Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy are employed to measure the dynamics of electron transport and recombination in the ZnO nanowire (NW) array-ZnO/layered basic zinc acetate (LBZA) nanoparticle (NP) composite dye-sensitized solar cells (DSSCs). The roles of the vertical ZnO NWs and insulating LBZA in the electron collection and transport in DSSCs are investigated by comparing the results to those in the TiO(2)-NP, horizontal TiO(2)-NW and vertical ZnO-NW-array DSSCs. The electron transport rate and electron lifetime in the ZnO NW/NP composite DSSC are superior to those in the conventional TiO(2)-NP cell due to the existence of the vertical ZnO NWs and insulating LBZA. It indicates that the ZnO NW/NP composite anode is able to sustain efficient electron collection over much greater thickness than the TiO(2)-NP cell does. Consequently, a larger effective electron diffusion length is available in the ZnO composite DSSC.

Determination of the electrical properties of 1D semiconductor nanostructures is important for material and growth process development as well as for further nanodevice design. Gate-dependent electrical-transport measurements of singlenanowire field-effect transistors (FETs) have been employed to investigate the electrical-transport properties of semiconductor nanowires.[ Apart from the Hall effect measurement for thin-film semiconductor materials, the capacitance-voltage (C-V) measurement is an alternative method of determining the doping concentrations in semiconductors. [5][6][7] Schottky or pn junctions, in which one side of the junction is much more heavily doped than the other side, are employed for C-V analysis. A fixed dc reverse bias with a small ac voltage superimposed on it is applied to the sample to measure the junction capacitance at a fixed frequency. The inverse capacitance squared is a linear function of the applied reverse-biased voltage; from this the built-in potential of the junction and the carrier concentration of the lightly doped side can be estimated from the intercept and the slope, respectively. [5] This Mott-Schottky approach is also taken when a Schottky barrier is formed at the interface of the semiconductor film and electrolyte to monitor the carrier concentrations of the semiconductor electrodes. [8][9][10] C-V

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