4 research outputs found
One-dimensional semiconductor in a polar solvent: Solvation and low-frequency dynamics of an excess charge carrier
Due to solvation, excess charge carriers on 1d semiconductor nanostructures
immersed in polar solvents undergo self-localization into polaronic states.
Using a simplified theoretical model for small-diameter structures, we study
low-frequency properties of resulting 1d adiabatic polarons. The combined
microscopic dynamics of the electronic charge density and the solvent leads to
macroscopic Langevin dynamics of a polaron and to the appearance of local
dielectric relaxation modes. Polaron mobility is evaluated as a function of
system parameters. Numerical estimates indicate that the solvated carriers can
have mobilities orders of magnitude lower than the intrinsic values.Comment: Typo in Eq.(12) has been correcte
Correlated theory of triplet photoinduced absorption in phenylene-vinylene chains
In this paper we present results of large-scale correlated calculations of
triplet photoinduced absorption (PA) spectrum of oligomers of
poly-(para)phenylenevinylene (PPV) containing up to five phenyl rings. In
particular, the high-energy features in the triplet PA spectrum of oligo-PPVs
are the focus of this study, which, so far, have not been investigated
theoretically, or experimentally. The calculations were performed using the
Pariser-Parr-Pople (PPP) model Hamiltonian, and many-body effects were taken
into account by means of multi-reference singles-doubles configuration
interaction procedure (MRSDCI), without neglecting any molecular orbitals. The
computed triplet PA spectrum of oligo-PPVs exhibits rich structure consisting
of alternating peaks of high and low intensities. The predicted higher energy
features of the triplet spectrum can be tested in future experiments.
Additionally, theoretical estimates of exciton binding energy are also
presented.Comment: To appear in Phys. Rev.
Large scale numerical investigation of excited states in poly(phenylene)
A density matrix renormalisation group scheme is developed, allowing for the
first time essentially exact numerical solutions for the important excited
states of a realistic semi-empirical model for oligo-phenylenes. By monitoring
the evolution of the energies with chain length and comparing them to the
experimental absorption peaks of oligomers and thin films, we assign the four
characteristic absorption peaks of phenyl-based polymers. We also determine the
position and nature of the nonlinear optical states in this model.Comment: RevTeX, 10 pages, 4 eps figures included using eps