Display substrate, manufacturing method thereof and display device
Technical Field
The invention belongs to the technical field of display, and particularly relates to a display substrate, a manufacturing method of the display substrate and a display device.
Technical Field
Quantum dots are solution-processed semiconductor nanocrystals that can be size-tuned for emission wavelength, have narrow emission bandwidths, nearly uniform photoluminescence quantum yields, and intrinsic photophysical stability. Since it is an inorganic crystal as an emission center, it has better characteristics than PLED (polymer OLED) and small molecule OLED in terms of stability.
Electroluminescent devices fabricated by solution processes are attractive because of their large area, low cost potential and compatibility with lightweight flexible plastic substrates. During the last two decades, the technological route of fabricating light emitting diodes by using solution process of copolymer or quantum dot has caused great enthusiasm. As shown in fig. 1, is a device structure of a quantum dot light emitting diode (QLED).
Inkjet printing is a low-cost, reliable, fast, and convenient patterning technology, and inkjet printing technology widely used in industry can be used to reduce cost and provide high-quality output. As shown in fig. 2, when R, G, B patch printing was performed, jetting was completed on the substrate 3 times using R, G, B quantum dot ink-jet heads.
As shown in fig. 3, when ink droplets are subjected to ink jet printing, it is necessary to form a Bank pattern on a substrate because the ink droplets have fluidity, and to prevent the ink of a certain sub-pixel from flowing to an adjacent sub-pixel to cause color crosstalk and affect display. Therefore, the dam material needs to have a certain ink-droplet-repelling property, and the flat layer below the dam pattern layer needs to have a certain ink-droplet-attracting property. As shown in fig. 4, when ink droplets are printed by ink jet, the positions where the ink droplets land may be deviated or may climb up a dam to affect display due to the influence of factors such as droplet size accuracy, ink ejection position accuracy, ink droplet ejection speed, and head movement speed.
Disclosure of Invention
In order to solve the technical problems, the invention provides a display substrate and a manufacturing method thereof, wherein an electrode pattern layer, a dam pattern layer and ink drops are charged by an electrostatic power supply in an ink-jet printing process of the display substrate, so that color mixing caused by drop-filling position deviation is avoided, and the extension effect of the ink drops is improved; the invention also provides a display device comprising the display substrate.
The technical scheme provided by the invention is as follows:
the invention discloses a display substrate, which comprises a substrate, an electrode pattern layer positioned on the substrate and a flat layer covering the electrode pattern layer, wherein the electrode pattern layer comprises a plurality of discrete pixel electrodes, and the distribution of a plurality of sub-pixels in the display substrate is defined by the distribution of the pixel electrodes; further comprising:
a dam pattern layer on the planarization layer, including a dam at an edge of each sub-pixel; forming a groove located within a corresponding sub-pixel from the sidewall of the bank and the planarization layer; the dam has conductivity;
the ink drop layer is formed by drying ink drops dripped into the groove in an ink jet printing mode; the ink droplets are electrically conductive and carry a positive charge;
and the electrostatic power supply is connected with the electrode pattern layer and the dam pattern layer and can apply positive potential or negative potential to the electrode pattern layer and the dam pattern layer respectively.
Preferably, the conductive ink drops comprise 0.01-5% by volume of a charge control agent, the charge control agent being a copper sulfide electrolyte or a fluorine-containing ionic surfactant.
Preferably, the whole of the dam is made of a conductive material, and the conductive material is a conductive resin material formed by adding a conductive dopant in an amount of 0.01-5% by volume.
Preferably, the conductive impurities are conductive carbon black, conductive dot fibers or metal particles.
Preferably, the dam is a laminated structure of a conductive material layer and an insulating material layer, and comprises a dam electrode layer on the flat layer and a dam structure layer covering the dam electrode layer;
the dyke electrode layer is a conductive material layer and comprises metal or conductive metal oxide; the dam structure layer is an insulating material layer.
