Exciton

About: Exciton is a research topic. Over the lifetime, 31603 publications have been published within this topic receiving 810642 citations.

Observation of solvatochromism in CdSe colloidal quantum dots

Abstract: We report solvatochromatic shifts in the absorption spectra of colloidal CdSe quantum dots that are consistent with the change in polarization energy of the quantum-confined exciton. Good agreement with theory is found when the screening from the ligand shell is included. The polarization energy also accounts for the spectral shift between dilute dispersions and close-packed quantum dot solids. Experiments with pure and mixed-size quantum dot solids suggest that solvatochromism dominates the redshift observed with quantum dot (2--6-nm diameter) solids.

Coherent nonlinear optical response of single quantum dots studied by ultrafast near-field spectroscopy.

Abstract: The nonlinear response of single GaAs quantum dots is studied in femtosecond near-field pump-probe experiments At negative time delays, transient reflectivity spectra show pronounced oscillatory structure around the quantum dot exciton line, providing the first evidence for a perturbed free induction decay of the excitonic polarization Phase-disturbing Coulomb interactions between the excitonic polarization and continuum excitations dominate the optical nonlinearity on ultrafast time scales A theoretical analysis based on the semiconductor Bloch equations accounts for this behavior

Using Resonance Energy Transfer to Improve Exciton Harvesting in Organic-Inorganic Hybrid Photovoltaic Cells**

Abstract: 141.5, 141.2, 140.7, 140.6, 140.2, 140.0, 139.8, 139.7, 139.2, 138.9, 138.6, 135.2, 134.8, 132.5, 132.4, 132.0, 131.6, 130.7, 130.4, 129.4, 129.1, 128.8, 128.0, 127.3, 126.8, 126.1, 90.7 (CCluster), 90.6 (CCluster), 73.1 (CCluster), 73.0 (CCluster). H and C NMR spectra were recorded in deuterated solvents, such as CD2Cl2, on a Bruker DPX 250 and a Bruker DRX 500 spectrometer, using the proton or carbon signal of the solvent as an internal standard. The thermolysis reactions were carried out in sealed quartz tubes in a temperature controlled electromagnetic oven. SEM measurements were performed on a LEO 1530 field-emission scanning electron microscope. High-resolution TEM studies were conducted on a Philips Tecnai F30 analytical TEM at an operating voltage of 300 kV and on a TEM EM420 electron microscope at an operating voltage of 120 kV. The samples were dispersed in ethanol under ultrasonic irradiation and the suspension was dropped onto a TEM copper grid with a carbon film. TGA measurements were performed on a Mettler Toledo TS0801R0 device at a heating rate of 10 °C min between 0 and 900 °C under an inert atmosphere.

Exciton-plasmon coupling interactions: from principle to applications

Abstract: Abstract The interaction of exciton-plasmon coupling and the conversion of exciton-plasmon-photon have been widely investigated experimentally and theoretically. In this review, we introduce the exciton-plasmon interaction from basic principle to applications. There are two kinds of exciton-plasmon coupling, which demonstrate different optical properties. The strong exciton-plasmon coupling results in two new mixed states of light and matter separated energetically by a Rabi splitting that exhibits a characteristic anticrossing behavior of the exciton-LSP energy tuning. Compared to strong coupling, such as surface-enhanced Raman scattering, surface plasmon (SP)-enhanced absorption, enhanced fluorescence, or fluorescence quenching, there is no perturbation between wave functions; the interaction here is called the weak coupling. SP resonance (SPR) arises from the collective oscillation induced by the electromagnetic field of light and can be used for investigating the interaction between light and matter beyond the diffraction limit. The study on the interaction between SPR and exaction has drawn wide attention since its discovery not only due to its contribution in deepening and broadening the understanding of SPR but also its contribution to its application in light-emitting diodes, solar cells, low threshold laser, biomedical detection, quantum information processing, and so on.

Donor bound-exciton excited states in zinc selenide

Abstract: Accurate measurements of donors in selective photoluminescence (SPL) and photoluminescence excitation (PLE) spectra have been made with a tunable dye laser for relatively pure vapor and solution-grown single crystals of ZnSe. The donor species are identified by reference to the work of Merz et al. Very accurate agreement is found for the $1s\ensuremath{-}2s,p$ excitation energies, though not for the absolute photon energies. A new bound exciton (BE) falling just above the donor BE is shown not to involve a further donor species. Improved values are derived for effective-mass donor binding energy, the electron effective mass, static dielectric constant, internal binding energy of the free exciton (FE), and the free-particle band gap in ZnSe. Large differences in the PLE spectra of excitons bound to ionized compared with neutral donors, as well as for neutral acceptors and other BE, are attributed to the dominance of free electron-hole pairs in the excitation channel for the former and FE for the latter luminescence. Landau-level effects appear in the PLE for ionized donor luminescence. New excited BE states appearing just below the $n=2$ FE energies are shown by SPL to involve neutral donors. Their wave-function character is contrasted with the donor bound-exciton excited states just below the $n=1$ FE. The nature of splittings observed in ionized donor BE is discussed.