Dielectric and AC conductivity studies have been carried out for chitosan-based proton-conducting electrolytes Chitosan-phosphoric acid (CP) and chitosan composite (CPS) electrolytes were prepared using the solution cast method In both systems, the frequency dependence of e r , M i and tan δ is non-Debye type The AC conductivity in both electrolytes follows the Jonscher power law Conduction mechanism studies show that the CP sample follows the quantum mechanical tunneling (QMT) model and the CPS electrolyte follows the overlapping large polaron-tunneling (OLPT) model

Electrical behavior of proton-conducting chitosan-phosphoric acid-based electrolytes

Doubled layered ITO/SnO2 conducting glass for substrate of dye-sensitized solar cells

Ti-10 wt % W alloys were produced via the electrochemical deoxidation of mixed TiO2+WO3 sintered precursors in a molten CaCl2 electrolyte at 1173 K. Fully metallic samples were retrieved after 15 h of reduction. This reduction time was longer than that observed for metallization of (Ti,Mo)O-2 sintered precursors. This was believed to occur as a result of significant differences in the reduction pathway, despite tungsten and molybdenum possessing similar interactions with titanium. It was found that the reduction initiated with the rapid reduction of WO3 to a fine W-Ti particulate. TiO2 then proceeded to reduce sequentially through the lower oxides, with concurrent formation of Ca(Ti,W)O-3. Between 1 and 3 h of reduction the sample is believed to be composed of Ca(Ti,W)O-3 and TiO. A comproportionation reaction between these two phases is then observed, resulting in the formation of W-Ti and CaTi2O4. However homogenization between the product titanium and W-Ti does not take place until the titanium is sufficiently deoxidized; thus, beta-Ti forms late in the reduction process. It is believed that the late formation of beta-Ti in the reduction process, coupled with the lack of a conductive metal oxide network, accounts for the relatively slow reduction time.

The Production of Ti–Mo Alloys from Mixed Oxide Precursors via the FFC Cambridge Process

Polyvinyl alcohol (PVA)-based proton conducting polymer electrolytes have been prepared by the solution cast technique. The conductivity is observed to increase from 10−9 to 10−4 S cm−1 as a result of orthophosphoric acid (H3PO4) addition. The plot of conductivity vs temperature shows that a phase transition occurred at 343 K in the sample PVA-33 wt% H3PO4. The β-relaxation peak is observed at 313 K. The glass transition temperature of PVA-33 wt% H3PO4 is 343 K. Orthophosphoric acid seems to play a dual role, i.e., as a proton source and as a plasticizer. The ac conductivity σac = Aωs was also calculated in the temperature range from 303 to 353 K. The conduction mechanism was inferred by plotting the graph of s vs T from which the conduction mechanism for sample PVA-17 wt% H3PO4 was inferred to occur by way of the overlapping large polaron tunneling (OLPT) model and the conduction mechanism for the sample PVA-33 wt% H3PO4 by way of the correlated barrier height (CBH) model.

Dielectric and conduction mechanism studies of PVA-orthophosphoric acid polymer electrolyte

Solar energy is conceivably the largest source of renewable energy at our disposal, but vital advances are expected to make solar cells economically viable. Biodegradable and flexible solar cells are currently under extensive investigation for environmentally-friendly electronic applications. Biomaterials based solar cell is emerging due to their sustainable, scalable, abundant, renewable, and environmentally-friendly energy production. This review highlights recent research progress in the emerging group of biomaterials and their integration for flexible solar cell devices. The more emphasis is given to the absolute recyclable solar cell technology, processing conditions and optimized processing conditions to produce a high amount of energy. This review briefly describes the recent progress in these classes of material, covering substrates and semiconductors. A prominent demand still exists for a next-generation of flexible, biodegradable and biocompatible solar cell substrate for ultimate energy generation application.

Flexible, biodegradable and recyclable solar cells: a review

Preparation and characterization of MOCVD thin films of indium tin oxide

Preparation and characterization of metallorganic chemical vapour deposited molybdenum (II) oxide (MoO) thin films

Thin films of LixMoyOz have been deposited on glass substrate in a one step chemical vapour deposition using a single source solid precursor. The films were characterized using Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffractometry, Scanning Electron Microscopy (SEM), Impedance Spectroscopy (IS), van der Pauw conductivity measurement and Ultraviolet-Visible Spectroscopy. Results of the characterization showed that the films are dendritic, polycrystalline and semiconducting with an optical transition energy of 3.0 eV. IS characterization gave a semicircle in the complex impedance plot. The conductivity vs. temperature plot showed a transition at 450 °C and also a hysteresis. Analysis showed the film to be mixture of phases.

Preparation and characterization of metallorganic chemical vapour deposited LixMoyOz using a single source solid precursor

period. The deposited films were characterized using Ultraviolet-Visible spectroscopy, X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). A direct optical band gap of 0.46 eV was obtained from the analysis of the absorption spectrum for lead sulphide and 2.17 eV for lead cadmium sulphide thin films. XRD revealed that both films are polycrystalline in nature, with face-centred cubic phase in PbS film and the presence of cubic and hexagonal phases of CdS and cubic phase of PbS in the PbCdS film. SEM micrographs also revealed polycrystalline nature with uniformly distributed grain estimated to be less than 1 µm in size for both films. It also showed that both films have textured surfaces. The EDX showed that both deposited films are non- stoichiometric and are cation deficient.

G. A. Adegboyega

Papers

Preparation and characterization of MOCVD thin films of indium tin oxide

Preparation and characterization of metallorganic chemical vapour deposited molybdenum (II) oxide (MoO) thin films

Preparation and characterization of metallorganic chemical vapour deposited LixMoyOz using a single source solid precursor

Synthesis and some properties of mocvd lead sulphide and lead cadmium sulphide thin films