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Band edge control of crystalline silicon by chemical functionalization of the surface

Plymale, Noah T. and Ramachandran, Anshul A. and Lim, Allison N. and Brunschwig, Bruce S. and Lewis, Nathan S. (2015) Band edge control of crystalline silicon by chemical functionalization of the surface. In: 250th American Chemical Society National Meeting & Exposition, August 16-20, 2015, Boston, MA.

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Methyl-termination of the silicon (111) crystal plane has been shown to yield nearly complete termination of the silicon atop sites with Me groups to yield exceptional stability to oxidn. and low elec. defect densities at the surface. However, Me groups impart a -0.4 eV surface dipole that shifts the semiconductor band-edge positions of p-type silicon unfavorably for the prodn. of fuels, namely hydrogen, from sunlight. Incorporation of electroneg. elements, such as fluorine, into alkyl monolayers can effectively reverse the unfavorable shift on the band-edge positions and maximize the efficiency of solar-fuels devices. Thus, a mixed methyl/4- fluorobenzyl monolayer has been developed herein to shift the band-edge positions on a sliding scale while maintaining low elec. defect densities at the surface. The band-edge positions were detd. using electrochem. measurements and photoelectron spectroscopy to develop a relationship between the band-edge positions and the monolayer compn. Samples with favorable band-edge positions for the prodn. of hydrogen were tested electrochem. to demonstrate the improved efficiency of devices fabricated using mixed methyl/4-fluorobenzyl monolayers compared with homogeneous Me monolayers. This work holds promise to motivate the development of a new class of solar-fuels devices based on chem. functionalization of semiconductor surfaces.

Item Type:Conference or Workshop Item (Paper)
Related URLs:
URLURL TypeDescription Website
Plymale, Noah T.0000-0003-2564-8009
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2015 American Chemical Society.
Record Number:CaltechAUTHORS:20150923-082551116
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60435
Deposited By: Tony Diaz
Deposited On:23 Sep 2015 19:48
Last Modified:03 Oct 2019 08:57

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