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Proceedings Paper

Shape engineering to promote head-tail interactions of electro-optic chromophores
Author(s): Cheng Zhang; Lianjie Zhang; Stephanie J. Benight; Benjamin C. Olbricht; Lewis E. Johnson; Bruce H. Robinson; Robert A. Norwood; Larry R. Dalton
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Paper Abstract

Alignment of dipolar chromophores lies at the heart of organic electro-optic materials research. Among all the factors (e.g., external electric field, temperature, conductivity, etc.) affecting alignment efficiency or order parameter, interchromophore electrostatic interaction has been the focus of attention in the last decade. The strength of dipole interaction is highly dependent not only on dipole moment but also on chromophore shape and chromophore number density. Antiparallel interaction is dominant in the solid state of conventional EO chromophores (long and flat) and prevents electro-optic coefficient (r33) from scaling with chromophore concentration. Despite the great amount of research along various approaches to enhancing alignment, order parameters of organic EO materials are still low (0.13- 0.2 v.s. 1 for a perfect alignment). Antiparallel interaction can be selectively attenuated by attaching bulky groups to the middle part of chromophore. However, it is synthetically challenging to provide sufficient steric protection without causing severe reduction of chromophore concentration. In this paper, we will present the first realization of atomeconomic steric protection of chromophore against H-aggregation in all directions and show evidences for the dominance of head-tail interaction over antiparallel interaction of a highly dipolar chromophore. With the novel shape, the EO coefficients of guest-host films of the chromophore do not show attenuation with increasing concentration up to 100 wt%. The dominance of head-tail interaction also enabled fabrication of optical quality thick films from the neat chromophore and allows poling induced alignment to retain at temperatures above the poling temperature – a phenomenon never observed for other chromophores.

Paper Details

Date Published: 10 September 2013
PDF: 8 pages
Proc. SPIE 8827, Optical Processes in Organic Materials and Nanostructures II, 882705 (10 September 2013); doi: 10.1117/12.2025676
Show Author Affiliations
Cheng Zhang, South Dakota State Univ. (United States)
Lianjie Zhang, South Dakota State Univ. (United States)
Stephanie J. Benight, Univ. of Washington (United States)
Benjamin C. Olbricht, Univ. of Washington (United States)
Univ. of Delaware (United States)
Lewis E. Johnson, Univ. of Washington (United States)
Bruce H. Robinson, Univ. of Washington (United States)
Robert A. Norwood, College of Optical Sciences, The Univ. of Arizona (United States)
Larry R. Dalton, Univ. of Washington (United States)

Published in SPIE Proceedings Vol. 8827:
Optical Processes in Organic Materials and Nanostructures II
Manfred Eich; Jean-Michel Nunzi; Rachel Jakubiak, Editor(s)

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