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Subfemtosecond charge driving with correlation-assisted band engineering in a wide-gap semiconductor
摘要： First-principles calculations indicate that, before falling into dielectric breakdown, charge transport induced by a strong-intensity few-cycle optical waveform in the subfemtosecond time domain can be precisely controlled depending on band distortion engineered by strain along the [0001] direction in wurtzite-AlN. It is further discovered from a model of electron-hole interaction that the subfemtosecond charge driving with band engineering can be substantially strengthened by excitonic correlation and dynamics. With these findings, we reveal band engineering to be a route to the ultrafast charge control of semiconductors and indeed suggest an unexplored prototype of solid-state petahertz (1015 Hz) device.
关键词： petahertz device,subfemtosecond charge driving,exciton correlation,wide-gap semiconductor,band engineering
更新于2025-09-11 14:15:04
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Intrinsically ultrastrong plasmon–exciton interactions in crystallized films of carbon nanotubes
摘要： In cavity quantum electrodynamics, optical emitters that are strongly coupled to cavities give rise to polaritons with characteristics of both the emitters and the cavity excitations. We show that carbon nanotubes can be crystallized into chip-scale, two-dimensionally ordered films and that this material enables intrinsically ultrastrong emitter–cavity interactions: Rather than interacting with external cavities, nanotube excitons couple to the near-infrared plasmon resonances of the nanotubes themselves. Our polycrystalline nanotube films have a hexagonal crystal structure, ～25-nm domains, and a 1.74-nm lattice constant. With this extremely high nanotube density and nearly ideal plasmon–exciton spatial overlap, plasmon–exciton coupling strengths reach 0.5 eV, which is 75% of the bare exciton energy and a near record for room-temperature ultrastrong coupling. Crystallized nanotube films represent a milestone in nanomaterials assembly and provide a compelling foundation for high-ampacity conductors, low-power optical switches, and tunable optical antennas.
关键词： nanotube,crystallized,exciton,plasmon,ultrastrong
更新于2025-09-11 14:12:44
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Dynamics of Frenkel Excitons in Pentacene
摘要： The dispersion relation for noninteracting excitons and the in?uence of perturbative corrections are examined in the case of pentacene structure. The values of exchange integrals are determined by nonlinear ?ts to the experimental dispersion data, obtained by the inelastic electron scattering reported in recent experiments. We obtain theoretical dispersion curves along four different directions in the Brillouin zone which possess the same periodicity as the experimental data. We also show that perturbative corrections are negligible since the exciton gap in the dispersion relation is huge in comparison to the exchange integrals.
关键词： exciton-exciton interactions,effective ?eld theory,Heisenberg model,Frenkel excitons
更新于2025-09-10 09:29:36
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Applied Nanophotonics || Energy transfer processes
摘要： In this chapter, we introduce the general phenomenon of excitation energy transfer, explain radiative and nonradiative types of energy transfer, and derive the basic processes of energy transfer. We look at the F?rster resonance energy transfer (FRET) in particular. We also describe Dexter energy transfer, charge transfer, exciton diffusion, and exciton dissociation. Finally, we summarize the modifications of FRET when using nanostructures with mixed dimensionalities and in different assemblies.
关键词： F?rster resonance energy transfer,nanostructures,FRET,charge transfer,exciton diffusion,energy transfer,Dexter energy transfer,exciton dissociation
更新于2025-09-10 09:29:36
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Molecular Design Strategies for Efficient Intramolecular Singlet Exciton Fission
摘要： The process of carrier multiplication via singlet fission can potentially exceed Shockley–Queisser limit on the efficiency of single-junction photovoltaics. In the recent past, theoretical analysis provided the principal guidelines on molecular design strategies for singlet fission. In this perspective, we focus instead on correlating experimental results for different classes of reported singlet fission materials to identify principles to aid in the design of new molecules for efficient intramolecular singlet fission. Building on an evaluation of several series of multichromophoric and polymeric singlet fission materials, we extract new suggested strategies for molecular design.
关键词： singlet fission,photovoltaics,exciton multiplication,intramolecular singlet fission,molecular design
更新于2025-09-10 09:29:36
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A novel protein binding strategy for energy-transfer-based photoelectrochemical detection of enzymatic activity of botulinum neurotoxin A
摘要： In this work, we propose a novel energy-transfer-based photoelectrochemical (PEC) platform for probing of protein-protein interaction, which associates intimately with zinc-dependent cleavage and substrate specificities in the enzymatic activities of botulinum neurotoxin (BoNT). Specifically, by using substrate protein SNAP-25 as the energy-transfer nanoprobe, an exciton-plasmon interaction (EPI) based strategy between CdS quantum dots (QDs) and Au nanoparticles (NPs) in a PEC system is constructed with the photocurrent declining. Interestingly, the EPI effect is then interrupted by the target botulinum neurotoxin serotype A light chain (BoNT-LCA) special cleavage of the probe SNAP-25, leading to the photocurrent recovery. Therefore, the enzymatic activity of BoNT-LCA could be sensitively detected with a detection limit of 1 pg/mL. Unlike conventional DNA-programable assembly, a protein probe is used to bridge the excitons and plasmons in this work, which provides a new route for the investigation of the EPI-based bioassay.
