阅读说明：本技术 喷墨打印方法、显示面板的制作方法及显示面板 (Ink-jet printing method, display panel manufacturing method and display panel ) 是由 向昌明 于 2021-08-24 设计创作，主要内容包括：本发明涉及一种喷墨打印方法、显示面板的制作方法及显示面板,所述喷墨打印方法通过对喷墨打印形成的有机溶液层进行光照,并实现光照强度的分区控制,即对应有机溶液层的中间区的光照强度与对应有机溶液层的边缘区的光照强度实现差异化,从而降低咖啡环效应,达到固化后薄膜厚度均一的目的。(The invention relates to an ink-jet printing method, a manufacturing method of a display panel and the display panel, wherein the ink-jet printing method illuminates an organic solution layer formed by ink-jet printing and realizes the partition control of illumination intensity, namely the illumination intensity of a middle area corresponding to the organic solution layer is different from the illumination intensity of an edge area corresponding to the organic solution layer, so that the coffee ring effect is reduced, and the purpose of uniform thickness of a cured film is achieved.)

1. A method of inkjet printing, comprising:

providing a substrate;

ink-jet printing an organic solution onto the substrate surface to form an organic solution layer, the organic solution layer comprising a middle region and an edge region surrounding the middle region;

and irradiating the organic solution layer to solidify to form an organic film layer, wherein the irradiation intensity corresponding to the edge region is different from the irradiation intensity corresponding to the middle region, so that the absolute value of the difference between the average thickness value of the organic film layer corresponding to the edge region and the average thickness value of the organic film layer corresponding to the middle region is less than or equal to 1.

2. The inkjet printing method according to claim 1, wherein the light used for the illumination in the step of illuminating the organic solution layer to cure and form the organic film layer is ultraviolet light, and the intensity of the ultraviolet light corresponding to the intermediate region is greater than the intensity of the ultraviolet light corresponding to the edge region.

3. The method of inkjet printing according to claim 2,

a first mask plate is arranged above the substrate to shield the ultraviolet light;

the first mask plate comprises a light-transmitting area and a light-proof area, and the light-transmitting area corresponds to the organic solution layer;

the light-transmitting regions comprise a first full light-transmitting region and a first semi-light-transmitting region surrounding the first full light-transmitting region, the first full light-transmitting region corresponds to the middle region, the first semi-light-transmitting region corresponds to the edge region, and the light transmittance of the first semi-light-transmitting region is smaller than that of the first full light-transmitting region, so that the ultraviolet illumination intensity of the first full light-transmitting region is greater than that of the first semi-light-transmitting region.

4. The method of inkjet printing according to claim 3,

a pixel limiting layer is formed on the substrate, a pixel opening which exposes at least part of the substrate is etched on the pixel limiting layer, and an organic solution is subjected to ink-jet printing to form the organic solution layer in the pixel opening;

the opaque region of the first mask corresponds to the pixel defining layer located outside the pixel opening.

5. The inkjet printing method of claim 4, wherein a width of the light-transmitting region of the first mask corresponds to a width of a port at an end of the pixel opening away from the substrate.

6. The inkjet printing method according to claim 4, wherein the pixel defining layers include a first defining layer and a second defining layer which are stacked, the first defining layer has a square cross-sectional shape, the second defining layer has a trapezoidal cross-sectional shape, the width of the second defining layer decreases from the end close to the substrate toward the end away from the substrate, and the distance between two adjacent second defining layers increases from the end close to the substrate toward the end away from the substrate.

7. The method of inkjet printing according to claim 1,

the light used for illuminating the organic solution layer to form the organic film layer through curing is infrared light, and the infrared illumination intensity corresponding to the middle area is smaller than that corresponding to the edge area;

a heating plate is disposed below the substrate to heat the organic solution layer.

