Package structure, electroluminescent display substrate, and fabrication method thereof

An electroluminescent display substrate, comprising:

• a basal substrate comprising a display area and a non-display area surrounding the display area;
• an electroluminescent device disposed on the basal substrate and located in the display area;
• and
• a package structure;
• wherein the package structure comprises a first package layer and a second package layer stacked on the basal substrate;
• a planarization layer and a wall are sandwiched between the first package layer and the second package layer;
• the first package layer and the second package layer seal the wall and the planarization layer;
• and
• an orthographic projection of the wall on the basal substrate surrounds an orthographic projection of the planarization layer on the basal substrate, and the planarization layer is restricted within an area enclosed by the wall;
• and wherein the orthographic projection of the wall on the basal substrate and the orthographic projection of the planarization layer on the basal substrate at least completely cover the display area.