Covalent Linking Greatly Enhances Photoinduced Electron Transfer in Fullerene-Quantum Dot Nanocomposites: Time-Domain Ab Initio Study.

Nonadiabatic molecular dynamics combined with time-domain density functional theory are used to study electron transfer (ET) from a CdSe quantum dot (QD) to the C60 fullerene, occurring in several types of hybrid organic/inorganic nanocomposites. By unveiling the time dependence of the ET process, we show that covalent bonding between the QD and C60 is particularly important to ensure ultrafast transmission of the excited electron from the QD photon-harvester to the C60 electron acceptor. Despite the close proximity of the donor and acceptor species provided by direct van der Waals contact, it leads to a notably weaker QD-C60 interaction than a lengthy molecular bridge.

Confinement by carbon nanotubes drastically alters the boiling and critical behavior of water droplets.

Vapor pressure grows rapidly above the boiling temperature, and past the critical point liquid droplets disintegrate. Our atomistic simulations show that this sequence of events is reversed inside carbon nanotubes (CNT). Droplets disintegrate first and at low temperature, while pressure remains low.

Vibrational energy transfer between carbon nanotubes and nonaqueous solvents: a molecular dynamics study.

We report molecular dynamics (MD) simulation of energy exchange between single-walled carbon nanotubes (CNTs) and two aprotic solvents, acetonitrile and cyclohexane. Following our earlier study of hydrated CNTs, we find that the time scales and molecular mechanisms of the energy transfer are largely independent of the nature of the surrounding medium, and therefore, should hold for other media including polymer matrices and DNA. The vibrational energy exchange between CNT and solvents exhibits two time-scales.

Solute-solvent interactions determine the effect of external electric field on the intensity of molecular absorption spectra.

The study of the electronic absorption spectra of 4-aminoazobenzene subjected to an external electric field in nonpolar and polar solvents shows that the field-induced change in the absorption intensity is dominated by the solvent-solute interaction. Moreover, solvent can determine the sign of the change of the absorption intensity. These experimental observations are supported by ab initio electronic structure calculations and are rationalized by analytic theory.

Dynamics of the photoexcited electron at the chromophore-semiconductor interface.

Electron dynamics at molecular-bulk interfaces play a central role in a number of different fields, including molecular electronics and sensitized semiconductor solar cells. Describing electron behavior in these systems is difficult because it requires a union between disparate interface components, molecules and solid-state materials, that are studied by two different communities, chemists and physicists, respectively. This Account describes recent theoretical efforts to bridge that gap by analyzing systems that serve as good general models of the interfacial electron dynamics.