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/layer 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.