Morphological control of platinum nanostructures for highly efficient dye-sensitized solar cells

Abstract

Cyclic electro-deposition (CED) is a cost-effective tool to synthesize nanostructures with a solution process, controllable morphology and high purity. Here we report novel platinum nanostructures fabricated according to CED at room temperature in solution containing H2PtCl6 precursor and NaNO3. Remarkable Pt nanostructures-from nanoclusters, nanosheets, nanograsses to nanoflowers-were produced through morphological control via variation of either period of CED scans or concentration of the precursor. Pt films with uniform nanograss structures have great electrocatalytic performance (electron-transfer resistance = 0.3 Omega) and intrinsic light-scattering (reflectivity similar to 50%), perfectly suitable for use as counter-electrodes for dye-sensitized solar cells (DSSCs). The DSSC device made with the Pt-nanograss counter-electrode and N719 dye attained efficiency eta = 9.61% of power conversion, which is 12% enhanced from that fabricated according to a conventional thermal decomposition method (eta = 8.55%) under similar experimental conditions. When the devices were further optimized with a thick TiO2 film (17 + 5 mu m) sensitized by Z907 dye using the CED-Pt counter-electrode, we obtained J(SC) (mA cm(-2)) = 19.44, V-OC (V) = 0.742, and FF = 0.736, giving an exceptional power conversion efficiency of 10.62%.