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Exciton
About: Exciton is a research topic. Over the lifetime, 31603 publications have been published within this topic receiving 810642 citations.
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TL;DR: In this article, the time-resolved difference absorption spectra of J-aggregates were measured by femtosecond pump-probe spectroscopy and the induced absorption near the J-band at 20 K was assigned to the transitions from (n + 1)-exciton states (n⩾1).
210 citations
TL;DR: In this article, the trastrong exciton-photon coupling of Frenkel molecular excitons is demonstrated at room temperature in a metal-clad microcavity containing a thin film of 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9, 9,9 di(4)-fluorene, and the results are interpreted in terms of the full Hopfield Hamiltonian, including anti-resonant terms.
Abstract: Ultrastrong exciton–photon coupling of Frenkel molecular excitons is demonstrated at room temperature in a metal-clad microcavity containing a thin film of 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl)fluorene. A giant Rabi splitting of Ω ∼ 1 eV is measured using angle-resolved reflectivity and bright photoluminescence is observed from the lower polariton branch. To obtain the virtual photon and exciton content of the polariton ground state, the results are interpreted in terms of the full Hopfield Hamiltonian, including anti-resonant terms. Also included is an analytical treatment of the often ignored and sometimes misinterpreted TM-polarized metal–insulator–metal plasmon–polariton.
210 citations
TL;DR: First-order perturbation theory is applied, in which an explicit form of the Coulomb-coupling operator that takes into account interface-polarization effects is used to analyze the exciton-exciton interaction energy as a function of the core and shell sizes and their dielectric properties.
Abstract: We study theoretically two electron-hole pair states (biexcitons) in core/shell hetero-nanocrystals with type II alignment of energy states, which promotes spatial separation of electrons and holes. To describe Coulomb interactions in these structures, we apply first-order perturbation theory, in which we use an explicit form of the Coulomb-coupling operator that takes into account interface-polarization effects. This formalism is used to analyze the exciton-exciton interaction energy as a function of the core and shell sizes and their dielectric properties. Our analysis shows that the combined contributions from quantum and dielectric confinement can result in strong exciton-exciton repulsion with giant interaction energies on the order of 100 meV. Potential applications of strongly interacting biexciton states include such areas as lasing, nonlinear optics, and quantum information.
209 citations
TL;DR: In this article, a standardized formulation for the lineshape problem was introduced, and the effect of lattice vibrations on the exciton absorption was used in a Monte Carlo calculation of the density of exciton states and the absorption spectra in the regime of weak scattering.
Abstract: A standardized formulation is introduced for the lineshape problem–the effect of lattice vibrations on the exciton absorption, and used in a Monte-Carlo calculation of the density of exciton states and the absorption spectra in the regime of weak scattering. For the direct edge, we obtain the asymmetric lineshape with a strongly decaying low-energy side while the high-energy side can be approximated by a life-time broadened Lorentzian. The linewidth is found to depend on temperature as T 2/3 , T 1 and T 3/2 for one-, two-, and three-dimensional lattices in agreement with renormalized perturbation theory in one and two dimensions. The discrepancy of the perturbational result ( T 2 ) in three dimensions is ascribed to the density of states which is most sensitive to disorder in this case. The shift of the absorption peak is found to be linear in T for low T , the origin of its sublinear behaviour for higher T is clarified.
209 citations
TL;DR: In this paper, the passivating effects of spincoated films of Na2S⋅9H2O on GaAs surfaces have been studied using roomtemperature photoluminescence (PL) and low-temperature PL spectroscopy.
Abstract: The passivating effects of spin‐coated films of Na2S⋅9H2O on GaAs surfaces have been studied using room‐temperature photoluminescence (PL) and low‐temperature PL spectroscopy. After passivation, the 300 K PL efficiency is increased on both n‐ and p‐type material; improvements of up to 2800× are observed. The surface field and surface recombination‐related notch features in the free and bound exciton emission spectra at low temperature are eliminated, implying that the residual band bending under illumination is less than 0.15 V.
209 citations