A display panel and a display device. The display panel comprises: a first base substrate (2), a liquid crystal layer (3), a waveguide layer (4), a grating layer, a quantum dot color filter layer (6), a first electrode (8), and a second electrode (7). The first electrode (8) and the second electrode (7) are constructed to adjust the refractive index of the liquid crystal layer (3) by changing a voltage applied thereon. The coupling efficiency for coupling light from the waveguide layer (4) is determined according to the difference between the refractive index of the liquid crystal layer (3) and the refractive index of the grating layer. A polarizer does not need to be provided in a display panel, thus avoiding the problem of quantum dot depolarization so that a quantum dot material can be applied to a liquid crystal display device, improving the transmittance of the display panel, and making a liquid crystal cell thinner so as to improve the response time of liquid crystals.