Photon correlations in colloidal quantum dot molecules controlled by the neck barrier
| Autor: | Somnath Koley, Jiabin Cui, Yossef.E. Panfil, Yonatan Ossia, Adar Levi, Einav Scharf, Lior Verbitsky, Uri Banin |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Matter. 5:3997-4014 |
| ISSN: | 2590-2385 |
| Popis: | 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. Comment: 28 pages, 5 figures, 2 schemes. SI - 13 pages, 11 figures |
| Databáze: | OpenAIRE |
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