Display panel and display device

A display panel, comprising a first substrate and a second substrate opposite to each other, and a liquid crystal layer, a first electrode, as second electrode, a waveguide layer and a grating layer that are between the first substrate and the second substrate;

• wherein,
• the waveguide layer is on a side of the liquid crystal layer proximal to the first substrate;
• and the grating layer is in contact with the liquid crystal layer;
• the first electrode and the second electrode are configured to adjust a refractive index of the liquid crystal layer by changing voltages applied thereto;
• and
• a coupling efficiency at which light is coupled out of the waveguide layer is determined according to a difference between a refractive index of the grating layer and the refractive index of the liquid crystal layer,
• wherein the first electrode is on a side of the waveguide layer proximal to the first substrate;
• the grating layer is on the side of the waveguide layer away from the first electrode;
• the liquid crystal layer is on a side of the grating layer away from the waveguide layer;
• and the second electrode is on a side of the second substrate proximal to the liquid crystal layer, and a refractive index of the waveguide layer is larger than a refractive index of the first electrode, and the refractive index of the first electrode is larger than or equal to the refractive index of the grating layer.