Oligothiophene dyes for guest-host liquid crystal displays

Three types of donor-acceptor-substituted bithiophene and terthiophene comp ounds were studied as dichroic dyes, which were dissolved in liquid crystal s. These compounds were found to have large absorption coefficients, high d ichroic ratios, excellent hues, and to be very attractive for guest-host-ty pe 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 crysta ls. One donor-acceptor-substituted bithiophene was found to behave as a pol arity indicator in various kinds of liquid crystal.