Efficient, thermally stable, second order nonlinear optical response in organic hybrid covalent/ionic self-assembled films

James R. Heflin, Matthew T. Guzy, Patrick J. Neyman, Kylie J. Gaskins, Charles Brands, Zhiyong Wang, Harry W. Gibson, Richey M. Davis, Kevin E. Van Cott

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

A covalent/electrostatic layer-by-layer self-assembly method was used to achieve polar ordering of a water soluble, reactive dye in the fabrication of nonlinear optical (NLO) films. We observed a quadratic relationship between the second harmonic intensity I and bilayer number for all films made with Procion Brown MX-GRN, demonstrating that the polar ordering of the chromophores is consistent in each successive bilayer. As the ionic strength of the dye deposition solution was increased to 0.5 M NaCl, the x zzz (2) of the films increased by approximately 250% to 50 × 10 -9 esu, with a corresponding average chromophore tilt angle of 38°. This was attributed to increased shielding of the dye charges which led to higher chromophore density in the bilayers. The electrooptic coefficient for films of 50 bilayers fabricated at 0.5 M NaCl was 14 ±2 pm/V. Importantly, these films exhibited excellent thermal stability, with only a 10% decrease in (I ) 1/2 after 36 h at 85 °C and then 24 h at 150 °C. Furthermore, the (I ) 1/2recovered completely upon cooling to room temperature. These results with a commodity textile dye point to the potential value of this class of reactive chromophores and this self-assembly method for fabrication of electrooptic materials at ambient conditions from aqueous solutions.

Original languageEnglish (US)
Pages (from-to)5723-5727
Number of pages5
JournalLangmuir
Volume22
Issue number13
DOIs
Publication statusPublished - Jun 20 2006

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ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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