Preparation Of Active Layer Research Articles

Poly(3‐hexylthiophene) Fibers for Photovoltaic Applications

AbstractA new method for the preparation of active layers of polymeric solar cells without the need for thermal post‐treatment to obtain optimal performance is presented. Poly(3‐hexylthiophene) (P3HT) nanofibers are obtained in highly concentrated solutions, which enables the fabrication of nanostructured films on various substrates. Here, the preparation of these fibers along with their characterization in solution and in the solid state is detailed. By mixing these nanofibers with a molecular acceptor such as [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) in solution, it is possible to obtain in a simple process a highly efficient active layer for organic solar cells with a demonstrated power conversion efficiency (PCE) of up to 3.6 %. The compatibility of the room‐temperature process developed herein with commonly used plastic substrates may lead to applications such as the development of large‐area flexible solar cells.

A modified method for the characterisation and activity determination of large area sources

Large area sources emitting alpha and beta radiations, respectively, are often used for calibrations of surface contamination monitors and meters. It is well known, however, that their properties are strongly influenced by their construction and by their active layer preparation. Non-uniformity of activity distributions over the active surface and the thickness of absorption and backscattering layers cause changes not only in the ratio of particle emission rate and activity but also in emitted particle spectra distributions. Consequently, different sources need to be characterised by one or more parameters related to their emitted particle spectra and used for their activity determination. A modified method based on simple particle absorption spectrometry has been developed. The correlation between a source characteristic parameter and its radiation detection efficiency is utilised for its activity estimation.

Calculating a Characteristic Bulk Current Density in the Cathode of a Hydrogen-Oxygen Fuel Cell with a Solid Polymer Electrolyte

The magnitude of currents of electrodes in hydrogen-oxygen fuel cells of all types is shown to be fully determined by values of the effective coefficient of gas diffusion, the effective coefficient of ionic conduction, and the characteristic bulk current density. The characteristic bulk current density is estimated in two versions for cathodes with Nafion: the catalyst is distributed in the bulk of substrate grains or at their external surface. The currents commensurate with those observed in experiments are given only by the second version. Means of computer-aided simulation are used to imitate the formation of fractal films composed of the catalyst particles on the surface substrate grains. The simulation means made it possible to link the magnitude of the specific surface area of platinum particles with its weight content in substrate grains. Electrochemical characteristics of the cathode with Nafion-the potential dependence of the optimum magnitude of the overall current and the thicknesses of the active layer and the weight of platinum in it, as well as the magnitudes of the optimum current generated by a unit weight of platinum—are calculated. A notion of “ norm” is introduced for the characteristic bulk current density of the cathode. 1 × 10−3 A cm−3 is the electrochemical-process intensity, which the technology of preparation of active layers of cathodes can provide at this stage in the development of fuel cells with a solid polymer electrolyte.

Langmuir-Blodgett deposition and optical diffraction of two-dimensional opal

Download options Please wait... Article information DOI https://doi.org/10.1039/B102162L Article type Paper Submitted 07 Mar 2001 Accepted 02 Oct 2001 First published 30 Oct 2001 Download Citation J. Mater. Chem., 2001,11, 3333-3336 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Langmuir–Blodgett deposition and optical diffraction of two-dimensional opal B. van Duffel, R. H. A. Ras, F. C. De Schryver and R. A. Schoonheydt, J. Mater. Chem., 2001, 11, 3333 DOI: 10.1039/B102162L To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Bart van Duffel Robin H. A. Ras Frans C. De Schryver Robert A. Schoonheydt

Effects of gas impurities in the sputtering environment on the stoichiometry and crystallinity of ZnS:Mn electroluminescent-device active layers

ZnS:Mn electroluminescent (EL) device active layers were prepared using the RF magnetron sputtering method employing a powder target. The active layer was prepared under specified sputtering conditions, and in situ analysis was carried out by quadrupole mass spectroscopy (QMS) and optical emission spectroscopy (OES). The effects of gas impurities as a function of the sputtering environment on the active layer quality, and EL device characteristics were examined. Gas impurities in the sputtering environment were observed by QMS. Gases of mass numbers 18 (H 2O), 28 (CO/N 2), and 32 (O 2) a.m.u. had unfavorable effects on the preparation of the active layer, which demonstrates the importance of reducing the concentration of these gases in the preparation of high quality active layers for EL devices. In the optical emission spectra in sputtering plasma, when the Ar (750.3 nm) peak intensity is normalized as unity, the inverse of emission intensity at 472.2 and 636.2 nm from Zn could be utilized as a quality factor of the sputtering environment.

The Performance of Polycrystalline Silicon Thin film Transistors and CMOS Driving Circuits with Various Active Films

ABSTRACTThe performance of poly-Si TFTs and CMOS circuits with various active films prepared by different deposition processes and annealing methods, such as SPC(Solid Phase Crystallization) and ELA(Excimer Laser Annealing), have been investigated. We have examined the effects of DC characteristics of poly-Si TFT, such as mobility, threshold voltage and ON- OFF- current level, on the dynamic performance of the CMOS circuits.We have fabricated poly-Si TFT devices and CMOS circuits with various process conditions, such as active layer preparation source gases, annealing method, film thickness and source/drain impurity doping. The TFTs with ELA active films exhibit much higher field effect mobility and ON/OFF current ratio than those with SPC active film due to low intragranular trap state density. The TFTs with active film deposited using Si2H6 have higher mobility and sub-threshold slope than those with active film deposited using SiH4 because of the large poly-Si grain size and less grain boundary defects. We have observed that the device ON-current, mobility and VTH are the dominant characteristics to control the operation speed of CMOS circuits. We have also found that the effects of active film thickness and source/drain doping process on the performance of CMOS ring oscillator may not be neglected and that it should be optimized for AMLCD applications.