The role played by the counter electrode (CE) in quantum dot sensitized solar cells (QDSSCs) is crucial: it is indeed responsible for catalyzing the regeneration of the redox electrolyte after its action to take back the oxidized light harvesters to the ground state, thus keeping the device active and stable. The activity of CE is moreover directly related to the fill factor and short circuit current through the resistance of the interface electrode-electrolyte that affects the series resistance of the cell. Despite that, too few efforts have been devoted to a comprehensive analysis of this important device component. In this work we combine an extensive electrochemical characterization of the most common materials exploited as CEs in QDSSCs (namely, Pt, Au, Cu2S obtained by brass treatment, and Cu2S deposited on conducting glass via spray) with a detailed characterization of their surface composition and morphology, aimed at systematically defining the relationship between their nature and electrocatalytic activity.
In this work, -Bi Ba Fe Mo O x x 0.8 0.2 13 (x = 0, 0.5, 0.10 and 0.15) ceramics were synthesized by conventional solid-state reaction to evaluate the influence of Ba 2+ and Mo 6+ co-doping on the structure, morphology, electrical, magnetic and optical properties of BiFeO 3 ceramic. Rietveld refinement of x-ray diffraction data was done to obtain the subtle structural information. A tetragonal structure of P4mm type was revealed for Bi Ba FeO 0.8 0.2 3 (x = 0) ceramic. Evolution of rhombohedral (R3c) phase was observed with Mo 6+ doping and a complete transformation to R3c phase from P4mm was found for 15 wt% Mo 6+ doping. This type of transformation causes distortion in the structure and results in changing bond angle. Magnetization was found to be improved with increasing the percentage of Mo 6+ up to 10 wt%. Canting of spin due to the change in Fe-O-Fe bond angle is believed to be the main reason behind this improvement. One secondary phase BaMoO 4 was found and becomes prominent with Mo 6+ doping. Possible formation of this impurity and its correlation with properties are explained. Microstructural analysis was done to observe the Ba 2+ and Mo 6+ co-doping effect on grain size and distribution. A correlation of grain size with electric and magnetic properties is drawn and elucidated. Dielectric constant shows an increasing trend with Mo 6+ doping. Reduction in oxygen vacancy, due to charge compensation upon high charged Mo 6+ addition, believed to be the staple reason behind the dielectric constant increment. Lastly, optical band gap energy found to be decreased with the addition of Mo 6+ and possible reasons behind this are evaluated. Overall, codoping of Ba 2+ and Mo 6+ found to have a positive influence over materials electrical, optical as well as magnetic property.
Grooves were etched in a conductive layer of a conductive, transparent glass, and a nanoporous TiO 2 film was deposited on both the conductive and nonconductive area. The width of the grooves was 100 μm and 150 μm. A transparent TiO 2 film was dye-sensitized, covered with an electrolyte, and sandwiched with a cover glass. The conductivity of the dye-sensitized TiO 2 film permeated with electrolyte was studied in the dark and under illumination, and was observed to be dependent on light intensity, wavelength and applied voltage. This study shows that dye-sensitized nanoporous films can be used as a wavelength dependent photoconductor.
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