Comparison between the electrical junction properties of H-terminated and methyl-terminated individual Si microwire/polymer assemblies for photoelectrochemical fuel production

The photoelectrical properties and stability of individual p-silicon (Si) microwire/polyethylenedioxythiophene/polystyrene sulfonate:Nafion/n-Si microwire structures, designed for use as arrays for solar fuel production, were investigated for both H-terminated and CH sub(3)-terminated Si microwires....

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Bibliographic Details
Published in:Energy & environmental science 2012-12, Vol.5 (12), p.9789-9794
Main Authors: Yahyaie, Iman, Ardo, Shane, Oliver, Derek R, Thomson, Douglas J, Freund, Michael S, Lewis, Nathan S
Format: Article
Language:English
Subjects:
Addition polymerization
Conducting polymers
Electric wire
Electrical junctions
Fuel production
Ohmic
Silicon
Stability
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Summary:The photoelectrical properties and stability of individual p-silicon (Si) microwire/polyethylenedioxythiophene/polystyrene sulfonate:Nafion/n-Si microwire structures, designed for use as arrays for solar fuel production, were investigated for both H-terminated and CH sub(3)-terminated Si microwires. Using a tungsten probe method, the resistances of individual wires, as well as between individual wires and the conducting polymer, were measured vs.time. For the H-terminated samples, the n-Si/polymer contacts were initially rectifying, whereas p-Si microwire/polymer contacts were initially ohmic, but the resistance of both the n-Si and p-Si microwire/polymer contacts increased over time. In contrast, relatively stable, ohmic behavior was observed at the junctions between CH sub(3)-terminated p-Si microwires and conducting polymers. CH sub(3)-terminated n-Si microwire/polymer junctions demonstrated strongly rectifying behavior, attributable to the work function mismatch between the Si and polymer. Hence, a balance must be found between the improved stability of the junction electrical properties achieved by passivation, and the detrimental impact on the effective resistance associated with the additional rectification at CH sub(3)-terminated n-Si microwire/polymer junctions. Nevertheless, the current system under study would produce a resistance drop of similar to 20 mV during operation under 100 mW cm super(-2) of Air Mass 1.5 illumination with high quantum yields for photocurrent production in a water-splitting device.
ISSN:1754-5692
1754-5706
DOI:10.1039/c2ee23115h