Reflective liquid crystal device and use thereof

A reflective liquid crystal device comprising:

• a first substrate layer;
• a first electrode layer disposed below the first substrate layer;
• a first pretilt homeotropic alignment film disposed below the first electrode layer;
• a guest-host liquid crystal layer comprising a liquid crystal compound and a dichroic dye, and disposed below the first pretilt homeotropic alignment film;
• a second pretilt homeotropic alignment film disposed below the guest-host liquid crystal layer;
• a second electrode layer disposed below the second pretilt homeotropic alignment film;
• a second substrate layer disposed below the second electrode layer;
• a quarter-wave plate disposed below the second substrate layer;
• and
• a reflective plate disposed below the quarter-wave plate,
• wherein an optical axis of the quarter-wave plate is formed at an angle of 40° to 50° with respect to an optical axis of the liquid crystal compound included in the horizontally aligned guest-host liquid crystal layer when an external electric field is applied,
• wherein the thicknesses of the guest-host liquid crystal layer, the first and second substrate layers and the first and second electrode layers satisfy the following Equation 1:
• 0.015<b/a<0.6 [Equation 1]
• wherein b represents a thickness of the guest-host liquid crystal layer, and a represents the sum of thicknesses of the first and second substrate layers and the first and second electrode layers, and wherein the reflective liquid crystal device satisfies the following Equation 2:
• A−B>40% [Equation 2]
• wherein A represents a reflectance in a state in which an external electric field is not applied, and B represents a reflectance in a state in which an external electric field is applied.