Fluorine-doped tin oxide (FTO) thin films were prepared, at different substrate temperatures, using dilute precursor solutions of di(n-butyl)tin(iv) diacetate (0.1 M DBTDA) by varying the F− concentration in the solution. Morphology of SEM image revels that grain size and its distribution are affected by the substrate temperature. At the lowest temperature (400°C) the grain size become the smallest and at the highest temperature grain size become larger while at moderate temperature it has a large distribution of grain sizes. XPS calculation reveals that fluorine doping will decrease when substrate temperature is increased. Carrier concentration measured from hall coefficient analysis is found to be varying with the amount of fluorine doping as well as with the surface area of the film. Mobility becomes the lowest for the lowest grained FTO and it is the highest for the largest grained FTO. The best film, has large distribution of grain sizes (50–400 nm), gives an electronic conductivity of 31.85 × 102 Ω−1 cm−1, sheet resistance of 4.4 Ω/square with over 80% transmittance (400–800 nm). Optimum conditions of the best FTO film were 0.1 M DBTDA, 0.3 M ammonium fluoride, in a mixture of propan-2-ol and water, at 470°C substrate temperature. Dye-sensitized solar cells were fabricated using both the FTO films thus prepared and with the commercial FTO film. The best efficiency of 6.48% was observed for the cell fabricated from the best FTO films prepared at 470°C whereas the cells fabricated from the commercial FTO shows 5.30% light-to-electricity conversion efficiency (Illumination–A.M 1.5, Cell active area–1 cm2, MPN based electrolyte–I−/I3−).
Polyaniline (PANI), acts as an electric insulator in the potential region greater than 0.7 V vs. Ag/AgCl. Even in the electroinactive potential region, the redox current of dissolved p-dimethoxybenzene was evident on a PANI film-modified electrode because p-dimethoxybenzene selectively permeates through the PANI film to reach the electrode substrate. For the electro-oxidation of the dissolved p-dimethoxybenzene, analyses of the rotating disk electrode (RDE) voltammograms using a PANI-modified RDE and steady-state current-potential curves using a PANI pellet electrode revealed that p-dimethoxybenzene was concentrated in the PANI during the electro-oxidation. Furthermore, the concentration increased the electric conductivity of PANI.
Porous glass made by phase separation shows large surface area due to the jungle gym structure and high chemical activity due to silanol groups. We performed electrochemical and gravimetric characterization of the adsorbed water in inner surface of porous glass under controlled humidity. Cyclic voltammograms obtained were explained in terms of the electrical resistance of adsorbed water containing H3O+ attributed to silanols and electrochemical reactions at the surface of sputter-deposited Au electrodes. The resistivity at relative humidity of 77% was ca. 104 Ω which was estimated to be 104–108 times smaller than that of silica glass slides. This result corresponds well to the conclusions from surface area value calculated from pore size measurement and gravimetry of adsorbed water.
The poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid) (PEDOT/PSS), in the form of aqueous dispersion of colloidal gel particles, had advantages as a cathode of aluminum solid capacitors due to facile fabrication and high material efficiency and cost performance. In this study, different grades of PEDOT/PSS with various conductivities and particles sizes were used to fabricate the capacitors, and equivalent series resistance (ESR) and capacitance (Cap) were evaluated. It was found that electrical conductivity of the PEDOT/PSS significantly increased by adding ethylene glycol and dimethyl sulfoxide, which reduced the ESR of capacitors at 1 MHz regardless of the particle size. On the other hand, the use of PEDOT/PSS with smaller particle size to fill in the pores of the etched aluminum electrode resulted in a decrease in ESR and increase of Cap at 120 Hz.
The various methods of spectral responsivity measurements for dye-sensitized solar cells (DSCs) were investigated using two starkly different types of cells: one cell involving a 3-Methoxypropionitrile (MPN) as a solvent of an electrolyte and the other, an ionic liquid electrolyte. A linear relationship was observed between the short-circuit current and monochromatic light intensity in the range of 0.05 to 4.0 mW cm−2, not only for the MPN based cell but also for the ionic liquid based cell, although the current response of the ionic liquid based cell was slower probably due to the high electrolyte viscosity. It was found that correct spectral responsivity measurements could be performed by a conventional AC method in which the chopping frequency was adjusted low enough to obtain a steady state current under illumination conditions similar to practical applications. While the spectral responsivity determined by the DC method was higher than that by the AC method under white bias irradiation, the DC method may be considered useful to compare the spectral responsivity of DSCs prepared by different manufacturers since errors caused by the use of a different bias light source by individual manufacturers would be eliminated.