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Both organohalide perovskites and colloidal quantum dots are attractive and promising materials for optoelectronic applications. Recent experiments have combined the two to create “quantum dot-in-perovskite” assemblies for highly efficient light emissions. In this work, we unravel photoexcitation dynamics at the interface between the perovskite and the quantum dot by means of first-principle non-adiabatic molecular dynamics simulations. We find that such assemblies adopt the type-I band structure and are free of defect states. The interfacial and the electronic structure are robust against the thermal fluctuations at 300K. The lowest excitation is predicted to be localized entirely on the quantum dot and the photoexcited charge transfer takes place in a picosecond timescale. The charge transfer dynamics of the photoexcited electron and hole exhibits a moderate asymmetry, which can be attributed to the differences in electronic coupling between the donor and the acceptor and the electron-phonon coupling. The ultrafast and balanced charge transfer dynamics endows the ‘dot-in-a-crystal’ devices with unprecedented performance, which could lead to important applications in photovoltaics, photocatalysis, and infrared light emissions.
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Hybridization and deconfinement in colloidal quantum dot molecules
The structural, electronic, and optical properties of CdSe/CdS core–shell colloidal quantum dot molecules, a new class of coupled quantum dot dimers, are explored using atomistic approaches. Unlike the case of dimers grown by molecular beam epitaxy, simulated strain profile maps of free-standing colloidal dimers show negligible additional strain resulting from the attachment. The electronic properties of the relaxed dimers are described within a semiempirical pseudopotential model combined with the Bethe–Salpeter equation within the static screening approximation to account for electron–hole correlations. The interplay of strain, hybridization (tunneling splitting), quantum confinement, and electron–hole binding energies on the optical properties is analyzed and discussed. The effects of the dimensions of the neck connecting the two quantum dot building blocks, as well as the shell thickness, are studied.
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- Award ID(s):
- 2026741
- PAR ID:
- 10440022
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- The Journal of Chemical Physics
- Volume:
- 157
- Issue:
- 13
- ISSN:
- 0021-9606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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