Method of manufacturing OLED using solvents with different vapor pressures

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

providing a base substrate, wherein the base substrate comprises a plurality of sub-pixel regions of different colors;

printing a solution of a light-emitting functional layer in the plurality of sub-pixel regions, wherein volumes of solutions in sub-pixel regions of different colors are positively correlated with saturated vapor pressures of the solutions in the sub-pixels regions of different colors; and

performing vacuum drying on the solution to form the light-emitting functional layer having a uniform film thickness;

wherein the solution comprises a first solvent and a second solvent that are miscible; and a saturated vapor pressure of the first solvent is less than a saturated vapor pressure of the second solvent;

wherein the sub-pixel regions comprise a plurality of red sub-pixel regions, a plurality of green sub-pixel regions and a plurality of blue sub-pixel regions; and

the printing the solution of the light-emitting functional layer in the plurality of sub-pixel regions comprises:

printing a first solution of the light-emitting functional layer in the plurality of red sub-pixel regions;

printing a second solution of the light-emitting functional layer in the plurality of green sub-pixel regions; and

printing a third solution of the light-emitting functional layer in the plurality of blue sub-pixel regions;

wherein a volume of the second solution is greater than or equal to a volume of the third solution and less than or equal to a volume of the first solution; and

a saturated vapor pressure of the second solution is greater than or equal to a saturated vapor pressure of the third solution and less than or equal to a saturated vapor pressure of the first solution;

wherein after providing the base substrate and before simultaneously printing the solution of the light-emitting functional layer in the plurality of sub-pixel regions, further comprising:

forming a pixel defining layer on the base substrate, wherein the pixel defining layer comprises a first pixel opening in the red sub-pixel region, a second pixel opening in the green sub-pixel region, and a third pixel opening in the blue sub-pixel region; wherein

an area of the third pixel opening is less than an area of the second pixel opening and greater than an area of the first pixel opening;

wherein the plurality of green sub-pixel regions comprise: a plurality of first-type green sub-pixel regions and a plurality of second-type green sub-pixel regions;

an area of a second pixel opening corresponding to the first-type green sub-pixel region is greater than an area of a second pixel opening corresponding to the second-type green sub-pixel region; and

a saturated vapor pressure of a second solution corresponding to the first-type green sub-pixel region is less than a saturated vapor pressure of a second solution corresponding to the second-type green sub-pixel region;

wherein a ratio of the saturated vapor pressure of the first solution to the saturated vapor pressure of the second solution corresponding to the first-type green sub-pixel region to the saturated vapor pressure of the second solution corresponding to the second-type green sub-pixel region to the saturated vapor pressure of the third solution is 1.746:1.404:1.378:1.

2 . The manufacturing method according to claim 1 , wherein a ratio of the saturated vapor pressure of the first solution to the saturated vapor pressure of the second solution to the saturated vapor pressure of the third solution is (2.5˜1):(2.5˜1):1.

3 . The manufacturing method according to claim 1 , wherein volume proportions of the first solvent in the first solution, the second solution and the third solution sequentially increase; and

volume proportions of the second solvent in the first solution, the second solution and the third solution sequentially decrease.

4 . The manufacturing method according to claim 3 , wherein

a volume proportion of the first solvent in the first solution is 5% to 30%, and a volume proportion of the second solvent in the first solution is 70% to 95%;

a volume proportion of the first solvent in the second solution is 30% to 60%, and a volume proportion of the second solvent in the second solution is 40% to 70%; and

a volume proportion of the first solvent in the third solution is 60% to 95%, and a volume proportion of the second solvent in the third solution is 5% to 40%.

5 . The manufacturing method according to claim 4 , wherein

the first solvent is one or any combination of cumene, isopropyltoluene, 1,3,5-trimethylbenzene, dimethylanisole, or p-diethylbenzene; and

the second solvent is one or any combination of chlorobenzene, cyclohexanone, or o-xylene.

6 . The manufacturing method according to claim 3 , wherein

the light-emitting functional layer is a hole injection layer or a light-emitting material layer, and the volume of the second solution is greater than the volume of the third solution and less than the volume of the first solution; or

the light-emitting functional layer is a hole transport layer.

7 . The manufacturing method according to claim 6 , The manufacturing method according to claim 6 , wherein the light-emitting functional layer is the hole injection layer or the hole transport layer, and a concentration of a functional material in the first solution, a concentration of a functional material in the second solution, and a concentration of a functional material in the third solution are the same; or

the light-emitting functional layer is the light-emitting material layer, and the concentration of the functional material in the first solution is greater than or equal to the concentration of the functional material in the third solution and less than or equal to the concentration of the functional material in the second solution.

