Ab Initio Time-Domain Study of Phonon-Assisted Relaxation of Charge Carriers in a PbSe Quantum Dot

Kilina, Svetlana; Craig, Colleen F.; Kilin, Dmitri S.; Prezhdo, Oleg V.

doi:10.1021/jp0669052

Cited by 112 publications

(173 citation statements)

References 67 publications

(235 reference statements)

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“…[22][23][24][25] The core electrons were simulated using the Vanderbilt pseudopotentials, 26 and all valence electrons were treated explicitly. The generalized gradient functional of Perdew and Wang (PW91) 27 was used to account for the electron exchange and correlation effects.…”

Section: Methods and Simulation Detailsmentioning

confidence: 99%

Electronic Properties of DNA Base Molecules Adsorbed on a Metallic Surface

et al. 2007

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The internal electronic structure of single deoxyribonucleic acid (DNA) base molecules (i.e., guanine, adenine, cytosine, and thymine) adsorbed on a metallic surface of Cu (111) is determined in detail using density functional theory (DFT) computations. In contrast to the intuitive beliefs that a molecule weakly interacts with a substrate and its electronic structure is only slightly perturbed, our simulations reveal strong hybridizations and interactions between molecular and metallic states. Stipulated by the symmetries of a base molecule and the Cu(111) surface, oxygen atoms of a base approach close to the substrate, breaking the parallel orientation of the π-system with respect to the surface. Such a behavior is the most pronounced for one oxygen containing bases, leading to the chemisorption of cytosine and guanine and to stronger hybridization of their electronic states with metallic ones. Oxygen free adenine, on the other hand, lies nearly flat on a Cu substrate and interacts weakly with the surface through physisorption. The calculated local electron density of states spectra demonstrate the absence of pure localized molecular states for all four DNA bases, yet they show the smallest delocalization for adenine and thymine and the largest for guanine and cytosine. The observed diversity of the geometrical and electronic structures of the nucleobases on the Cu substrate provides guidelines for interpreting DNA tunneling spectra in the scanning tunneling microscopy (STM) measurements. Our results open a new prospective for understanding biomolecule adsorbates and have an important implication for a possible differentiation of nucleotide sequences in DNA through STM.

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Section: Methods and Simulation Detailsmentioning

confidence: 99%

Electronic Properties of DNA Base Molecules Adsorbed on a Metallic Surface

et al. 2007

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“…A complete understanding of cooling in NCs that is consistent with all experimental observations is still lacking [55]. A recent calculation of carrier relaxation in PbSe NCs based upon a time-dependent density functional theory [35] found that the density of states is much greater than what is typically assumed, but that most of these states are dark and do not contribute to the absorption spectrum. These dark states are coupled to light states via a variety of NC vibrations (phonons) and can therefore participate in carrier relaxation.…”

Section: Carrier Cooling In Semiconductor Ncsmentioning

confidence: 99%

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Beard¹,

Ellingson²

2008

Laser & Photonics Reviews

141

131

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Within the range of photon energies illuminating the Earth's surface, absorption of a photon by a conventional photovoltaic semiconductor device results in the production of a single electron-hole pair; energy of a photon in excess of the semiconductor's bandgap is efficiently converted to heat through electron and hole interactions with the crystal lattice. Recently, colloidal semiconductor nanocrystals and nanocrystal films have been shown to exhibit efficient multiple electron-hole pair generation from a single photon with energy greater than twice the effective band gap. This multiple carrier pair process, referred to as multiple exciton generation (MEG), represents one route to reducing the thermal loss in semiconductor solar cells and may lead to the development of low cost, high efficiency solar energy devices. We review the current experimental and theoretical understanding of MEG, and provide views to the nearterm future for both fundamental research and the development of working devices which exploit MEG. MEG E g E hνAbsorption of a single photon with energy in excess of two times the band gap, Eg, produces multiple excitons at the band edge. TEM picture of typical PbSe nanocrystals.

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“…A c c e p t e d M a n u s c r i p t 27 Recently, a nonadiabatic molecular dynamics method was established [39,102] in order to simulate the electron relaxation process in QDs [103][104][105]. The method has been used to investigate different systems, as discussed below.…”

Section: Electron-phonon Relaxationmentioning

confidence: 99%

“…The method has been used to investigate different systems, as discussed below. For further reading, please, consult references [39,46,[103][104][105][106][107][108][109][110][111][112][113].…”

Section: Electron-phonon Relaxationmentioning

confidence: 99%

“…However, PbSe QDs exhibit ultrafast intraband charge-phonon relaxation signifying that no phonon bottleneck exists [120,121]. Taking Figure 12 presents the relaxation dynamics of electron and hole, by coupling to phonons [25,103,105]. The charge carriers visit many states during relaxation, and none of the intermediate states plays a special role.…”

Section: Relaxation In Semiconductor Nanocrystalsmentioning

confidence: 99%

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Time-domain ab initio modeling of excitation dynamics in quantum dots

Neukirch¹,

Hyeon‐Deuk²,

Prezhdo³

2014

Coordination Chemistry Reviews

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The review discusses the results of ab initio time-dependent density functional theory and nonadiabatic molecular dynamics simulations of photoinduced dynamics of charges, excitons, plasmons, and phonons in semiconductor and metallic quantum dots (QD). The simulations create an explicit timedomain representation of the excited-state processes, including elastic and inelastic electron-phonon scattering, multiple exciton generation, fission, and recombination. These nonequilibrium phenomena control the optical and electronic properties of QDs. Our approach can account for QD size and shape, as well as chemical details of QD structure, such as dopants, defects, core/shell regions, surface ligands, and unsaturated bonds. Each of these variations significantly alters the properties of photoexcited QDs.The insights reported in this review provide a comprehensive understanding of the excited-state dynamics in QDs and suggest new ways of controlling the photo-induced processes. The design principles that follow, guide development of photovoltaic cells, electronic and spintronic devices, biological labels, and other systems rooted in the unique physical and chemical properties of nanoscale materials.

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Ab Initio Time-Domain Study of Phonon-Assisted Relaxation of Charge Carriers in a PbSe Quantum Dot

Cited by 112 publications

References 67 publications

Electronic Properties of DNA Base Molecules Adsorbed on a Metallic Surface

Electronic Properties of DNA Base Molecules Adsorbed on a Metallic Surface

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Time-domain ab initio modeling of excitation dynamics in quantum dots

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