Light-induced changes of optical and electrical properties in bent-core azo compounds

A. Jákli, V. Prasad, D. S. Shankar Rao, G. Liao, I. Jánossy

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

We have studied the optical and electrical properties of two bent-core substances with an azo linkage in their cores. Pump-probe laser studies, direct textural observations, and spectrophotometric recordings show an initial decrease of light transmission, which at larger light intensities (∼ 1 mW/mm 2) is followed by a bleaching. Simultaneously the electrical properties (electric conductivity, antiferroelectric polarization, switching threshold, and switching time) decreased monotonically with increasing light intensities. The monotonic decrease of electrical properties indicates that the darkening and bleaching have the same origin, namely, the photochemical isomerization of the azo linkage from the trans to the cis isomer. The material with cis isomer has a lower clearing point and phase separates from the trans-rich domains. Initially the size of the separated isotropic domains is below the visible range, which causes increased scattering. As the size of the isotropic domains increase the scattering disappears and the transmittance becomes the average of the transmittances in the polar tilted smectic and isotropic phases.

Original languageEnglish
Article number021709
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume71
Issue number2
DOIs
Publication statusPublished - Feb 1 2005

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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