Preferably, the dam is a laminated structure of a conductive material layer and an insulating material layer, and comprises a dam structure layer located on the flat layer and a dam electrode layer covering the dam structure layer;
the dam structure layer is an insulating material layer; the dam electrode layer is a conductive material layer including a metal or a conductive metal oxide.
The invention discloses a manufacturing method of a display substrate, which comprises the following steps:
the first step is as follows: forming an electrode pattern layer on a substrate, wherein the electrode pattern layer comprises a plurality of discrete pixel electrodes, and the distribution of a plurality of sub-pixels in the display substrate is defined by the distribution of the pixel electrodes;
the second step is that: forming a flat layer on the electrode pattern layer;
the third step: forming a dam pattern layer on the flat layer, wherein the dam pattern layer comprises a dam positioned at the edge of each sub-pixel, and a groove positioned in the corresponding sub-pixel is formed by the side wall of the dam and the flat layer;
the fourth step: the electrostatic power supply is respectively connected with the electrode pattern layer, the dam pattern layer and the nozzle for dripping ink drops; (ii) a
The fifth step: applying a negative potential to a pixel electrode in the sub-pixel through an electrostatic power supply, and applying a positive potential to the dam pattern layer; controlling the spray head to generate ink drops with positive charges to be dropped into the groove;
and a sixth step: applying positive potential to a pixel electrode in the sub-pixel through an electrostatic power supply, applying negative potential to the dam pattern layer, and waiting for ink drop extension;
the seventh step: and after the dynamics of the ink drops are stable, controlling the electrostatic power supply to cancel the electric potential applied to the electrode pattern layer and the dam pattern layer.
Preferably, the third step includes:
forming a film on the flat layer by using metal and patterning to form a dam electrode layer, wherein the dam electrode layer is positioned at the edge of the corresponding sub-pixel;
and forming a dam structure layer on the dam electrode layer by using an insulating material, wherein the dam electrode layer and the dam structure layer jointly form the dam pattern layer.
Preferably, the third step includes:
forming a dam structure layer on the flat layer by using an insulating material, wherein the dam structure layer is positioned at the edge of the corresponding sub-pixel;
and forming a film by using metal on the dam structure layer and patterning to form a dam electrode layer, wherein the dam structure layer and the dam electrode layer jointly form the dam pattern layer.
The invention also discloses a display device which is characterized by comprising any one of the display substrates. Compared with the prior art, the invention can bring at least one of the following beneficial effects:
1. in the droplet dropping stage, the electrode pattern layer and the droplets are charged oppositely by an electrostatic power supply, so that the dam pattern layer and the droplets are charged identically; even if the dripping position is deviated, ink drops dripped on the edge of the dam pattern layer can fall back into a groove formed by the dam pattern layer;
2. in the ink drop spreading stage, the electrode pattern layer and the ink drops are charged the same through an electrostatic power supply, the dam pattern layer and the ink drops are charged oppositely, the ink drops falling to the vicinity of the center point of the sub-pixel are pushed away to the periphery, and spreading of the ink drops is accelerated.
Drawings
The present invention will be further described in the following detailed description of preferred embodiments, which is to be read in connection with the accompanying drawings.
FIG. 1 is a schematic structural diagram of a conventional quantum dot light-emitting diode;
FIG. 2 is a schematic diagram of a prior art inkjet printing method;
FIG. 3 is a schematic diagram of an ink-jet printing step of a conventional display substrate;
FIG. 4 is a schematic diagram illustrating a position shift of a conventional inkjet printing apparatus;
FIG. 5 is a schematic view of a display substrate according to an embodiment of the present invention;
FIG. 6 is a schematic illustration of one of the ink jet printing steps for the display substrate shown in FIG. 5;
FIG. 7 is a top view of a sub-pixel in the manufacturing step shown in FIG. 6;
FIG. 8 is a second schematic diagram illustrating an ink jet printing step of the display substrate shown in FIG. 5;
FIG. 9 is a top view of a sub-pixel in the manufacturing step shown in FIG. 8;
FIG. 10 is a third schematic view of an ink jet printing step of the display substrate of FIG. 5;
FIG. 11 is a top view of a sub-pixel in the manufacturing step shown in FIG. 10;
fig. 12 is a schematic structural diagram of a display substrate according to another embodiment of the invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".