8 . A display substrate, comprising:

a base substrate, comprising a plurality of sub-pixel regions of different light-emitting colors; wherein the plurality of sub-pixel regions comprise a plurality of red sub-pixel regions, a plurality of green sub-pixel regions and a plurality of blue sub-pixel regions;

a pixel defining layer, disposed on the base substrate, and comprising a pixel opening in each sub-pixel region; and

a light-emitting functional layer, disposed on a side of the pixel defining layer facing away from the base substrate; wherein the light-emitting functional layer is at least partially located within the pixel opening, and the light-emitting functional layer in the pixel opening comprises a central region away from the pixel defining layer, a climbing region in contact with the pixel defining layer, and a transition region between the central region and the climbing region; wherein

the light-emitting functional layer comprises a hole injection layer, a hole transport layer and a light-emitting material layer;

wherein one of the following cases are comprised:

case 1:

in the blue sub-pixel region, a thickness of a central region of the hole injection layer is 30 nm to 35 nm, a thickness of a transition region of the hole injection layer is 35 nm to 50 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 50 nm; a thickness of a central region of the hole transport layer is 20 nm to 25 nm, a thickness of a transition region of the hole transport layer is 25 nm to 40 nm, and a thickness of a climbing region of the hole transport layer is greater than 40 nm; and a thickness of a central region of a blue light-emitting material layer is 60 nm to 65 nm, a thickness of a transition region of the blue light-emitting material layer is 65 nm to 80 nm, and a thickness of a climbing region of the blue light-emitting material layer is greater than 80 nm;

in the green sub-pixel region, a thickness of a central region of the hole injection layer is 40 nm to 45 nm, a thickness of a transition region of the hole injection layer is 45 nm to 60 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 60 nm; a thickness of a central region of the hole transport layer is 20 nm to 25 nm, a thickness of a transition region of the hole transport layer is 25 nm to 40 nm, and a thickness of a climbing region of the hole transport layer is greater than or equal to 40 nm; and a thickness of a central region of a green light-emitting material layer is 80 nm to 85 nm, a thickness of a transition region of the green light-emitting material layer is 85 nm to 100 nm, and a thickness of a climbing region of the green light-emitting material layer is greater than or equal to 100 nm; and

in the red sub-pixel region, a thickness of a central region of the hole injection layer is 40 nm to 45 nm, a thickness of a transition region of the hole injection layer is 45 nm to 60 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 60 nm; a thickness of the central region of the hole transport layer is 20 nm to 25 nm, a thickness of a transition region of the hole transport layer is 25 nm to 40 nm, and a thickness of a climbing region of the hole transport layer is greater than or equal to 40 nm; and a thickness of a central region of a red light-emitting material layer is 120 nm to 125 nm, a thickness of a transition region of the red light-emitting material layer is 125 nm to 140 nm, and a thickness of a climbing region of the red light-emitting material layer is greater than or equal to 140 nm;

case 2:

in the blue sub-pixel region, a thickness of a central region of the hole injection layer is 6 nm to 11 nm, a thickness of a transition region of the hole injection layer is 11 nm to 26 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 26 nm; a thickness of a central region of the hole transport layer is 11 nm to 16 nm, a thickness of a transition region of the hole transport layer is 16 nm to 31 nm, and a thickness of a climbing region of the hole transport layer is greater than 31 nm; and a thickness of a central region of a blue light-emitting material layer is 55 nm to 60 nm, a thickness of a transition region of the blue light-emitting material layer is 60 nm to 75 nm, and a thickness of a climbing region of the blue light-emitting material layer is greater than 75 nm;

in the green sub-pixel region, a thickness of a central region of the hole injection layer is 6 nm to 11 nm, a thickness of a transition region of the hole injection layer is 11 nm to 26 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 26 nm; a thickness of a central region of the hole transport layer is 16 nm to 21 nm, a thickness of the transition region of the hole transport layer is 21 nm to 36 nm, and a thickness of the climbing region of the hole transport layer is greater than or equal to 36 nm; and a thickness of a central region of a green light-emitting material layer is 63 nm to 68 nm, a thickness of a transition region of the green light-emitting material layer is 68 nm to 83 nm, and a thickness of a climbing region of the green light-emitting material layer is greater than or equal to 83 nm; and

in the red sub-pixel region R, a thickness of a central region of the hole injection layer is 12 nm to 17 nm, a thickness of a transition region of the hole injection layer is 17 nm to 32 nm, and a thickness of a climbing region of the hole injection layer is greater than or equal to 32 nm; a thickness of a central region of the hole transport layer is 21 nm to 26 nm, a thickness of a transition region of the hole transport layer is 26 nm to 41 nm, and a thickness of a climbing region of the hole transport layer is greater than or equal to 41 nm; and a thickness of a central region of a red light-emitting material layer is 87 nm to 92 nm, a thickness of a transition region of the red light-emitting material layer is 92 nm to 107 nm, and a thickness of a climbing region of the red light-emitting material layer is greater than or equal to 107 nm.

