Electrical junction behavior of Poly(3,4-ethylenedioxythiophene) (PEDOT) contacts to H-terminated and CH3-Terminated p-, n-, and n +-Si(111) surfaces

Michael G. Walter, Xueliang Liu, Leslie E. O'Leary, Bruce S. Brunschwig, Nathan S Lewis

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19 Citations (Scopus)

Abstract

The electronic and photovoltaic properties of junctions between the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and Si(111) surfaces have been investigated for a range of doping types, doping levels, and surface functionalization of the Si. PEDOT-poly(styrenesulfonate) (PSS) formed ohmic, low resistance contacts to H-terminated and CH3-terminated p-type Si(111) surfaces. In contrast, PEDOT formed high barrier height (0.8-1.0 V) contacts to n-Si(111) surfaces, with CH3-terminated n-Si(111)/PEDOT contacts showing slightly higher barrier heights (1.01 eV) than H-terminated n-Si(111)/PEDOT contacts (0.89 V). PEDOT contacts to CH3-terminated and H-terminated n-Si(111) surfaces both produced photovoltages under illumination in accord with the Shockley diode limit based on bulk/recombination diffusion in the semiconductor. Such devices produced solar energy-conversion efficiencies of 5.7% under 100 mW cm-2 of simulated air mass 1.5 illumination. The electrical properties of PEDOT contacts to CH 3-terminated Si surfaces were significantly more stable in an air ambient than the electrical properties of PEDOT contacts to H-terminated Si surfaces. PEDOT films produced a low resistance, tunnel-barrier type of ohmic contact to n+-Si(111) surfaces. Hence, through various combinations of doping type, doping level, and surface functionalization, the PEDOT/Si contact system offers a wide range of opportunities for integration into monolithic photovoltaic and/or artificial photosynthetic systems.

Original languageEnglish
Pages (from-to)14485-14492
Number of pages8
JournalJournal of Physical Chemistry C
Volume117
Issue number28
DOIs
Publication statusPublished - Jul 18 2013

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ASJC Scopus subject areas

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

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