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2-Methyl-4-propoxypyridine, a new pyridine derivative, has been synthesized and used as an additive in the liquid electrolyte of dye-sensitized solar cells (DSSCs). Compared with 2-methylpyridne and 4-tertpyridine, they were employed to study the influence of the pyridine derivative additives on the rate of recombination at the electrode/dye/electrolyte interfaces and band edge shift of TiO 2 , which were measured by time-resolved mid-infrared absorption spectroscopy and Mott-Schottky analysis, respectively. It was found that the rate of interfacial charge recombination was enhanced when the pyridine derivative additives were present in the electrolyte. Meanwhile, the additives caused a negative shift of the band edge. However, the net effect of pyridine derivative addition was to improve the open-circuit photovoltage according to the photoelectrochemical measurement, indicating that negative shift of conduction band of TiO 2 was a predominant factor in improving the open-circuit photovoltage. Also, the result was strongly supported by the dark current measurement. Therefore, it provides a microscopic account for the function of the pyridine derivative additives on the open-circuit photovoltage enhancement of the DSSCs. Furthermore, the decrease of the short-circuit photocurrent of the cells was also attributed to the slower dye regeneration due to the addition of additives from the results of cyclic voltammetry measurement.

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An effective and versatile room temperature soft chemical route was employed to deposit n-Bi2S3 films followed by p-CuSCN films onto fluorine doped tin oxide (FTO) coated glass substrates. Well optimized preparative parameters led to the formation of a good heterojunction between the n-Bi2S3 and p-CuSCN films without any post-annealing treatment. An interconnected microflake of CuSCN on to the nanocrystalline Bi2S3 film enables a high porous structure in the top layer. The device was completed by ensuring silver as a front and FTO as a back ohmic contact, and exposed to sense the liquefied petroleum gas (LPG) at room temperature (27 °C). The upper porous structure allowed enough room for the gas species to adsorb and de-adsorb easily at the interface. The device exhibited more than 70% response at 1370 ppm of LPG, and the process suggests the possibility to develop a room temperature LPG sensing device with a low cost chemical method.

The ZnO-modified TiO 2 electrode was prepared by adding Zn(CH 3 COO) 2 ·2H 2 O to the TiO 2 colloid during the sol-gel production process, and was used in dye-sensitized solar cells (DSCs). The open circuit voltage (V OC ) and fill factor (ff) of the cells were improved significantly. The performances of the ZnO-modified TiO 2 electrode such as dark current, transient photocurrent, impedance, absorption spectra, and flat band potential (V fb ) were investigated. It is found that the interface charge recombination impedance increases and V fb shifts about 200 mV toward the cathodic potential. The effect mechanism of ZnO modification on the performance of DSCs may be that ZnO occupies the surface states of the TiO 2 film.