton localization suppressing Auger decay. In the neck-filled architectures, the larger hybridization energy (delta E approx.20-30meV) leads to exciton delocalization while activating the fast charged and multi-exciton Auger decay processes. This work sets an analogy for the artificial molecule CQDMs with regular molecules, where the two distinct regimes of weak- and strong-coupling correspond to ionic- or covalent- type bonding, respectively.
arXiv comment28 pages, 5 figures, 2 schemes. SI - 13 pages, 11 figures
References in corpus (18)
- Electron transport through double quantum dots
- Superfluorescence from Lead Halide Perovskite Quantum Dot Superlattices
- Coherent control of tunneling in a quantum dot molecule
- Colloidal Quantum Nanostructures: Emerging Materials for Display Applications
- Quantum Communication Using Semiconductor Quantum Dots
- Coupled Colloidal Quantum Dot Molecules
- Nearly Blinking-Free, High-Purity Single-Photon Emission by Colloidal InP/ZnSe Quantum Dots
- Perspective on Coupled Colloidal Quantum Dot Molecules
- Robust states in semiconductor quantum dot molecules
- Electrical control of single-photon emission in highly-charged individual colloidal quantum dots
- Heralded spectroscopy reveals exciton-exciton correlations in single colloidal quantum dots
- Electronic coupling in colloidal quantum dot molecules; The case of CdSe/CdS core/shell homodimers
- Neck Barrier Engineering in Quantum Dot Dimer Molecules via Intra-Particle Ripening
- Effect of charging on CdSe/CdS dot-in-rods single-photon emission
- Complete mapping of interacting charging states in single coupled colloidal quantum dot molecules
- Semiconductor Bowtie Nanoantenna from Coupled Colloidal Quantum Dot Molecules
- Dipole-Coupled Defect Pairs as Deterministic Entangled Photon Pair Sources
- Twisting enabled charge transfer excitons in epitaxially fused quantum dot molecules