A display device for displaying image information including an image generator circuit and a photo-switchable screen is provided. The image generator circuit outputs an output image. The photo-switchable screen operates in a first operation mode or a second operation mode. In response to the photo-switchable screen operating in the first operation mode, the photo-switchable screen has a first light-transmittance, and the photo-switchable screen generates the image information according to the output image. In response to the photo-switchable screen operating in the second operation mode, the photo-switchable screen has a second light-transmittance. The first light-transmittance is less than the second light-transmittance.