8. The method of inkjet printing according to claim 7,

the edge region of the layer of organic solution comprises a first edge region surrounding the intermediate region and a second edge region surrounding the first edge region;

a second mask is arranged above the substrate to shield the infrared light, the second mask comprises a general light-transmitting area, a second semi-light-transmitting area surrounding the general light-transmitting area and a second full light-transmitting area surrounding the second semi-light-transmitting area, the general light-transmitting area corresponds to the middle area, the second semi-light-transmitting area corresponds to the first edge area, the second full light-transmitting area corresponds to the second edge area, and the light transmittance of the general light-transmitting area is smaller than the light transmittance of the second semi-light-transmitting area and smaller than the light transmittance of the second full light-transmitting area, so that the infrared illumination intensity of the general light-transmitting area is smaller than the infrared illumination intensity of the second semi-light-transmitting area and smaller than the infrared illumination intensity of the second full light-transmitting area.

9. A method of manufacturing a display panel, the method comprising the inkjet printing method according to any one of claims 1 to 8.

10. A display panel produced by the production method according to claim 9.

Technical Field

The invention relates to the technical field of display, in particular to an ink-jet printing method, a manufacturing method of a display panel and the display panel.

Background

In the field of Organic Light Emitting Diode (OLED) Display and Liquid Crystal Display (LCD), an Organic functional layer or other film structure is usually formed by inkjet printing or the like. The ink-jet printing needs vacuum drying and baking drying to remove redundant solvent to form a dry film, because of factors such as the tension of liquid drops formed by organic solution, the evaporation rate of the central part with small volume and unit area in the liquid drops is different from that of the edge position with large volume and unit area, the thicker the volatile atmosphere at the position close to the center, the closer to the saturated state, the less the solution below the liquid drops is dry; the thinner the atmosphere above, the more volatile the solvent, the closer to the edge area. As the periphery is dried quickly, the solution can move outwards in the drying process, and as a result, the film forming in the pixel unit is uneven after drying, the shape of the film with thick periphery and thin middle is formed, the shape of the film is poor, the uniformity of the thickness of the film is poor, and the service life and the display effect of the device are greatly influenced.

Disclosure of Invention

The invention aims to solve the problem that the thickness uniformity of a film formed by the existing ink-jet printing is poor.

To achieve the above object, the present invention provides an inkjet printing method comprising:

providing a substrate;

ink-jet printing an organic solution onto the substrate surface to form an organic solution layer, the organic solution layer comprising a middle region and an edge region surrounding the middle region;

and irradiating the organic solution layer to solidify to form an organic film layer, wherein the irradiation intensity corresponding to the edge region is different from the irradiation intensity corresponding to the middle region, so that the absolute value of the difference between the average thickness value of the organic film layer corresponding to the edge region and the average thickness value of the organic film layer corresponding to the middle region is less than or equal to 1.

Optionally, the light used for illuminating in the step of illuminating the organic solution layer to form the organic film layer by curing is ultraviolet light, and the ultraviolet illumination intensity corresponding to the middle region is greater than the ultraviolet illumination intensity corresponding to the edge region.

Optionally, a first mask is disposed above the substrate to shield the ultraviolet light; the first mask plate comprises a light-transmitting area and a light-proof area, and the light-transmitting area corresponds to the organic solution layer; the light-transmitting regions comprise a first full light-transmitting region and a first semi-light-transmitting region surrounding the first full light-transmitting region, the first full light-transmitting region corresponds to the middle region, the first semi-light-transmitting region corresponds to the edge region, and the light transmittance of the first semi-light-transmitting region is smaller than that of the first full light-transmitting region, so that the ultraviolet illumination intensity of the first full light-transmitting region is greater than that of the first semi-light-transmitting region.

Optionally, a pixel defining layer is formed on the substrate, a pixel opening exposing at least a portion of the substrate is etched on the pixel defining layer, and an organic solution is inkjet printed in the pixel opening to form the organic solution layer; the opaque region of the first mask corresponds to the pixel defining layer located outside the pixel opening.

Optionally, the width of the light-transmitting area of the first mask corresponds to the width of a port at one end of the pixel opening, which is far away from the substrate.

Optionally, the pixel defining layer includes a first defining layer and a second defining layer, which are stacked, the cross-sectional shape of the first defining layer is square, the cross-sectional shape of the second defining layer is trapezoid, the width of the second defining layer gradually decreases from one end close to the substrate to one end away from the substrate, and the distance between two adjacent second defining layers gradually increases from one end close to the substrate to one end away from the substrate.

