The Effects of the TiO2 Films Thickness on the Performance of Quasi-Solid Dye-Sensitized Solar Cells

The dye – sensitized solar cell (DSSC) is an attractive and promising device for solar cell applications that have been intensively investigated worldwide. DSSC consists of a namo TiO2 film of the photo electrode, dye molecules absorbed on the surface of TiO2 film, an electrolyte layer and a Pt counter electrode. Among these, the nanoporous TiO2 film plays an important role because it can adsorb a large amount of dye molecules which provide electrons. Therefore, the TiO2 film affects the cell performance. In this paper, the characteristics of DSSCs with different TiO2 film thicknesses were studied by using electrochemical impedance spectroscopy(EIS). The impedance component attributed to TiO2|electrolyte interface indicated that the small semicircle and low characteristic frequency was essential for high performance DSSC. An optimum overall conversion efficiency( ％) of 5.54% was obtained in the DSSC assembled with the TiO2 film thickness of 8.86μm.

A Study of The Viability of Poly(O-Methoxyanhine) Layer-by-Layer Films as Gas Sensors

ABSTRACTThe electrical properties of layer-by-layer films of poly(o-methoxyaniline) (POMA) alternated with poly(vinylsulfonic acid) (PVS) have been investigated as a function of the surrounding atmosphere, in order to probe the sensitivity of POMA/PVS as a gas sensor. The POMA films have their conductivity increased with increasing humidity, near to one order of magnitude higher for 100% relative humidity when compared to nitrogen. The d.c. applied field may affect the POMA films, for these films become practically insulating if the field is applied for a prolonged time (typically 10-20 h) in humid air. In order to circumvent this problem, a.c. impedance measurements were conducted. For samples in nitrogen, oxygen and carbon dioxide, the real part of the complex impedance increases only when the frequency is lowered below 10 kHz. In a humid atmosphere, the onset for the real part occurs at higher frequencies than for dry atmospheres. Furthermore, at a fixed frequency in the range from 10 to 100 kHz this impedance component increases with the relative humidity.