Wide band variable transmittance optical device and mixture

An optical device comprising:

• a cell comprising a guest-host mixture of a liquid crystal host and a dichroic guest dye material contained between a pair of plastic substrates,
• wherein the liquid crystal host has an axis orientation that is alterable between a clear state orientation when no voltage is applied to the cell and a dark state orientation perpendicular thereto when a voltage is applied to the cell;
• wherein the liquid crystal host comprises a chiral nematic material with a thickness to pitch ratio (d/p) of less than 0.9 but greater than 0.25;
• wherein the dichroic guest dye material comprises one or more dichroic dyes;
• wherein said guest-host mixture has an order parameter, Smix, greater than 0.78 and a nematic-isotropic transition temperature TNI greater than 40° C.;
• wherein said pair of plastic substrates have an optical retardation with less than ±20% variation in uniformity for any given wavelength of incident light;
• wherein the optical device does not use polarizers;
• wherein the optical device exhibits a wide absorption band having an aggregate full width at half maximum (A-FWHF) that is greater than 175 nm within a visible wavelength range of 400-700 nm;
• and
• wherein the optical device has a variable transmission with a dark state transmission equal to or below 40% and a transmission swing between the clear state orientation and the dark state orientation greater than or equal to 30%.