Nanofabrication of uniform and stabilizer-free self-assembled platinum monolayers as counter electrodes for dye-sensitized solar cells

Abstract

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 B3 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 H 2 PtCl 6 and ethylene glycol at 110 1C, 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 (Z ¼ 9.2%) comparable with those fabricated using a conventional thermal decomposition method (Z ¼ 9.1%) or a cyclic electrodeposition method (Z ¼ 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.

Photofabrication of Highly Transparent Platinum Counter Electrodes at Ambient Temperature for Bifacial Dye Sensitized Solar Cells

“…Liquid electrolytes are usually comprised of iodide/triiodide (I − /I 3− ) and cobalt complexes (Co 2+ /Co 3+ ) redox couples 16 , 17 . Highly electrocatalytic materials like platinum (Pt) are used to reduced I 3− to I − at the interface of the electrolyte/CE in order to sustain the flow of current and regenerate molecules of the oxidized sensitizer in the DSSCs devices 18 , 19 .…”

Improving catalyst stability in nano-structured solar and fuel cells

“…Different methods have been used to deposit Pt onto the CE substrate including thermally platinized [22][23][24], sputtering [22][23][24]26], chemical deposition [22,[28][29][30], electrochemical deposition [22,[30][31][32][33][34][35], spin coating [22,36,37], dip coating [22,38,39], screen printing [40,41] and spray coating utilizing electrostatic inkjet printing [42]. These deposition methods have some advantages and limitations.…”

“…using polymer as CE substrates. It was found that deposition method affects the performance of the Pt catalyst on CE substrate [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. One of the prominent advantages of using Pt catalyst is that it makes it possible to achieve semi-transparent DSCs.…”

Utilization of Size-Controlled Squid Ink Particles as Enhancer for the Porosity of Titania Electrode in Dye-Sensitized Solar Cell

“…TiO 2 particles with a diameter of a few hundred nanometers have been continually used for scattering layers, because such large particles can diffuse visible light. [29][30][31] In the TiO 2 film electrodes using large particles, dye aggregation occurred on intergranular pores owing to the physical adsorption of the dye molecule, which was responsible for the low electron injection yield. 32) If one fabricated an active layer consisting of TiO 2 particles with a diameter of approximately 30 nm, further enhancement of the PCE would be expected.…”