Atomistic effect of laterally and vertically growth shell on physical behaviours of CdSe/CdTe type-II core/crown and core/shell nanoplatelets: tight-binding theory

Utilizing the atomistic tight-binding theory, the impact of the lateral and vertical potential confinement by the coated shell on the CdSe/CdTe core/crown and core/shell nanoplatelets (NPLs) is attained. The spatial charge separation and encapsulated shell have a noteworthy impact on the electronic structures and optical properties because of the type-II band profile. The reduced band gaps with the growing laterally and vertically passivated shell thicknesses are due to the quantum confinement phenomena. The optical band gaps adjusted across the visible light are achieved by the shell thickness change. The excitonic binding energies of CdSe/CdTe core/shell NPLs are larger than those of CdSe/CdTe core/crown NPLs. Thanks to the spatial charge separation, a shortening of the oscillation strengths is concomitant with an increase of the radiative lifetimes. Overall, this scientific research underlines the importance of the theoretical understanding and practical control by lateral and vertical confinement of heterostructure NPLs.

A comprehensive analytical model for ambipolar transport in nano-dimensional VOPc/p-6P OHJFET for applications in organic electronics

This paper presents a compact analytical DC model for high mobility VOPc (vanadyl pthalocyanine)/p-6P (para-sexiphenyl) ambipolar organic heterojunction field-effect transistor (OHJFET). The proposed model accounts for both unipolar and ambipolar regimes of VOPc/p-6P ambipolar OHJFET by considering spatial charge carrier density in the channel. The model incorporates subthreshold conduction phenomenon in addition to describing beyond threshold transport. The model is extended to describe ambipolar regime occurring in subthreshold region at low drain to source voltage, VDS. Device characteristics and various parameters obtained are presented and are further used to model recombination zone and channel potential profile. Results obtained, are compared with available experimental data and a good match is observed.

Visualization of Spatial Charge in Thermally Poled Glasses via Nanoparticles Formation

It is shown for the first time that the vacuum poling of soda-lime silicate glass and the subsequent processing of the glass in a melt containing silver ions results in the formation of silver nanoparticles buried in the subanodic region of the glass at a depth of 800–1700 nm. We associate the formation of nanoparticles with the transfer of electrons from negatively charged non-bridging oxygen atoms to silver ions, their reduction as well as their clustering. The nanoparticles do not form in the ion-depleted area just beneath the glass surface, which indicates the absence of a spatial charge (negatively charged oxygen atoms) in this region of the vacuum-poled glass. In consequence, the neutralization of the glass via switching of non-bridging oxygen bonds to bridging ones, which leads to the release of oxygen, should occur in parallel with the shift of calcium, magnesium, and sodium ions into the depth of the glass.