The display substrate of the present invention has a structure as shown in fig. 5, and includes a base substrate 01, an electrode pattern layer 02 on the base substrate 01, a flat layer 03 covering the electrode pattern layer 02, and a bank pattern layer 04 on the flat layer 03.
The electrode pattern layer 02 includes a plurality of discrete pixel electrodes, the pixel electrodes are arranged in a matrix or other regular arrangement, and the distribution of the pixel electrodes defines the distribution of a plurality of sub-pixels in the display substrate.
The planarization layer 03 includes one or more insulating organic materials, and the planarization layer 03 covers the electrode pattern layer 02 and forms a relatively flat upper surface.
The dam pattern layer 04 comprises dams at the edge of each sub-pixel, and grooves in the corresponding sub-pixels are formed by the side walls of the dams and the underlying flat layer 03; the dam has conductivity and can be at a corresponding potential after being injected with positive or negative charges.
The display substrate further comprises an ink drop 05 layer, wherein the ink drop 05 layer is formed by drying the ink drop 05 dripped into the groove in an ink-jet printing mode; the ink droplets 05 are electrically conductive and have a positive or negative charge.
In addition, the display substrate includes an electrostatic power supply 07, the electrostatic power supply 07 is connected to the electrode pattern layer 02 and the bank pattern layer 04, and a positive potential and a negative potential can be applied to the electrode pattern layer 02 and the bank pattern layer 04, respectively; the electrostatic power supply 07 may also be connected to a head 06 for dropping ink droplets 05, and controls the head 06 to eject ink droplets 05 with electric charges.
The invention discloses a manufacturing method of the display panel, which comprises the steps of forming an electrode pattern layer 02, a flat layer 03 and a dam pattern layer 04 on a substrate 01 in sequence, and then carrying out ink-jet printing, wherein the ink-jet printing can be carried out for multiple times according to areas and ink drop types. In the method for manufacturing a display panel of the present invention, the single inkjet printing step includes: and three stages of dripping of the ink drop 05, extending of the ink drop 05 and finishing of ink-jet printing. In the dripping stage of the ink droplets 05, the electrode pattern layer 02 and the ink droplets 05 are oppositely charged by the electrostatic power supply 07, so that the dam pattern layer 04 and the ink droplets 05 are charged identically; even if the dripping position is deviated, the ink drops 05 dripped on the edge of the dam pattern layer 04 can fall back into the groove formed by the surrounding of the dam pattern layer 04, so that the color mixing caused by the dripping deviation is avoided. In the ink drop 05 spreading stage, the electrode pattern layer 02 and the ink drops 05 are charged the same by the electrostatic power supply 07, so that the dam pattern layer 04 and the ink drops 05 are charged oppositely, and the ink drops 05 falling near the center point of the sub-pixel are pushed away to the periphery, so that the spreading of the ink drops 05 is accelerated. At the end of the ink jet printing, after the ink droplets 05 are stabilized dynamically, the electrostatic power supply 07 is controlled to remove the potential applied to the electrode pattern layer 02 and the bank pattern layer 04.
The invention is explained in detail below by way of examples:
the first embodiment is as follows:
as shown in fig. 5, the display device of the present embodiment includes a base substrate 01, an electrode pattern layer 02 on the base substrate 01, a planarization layer 03 covering the electrode pattern layer 02, and a bank pattern layer 04 on the planarization layer 03.
