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Enhancing Electron Collection Efficiency and Effective Diffusion Length in Dye-Sensitized Solar Cells



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 TiO2–NP, horizontal TiO2–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 TiO2–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 TiO2–NP cell does. Consequently, a larger effective electron diffusion length is available in the ZnO composite DSSC.