Modeling of radiative - conductive heat transfer in compositing materials

A layer of composite material is investigated, which is heated one-sidedly with one-dimensional energy transfer accounting for thermal conductivity and radiation. A mathematical model is suggested for non-stationary coefficient thermophysical problem under radiative-conductive heat transfer in a material layer. Temperature dependencies of thermal capacity and thermal conductivity coefficient of composite radio-transparent material have been determined through numerical modeling by solving the coefficient reverse problem of thermal conductivity

On Properties of Boundaries and Electron Conductivity in Mesoscopic Polycrystalline Silicon Films for Memory Devices

We present the results of molecular dynamics modeling on the structural properties of grain boundaries (GB) in thin polycrystalline films. The transition from crystalline boundaries with low mismatch angle to amorphous boundaries is investigated. It is shown that the structures of the GBs satisfy a thermodynamical criterion. The potential energy of silicon atoms is closely related with a geometrical quantity -- tetragonality of their coordination with their nearest neighbors. A crossover of the length of localization is observed. To analyze the crossover of the length of localization of the single-electron states and properties of conductance of the thin polycrystalline film at low temperature, we use a two-dimensional Anderson localization model, with the random one-site electron charging energy for a single grain (dot), random non-diagonal matrix elements, and random number of connections between the neighboring grains. The results on the crossover behavior of localization length of the single-electron states and characteristic properties of conductance are presented in the region of parameters where the transition from an insulator to a conductor regimes takes place.Comment: 8 pages, 3 figure

Modeling of radiative - conductive heat transfer in compositing materials

A layer of composite material is investigated, which is heated one-sidedly with one-dimensional energy transfer accounting for thermal conductivity and radiation. A mathematical model is suggested for non-stationary coefficient thermophysical problem under radiative-conductive heat transfer in a material layer. Temperature dependencies of thermal capacity and thermal conductivity coefficient of composite radio-transparent material have been determined through numerical modeling by solving the coefficient reverse problem of thermal conductivity

Dynamics of combined electron beam and laser dispersion of polymers in vacuum

The mechanisms of the impact of the laser assisting effect on the dispersion kinetics and on the structure of the deposited layers in electron beam dispersion of a polymer target were analyzed. The proposed model and analytical expressions adequately describe the kinetic dependence of the polymer materials dispersion rate in a vacuum on the intensity of laser processing of their dispersion zone

Properties of cage rearrangements observed near the colloidal glass transition

We use confocal microscopy to study the motions of particles in concentrated colloidal systems. Near the glass transition, diffusive motion is inhibited, as particles spend time trapped in transient ``cages'' formed by neighboring particles. We measure the cage sizes and lifetimes, which respectively shrink and grow as the glass transition approaches. Cage rearrangements are more prevalent in regions with lower local concentrations and higher disorder. Neighboring rearranging particles typically move in parallel directions, although a nontrivial fraction move in anti-parallel directions, usually from pairs of particles with initial separations corresponding to the local maxima and minima of the pair correlation function $g(r)$, respectively.Comment: 5 pages, 4 figures; text & figures revised in v

Ion-beam sputtering of NiO hole transporting layers for p-i-n halide perovskite solar cells

Ion-beam sputtering offers significant benefits in terms of deposition uniformity and pinhole-free thin-films without limiting the scalability of the process. In this work, the reactive ion-beam sputtering of nickel oxide has been developed for the hole transporting layer of a p-i-n perovskite solar cells (PCSs). The process is carried out by oxidation of the scattered Ni particles with additional post-treatment annealing regimes. Using deposition rate of 1.2 nm/min allowed growth of very uniform NiO coating with the roughness below 0.5 nm on polished Si wafer (15x15 cm2). We performed a complex investigation of structural, optical, surface and electrical properties of the NiO thin-films. The post-treatment annealing (150-300C) was considered as an essential process for improvement of the optical transparency, decrease of defects concentration and gain of the charge carrier mobility. As result, the annealed ion-beam sputtered NiO films delivered a power conversion efficiency (PCE) up to 20.14%, while device without post-treatment reached the value of 11.84%. The improvement of the output performance originated from an increase of the short-circuit current density (Jsc), open circuit voltage (Voc), shunt and contact properties in the devices. We also demonstrate that the ion-beam sputtering of NiO can be successfully implemented for the fabrication of large area modules (54.5 cm2) and PSCs on a flexible plastic substrate (125 microns)