Phase delay device comprising a liquid crystal layer having a spiral structure, preparation method, and display device

A phase delay device, comprising a linear polarization layer, an alignment layer and a liquid crystal layer;

• the linear polarization layer being located at a side of a light source, and configured to convert a received light to a linear polarization light;
• the alignment layer being located at a side of the linear polarization layer away from the light source, and configured to align liquid crystals of a first subpart of the liquid crystal layer based on a preset alignment angle;
• the liquid crystal layer being located at a side of the alignment layer away from the linear polarization layer, the liquid crystal layer comprising a first subpart, a second subpart and a third subpart, the first subpart being adjacent to the alignment layer, the second subpart being a spiral structure with a preset spiral angle, and a liquid crystal alignment angle of the third subpart being determined based on the preset alignment angle and the preset spiral angle;
• the liquid crystal layer being configured to convert the linear polarization light into circular polarization light through the spiral structure of the second subpart;
• the liquid crystal layer being a liquid crystal layer including negative distribution liquid crystals, and birefringence of the liquid crystal layer not decreasing with an increase of visible light wavelength;
• the spiral angle of the second subpart and a target delay of the liquid crystal layer being determined based on the alignment angle for the first subpart and a wavelength of light at a preset band;
• a ratio of a wavelength of light in respective visible light band contained in the preset band to a corresponding first delay being in a preset ratio range, and the first delay being a delay corresponding to the visible light band in the target delay.