Wide application of dichroic dye-doped liquid crystal device (DLCD) devices has been proposed, which removes conventional film-type polarizer in reflective LCD and OLED. Combination of DLCD, quarter-wave film and reflector can realize effective reflective LCD. In addition, by replacing conventional polarizer to switchable DLCD in OLED, the proper level of a low reflection is achieved, and more interestingly high brightness OLED can be realized if the optic axis of DLC is switched to vertical alignment when there is no ambient light, which could save power consumption and life time of OLED. Further DLCD can be applied to bi-functional device functioning as both smart mirror and light shutter.