The construction of tandem dye-sensitized solar cells from chemically-derived nanoporous photoelectrodes

A tandem dye-sensitized solar cell (tandem-DSSC) was synthesized on the basis of thin-film semi-conductor electrodes. The nanoporous p-type NiO films were successfully obtained by simultaneous deposition of Al and Ni, followed by selective etching of Al and oxidation. Likewise, the n-type photo-anode was made where Ag was etched in nitric acid after the initial formation of Ag/TiO sub(2) nano-composites. Such dye-sensitized photoelectrodes were combined to construct a tandem solar cell which exhibited an enhanced open-circuit voltage. Also, the tandem devices were subjected to various light fluxes to correlate the experimental cell parameters (open-circuit voltage, short-circuit current, fill factor, recombination shunt resistance, etc.) with the ideal one-diode model. Interestingly, impedance spectra of the tandem cell was well matched with the parameters from each of the n-type or p-type DSSC, indicative of successfully-designed tandem structure.