Dithiol-capped Cdse nanoparticle Fims prepared by a soft chemistry method.

Bulk heterojunction solar cells require adequuate concentrations of the nanoparticulated n-type semiconductor within the polymeric matrix, but also a good interfacial interaction between the. Thiol and dithiol molecules have been devised as good candidates to provide interaction betwen the components as well as electrical conduction by tunnel effect, with the advantage of polar heads that would increase nanoparticle-nanoparticles structuring in a tridimensional net

STRUCTURAL AND OPTICAL PROPERTIES OF ZnO:Al FILMS PREPARED BY ULTRASONIC SPRAY PYROLYSIS

Thin films of non-stoichiometric and doped metallic oxides of ZnO, In2O3 ,SnO2, CdO, In2O3:Sn (ITO),SnO2:F, In2O3:F, ZnO:Al etc. have attracted a large interest because of their high electrical conductivity and optical transmittance in the visible region of solar spectrum making them suitable for their application in different kinds of opto-electronic devices. Because of the fact that a high conductivity and a high transmittance in the visible region can be achieved simultaneously, they are used as transparent electrodes in thin film solar cells. Among these materials, zinc oxide was felt important compared with tin oxide and indium oxide due to its stability in hydrogen plasma, which is of unique importance in amorphous and microcrystalline silicon areas. The spray technique is one of the most commonly used technique for preparation of transparent and conducting oxides owing to its simplicity, safety, non-vacuum system of deposition and hence inexpensive method for large area coatings. By characterizing the deposition parameters especially the spraying temperature, flow rate and the amount of doping concentration, it is possible to deposit Al-doped ZnO (AZO) thin films having suitable values of sheet resistance and transmittance. Films of zinc oxide doped with Al (ZnO:Al) are prepared using the spray pyrolysis technique. In this work the effect of doping Al on the physical properties of ZnO:Al is studied. Polycrystalline ZnO:Al films with the different Al concentration ([Al]/[Zn] in the starting solution was varied from 0 to 0.2 wt.%) were prepared. We varied the substrate temperature and deposition time. These films were confirmed to show the high crystallinity by X-ray diffraction technique. The optical transmittance was varied form 90% to 40% in visible range depending of the film thickness

CdS SENSITIZED TiO2 NANOCRYSTALLINE PHOTOANODES FOR SOLAR CELLS

Dye-sensitized nanocrystalline solar cells (DSSC) are a promising alternative to conventional p–n junction solar cells. The advantage of DSSCs over other types of photovoltaic cells is the relative simplicity of their assembly. The conventional DSSC is made from a mesoporous TiO2 film with adsorbed organo-ruthenium dye molecules as light absorber. It was shown that in a mixed TiO2/CdS particle system, prior to semiconductor–electrolyte charge transfer, electrons that were photogenerated in the lower band gap CdS, were transferred to the TiO2 while the holes remained in the CdS. In this work we grown CdS sensitized TiO2 photoelectrodes and studied the photoelectrochemical properties. The photoelectrodes were made using nanoparticles of TiO2 (PM25); and nanorods based on nanofibers of TiO2 obtained by electrospinning. The TiO2 nanoparticles and nanorods were sensitized with CdS using chemical bath deposition. The grown of the photoelectrodes over the ITO plates were made using a mixture of Pechini-type sol and TiO2 sensitized; and doctor-blading and sintering. The samples were characterized by X ray Diffraction, Scanning Electron Microscopy, Current-Voltage and Electrochemical Impedance Spectroscopy. A conversion efficiency of 2.5 % was achieved

Stoichiometry Calculation in BaxSr1−xTiO3 Solid Solution Thin Films, Prepared by RF Cosputtering, Using X-Ray Diffraction Peak Positions and Boltzmann Sigmoidal Modelling

A novel procedure based on the use of the Boltzmann equation to model the x parameter, the film deposition rate, and the optical band gap of BaxSr1−xTiO3 thin films is proposed. The BaxSr1−xTiO3 films were prepared by RF cosputtering from BaTiO3 and SrTiO3 targets changing the power applied to each magnetron to obtain different Ba/Sr contents. The method to calculate x consisted of fitting the angular shift of (110), (111), and (211) diffraction peaks observed as the density of substitutional Ba2+ increases in the solid solution when the applied RF power increases, followed by a scale transformation from applied power to x parameter using the Boltzmann equation. The Ba/Sr ratio was obtained from X-ray energy dispersive spectroscopy; the comparison with the X-ray diffraction derived composition shows a remarkable coincidence while the discrepancies offer a valuable diagnosis on the sputtering flux and phase composition. The proposed method allows a quick setup of the RF cosputtering system to control film composition providing a versatile tool to optimization of the process