Eric A. Schiff

Bio: Eric A. Schiff is an academic researcher from Syracuse University. The author has contributed to research in topics: Amorphous silicon & Silicon. The author has an hindex of 28, co-authored 151 publications receiving 3044 citations. Previous affiliations of Eric A. Schiff include Korea University & University of Chicago.

Ambipolar Diffusion of Photocarriers in Electrolyte-Filled, Nanoporous TiO2†

Abstract: We report transient photocurrent measurements on solar cell structures based on dye-sensitized, porous TiO2 films filled with a liquid electrolyte. The measurements are interpreted as ambipolar dif...

The Cosmological Kibble Mechanism in the Laboratory: String Formation in Liquid Crystals

Abstract: The production of strings (disclination lines and loops) has been observed by means of the Kibble mechanism of domain (bubble) formation in the isotropic-nematic phase transition of the uniaxial nematic liquid crystal 4-cyano-49- n -pentylbiphenyl. The number of strings formed per bubble is about 0.6. This value is in reasonable agreement with a numerical simulation of the experiment in which the Kibble mechanism is used for the order parameter space of a uniaxial nematic liquid crystal.

Non-Gaussian transport measurements and the Einstein relation in amorphous silicon.

Abstract: We propose an experimental procedure for testing the Einstein relation for carrier drift and diffusion in semiconductors exhibiting non-Gaussian or dispersive transport. We present corresponding hole time-of-flight and steady-state photocarrier grating measurements in hydrogenated amorphous silicon ( $a\ensuremath{-}\mathrm{S}\mathrm{i}:\mathrm{H}$). For a range of mobilities ${10}^{\ensuremath{-}5}\char21{}{10}^{\ensuremath{-}2}\mathrm{cm}{}^{2}/\mathrm{V}\mathrm{s}$ we find that our estimates of hole diffusion are approximately twice as large as predicted by the Einstein relation and the mobility measurements. We consider the deviation to represent an upper bound to any true failure of the Einstein relation for hole transport in $a\ensuremath{-}\mathrm{S}\mathrm{i}:\mathrm{H}$.

Amorphous Silicon-Based Solar Cells

Abstract: Crystalline semiconductors are very well known, including silicon (the basis of the integrated circuits used in modern electronics), Ge (the material of the first transistor), GaAs and the other III-V compounds (the basis for many light emitters), and CdS (often used as a light sensor). In crystals, the atoms are arranged in near-perfect, regular arrays or lattices. Of course, the lattice must be consistent with the underlying chemical bonding properties of the atoms. For example, a silicon atom forms four covalent bonds to neighboring atoms arranged symmetrically about it. This “tetrahedral” configuration is perfectly maintained in the “diamond” lattice of crystal silicon.

Low-mobility solar cells: a device physics primer with application to amorphous silicon

Abstract: The properties of pin solar cells based on photogeneration of charge carriers into low-mobility materials were calculated for two models. Ideal p- and n-type electrode layers were assumed in both cases. The first, elementary case involves only band mobilities and direct electron–hole recombination. An analytical approximation indicates that the power in thick cells rises as the 1 4 power of the lower band mobility, which reflects the buildup of space-charge under illumination. The approximation agrees well with computer simulation. The second model includes exponential bandtail trapping, which is commonly invoked to account for very low hole drift mobilities in amorphous silicon and other amorphous semiconductors. The two models have similar qualitative behavior. Predictions for the solar conversion efficiency of amorphous silicon-based cells that are limited by valence bandtail trapping are presented. The predictions account adequately for the efficiencies of present a-Si : H cells in their “as-prepared” state (without light-soaking), and indicate the improvement that may be expected if hole drift mobilities (and valence bandtail widths) can be improved.

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

The random walk's guide to anomalous diffusion: a fractional dynamics approach

Abstract: Fractional kinetic equations of the diffusion, diffusion–advection, and Fokker–Planck type are presented as a useful approach for the description of transport dynamics in complex systems which are governed by anomalous diffusion and non-exponential relaxation patterns. These fractional equations are derived asymptotically from basic random walk models, and from a generalised master equation. Several physical consequences are discussed which are relevant to dynamical processes in complex systems. Methods of solution are introduced and for some special cases exact solutions are calculated. This report demonstrates that fractional equations have come of age as a complementary tool in the description of anomalous transport processes.

Nanowire dye-sensitized solar cells

Abstract: Excitonic solar cells1—including organic, hybrid organic–inorganic and dye-sensitized cells (DSCs)—are promising devices for inexpensive, large-scale solar energy conversion. The DSC is currently the most efficient2 and stable3 excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light-harvesting molecules. However, nanoparticle DSCs rely on trap-limited diffusion for electron transport, a slow mechanism that can limit device efficiency, especially at longer wavelengths. Here we introduce a version of the dye-sensitized cell in which the traditional nanoparticle film is replaced by a dense array of oriented, crystalline ZnO nanowires. The nanowire anode is synthesized by mild aqueous chemistry and features a surface area up to one-fifth as large as a nanoparticle cell. The direct electrical pathways provided by the nanowires ensure the rapid collection of carriers generated throughout the device, and a full Sun efficiency of 1.5% is demonstrated, limited primarily by the surface area of the nanowire array.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.