Display substrate and preparation method thereof, and display apparatus

1. A display substrate, comprising:

a substrate and a plurality of pixel units disposed in matrix on the substrate, wherein:

each pixel unit comprises a plurality of sub-pixels, and each sub-pixel comprises a driving structure layer on the substrate, a first electrode and a first pixel define layer on the driving structure layer, and a light absorption layer disposed on the first pixel define layer, wherein the driving structure layer comprises a thin film transistor, and a drain electrode of the thin film transistor is connected to the first electrode;

the first pixel define layer comprises a plurality of first barriers and a first pixel opening disposed between the first barriers, the first pixel opening exposes at least part of the first electrode, and the first pixel opening comprises a first surface close to the first electrode, a second surface opposite to the first surface and a first sidewall between the first surface and second surface; the first pixel opening communicates with the first surface and the second surface;

the light absorption layer covers the first barriers and at least part of the first sidewall;

the display substrate further comprises a second pixel define layer disposed on the light absorption layer, and the second pixel define layer covers the light absorption layer;

the second pixel define layer comprises a plurality of second barriers and a second pixel opening disposed between the second barriers, and the second pixel opening exposes at least part of the first electrode;

the second pixel opening comprises a third surface close to the first electrode, a fourth surface opposite to the third surface and a second sidewall between the third surface and fourth surface; the second pixel opening communicates with the third surface and the fourth surface;

an orthographic projection of the third surface on the substrate is overlapped with an orthographic projection of the first surface on the substrate, or the orthographic projection of the third surface on the substrate is within a range of the orthographic projection of the first surface on the substrate; and

the first sidewall forms a first slope angle with a plane on which the substrate is located, and the second sidewall comprises a first side surface close to the first electrode and a second side surface away from the first electrode; the first side surface forms a second slope angle with the plane on which the substrate is located, and the second slope angle is greater than the first slope angle.

2. The display substrate of claim 1 , wherein an edge of an orthographic projection of the light absorption layer on the substrate coincides with an edge of an orthographic projection of the first surface on the substrate, or the edge of the orthographic projection of the light absorption layer on the substrate is located outside the orthographic projection of the first surface on the substrate; and the edge of the orthographic projection of the light absorption layer on the substrate is located within an orthographic projection of the second surface on the substrate.

3. The display substrate of claim 1 , wherein the first pixel define layer has a thickness of 0.5 to 1.5 microns, the light absorption layer has a thickness of 0.5 to 1 micron, and the second pixel define layer has a thickness of 0.2 to 0.6 microns.

4. The display substrate of claim 1 , wherein the light absorption layer is made of a light absorbing material or a pixel define layer material doped with light absorbing particles, wherein the light absorbing particles are carbon black particles or black chromium particles, and the pixel define layer material is polyimide, acrylic or polyethylene terephthalate.

5. A display apparatus, comprising the display substrate of claim 1 .

6. A preparation method for a display substrate, comprising:

forming a driving structure layer and a first planarization layer on a substrate;

forming a first electrode and a first pixel define layer on the first planarization layer, wherein the first pixel define layer comprises a plurality of first barriers and a first pixel opening disposed between the first barriers, the first pixel opening exposes at least part of the first electrode, and the first pixel opening comprises a first surface close to the first electrode, a second surface opposite to the first surface and a first sidewall between the first surface and second surface; the first pixel opening communicates with the first surface and the second surface;

forming a light absorption layer on the first pixel define layer, wherein the light absorption layer covers the first barriers and at least part of the first sidewall; and

sequentially forming an organic light-emitting layer, a second electrode and an encapsulation layer,

wherein before sequentially forming the organic light-emitting layer, the second electrode and the encapsulation layer, the preparation method further comprises:

forming a second pixel define layer on the light absorption layer, wherein the second pixel define layer covers the light absorption layer; the second pixel define layer comprises a plurality of second barriers and a second pixel opening disposed between the second barriers, and the second pixel opening exposes at least part of the first electrode,

wherein the second pixel opening comprises a third surface close to the first electrode, a fourth surface opposite to the third surface and a second sidewall between the third surface and fourth surface; the second pixel opening communicates with the third surface and the fourth surface;

wherein an orthographic projection of the third surface on the substrate is overlapped with an orthographic projection of the first surface on the substrate, or the orthographic projection of the third surface on the substrate is within a range of the orthographic projection of the first surface on the substrate; and

wherein the first sidewall forms a first slope angle with a plane on which the substrate is located, and the second sidewall comprises a first side surface close to the first electrode and a second side surface away from the first electrode; the first side surface forms a second slope angle with the plane on which the substrate is located, and the second slope angle is greater than the first slope angle.

7. The preparation method of claim 6 , wherein the first pixel define layer is formed by a positive photolithography technique, and the light absorption layer is formed by a negative photolithography technique.

8. The preparation method of claim 6 , wherein an edge of an orthographic projection of the light absorption layer on the substrate coincides with an edge of an orthographic projection of the first surface on the substrate, or the edge of the orthographic projection of the light absorption layer on the substrate is located outside the orthographic projection of the first surface on the substrate; and the edge of the orthographic projection of the light absorption layer on the substrate is located within an orthographic projection of the second surface on the substrate.