WO2021031247A1

WO2021031247A1 - Ink composition

Info

Publication number: WO2021031247A1
Application number: PCT/CN2019/104665
Authority: WO
Inventors: 史婷; 李文杰
Original assignee: 深圳市华星光电半导体显示技术有限公司
Priority date: 2019-08-20
Filing date: 2019-09-06
Publication date: 2021-02-25
Also published as: CN110484058A

Abstract

Disclosed in the present invention is an ink composition. The ink composition comprises: a hole injection layer material in an amount of 0.1-30% by weight of the ink composition; an organic solvent in an amount of 10-99.9% by weight of the ink composition; a morphology conditioning agent comprising a plurality of ellipsoidal particles and in an amount of 0.5-10% by weight of the ink composition; a surface tension modifier in an amount of 0.1-5% by weight of the ink composition; and a viscosity modifier in an amount of 0.1-5% by weight of the ink composition.

Description

Ink composition

Technical field

The present invention relates to an ink composition, and particularly relates to an ink composition that can be used for inkjet printing to form a hole injection layer.

Background technique

Organic electroluminescent diode (OLED) has become an emerging technology in the display field due to its advantages of high brightness, self-luminescence, fast response and low driving voltage. However, due to the high cost of vacuum thermal evaporation, its large-scale commercialization is limited . Inkjet printing has the advantages of high material utilization and is a key technology to solve the cost problem of large-size OLED display. This method uses multiple nozzles to drop the ink of each functional layer of the OLED into the predetermined pixel area, and then obtain the required by drying. Various organic functional layer films.

The thickness and morphology of the organic functional layer film are critical to the luminescence characteristics of OLEDs. Especially in the solution processing process, the optimization of the film morphology is even more important. During the solution processing, the capillary flow will cause the film to exhibit a coffee ring effect. The viscosity of the ink, the surface tension, the interaction with the substrate, the process temperature and the vacuum drying conditions will all affect the final film morphology of the organic functional layer. For example, if the film climbs higher along the pixel dam (especially the hole injection layer film), it will cause leakage current paths inside the OLED device and reduce the life of the device; if the film has poor uniformity, it will directly lead to the uniformity of light emission. If it is poor, the efficiency and lifetime of the device will be greatly reduced.

Therefore, it is necessary to provide an ink composition to solve the problems existing in the prior art.

technical problem

During the solution processing, the capillary flow will cause the film to exhibit a coffee ring effect. The viscosity of the ink, the surface tension, the interaction with the substrate, the process temperature and the vacuum drying conditions will all affect the final film morphology of the organic functional layer. For example, if the film climbs higher along the pixel dam (especially the hole injection layer film), it will cause leakage current paths inside the OLED device and reduce the life of the device; if the film has poor uniformity, it will directly lead to the uniformity of light emission. If it is poor, the efficiency and lifetime of the device will be greatly reduced.

Technical solutions

The main purpose of the present invention is to provide an ink composition, which utilizes the added ellipsoidal particles to effectively suppress the coffee ring effect, and also for the pining point of the interface between the film surface of the hole injection layer and the substrate after drying. It has a certain pinning effect, which can greatly reduce the climbing point and reduce the leakage current path.

To achieve the above objective, an embodiment of the present invention provides an ink composition, which comprises: a hole injection layer material, which is 0.1 to 30% by weight of the ink composition; and an organic solvent, which is 10 to 99.9% of the ink composition; a morphology modifier comprising several ellipsoidal particles, the morphology modifier is 0.5 to 10% by weight of the ink composition; a surface tension modifier , By weight, 0.1 to 5% of the ink composition; and a viscosity regulator, by weight, 0.1 to 5% of the ink composition.

In an embodiment of the present invention, the organic solvent is an alcohol.

In an embodiment of the present invention, the boiling point of the organic solvent is greater than 200°C.

In an embodiment of the present invention, the aspect ratio of the ellipsoidal particles is greater than 1.2.

In an embodiment of the present invention, the ellipsoidal particles are electrically conductive.

In an embodiment of the present invention, the viscosity modifier is one or more of alcohols, ethers, esters, phenols and amines.

In an embodiment of the present invention, the viscosity of the ink composition is 1-10 cps.

In an embodiment of the present invention, the surface tension of the ink composition is 30-40 dyne/cm (dyne/cm).

To achieve the above objective, another embodiment of the present invention provides an ink composition comprising a hole injection layer material, which is 0.1 to 30% by weight of the ink composition; and an organic solvent, which is 10 to 99.9% of the ink composition; a morphology modifier comprising several ellipsoidal particles, the morphology modifier is 0.5 to 10% by weight of the ink composition; a surface tension modifier , By weight, 0.1 to 5% of the ink composition; and a viscosity modifier, by weight, 0.1 to 5% of the ink composition, wherein the ellipsoidal particles are conductive and have a The aspect ratio is greater than 1.2.

In an embodiment of the present invention, the ellipsoidal particle is a metal particle or a metal oxide particle.

In an embodiment of the present invention, the organic solvent is an alcohol.

