Carrier transport processes in dye sensitized solar cells based on Zn2SnO4 nanostructures studied by intensity modulated photocurrent/photovoltage spectroscopy

In this work, the electron transport and recombination processes in dye sensitized solar cells (DSSCs) based on Zn2SnO4 nanowires and nanoparticles were studied by intensity modulated photocurrent spectroscopy (IMPS)/photovoltage spectroscopy. Two distinct transport time constants were obtained from the IMPS spectra of Zn2SnO4 nanowire-DSSCs, which were associated with a fast, direct transport through the single crystalline structure of the nanowires and a slow, percolation transport that was assisted by the nanowire surface states, respectively. The charge collection efficiency for the fast transport process was close to unity in all the measurements at different light intensities, indicating that the overall charge collection efficiency of nanowire-DSSCs could be enhanced if the slow transport process could be suppressed.