Ultralow surface energy self-assembled monolayers of iodo-perfluorinated alkanes on silica driven by halogen bonding

Keyun Shou, Jun Ki Hong, Elliot S. Wood, James M. Hook, Andrew Nelson, Yanting Yin, Gunther G. Andersson, Antonio Abate, Ullrich Steiner, Chiara Neto

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Compact self-assembled monolayers (SAMs) of perfluorododecyl iodide (I-PFC12) of reproducible thickness (1.2 nm) are shown to form on silicon wafers. The SAMs have a high fluorine content (95%) and convey an extremely low surface energy to the silicon wafers (4.3 mN m -1 ), lower than previously reported in the literature for perfluorinated monolayers, and stable for over eight weeks. Shorter chain iodo-perfluorinated (I-PFC8) or bromo-perfluorinated molecules (Br-PFC10) led to less dense layers. The monolayers are stable to heating up to 60 °C, with some loss up to 150 °C. The I-PFC12 monolayer increases the work function of silicon wafers from 3.6 V to 4.4 eV, a factor that could be gainfully used in photovoltaic applications. The I-PFC12 monolayers can be transferred into patterns onto silica substrates by micro-contact printing. The NMR data and the reproducible thickness point to an upright halogen bonding interaction between the iodine in I-PFC12 and the surface oxygen on the native silica layer.

Original languageEnglish
Pages (from-to)2401-2411
Number of pages11
JournalNanoscale
Volume11
Issue number5
DOIs
Publication statusPublished - 7 Feb 2019
Externally publishedYes

Keywords

  • perfluorocarbons
  • momolayer
  • electronics sector

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