Display substrate, manufacturing method thereof, display panel

1. A display substrate comprising:

a base substrate; and

a pixel defining layer on the base substrate,

wherein the pixel defining layer comprises a first defining layer and a second defining layer on the first defining layer,

wherein the first defining layer defines a plurality of lower openings,

wherein the second defining layer defines a plurality of upper openings corresponding to the plurality of lower openings,

wherein respective orthographic projections of respective bottom surfaces of ones of the plurality of the upper openings adjacent the first defining layer on the base substrate overlap respective orthographic projections of corresponding lower openings on the base substrate,

wherein the respective orthographic projections of the respective bottom surfaces of the ones of the plurality of upper openings have equal respective areas,

wherein the plurality of lower openings comprise a first lower opening, a second lower opening and a third lower opening, and of the display substrate comprise a first pixel, a second pixel and a third pixel,

wherein the first lower opening, the second lower opening and the third lower opening form a first cavity, a second cavity and a third cavity respectively together with a corresponding upper opening of the plurality of upper openings for accommodating respective light emitting structures of the first pixel, the second pixel and the third pixel, and

wherein an area of an orthographic projection of the third lower opening on the base substrate is different from an area of an orthographic projection of the first lower opening on the base substrate or an orthographic projection of the second lower opening on the base substrate,

wherein respective lower openings and respective upper openings of each of the first cavity, the second cavity and the third cavity define a step formed by a material of the first defining layer, and

wherein the respective lower openings transition to the respective upper openings via the step,

wherein the respective light emitting structures of the first pixel, the second pixel and the third pixel comprise respective hole injection layers,

wherein the respective hole injection layers cover an upper surface of the first defining layer within a corresponding first cavity, second cavity, or third cavity, and

wherein respective hole injection layers in the first cavity, the second cavity and the third cavity have a substantially equal thickness.

2. The display substrate according to claim 1 , wherein ones of the light emitting structures comprise a hole injection layer, a hole transport layer, and an organic light emitting layer laminated in a corresponding first cavity, second cavity, or third cavity.

3. The display substrate according to claim 1 ,

wherein a material of the first defining layer comprises at least one selected from silicon dioxide or silicon nitride, and

wherein a material of the second defining layer comprises polyimide.

4. The display substrate according to claim 1 , wherein the respective light emitting structures further comprise a respective anode below a respective one of the plurality of lower openings and in contact with the respective hole injection layers, and a respective cathode as a corresponding top structure of the respective light emitting structures.

5. The display substrate according to claim 1 , wherein corresponding ones of the plurality of the upper openings of the first cavity, the second cavity and the third cavity have a same volume.

6. A display panel comprising the display substrate according to claim 1 .

7. A method for manufacturing a display substrate, comprising:

fabricating the pixel defining layer of claim 1 on the base substrate; and

forming respective hole injection layers in the first cavity, the second cavity, and the third cavity by inkjet printing.

8. The method according to claim 7 , wherein the fabricating the pixel defining layer comprises:

forming the first defining layer on the base substrate with a first material; and

forming the second defining layer on the first defining layer with a second material.

9. The method according to claim 7 , wherein the fabricating the pixel defining layer comprises:

forming a first film layer and a second film layer on the base substrate successively, and

performing a patterning process on the first film layer and the second film layer to form the plurality of the lower openings in the first film layer and form the plurality of the upper openings in the second film layer, thereby obtaining the first defining layer and the second defining layer, respectively.

10. The method according to claim 9 ,

wherein a material for forming the first film layer comprises at least one material selected from silicon dioxide or silicon nitride, and

wherein a material for forming the second film layer comprises polyimide.

11. The method according to claim 7 ,

wherein the first pixel, the second pixel, and the third pixel comprise an R pixel, a G pixel, and a B pixel, respectively,

wherein the area of the orthographic projection of the second lower opening in the second cavity on the base substrate is greater than the area of the orthographic projection of the first lower opening in the first cavity on the base substrate and less than the area of the orthographic projection of the third lower opening in the third cavity on the base substrate.

12. The method according to claim 7 , wherein the forming respective hole injection layers in the first cavity, the second cavity, and the third cavity by inkjet printing comprises:

controlling an inkjet printing apparatus such that a same amount of a solution of a hole injection layer material flows from each nozzle at a time; and

drying the solution of the hole injection layer material in the first cavity, the second cavity, and the third cavity to obtain hole injection layers having substantially a same thickness.

13. The method according to claim 7 , wherein corresponding ones of the plurality of the upper openings of the first cavity, the second cavity and the third cavity have a same volume.

14. A display substrate comprising:

a base substrate; and

a pixel defining layer on the base substrate,

wherein the pixel defining layer comprises a first defining layer and a second defining layer on the first defining layer,

wherein the first defining layer defines a plurality of lower openings,

wherein the second defining layer defines a plurality of upper openings corresponding to the plurality of lower openings,

wherein respective orthographic projections of respective bottom surfaces of ones of the plurality of the upper openings adjacent the first defining layer on the base substrate overlap respective orthographic projections of corresponding lower openings on the base substrate,

wherein the respective orthographic projections of the respective bottom surfaces of the ones of the plurality of upper openings have equal respective areas,

wherein the plurality of lower openings comprise a first lower opening, a second lower opening and a third lower opening, and the display substrate comprise a first pixel, a second pixel and a third pixel,

wherein the first lower opening, the second lower opening and the third lower opening form a first cavity, a second cavity and a third cavity respectively together with a corresponding upper opening of the plurality of upper openings for accommodating respective light emitting structures of the first pixel, the second pixel and the third pixel, and

wherein an area of an orthographic projection of the third lower opening on the base substrate is different from an area of an orthographic projection of the first lower opening on the base substrate or an orthographic projection of the second lower opening on the base substrate,

wherein the first pixel, the second pixel, and the third pixel comprise an R pixel, a G pixel, and a B pixel, respectively,

wherein the area of the orthographic projection of the second lower opening in the second cavity on the base substrate is greater than the area of the orthographic projection of the first lower opening in the first cavity on the base substrate and less than the area of the orthographic projection of the third lower opening in the third cavity on the base substrate.

15. The display substrate according to claim 14 ,

wherein respective lower openings and respective upper openings of each of the first cavity, the second cavity and the third cavity define a step formed by a material of the first defining layer, and

wherein the respective lower openings transition to the respective upper openings via the step.