arXiv subjects

Shota Ono

Publications and source records attributed to Shota Ono.

46 records · Page 3Linked to original sources

arXiv2016

Combined impact of entropy and carrier delocalization on charge transfer exciton dissociation at the donor-acceptor interface

Several models of the charge transfer exciton (CTE) have been proposed to explain its dissociation at the donor-acceptor (DA) interface. However, the underlying physics is still under debate. Here, we derive temperature ($T$)-dependent tight-binding model for an electron-hole pair at the DA interface. The main finding is the existence of the localization-delocalization transition at a critical $T$, which can explain the CTE dissociation. The present study highlights the combined effect of entropy (finite-$T$) and carrier delocalization in the CTE dissociation.

cond-mat.mes-hall↗

arXiv2016

Linear response theory for electron-hole pair kinetics: exciton formation

A linear response theory for electron-hole pair density is developed, which constitutes a new theoretical method, and a definition of exciton density in a first-principles context is derived by considering both the electron-hole attractive interaction and the screening effect. This allows the exciton time evolution to be examined. This formulation is applied to a jellium model in order to prove the existence of a transient exciton, and to observe crossover from a transient to a stable exciton in response to decreased electron density. The exciton formation mechanism is also revealed.

cond-mat.str-el↗

arXiv2016

Minimal model for charge transfer excitons at the dielectric interface

Theoretical description of the charge transfer (CT) exciton across the donor-acceptor interface without the use of a completely localized hole (or electron) is a challenge in the field of organic solar cells. We calculate the total wavefunction of the CT exciton by solving an effective two-particle Schrodinger equation for the inhomogeneous dielectric interface. We formulate the magnitude of the CT and construct a minimal model of the CT exciton under the breakdown of inversion symmetry. We demonstrate that both a light hole mass and a hole localization along the normal to the dielectric interface are crucial to yield the CT exciton.

cond-mat.mes-hall↗

arXiv2015

Tomonaga-Luttinger liquid theory for metallic fullurene polymers

We investigate the low energy behavior of local density of states in metallic C$_{60}$ polymers theoretically. The multichannel bosonization method is applied to electronic band structures evaluated from first principles calculation, by which the effects of electronic correlation and nanoscale corrugation in the atomic configuration are fully taken into account. We obtain a closed-form expression for the power law anomalies in the local density of states, which successfully describes the experimental observation on the \fu polymers in a quantitative manner. An important implication from the closed-form solution is the existence of an experimentally unobserved crossover at nearly a hundred milli-electron volts, beyond which the power law exponent of the \fu polymers should change significantly.

cond-mat.mes-hall↗

arXiv2012

Unifying explanation for carrier relaxation anomaly in gapped systems

We develop a theory to describe energy relaxation of photo-excited carriers in low-temperature ordered states with band gap opening and formulate carrier relaxation time $τ$ near and below transition temperature $T_{\mathrm{c}}$ by quantifying contributions from different carrier-phonon scatterings to the relaxation rate. The theory explains anomalous experimental observations of $τ$ in gapped systems. Transverse acoustic (TA) phonon modes play a crucial role in carrier relaxation; their heat capacity determines $τ$-divergence near $T_{\mathrm{c}}$. The theory is validated by fitting $τ$ of fullerene polymers onto a theoretical curve.

cond-mat.mes-hall↗

arXiv2011

Flexible control of the Peierls transition in metallic C$_{60}$ polymers

The metal-semiconductor transition of peanut-shaped fullerene (C$_{60}$) polymers is clarified by considering the electron-phonon coupling in the uneven structure of the polymers. We established a theory that accounts for the transition temperature $T_c$ reported in a recent experiment and also suggests that $T_c$ is considerably lowered by electron doping or prolonged irradiation during synthesis. The decrease in $T_c$ is an appealing phenomenon with regard to realizing high-conductivity C$_{60}$-based nanowires even at low temperatures.

cond-mat.mes-hall↗

arXiv2011

Phonon dispersion and electron-phonon interaction in peanut-shaped fullerene polymers

We reveal that the periodic radius modulation peculiar to one-dimensional (1D) peanut-shaped fullerene (C$_{60}$) polymers exerts a strong influence on their low-frequency phonon states and their interactions with mobile electrons. The continuum approximation is employed to show the zone-folding of phonon dispersion curves, which leads to fast relaxation of a radial breathing mode in the 1D C$_{60}$ polymers. We also formulate the electron-phonon interaction along the deformation potential theory, demonstrating that only a few set of electron and phonon modes yields a significant magnitude of the interaction relevant to the low-temperature physics of the system. The latter finding gives an important implication for the possible Peierls instability of the C$_{60}$ polymers suggested in the earlier experiment.

cond-mat.mes-hall↗

arXiv2010

Manipulating the Tomonaga-Luttinger exponent by electric field modulation

We establish a theoretical framework for artificial control of the power-law singularities in Tomonaga-Luttinger liquid states. The exponent governing the power-law behaviors is found to increase significantly with an increase in the amplitude of the periodic electric field modulation applied externally to the system. This field-induced shift in the exponent indicates the tunability of the transport properties of quasi-one-dimensional electron systems.

cond-mat.mes-hall↗

arXiv2009

Low-Temperature Resistivity Anomalies in Periodic Curved Surfaces

Effects of periodic curvature on the the electrical resistivity of corrugated semiconductor films are theoretically considered. The presence of a curvature-induced potential affects the motion of electrons confined to the thin curved film, resulting in a significant resistivity enhancement at specific values of two geometric parameters: the amplitude and period of the surface corrugation. The maximal values of the two parameters in order to observe the corrugation-induced resistivity enhancement in actual experiments are quantified by employing existing material constants.

cond-mat.mes-hall↗

arXiv2009

Tuning the electrical resistivity of semiconductor thin films by nanoscale corrugation

The low-temperature electrical resistivity of corrugated semiconductor films is theoretically considered. Nanoscale corrugation enhances the electron-electron scattering contribution to the resistivity, resulting in a stepwise resistivity development with increasing corrugation amplitude. The enhanced electron scattering is attributed to the curvature-induced potential energy that affects the motion of electrons confined to a thin curved film. Geometric conditions and microscopic mechanism of the stepwise resistivity are discussed in detail.

cond-mat.mes-hall↗