关键词： CdS QDs,Exciton–plasmon interaction,Energy transfer,Botulinum neurotoxin A,Photoelectrochemical detection
更新于2025-09-10 09:29:36
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Enhanced excitonic emission efficiency in porous GaN
摘要： We investigate the optical properties of porous GaN films of different porosities, focusing on the behaviors of the excitonic features in time-integrated and time-resolved photoluminescence. A substantial enhancement of both excitonic emission intensity and recombination rate, along with insignificant intensity weakening under temperature rise, is observed in the porous GaN films. These observations are in line with (i) the local concentration of electric field at GaN nanoparticles and pores due to the depolarization effect, (ii) the efficient light extraction from the nanoparticles. Besides, the porosification enlarges the surface of the air/semiconductor interface, which further promotes the extraction efficiency and suppresses non-radiative recombination channels. Our findings open a way to increasing the emission efficiency of nanophotonic devices based on porous GaN.
关键词： light extraction,exciton,porous GaN,photoluminescence,depolarization effect
更新于2025-09-10 09:29:36
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A Review on Theoretical Studies of Optical and Electrical Parameters Values of Thin films
摘要： This article provides an overview of research on nanoparticles quantum confinement processing of nanoparticles and processing applications in theoretical concepts of optical and electrical studies. The main text of this review is organized into two sections. Section 1 discusses the use of optical methods for the applications of nanoparticles and its model exciton properties of nanostructured particles and in section 2 discusses for dispersion of agglomerated nanoparticles and its various equations for all, such as photo luminescent and transparent conductive materials. These studies explain the theoretical equations of both nanoparticles and thin film.
关键词： Bohr radius,Exciton,Luminescent,Complex impedence spectroscopy (CIS)
更新于2025-09-10 09:29:36
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Excitonic Tunneling in the AB-bilayer Graphene Josephson Junctions
摘要： We have considered the AB-stacked bilayer graphene tunnel junction construction. The bilayers are supposed to be in the charge equilibrium states and at the half-filling in each of the electronic layers of the construction and at each value of the external gate potential. By considering the interacting bilayers in both sides of the junction and by taking into account both intralayer and interlayer Coulomb interaction effects, we have calculated the normal and excitonic tunnel currents through the junction. The electronic band renormalizations have been taken into account, due to the excitonic pairing effects and condensation in the BLGs. The exact four-band energy dispersions, including the excitonic renormalizations, have been used for the bilayers without any low-energy approximation. The normal and excitonic tunneling currents have been calculated for different values of the gate potential and for different values of the interlayer interaction parameters in both sides of the tunnel junction. We demonstrate the existence of the excitonic Josephson current through the junction which persist even for the non-interacting bilayer graphene junction. For the non-interacting case, the mechanism of the excitonic condensates formation and tunneling between the condensates is attributed to the interlayer hopping between the layers. The role of the charge neutrality point has been discussed in details.
关键词： Exciton condensation,Excitonic pairing,Josephson junction,Bilayer graphene
更新于2025-09-10 09:29:36
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Coupling to Charge Transfer States Is the Key to Modulate the Optical Bands for Efficient Light-Harvesting in Purple Bacteria.
摘要： The photosynthetic apparatus of purple bacteria uses exciton delocalization and static disorder to modulate the position and broadening of its absorption bands, leading to efficient light harvesting. Its main antenna complex, LH2, contains two rings of identical bacteriochlorophyll pigments, B800 and B850, absorbing at 800 nm and at 850 nm, respectively. It has been an unsolved problem why static disorder of the strongly coupled B850 ring is several times larger than that of the B800 ring. Here we show that mixing between excitons and charge transfer states in the B850 ring is responsible for the effect. The linear absorption spectrum of the LH2 system is simulated by using a multi-scale approach with an exciton Hamiltonian generalized to include the charge transfer states that involve adjacent pigment pairs, with static disorder modelled microscopically by molecular dynamics simulations. Our results show that a sufficient inhomogeneous broadening of the B850 band, needed for efficient light-harvesting, is only obtained by utilizing static disorder in the coupling between local excited and inter-pigment charge transfer states.
关键词： exciton delocalization,B850,B800,charge transfer states,purple bacteria,LH2,molecular dynamics simulations,static disorder,bacteriochlorophyll pigments,photosynthetic apparatus,light harvesting
更新于2025-09-10 09:29:36