Organic light-emitting diode (OLED) display panel, pixel define layer (PDL) and preparation method thereof

1. A pixel define layer (PDL) in an organic light-emitting diode (OLED) display panel, comprising a first PDL and a second PDL overlapped on the first PDL, wherein

the first PDL is a hydrophobic film layer provided with an opening corresponding to a luminous region of a sub-pixel unit; and

the second PDL is a hydrophilic film layer provided with an opening corresponding to the opening of the first PDL, wherein the hydrophobic film layer is a photoresist film layer.

2. The PDL according to claim 1 , wherein the opening of the second PDL are less than the corresponding opening of the first PDL in size, so that the two corresponding openings of the first PDL and the second PDL together forms a filling area of an organic light-emitting material to be filled, having a narrow upper portion and a wide lower portion.

3. The PDL according to claim 2 , wherein the filling area of the organic light-emitting material to be filled, having the narrow upper portion and the wide lower portion, is in a shape of a recess, and any side wall of the recess is in a shape of a trapezoid with a smooth surface.

4. The PDL according to claim 1 , wherein the hydrophilic film layer is a silicon oxide, silicon nitride or silicon oxynitride film layer.

5. The PDL according to claim 1 , wherein a thickness of the first PDL is 3 to 5 times more than the thickness of the second PDL.

6. An Organic Light-Emitting Diode (OLED) display panel, comprising: a substrate; a plurality of sub-pixel units arranged in matrixes and disposed on the substrate, in which each sub-pixel unit is provided with a thin film transistor (TFT); and a pixel define layer (PDL) disposed on the substrate and configured to cover TFTs, in which the PDL is the PDL according to any one of claims 1 to 3 or 4 to 5 .

7. The PDL according to claim 2 , wherein the hydrophobic film layer is a photoresist film layer.

8. The PDL according to claim 2 , wherein the hydrophilic film layer is a silicon oxide, silicon nitride or silicon oxynitride film layer.

9. The PDL according to claim 2 , wherein a thickness of the first PDL is 3 to 5 times more than the thickness of the second PDL.

10. The PDL according to claim 3 , wherein the hydrophobic film layer is a photoresist film layer.

11. The PDL according to claim 3 , wherein the hydrophilic film layer is a silicon oxide, silicon nitride or silicon oxynitride film layer.

12. The PDL according to claim 3 , wherein a thickness of the first PDL is 3 to 5 times more than the thickness of the second PDL.

13. The PDL according to claim 1 , wherein the PDL consists of a first PDL and a second PDL.

14. A method for preparing the pixel define layer (PDL) in the Organic Light-Emitting Diode (OLED) display panel according to claim 1 , comprising:

forming a hydrophobic film layer and a hydrophilic film layer for covering a whole substrate respectively and sequentially; and

forming openings of the hydrophilic film layer and openings of the hydrophobic film layer, which are distributed according to an opening pattern, by patterning the hydrophilic film layer and the hydrophobic film layer according to a predetermined opening pattern of the PDL.

15. The method according to claim 14 , wherein the hydrophobic film layer is obtained by coating a first photoresist film layer, which covers the whole substrate and has a default thickness, on the substrate by a coating process, and solidifying the first photoresist film layer at a temperature of 150 to 250 centigrade.

16. The method according to claim 15 , wherein the hydrophilic film layer is obtained by depositing a silicon nitride, silicon oxide or silicon oxynitride film layer for covering the whole substrate on the solidified first photoresist film layer by chemical vapor deposition (CVD).

17. The method according to claim 16 , further comprising: forming a positive photoresist film layer for covering the whole substrate on the silicon nitride, silicon oxide or silicon oxynitride film layer after the silicon nitride, silicon oxide or silicon oxynitride film layer is formed; and

simultaneously exposing the second photoresist film layer and the first photoresist film layer corresponding to the opening pattern for 5,000 to 7,000 milliseconds according to the default opening pattern of the PDL, in which any side wall of an exposure area of the second photoresist film layer and the first photoresist film layer is in a shape of a trapezoid with a narrow upper portion and a wide lower portion.

18. The method according to claim 17 , further comprising: after exposure, firstly, developing the second photoresist film layer, removing a portion of the second photoresist corresponding to the opening pattern, obtaining openings of the second photoresist film layer, and exposing the silicon nitride, silicon oxide or silicon oxynitride film layer disposed beneath the second photoresist film layer;

secondly, etching the exposed silicon nitride, silicon oxide or silicon oxynitride film layer by a dry etching process, forming openings corresponding to the openings of the second photoresist film layer, and exposing the first photoresist film layer disposed beneath the silicon nitride, silicon oxide or silicon oxynitride film layer;

thirdly, developing the exposed first photoresist film layer, removing the first photoresist film layer in exposure areas, and forming the openings of the first photoresist film layer; and

finally, stripping the remaining second photoresist film layer on the silicon nitride, silicon oxide or silicon oxynitride film layer.