9 . The display substrate according to claim 8 , wherein

a shape contour of an orthographic projection of the light-emitting functional layer on the base substrate is roughly same as that of the pixel opening on the base substrate;

a region radiating outward from a center of the light-emitting functional layer and covering 70% to 90% of an entire area of the orthographic projection of the light-emitting functional layer is the central region;

a region covering the pixel defining layer and covering 0 to 5% of the entire area of the orthographic projection of the light-emitting functional layer is the climbing region; and

a region located between the climbing region and the central region and covering 5% to 30% of the entire area of the orthographic projection of the light-emitting functional layer is the transition region.

10 . The display substrate according to claim 8 , wherein thickness uniformity of the light-emitting functional layer within the pixel opening in each sub-pixel region is positively correlated with an area of the pixel opening in the sub-pixel region.

11 . The display substrate according to claim 10 , wherein the sub-pixel regions comprise a first sub-pixel region, a second sub-pixel region and a third sub-pixel region, the pixel opening comprises a first pixel opening located in the first sub-pixel region, a second pixel opening located in the second sub-pixel region, and a third pixel opening located in the third sub-pixel region, and an area of the third pixel opening is greater than an area of the first pixel opening and less than an area of the second pixel opening;

wherein

thickness uniformity of the hole injection layer in the first pixel opening, the third pixel opening and the second pixel opening sequentially increases;

thickness uniformity of the hole transport layer in the first pixel opening, the third pixel opening and the second pixel opening sequentially increases; and

thickness uniformity of the light-emitting material layer in the first pixel opening, the third pixel opening and the second pixel opening sequentially increases.

12 . The display substrate according to claim 8 , wherein the sub-pixel regions comprise a first sub-pixel region, a second sub-pixel region and a third sub-pixel region;

an average thickness of the hole injection layer in the first sub-pixel region is 40 nm to 50 nm, an average thickness of the hole injection layer in the second sub-pixel region is 40 nm to 50 nm, and an average thickness of the hole injection layer in the third sub-pixel region is 30 nm to 40 nm;

an average thickness of the hole transport layer in the first sub-pixel region is 20 nm to 28 nm, an average thickness of the hole transport layer in the second sub-pixel region is 20 nm to 27 nm, and an average thickness of the hole transport layer in the third sub-pixel region is 20 nm to 27 nm; and

an average thickness of the light-emitting material layer in the first sub-pixel region is 120 nm to 135 nm, an average thickness of the light-emitting material layer in the second sub-pixel region is 80 nm to 95 nm, and an average thickness of the light-emitting material layer in the third sub-pixel region is 60 nm to 72 nm.

13 . The display substrate according to claim 8 , wherein the sub-pixel regions comprise a first sub-pixel region, a second sub-pixel region and a third sub-pixel region;

an average thickness of the hole injection layer in the first sub-pixel region is 12 nm to 20 nm, an average thickness of the hole injection layer in the second sub-pixel region is 6 nm to 12 nm, and an average thickness of the hole injection layer in the third sub-pixel region is 6 nm to 12 nm;

an average thickness of the hole transport layer in the first sub-pixel region is 21 nm to 30 nm, an average thickness of the hole transport layer in the second sub-pixel region is 16 nm to 26 nm, and an average thickness of the hole transport layer in the third sub-pixel region is 11 nm to 20 nm; and

an average thickness of the light-emitting material layer in the first sub-pixel region is 87 nm to 105 nm, an average thickness of the light-emitting material layer in the second sub-pixel region is 63 nm to 78 nm, and an average thickness of the light-emitting material layer in the third sub-pixel region is 55 nm to 70 nm.

14 . The display substrate according to claim 11 , further comprising:

an electron transport layer, an electron injection layer and a second electrode which are arranged sequentially on a side of the light-emitting material layer facing away from the base substrate;

wherein the electron transport layer, the electron injection layer and the second electrode respectively cover all of the sub-pixel regions.

15 . The display substrate according to claim 8 , wherein the pixel defining layer comprises first pixel dams and second pixel dams, a height of the first pixel dam is greater than a height of the second pixel dam, adjacent first pixel dams define a plurality of sub-pixel regions, and adjacent second pixel dams define one sub-pixel region;

a same light-emitting functional layer is arranged in the plurality of sub-pixel regions defined by the adjacent first pixel dams, and a height of the light-emitting functional layer is greater than the height of the second pixel dam;

total regions, each consisting of the plurality of sub-pixel regions defined by the adjacent first pixel dams and in a long strip shape are distributed in a matrix; and

a short edge of the total region extends in a row direction, and all the light-emitting functional layers in the total region in a same column are same in material, and are formed through one inkjet printing process.