Browsing by Author "Wu, Hsin-Hui"

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Morphological control of platinum nanostructures for highly efficient dye-sensitized solar cells
(2012)
Li, Lu-Lin
;
Chang, Chia-Wei
;
Wu, Hsin-Hui
;
Shiu, Jia-Wei
;
Wu, Po-Ting
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%.
Nanofabrication of uniform and stabilizer-free self-assembled platinum monolayers as counter electrodes for dye-sensitized solar cells
(2014-08-01)
Li, Lu-Lin
;
Wu, Hsin-Hui
;
Tsai, Chia-Hung
;
Diau, Eric Wei-Guang
;
交大名義發表
We report a two-step dip-coating approach for the fabrication of self-assembled monolayers of platinum nanocrystals (SAM-Pt) with a particle size of similar to 3 nm and that are uniformly deposited on a transparent conducting oxide (TCO) surface to serve as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). In the first step, we prepared a polyol solution containing H2PtCl6 and ethylene glycol at 110 degrees C, in which the reduction kinetics were controlled by adding various proportions of NaOH. In the second step, we immersed a thiol-modified TCO substrate into the polyol solution with monodispersed Pt nanoparticles prepared at pH 3.7 at approximately 295 K to complete the nanofabrication. The DSSC devices using Z907 dye as a photosensitizer and the CE prepared using this SAM-Pt approach attained notable photovoltaic performance (eta = 9.2%) comparable with those fabricated using a conventional thermal decomposition method (eta = 9.1%) or a cyclic electrodeposition method (eta = 9.3%) under the same experimental conditions. We emphasize that the SAM-Pt films feature a clean surface, uniform morphology, narrow size distribution, small Pt loading and great catalytic activity; the present approach is hence not only suitable for DSSCs but also applicable for many other energy-related applications that require platinum as an efficient catalyst.