Realization of expeditious layer-by-layer siloxane-based self-assembly as an efficient route to structurally regular acentric superlattices with large electro-optic responses

Peiwang Zhu, Milko E. Van der Boom, Hu Kang, Guennadi Evmenenko, Pulak Dutta, Tobin J. Marks

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

A new, expeditious siloxane-based layer-by-layer assembly process for the formation of intrinsically polar organic electro-optic thin films is described using highly reactive-SiCl2I- functionalized, silyl-protected donor-acceptor azo-benzene chromophore derivatives and octachlorotrisiloxane as a deprotecting reagent/interlayer precursor. This all-"wet-chemical" two-step process can be efficiently implemented in a vertical dipping procedure to yield polar films consisting of 40 alternating chromophore and capping layers. Each nanoscale bilayer (chromophore + polysiloxane layer ≈ 3.26-nm thick) can be grown in ≈40 min - at least 1 order of magnitude more rapidly than previous siloxane-based solution deposition methodologies. Chromophore monolayer deposition from solution reaches completion in ≈15 min at 55°C. The adherent, structurally regular assemblies exhibit appreciable electro-optic responses (χ(2) ∼ 180 pm/V and r33 ∼ 65 pm/V determined by SHG measurements at 1064 nm) and high chromophore surface densities (≈40 Å2/chromophore) and have been characterized by a full complement of physicochemical techniques: optical spectroscopy, aqueous contact-angle measurements, specular X-ray reflectivity, atomic force microscopy, and angle-dependent polarized second-harmonic generation.

Original languageEnglish
Pages (from-to)4982-4989
Number of pages8
JournalChemistry of Materials
Volume14
Issue number12
DOIs
Publication statusPublished - Dec 1 2002

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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