The electrode pattern layer 02 includes a plurality of discrete pixel electrodes, the pixel electrodes are arranged in a matrix or other regular arrangement, and the distribution of the pixel electrodes defines the distribution of a plurality of sub-pixels in the display substrate. The pixel electrode in the electrode pattern layer 02 is made of a material such as metal, conductive metal oxide, or the like, for example, chromium, aluminum, copper, silver, ITO (indium tin oxide), or the like.
The planarization layer 03 includes one or more insulating organic materials, and the planarization layer 03 covers the electrode pattern layer 02 and forms a relatively flat upper surface.
The dam pattern layer 04 includes a dam at the edge of each sub-pixel, and a groove in the corresponding sub-pixel is formed by the sidewall of the dam and the underlying planarization layer 03. The adjacent sub-pixels can share a part of dams at the connected positions, and the cross section of a groove formed after the dams are closed is circular, rectangular, rounded rectangular, hexagonal and the like. The whole dam is made of conductive material, the conductive material is conductive resin material formed by adding conductive adulterant whose volume ratio is 0.01% -5%, the conductive adulterant can be conductive carbon black, conductive point fiber and metal particle.
The display substrate further comprises an ink drop layer, wherein the ink drop layer is formed by drying ink drops 05 which are dripped into the grooves in an ink jet printing mode; the ink drop 05 has conductivity and is positively charged, and the conductive ink drop 05 is added with a charge control agent such as electrolyte and ionic surfactant, etc. accounting for 0.01-5% of the volume of the ink drop 05 to obtain accurate conductivity; specifically, the charge control agent may be a copper sulfide electrolyte or a fluorine ion-containing surfactant.
In addition, the display substrate includes an electrostatic power supply 07, the electrostatic power supply 07 is connected to the electrode pattern layer 02 and the bank pattern layer 04, and charges may be injected into the electrode pattern layer 02 and the bank pattern layer 04, respectively, to apply a positive potential or a negative potential thereto; the electrostatic power supply 07 may also be connected to a head 06 for dropping ink droplets 05, and controls the head 06 to eject ink droplets 05 with positive charges.
The method for manufacturing a display substrate in this embodiment includes the following steps:
the first step is as follows: forming an electrode pattern layer 02 on a substrate 01, wherein the electrode pattern layer 02 comprises a plurality of discrete pixel electrodes, and the distribution of a plurality of sub-pixels in a display substrate is defined by the distribution of the pixel electrodes;
the second step is that: forming a planarization layer 03 on the electrode pattern layer 02;
the third step: forming a bank pattern layer 04 on the planarization layer 03, the bank pattern layer 04 including a bank at an edge of each sub-pixel; forming a groove located in the corresponding sub-pixel from the sidewall of the bank and the planarization layer 03;
the fourth step: an electrostatic power supply 07 is connected to the electrode pattern layer 02, the dam pattern layer 04, and a head 06 for dropping ink droplets 05;
fifth step (drop 05 dropping): as shown in fig. 6, a negative potential is applied to the pixel electrode in the sub-pixel by the electrostatic power supply 07, a positive potential is applied to the bank pattern layer 04, and the nozzle 06 is controlled to generate a positively charged ink droplet 05 to be dropped into the sub-pixel; even if the dripping position is deviated, the ink drop 05 dripped on the edge of the dam pattern layer 04 generates repulsion because the charge polarities of the dam pattern layer 04 and the ink drop 05 are the same, and the ink drop 05 also falls back into the groove formed by the dam pattern layer 04 in a surrounding way; the top view of the display substrate at this stage is shown in FIG. 7;
sixth step (ink droplet 05 development): as shown in fig. 8, a positive potential is applied to the pixel electrode in the sub-pixel by the electrostatic power supply 07, a negative potential is applied to the conductive bank pattern layer 04 in the sub-pixel, and the ink droplet 05 is waited for to spread; the positively charged ink droplets 05 dropped into the sub-pixels are opposite in polarity to the charge carried by the dam pattern layer 04, and the ink droplets 05 spread out rapidly in the grooves; meanwhile, the positively charged ink drop 05 has the same charge polarity as the lower electrode pattern layer 02, so that the ink drop 05 dropped near the center point of the sub-pixel is pushed away to the periphery, and the spreading of the ink drop 05 is accelerated; the top view of the display substrate at this stage is shown in FIG. 9;
