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Flows, Gradients, and Transport Properties
Published in Joel L. Plawsky, Transport Phenomena Fundamentals, 2020
Charge transport and mass transport are intimately related because charges are carried by physical particles such as electrons, holes, or ions, and these can be modeled to move about a medium as molecules do. The flux of charge can be related to the same mechanisms we had for the flux of mass. j→i=j→iD+j→iE+j→iT
Eddy Current Detector Parameters
Published in Don E. Bray, Roderic K. Stanley, Nondestructive Evaluation, 2018
Don E. Bray, Roderic K. Stanley
The resistivity of a metal such as copper is the ratio of the electric field (in volts/meter) within the material to the rate of charge transport per unit cross-sectional area. It may be visualized as the effect of the retarding interactions of the material lattice on the conduction electron cloud, i.e., the current within the conductor.
Halide Perovskite Photovoltaics
Published in Sam Zhang, Materials for Energy, 2020
In view of these, charge mobility and diffusion length affect charge transport process, which are in turn influenced by defect concentration, microstructure and impurity, composition, and band structure. In this section, we discuss the influencing factors along with strategies to enhance the charge transport process.
Numerical investigation of the multi-pin electrohydrodynamic dryer: Effect of cross-flow air stream
Published in Drying Technology, 2019
Chongshan Zhong, Alex Martynenko, Patrick Wells, Kazimierz Adamiak
Three forces drive the motion of positive ions: diffusion, convection, and Coulomb ones. This charge transport creates an electric current, hence the vector of current density () can be defined as: where Dc is the diffusion coefficient of positive ions (m2/s), stands for the normal component of gas velocity vector (m/s); b represents the ion mobility, which is assumed equal to 1.43 × 10−4 m2/(V·s) for positive ions.[17] The second term of Eq. (3)represents effect of charge convection in the direction of current flow. Since this effect is much smaller than the ionic wind velocity, this term is usually neglected.[17] The current density vector must satisfy the law of charge conservation:[18]
Thermoelectric materials and applications for energy harvesting power generation
Published in Science and Technology of Advanced Materials, 2018
Ioannis Petsagkourakis, Klas Tybrandt, Xavier Crispin, Isao Ohkubo, Norifusa Satoh, Takao Mori
In more recent years, Kim et al. [48] have measured the Seebeck coefficient of the PEDOT:PSS and its behavior versus temperature. It was reminiscent of that of a heavily doped semiconductor in the metallic regime of the Mott’s transition. In comparison with other conducting polymers, PEDOT:PSS is solution processible and can be printed in films showing a high electrical conductivity (> 1000 S/cm). Jiang et al. [49] pinpointed that the addition of a high boiling point solvent improved the figure of merit of the conducting polymer due to an enhanced electrical conductivity. The effect of the high boiling point solvents such as dimethylsulfoxide (DMSO) and ethylene glycol (EG) on the thermoelectric properties of PEDOT:PSS was especially highlighted in the work by Kim et al. [50] After bathing the PEDOT:PSS films in DMSO and EG to remove any excess of insulating PSS, they managed to enhance the polymer power factor to 469 μWm−1K−2. Combined with a relatively low thermal conductivity of 0.42 Wm−1K−1, the figure of merit reached 0.42. Palumbiny et al. [51] later demonstrated that this kind of treatment enhances the thin film crystallinity, as the high boiling point solvents act as plasticizers and slow down the crystallization kinetics. As a result, the polymer chains are allowed to rearrange in the thin film, increasing the degree of crystallinity and facilitating the charge transport in the system (Figure 6) [51–53].
Theoretical investigation of the nitrogen-heterocyclic as π-linker in diphenylthienylamine-based dyes adsorbed on TiO2 nanotubes for DSSCs applications
Published in Molecular Physics, 2021
Ohoud S. Al-Qurashi, Nuha Wazzan
The semiconductor electrode is one of the factors that affect the power conversion efficiency of DSSCs. Several studies have been reported semiconductors-based DSSC such as titanium dioxide (TiO2), zinc oxide (ZnO), and tine dioxide (SnO2), [7–10]. TiO2 based DSSC was found as an appropriate photo-electrode compared to other metal oxide semiconductors due to its wide bandgap. In this work, we designed a TiO2 nanotube (TiO2NT) from rutile TiO2. It is composed of 96 atoms (32 Ti atoms and 64 Oxygen atoms), the obtained Ti-O bond lengths after the optimisation/relaxation process are provided in Table SD 1. The suitability of the designed TiO2 surface was evident from the good agreement with the experimental data [11]. The difference between the two values is 1.74 eV. TiO2NT model was used instead of TiO2 film because TiO2NT shows better performance compared to bulk TiO2, according to the literature [12–14]. It has a unique optical property such as strong adsorption capacity, better electron transference paths, high electron mobility, and rises charge transport capacity. This nanostructured TiO2 can attach and adsorb different potential materials. However, up to date, the investigation of their profound structures and applications has not been fully explored [15]. Maybe the work of Hoyer [16] was the first effort to produce titania nanotubes. After that, several attempts were used to prepare TiO2 nanotubes, and the synthesis methods included the electrochemical deposition method, sol–gel techniques, hydro/solvothermal methods, and so on [15]. Various theoretical studies have also attempted to investigate the structural and electronic properties of TiO2NT in different fields [13,17–20].