Optionally, the light used for the illumination in the step of illuminating the organic solution layer to form the organic film layer by curing is infrared light, and the infrared illumination intensity corresponding to the middle region is less than the infrared illumination intensity corresponding to the edge region; a heating plate is disposed below the substrate to heat the organic solution layer.

Optionally, the edge regions of the layer of organic solution comprise a first edge region surrounding the intermediate region and a second edge region surrounding the first edge region; a second mask is arranged above the substrate to shield the infrared light, the second mask comprises a general light-transmitting area, a second semi-light-transmitting area surrounding the general light-transmitting area and a second full light-transmitting area surrounding the second semi-light-transmitting area, the general light-transmitting area corresponds to the middle area, the second semi-light-transmitting area corresponds to the first edge area, the second full light-transmitting area corresponds to the second edge area, and the light transmittance of the general light-transmitting area is smaller than the light transmittance of the second semi-light-transmitting area and smaller than the light transmittance of the second full light-transmitting area, so that the infrared illumination intensity of the general light-transmitting area is smaller than the infrared illumination intensity of the second semi-light-transmitting area and smaller than the infrared illumination intensity of the second full light-transmitting area.

In order to achieve the above object, the present invention further provides a manufacturing method of a display panel, including the inkjet printing method as described above.

In order to achieve the above object, the present invention further provides a display panel, which is manufactured by the manufacturing method of the display panel.

The invention has the beneficial effects that the invention provides the ink-jet printing method, the manufacturing method of the display panel and the display panel, the organic solution layer formed by ink-jet printing is illuminated, and the subarea control of illumination intensity is realized, namely, the illumination intensity of the middle area corresponding to the organic solution layer is different from the illumination intensity of the marginal area corresponding to the organic solution layer, so that the coffee ring effect is reduced, and the purpose of uniform thickness of the cured film is achieved.

Drawings

The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.

FIG. 1a is a schematic structural diagram of an existing inkjet printing method for forming an organic film layer on a substrate after UV curing;

FIG. 1b is a schematic structural diagram of an existing inkjet printing method for forming an organic film layer on a substrate after infrared light curing;

FIG. 2 is a schematic flow chart of an ink jet printing method employing UV curing in an exemplary embodiment of the invention;

FIG. 3 is a schematic diagram of a UV light curing architecture for an ink jet printing process according to an exemplary embodiment of the present invention;

fig. 4 is a schematic structural diagram of an organic film layer formed on a substrate by ultraviolet irradiation curing in an inkjet printing method according to an exemplary embodiment of the present invention;

FIG. 5 is a schematic flow chart illustrating curing with infrared light in an inkjet printing method according to an exemplary embodiment of the present invention;

FIG. 6 is a schematic diagram of a structure cured by infrared light in an inkjet printing method according to an exemplary embodiment of the present invention;

fig. 7 is a schematic structural diagram of an inkjet printing method according to an exemplary embodiment of the present invention, in which an organic film layer is formed on a substrate by curing with infrared light.

The parts in the figure are numbered as follows:

100. 100a, a substrate, 101, an organic solution layer, 101a, a middle area, 101b, an edge area, 102a, 102b, an organic film layer, 1021a, a center area, 1021b, a convex area, 1021c, a concave area, 103, a concave arc, 104, a mark point, 110, a pixel defining layer, 111, a pixel opening, 112, a first defining layer, 113, a second defining layer;

201. a first mask plate 2011, a light transmission region 2011a, a first full light transmission region 2011b, a first semi-light transmission region 2012, a light non-transmission region 202, a second mask plate 2021, a general light transmission region 2022, a second semi-light transmission region 2023 and a second full light transmission region;

300. heating the plate.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The ink-jet printing method illuminates the organic solution layer formed by ink-jet printing and realizes the partition control of illumination intensity, namely the illumination intensity of the middle area corresponding to the organic solution layer and the illumination intensity of the edge area corresponding to the organic solution layer are differentiated, so that the coffee ring effect is reduced, and the purpose of uniform thickness of the solidified film is achieved. As a typical application, the inkjet printing method may be applied to a manufacturing process of a display panel, such as a display panel of an OLED display and a display panel of a thin film transistor liquid crystal display, and the manufactured display panel may be applied to a mobile terminal, such as a digital camera, a video camera, a camcorder, a personal digital assistant, a smart phone, an ultra-thin notebook computer, a tablet computer, a flexible display, and the like.

