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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: Through controlled annealing of intimately mixed blends of the polyfluorene copolymers poly(9,9‘-dioctylfluorene-co-bis(N,N‘-(4,butylphenyl))bis(n,N'-phenyl-1,4-phenylene)diamine) (PFB) and poly( 9,9'dioectylflluorenes-co)-benzothiadiazole) (F8BT) as discussed by the authors, the authors observed the change
Abstract: Through controlled annealing of intimately mixed blends of the polyfluorene copolymers poly(9,9‘-dioctylfluorene-co-bis(N,N‘-(4,butylphenyl))bis(N,N‘-phenyl-1,4-phenylene)diamine) (PFB) and poly(9,9‘-dioctylfluorene-co-benzothiadiazole) (F8BT) we observe the change in charge generation dynamics and photovoltaic performance as the length of nanoscale phase separation is varied from 5 nm or less to greater than 40 nm. We find that device efficiency is optimized for a phase separation of ∼20 nm, significantly larger than the exciton diffusion length of ∼5−10 nm. Femtosecond time-resolved transient absorption measurements confirm that the charge generation time is longer and charge generation efficiency is lower in films with a more evolved morphology. Photoluminescence quantum efficiency is also observed to monotonically increase with annealing temperature consistent with a decrease in exciton dissociation resulting from a coarsening of phases. Using a Monte Carlo model of exciton diffusion and dissociation ...
219 citations
TL;DR: In this paper, optical absorption spectra and excitons in conjugated polymers from first principles were investigated. And the calculated exciton wave functions were very extended in real space.
Abstract: We investigate optical absorption spectra and excitons in conjugated polymers from first principles. This is done by calculating the one-particle and the two-particle Green{close_quote}s function, including relevant many-body effects, and evaluating quasiparticle and optical excitations. Trans-polyacetylene and poly-phenylene-vinylene are studied as prototype long chain polymers. The electron-hole interaction gives rise to large exciton binding energies ({approximately}1 thinspthinspeV) and dramatically alters the optical spectra. The calculated exciton wave functions are very extended in real space. {copyright} {ital 1999} {ital The American Physical Society}
219 citations
TL;DR: In this paper, coherent acoustic phonons were observed in PbS quantum dots using femtosecond optical techniques, and the phonons are generated through the deformationpotential coupling to the quantum-dot exciton.
Abstract: Coherent acoustic phonons in PbS quantum dots are observed using femtosecond optical techniques. This is the first observation of coherent acoustic phonons in a semiconductor quantum dot; the phonons are generated through the deformation-potential coupling to the quantum-dot exciton. The acoustic modes are weakly damped, and we also find extremely weak coupling ( $S\ensuremath{\sim}0.01$) to the optical modes. These conclusions have important consequences for the vibronic nature of the exciton transition in the quantum dot and its dephasing.
219 citations
TL;DR: In this article, the authors provide a complete theory of absorption, which incorporates both static and dynamic effects of Fermi sea, and analyze frequency and doping dependence of optical conductivity in detail.
Abstract: Monolayer two-dimensional transition metal dichalcogenide (TMDCs) exhibit exceptionally strong spin-orbit and electron-electron interaction effects and have provided a rich new playground for the exploration of exciton physics. Recent experiments have demonstrated that in the presence of excess charge carriers the prominent excitonic features in optical absorption split into two separate peaks. The appearance of the additional peak is usually attributed to the presence of trions, charged fermionic quasiparticles formed by binding two electrons to one hole or two holes to one electron. The authors here argue that in the density range for which amplitudes of two peaks are comparable three-particle physics is of importance, and the appropriate picture is one of excitons interacting with the Fermi sea formed by additional charge carriers. These interactions result in the dressing of excitons into exciton-polarons. The exciton spectrum splits into a lower energy attractive exciton-polaron branch, normally identified as a trion branch, and a higher energy repulsive exciton-polaron branch, normally identified as an exciton branch. The authors provide a complete theory of absorption, which incorporates both static and dynamic effects of Fermi sea, and analyze frequency and doping dependence of optical conductivity in detail. The calculated density dependence of peak splitting and their amplitudes and widths are in agreement with recent experiments.
219 citations
TL;DR: This corrects the article DOI: 10.1038/srep24105 to indicate that the author of the paper is a doctor of medicine rather than a scientist, as previously reported.
Abstract: Scientific Reports 6: Article number: 24105; published online: 07 April 2016; updated: 05 April 2018. This article contains an error in Figure 2, where the same image was inadvertently shown in both panel (a) and (b). The correct Figure 2 appears below:
218 citations