Surface Passivation and Positive Band-Edge Shift of p-Si(111) Surfaces Functionalized with Mixed Methyl/Trifluoromethylphenylacetylene Overlayers

Miguel Cabán-Acevedo, Kimberly M. Papadantonakis, Bruce S. Brunschwig, Nathan S. Lewis

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)16338-16349
Number of pages12
JournalJournal of Physical Chemistry C
Volume124
Issue number30
DOIs
Publication statusPublished - Jul 30 2020

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Fingerprint Dive into the research topics of 'Surface Passivation and Positive Band-Edge Shift of p-Si(111) Surfaces Functionalized with Mixed Methyl/Trifluoromethylphenylacetylene Overlayers'. Together they form a unique fingerprint.

Cite this