In one embodiment of the present invention, referring to fig. 2 to 4, an inkjet printing method includes the steps of:

s100, providing a substrate 100;

s110, printing an organic solution on the surface of the substrate 100 in an inkjet mode to form an organic solution layer 101, wherein the organic solution layer 101 comprises a middle area 101a and an edge area 101b surrounding the middle area 101 a;

s120, ultraviolet light irradiates the organic solution layer 101 to be cured to form an organic film layer 102, wherein the ultraviolet light irradiation intensity corresponding to the edge region 101b is smaller than that corresponding to the middle region 101 a.

Specifically, in the present embodiment, a pixel defining layer 110 is formed on a surface of a substrate 100, a pixel opening 111 exposing at least a portion of the substrate 100 is etched on the pixel defining layer 110, and an organic solution is inkjet printed in the pixel opening 111 to form an organic solution layer 101. The pixel defining layer 110 includes a first defining layer 112 and a second defining layer 113 stacked, the first defining layer 112 has a square cross-sectional shape, the second defining layer 113 has a trapezoidal cross-sectional shape, the width of the second defining layer 113 gradually decreases from one end close to the substrate 100 to one end away from the substrate 100, the distance between two adjacent second defining layers 113 gradually increases from one end close to the substrate 100 to one end away from the substrate 100, so as to form an inverted trapezoidal cross-sectional structure, and due to the surface tension of the organic solution droplets, referring to fig. 1a, the organic solution layer 101 forms a convex arc shape with a cross-sectional shape higher than two sides in the middle in the pixel opening 111.

In order to realize that the ultraviolet illumination intensity corresponding to the edge region 101b is less than the ultraviolet illumination intensity corresponding to the middle region 101a, referring to fig. 2, in this embodiment, a first Mask 201(Mask) is disposed above the substrate 100, and the first Mask 201 includes a light-transmitting region 2011 and a light-tight region 2012 surrounding the light-transmitting region 2011. The opaque region 2012 corresponds to the pixel defining layer 110 outside the pixel opening 111. The width of the light-transmitting area 2011 of the first mask 201 corresponds to the width of the port at one end of the pixel opening 111 far away from the substrate 100.

The light-transmitting regions 2011 include a first full light-transmitting region 2011a and a first half light-transmitting region 2011b surrounding the first full light-transmitting region 2011a, the first full light-transmitting region 2011a corresponds to the middle region 101a, the first half light-transmitting region 2011b corresponds to the edge region 101b, and the light transmittance of the first half light-transmitting region 2011b is smaller than that of the first full light-transmitting region 2011a, so that the intensity of ultraviolet light transmitted through the first full light-transmitting region 2011a is greater than that of ultraviolet light transmitted through the first half light-transmitting region 2011 b. Therefore, the ultraviolet irradiation intensity received by the middle area 101a is greater than that received by the edge area 101b, and the curing speed of the middle area 101a is greater than that of the edge area 101b, so that the organic film layer 102 is formed by fast curing, and the coffee ring appearance formed by the excessively fast evaporation rate of the organic solution in the middle area 101a in a liquid state is avoided.

In this embodiment, an absolute value of a difference between an average thickness value of the organic film layer 102 corresponding to the edge region 101b and an average thickness value of the organic film layer 102 corresponding to the middle region 101a is less than or equal to 1.

In the present embodiment, the width d of the first full-transmission region 2011a and the width a of the first half-transmission region 2011b are set as follows:

referring to fig. 1a, the shape of the upper surface of the organic film 102a formed on the substrate 100a after being cured by ultraviolet light is a concave arc 103, the vertical distance between the lowest point of the concave arc 103 and the upper surface of the substrate 100a is M, the vertical distance is taken as an axis, the positions of the upper surface of the substrate corresponding to 90% (i.e., 90% M) of the vertical distance between the concave arc 103 and the upper surface of the substrate 100a are respectively marked toward both sides to form mark points 104, the distance between the two mark points 104 is D ', and the distance between the highest points on both sides of the concave arc 103 is D, so that the width D of the first full light transmission area 2011a is equal to D ', and the width a > (D-D ')/2 of the first half light transmission area 2011 b.

