Room-temperature plasma enhanced atomic layer deposition of aluminum silicate and its application in dye-sensitized solar cells

Abstract

The authors present a plasma enhanced room-temperature atomic layer deposition (ALD) technique for depositing aluminum silicate on TiO2 photoanodes for dye-sensitized solar cells. In the ALD process, adsorption of the precursor is completed in a two-step process involving sequential application of a subsaturation quantity of tris(dimethylamino)silane (TDMAS) and an Al precursor trimethylaluminum to the target surface. The Al-to-Si atomic ratio is controlled by the initial coverage of TDMAS on the sample surface. Aluminum-silicate coatings with a balanced composition of Al and Si are applied to the TiO2 nanoparticle photoanodes in N719-based dye-sensitized solar cells. A one-cycle ALD coating improves the short circuit current density, suggesting the enhancement of N719 dye adsorption or charge separation at the interface of the dye and TiO2 photoanode. Electro-impedance analysis suggests that the improved power generation does not correlate with the charge recombination of electrons in TiO2 and I3− ions in the redox electrolyte. The mechanism behind the improvement in the coated photoanode samples is discussed in this paper.