seventh step (end of ink-jet printing): after the dynamics of the ink droplets 05 are stabilized, controlling the electrostatic power supply 07 to remove the potential applied to the electrode pattern layer 02 and the dam pattern layer 04 as shown in fig. 10; the top view of the display substrate at this stage is shown in FIG. 11;
example two:
the second embodiment is obtained by modifying the first embodiment, and the difference between the second embodiment and the first embodiment is as follows:
as shown in fig. 12, the display substrate of this embodiment has a structure in which a bank is a stacked structure of a conductive material layer and an insulating material layer, and a bank pattern layer 04 includes a bank electrode layer 041 on a planarization layer 03 and a bank structure layer 042 covering the bank electrode layer 041. The bank electrode layer 041 is a conductive material layer, and is formed of a conductive material such as metal or metal oxide, for example: at least one of aluminum, copper, silver, indium tin oxide; the dam structure layer 042 is an insulating material layer containing one or more organic materials or inorganic insulating materials. The electrostatic power supply 07 may apply a positive voltage or a negative voltage to the bank internal electrode.
The manufacturing method of the display substrate of the present embodiment is different from the first embodiment in that the third step includes:
forming a film on the planarization layer 03 by using a metal and patterning the film to form a dam electrode layer 041, where the dam electrode layer 041 is located at the edge of the corresponding sub-pixel;
the bank electrode layer 041 is formed of an insulating material to form a bank structure layer 042, and the bank electrode layer 041 and the bank structure layer 042 together form a bank pattern layer 04.
Example three:
the third embodiment is obtained by modifying the first embodiment, and the difference between the third embodiment and the first embodiment is as follows:
the bank is a stacked structure of a conductive material layer and an insulating material layer, and the bank pattern layer 04 includes a bank structure layer 042 on the planarization layer 03 and a bank electrode layer 041 covering the bank structure layer 042. The dam structure layer 042 is an insulating material layer containing one or more organic materials or inorganic insulating materials; the bank electrode layer 041 is a conductive material layer, and is formed of a conductive material such as metal or metal oxide, for example: at least one of aluminum, copper, silver, indium tin oxide; the electrostatic power supply 07 may apply a positive voltage or a negative voltage to the bank electrode.
The manufacturing method of the display substrate of the present embodiment is different from the first embodiment in that the third step includes:
forming a bank structure layer 042 on the planarization layer 03 from an insulating material, the bank structure layer 042 being located at an edge of the corresponding sub-pixel;
a bank electrode layer 041 is formed by forming a film of a metal on the bank structure layer 042 and patterning the film, and the bank structure layer 042 and the bank electrode layer 041 together form a bank pattern layer 04.
In other embodiments, the dam may be a stacked structure in which an insulating material layer embeds a conductive material layer, or a stacked structure of a plurality of conductive material layers and a plurality of insulating material layers.
The invention also discloses a display device comprising any one of the display substrates.
It should be noted that it is within the scope of the present invention that the control ink droplets 05 in the above embodiment are charged with positive charges, and the control ink droplets 05 in other embodiments are charged with negative charges, and that the positive potentials of the electrode pattern layer 02 and the bank pattern layer 04 described above are replaced with negative potentials and negative potentials with positive potentials, respectively.
It should be noted that the above mentioned embodiments are only preferred embodiments of the present invention, but the present invention is not limited to the details of the above embodiments, and it should be noted that, for those skilled in the art, it is possible to make various modifications and amendments within the technical concept of the present invention without departing from the principle of the present invention, and various modifications, amendments and equivalents of the technical solution of the present invention should be regarded as the protection scope of the present invention.