Display substrate and display device

A display substrate, comprising:

• a pixel defining layer having a plurality of openings;
• a plurality of light emitting devices;
• a portion of each light emitting device in at least a part of the plurality of light emitting devices being located in an opening;
• and the light emitting device including a first light-emitting layer and a cathode that are disposed sequentially;
• first isolation portions disposed on the pixel defining layer;
• a first isolation portion being located between two adjacent openings;
• and the first isolation portion separating first light-emitting layers and cathodes of light emitting devices located in the two adjacent openings;
• a light adjustment layer covering the pixel defining layer, the plurality of light emitting devices and the first isolation portions;
• and a refractive index of the light adjustment layer being different from a refractive index of the first isolation portion;
• and
• a second isolation portion disposed between the pixel defining layer and the first isolation portion;
• and a refractive index of the second isolation portion being different from the refractive index of the light adjustment layer and the refractive index of the first isolation portion, wherein the first isolation portion is in contact with the second isolation portion, and the refractive index of the first isolation portion is greater than the refractive index of the light adjustment layer, and the refractive index of the light adjustment layer is greater than the refractive index of the second isolation portion.