TY - JOUR
T1 - Surface Passivation and Positive Band-Edge Shift of p-Si(111) Surfaces Functionalized with Mixed Methyl/Trifluoromethylphenylacetylene Overlayers
AU - Cabán-Acevedo, Miguel
AU - Papadantonakis, Kimberly M.
AU - Brunschwig, Bruce S.
AU - Lewis, Nathan S.
N1 - Funding Information:
M.C. acknowledges support from the Ford Foundation under the Postdoctoral Scholar Fellowship program. B.S.B. and M.C. acknowledge support from the National Science Foundation CCI Solar Fuels Program under grant no. CHE-1305124. N.S.L. and M.C. acknowledges support from the National Science Foundation under grant no. CHE-1808599. Instrumentation support was provided by the Molecular Materials Resource Center of the Beckman Institute at the California Institute of Technology.
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/7/30
Y1 - 2020/7/30
N2 - Chemical functionalization of semiconductor surfaces can provide high-efficiency photoelectrochemical devices through molecular-level control of the energetics, surface dipole, surface electronic defects, and chemical reactivity at semiconductor/electrolyte junctions. We describe the covalent functionalization by nucleophilic addition chemistry of p-Si(111) surfaces to produce mixed overlayers of trifluoromethylphenylacetylene (TFMPA) and methyl moieties. Functionalization of Cl-terminated Si(111) surfaces with TFMPA moieties introduced a positive surface molecular dipole that in contact with CH3CN or Hg produced a positive band-edge shift of the semiconductor relative to junctions with CH3-Si(111) surfaces. Methylation of the Cl/TFMPA surfaces using methylmagnesium chloride resulted in the degradation of the TFMPA moieties, whereas methylation using methylzinc chloride allowed controlled production of mixed TFMPA/methyl-terminated surfaces and permitted reversal of the order of the functionalization steps so that nucleophilic addition of TFMPA could be accomplished after methylation of Cl-Si(111) surfaces. Mixed TFMPA/methyl functionalization resulted in a Si(111) surface with surface recombination velocities of 2 × 102 cm s-1 that exhibited an â150 mV positive band-edge shift relative to CH3-Si(111) surfaces.
AB - Chemical functionalization of semiconductor surfaces can provide high-efficiency photoelectrochemical devices through molecular-level control of the energetics, surface dipole, surface electronic defects, and chemical reactivity at semiconductor/electrolyte junctions. We describe the covalent functionalization by nucleophilic addition chemistry of p-Si(111) surfaces to produce mixed overlayers of trifluoromethylphenylacetylene (TFMPA) and methyl moieties. Functionalization of Cl-terminated Si(111) surfaces with TFMPA moieties introduced a positive surface molecular dipole that in contact with CH3CN or Hg produced a positive band-edge shift of the semiconductor relative to junctions with CH3-Si(111) surfaces. Methylation of the Cl/TFMPA surfaces using methylmagnesium chloride resulted in the degradation of the TFMPA moieties, whereas methylation using methylzinc chloride allowed controlled production of mixed TFMPA/methyl-terminated surfaces and permitted reversal of the order of the functionalization steps so that nucleophilic addition of TFMPA could be accomplished after methylation of Cl-Si(111) surfaces. Mixed TFMPA/methyl functionalization resulted in a Si(111) surface with surface recombination velocities of 2 × 102 cm s-1 that exhibited an â150 mV positive band-edge shift relative to CH3-Si(111) surfaces.
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U2 - 10.1021/acs.jpcc.0c02017
DO - 10.1021/acs.jpcc.0c02017
M3 - Article
AN - SCOPUS:85089888827
VL - 124
SP - 16338
EP - 16349
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 30
ER -