Display backplane, method for manufacturing the same and display device

A display device, comprising a display backplane, wherein the display backplane comprises a base substrate, a thin film transistor array layer, a protective layer, a planarization layer, and a light-emitting element are laminated one on another in sequence on the base substrate;

• wherein the protective layer is configured to cover a source electrode or a drain electrode of the thin film transistor array layer;
• wherein a first through hole is formed in the protective layer, and the first through hole is used to expose the source electrode or the drain electrode;
• a second through hole is formed in the planarization layer, and the first through hole and the second through hole are connected;
• wherein the source electrode or the drain electrode of the thin film transistor array layer is electrically connected to an anode of the light-emitting element via the first through hole and the second through hole;
• wherein each of the first through hole and the second through hole comprises a sidewall that is inclined with respect to the base substrate;
• wherein a thickness of the planarization layer is at least 2 μm;
• wherein the planarization layer has two opposite sidewalls along a cross-section that are inclined with respect to the base substrate, one of two opposite sidewalls of the planarization layer has a step-like structure at the second through hole, and the other of the two opposite sidewalls of the planarization layer does not have a step-like structure at the second through hole;
• the step-like structure of the planarization layer comprises a first sidewall, a second sidewall and a connecting member connecting the first sidewall and the second sidewall, and materials of the first sidewall, the second sidewall and the connecting member are the same;
• the first sidewall and a third sidewall of the first through hole that is inclined with respect to the base substrate are coplanar, and the other of the two opposite sidewalls of the planarization layer is not coplanar with another sidewall opposite to the third sidewall of the first through hole;
• the planarization layer comprises a first plane and a second plane that are parallel to a third plane where base substrate is located, the first plane and the second plane are opposite to each other, the first plane is adjacent to the protective layer, the second plane is adjacent to the light-emitting element, and one of a height from the first plane to the connecting member and a height from the connecting member to the second plane is greater than a thickness of the protective layer.