The light transmittance of the first semi-transparent area 2011b is about 50%, which may be 40-70% in this embodiment. The wavelength of the ultraviolet light is 275-365 nm, and the ultraviolet light is cured at normal temperature.

As an improvement, referring to fig. 5 to 7, the inkjet printing method provided by the present invention includes the following steps:

s210, providing a substrate 100;

s220, printing an organic solution on the surface of the substrate 100 in an ink-jet mode to form an organic solution layer 101, wherein the organic solution layer 101 comprises a middle area 101a and an edge area 101b surrounding the middle area 101 a;

s230, infrared light is applied to the organic solution layer 101 to solidify and form an organic film layer 102, and the ultraviolet light intensity corresponding to the edge region 101b is greater than that corresponding to the middle region 101 a;

s240, disposing a heating plate 300 under the substrate 100, and heating the organic solution layer 101 by the heating plate 300 to form the organic film layer 102 by curing while infrared light is emitted.

The infrared heating and hot plate 300 cooperating curing method is commonly used for PI alignment film liquid drop curing, and the temperature of the hot plate 300 is as follows: heating at 90-130 ℃ for a period of time: 100-200s, infrared wavelength 2.5-15 um, thickness of the organic solution layer 101 before curing is about 4000nm, and thickness of the organic film layer 102 after curing is about 100 nm.

Specifically, in this embodiment, in order to achieve that the ultraviolet illumination intensity corresponding to the edge region 101b is greater than the ultraviolet illumination intensity corresponding to the middle region 101a, referring to fig. 6, a second mask 202 is disposed above the substrate 100 to block the infrared light, and further distinguish the edge region 101b to form a first edge region 1011b and a second edge region 1012b surrounding the first edge region 1011 b. The second mask 202 includes a general transparent region 2021, a second semi-transparent region 2022 surrounding the general transparent region 2021, and a second full-transparent region 2023 surrounding the second semi-transparent region 2022, the general transparent region 2021 corresponds to the middle region 101a, the second semi-transparent region 2022 corresponds to the first edge region 1011b, the second full-transparent region 2023 corresponds to the second edge region 1012b, and the light transmittance of the general transparent region 2021 < the light transmittance of the second semi-transparent region 2022 < the light transmittance of the second full-transparent region 2023, so that the intensity of infrared light transmitted through the general transparent region 2021 < the intensity of infrared light transmitted through the second semi-transparent region 2022 < the intensity of infrared light transmitted through the second full-transparent region 2023. Therefore, the infrared illumination intensity received by the middle area 101a is smaller than that received by the edge area 101b, the infrared illumination heating is combined with the heating plate 300 to heat the organic solution layer, and the coffee ring appearance is avoided due to the fact that the evaporation rate of the organic solution in the middle area 101a is too high when the organic solution is in a liquid state due to the design of zone heating.

In this embodiment, an absolute value of a difference between an average thickness value of the organic film layer 102 corresponding to the edge region 101b and an average thickness value of the organic film layer 102 corresponding to the middle region 101a is less than or equal to 1.

In the present embodiment, the width L1 of the second semi-transmissive region 2022 and the width L2 of the second fully transmissive region 2023 are set as follows:

the average film thickness of the organic film 102 is M, the shape of the organic film 102b formed on the substrate 100b after being cured by infrared light is shown in fig. 1b in the conventional inkjet printing method, the two ends of the organic film 102b are respectively formed with a convex region 1021b, the region between the convex region 1021b and the central region 1021a is a concave region 1021c, the film thickness of the central region 1021a is M, the thicknesses of the two ends of the concave region 1021c are both 90% M, the width of the concave region 1021c is s1, the width of the convex region 1021b is s2, the width of the general transparent region 2021 corresponds to the width of the central region 1021a, the width L1 of the second semi-transparent region 2022 is the same as s1, and the width L2 of the second full-transparent region 2023 is not less than s 2.

In this embodiment, the transmittance of the second fully transparent region 2023 to infrared light is not less than 90%, the transmittance of the second semi-transparent region 2022 to infrared light is about 50%, which may be 40-70% in this embodiment, and the transmittance of the general transparent region 2021 to infrared light is less than 30%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that various modifications and decorations can be made by those skilled in the art without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.