The electron subband structure in a thin (100) silicon film is analyzed based on a two-band k·p theory. For unprimed subbands the dependence of the nonparabolicity parameter on film thickness is obtained. The two-band k·p theory gives a thickness dependence of the effective masses for primed subbands. Limitations of the model are discussed. The importance of the nonparabolicity parameter depend...

Density functional theory calculation was conducted to determine the optoelectronic properties of bismuth titanate sillenite (Bi12TiO20) and perovskite-like (Bi4Ti3O12) structures. The lattice parameters were experimentally obtained from Rietveld analysis. The density functional perturbation theory approach was used with the standard Perdew-Burke-Ernzerhof functional and screened Coulomb hybrid...

A semiempirical theory for the excitation and subsequent relaxation of nonthermal electrons is described. The theory, which applicable to ultrafast-laser excited metals, based on Boltzmann transport equation carrier distribution function $f(\ensuremath{\epsilon},t)$ includes electron-phonon, electron-electron, electron-photon scattering integrals in forms that explicitly depend electronic densi...

The synthesis, characterization, and charge transport performance of novel copolymers PNDIFu2 made from alternating naphthalene diimide (NDI) and bifuran (Fu2) units are reported. Usage of potentially biomass-derived Fu2 as alternating repeat unit enables flattened polymer backbones due to reduced steric interactions between the imide oxygens and Fu2 units, as seen by density functional theory ...

Understanding thermal transport in nanoscale systems presents important challenges to both theory and experiment. In particular, the concept of local temperature at the nanoscale appears difficult to justify. Here, we propose a theoretical approach where we replace the temperature gradient with controllable external blackbody radiations. The theory recovers known physical results, for example, ...

elphbolt is a modern Fortran (2018 standard) code for efficiently solving the coupled electron-phonon Boltzmann transport equations from first principles. Using results density functional and perturbation theory as inputs, it can calculate effect of non-equilibrium phonons on electronic (phonon drag) electrons phononic (electron in fully self-consistent manner obeying constraints mandated by th...

Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extrac...

Thin films of metallically conductive titanium mononitride and carbide were prepared by means of electron beam evaporation. The composition of the samples could be changed over appreciable ranges by introducing nitrogen in the system or adding carbon to the pure starting material, respectively. The transport properties of the resulting compounds were studied as a function of nonstoichiometry an...

We study the tunneling density of states ~DOS! of the interacting electron gas beyond the diffusive limit. A strong correction to the DOS persists even at electron energies exceeding the inverse transport relaxation time, which could not be expected from the well-known Altshuler-Aronov-Lee ~AAL! theory. This correction originates from the interference between the electron waves scattered by an ...

We present a theory of the metal-insulator transition in a disordered two-dimensional electron gas. A quantum critical point, separating the metallic phase, which is stabilized by electronic interactions, from the insulating phase, where disorder prevails over the electronic interactions, has been identified. The existence of the quantum critical point leads to a divergence in the density of st...