Oligothiophene dyes for guest-host liquid crystal displays

Three types of donor-acceptor-substituted bithiophene and terthiophene compounds were studied as dichroic dyes, which were dissolved in liquid crystals. These compounds were found to have large absorption coefficients, high dichroic ratios, excellent hues, and to be very attractive for guest-host-type liquid crystal displays. They also showed good solvatochromic behaviour in liquid crystal and cyclohexane solutions. These properties were found to be closely related to the solubilities of these compounds in liquid crystals. One donor-acceptorsubstituted bithiophene was found to behave as a polarity indicator in various kinds of liquid crystal.