In an embodiment of the present invention, the surface tension of the ink composition is 30-40 dynes/cm.

Beneficial effect

An ink composition provided by an embodiment of the present invention utilizes the added ellipsoidal particles to effectively suppress the coffee ring effect, and for the pining point of the interface between the film surface of the hole injection layer and the substrate after drying. It also has a certain pinning effect, which can greatly reduce the climbing point and reduce the leakage current path.

Embodiments of the invention

In order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, the following will specifically cite the preferred embodiments of the present invention, which are described in detail as follows. Furthermore, the singular forms "a", "an" and "the" mentioned in the present invention include plural references unless the context clearly dictates otherwise. The numerical range (such as 10%～11% of A) includes the upper and lower limits (ie 10%≦A≦11%) unless otherwise specified; if the numerical range does not define the lower limit (such as less than 0.2% of B , Or B below 0.2%), it means that its lower limit may be 0 (ie 0%≦B≦0.2%). The above terms are used to describe and understand the present invention, but not to limit the present invention.

An embodiment of the present invention provides an ink composition, which mainly includes a hole injection layer material, an organic solvent; a morphology modifier including a plurality of ellipsoidal particles; a surface tension modifier; and a viscosity modifier .

Preferably, the material of the hole injection layer is 0.1 to 30% by weight of the ink composition, and may be, for example, 0.1, 0.5, 1.5, 5.5, 10, 20, or 30%, but is not limited thereto. The hole injection layer (or hole transport layer) material can be polyparaphenylene vinylene, polythiophene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], etc. .

In an embodiment of the present invention, the organic solvent is an alcohol, such as glycerol, ethylene glycol, butanol and the like. Preferably, the boiling point of the organic solvent is greater than 200°C but not higher than 300°C, and may be, for example, 200, 250, 275 or 300°C. Preferably, the organic solvent is 10 to 99.9% by weight of the ink composition, and may be, for example, 10, 20, 30, 40, 50, 75, 85, or 95%, but is not limited thereto. The organic solvent may be a single organic compound or an organic solvent system formed by a mixture of multiple organic solvents.

Preferably, the morphology adjusting agent is 0.5 to 10% by weight of the ink composition, and may be, for example, 0.5, 1.5, 3.5, 5.5, 7.5, or 10%, but is not limited thereto. In an embodiment of the present invention, the ellipsoidal particles are used to improve the film-forming properties of the ink composition, thereby adjusting the surface of the ink composition after forming a hole injection layer (or hole transport layer) Shape, reduce the influence of coffee ring effect. Preferably, the ellipsoidal particles have an aspect ratio greater than 1.2. The aspect ratio referred to here is the ratio of the length of the upper and lower ends to the width of the left and right sides in the sphere of the ellipsoidal particle, wherein the length and the width are perpendicular to each other. In an embodiment of the present invention, the ellipsoidal particles are conductive, and can be metal particles or metal oxide particles, for example, gold particles, tungsten oxide, or molybdenum oxide.

Preferably, the surface tension adjusting agent is 0.1 to 5% by weight of the ink composition, and may be, for example, 0.1, 0.5, 1.0, 2.5, 3.5, or 5%, but is not limited thereto. The surface tension modifier may be at least one of imidazole and its derivatives, phenol and hydroquinone, so that the ink composition can meet the requirements of inkjet printing.

Preferably, the viscosity modifier is 0.1 to 5% by weight of the ink composition, and can be, for example, 0.1, 0.5, 1.0, 2.5, 3.5, or 5%, but is not limited thereto. In an embodiment of the present invention, the viscosity modifier is one or more of alcohols, ethers, esters, phenols and amines, such as propyl acetate, methyl butanone, triacetin, etc. Ethanolamine or diethanolamine can make the ink composition meet the requirements of inkjet printing.

By selecting the ratio, preferably, the viscosity of the ink composition is 1-10 cps. In an embodiment of the present invention, the surface tension of the ink composition is 30-40 dyne/cm (dyne/cm).

The preparation method of the ink composition of the present invention may, for example, adopt the following steps:

Step S1: placing a hole injection layer material and several ellipsoidal particles in an organic solvent according to a preset ratio, and then stirring or shaking to obtain a mixed solution in which the ellipsoidal particles are dispersed; and

Step S2: During the stirring, a viscosity regulator and a surface tension regulator are added according to a preset ratio to obtain the ink composition.

The steps described above for preparing the ink composition are only an example and not the only method.

Compared with the prior art, the ink composition of the present invention is an ink composition that can form a hole transport layer (or hole injection layer) by inkjet printing, which uses conductive ellipsoidal particles as an additive. The substance is mixed with solvents, viscosity modifiers, surface tension modifiers, etc. at the same time, and by adjusting the ratio of each component, a hole injection layer film with excellent performance can be obtained after drying. The ink can utilize the inter-particle attraction between the conductive ellipsoidal particles, effectively suppress the coffee ring effect, and obtain a highly uniform film morphology.

The present invention has been described in the above-mentioned related embodiments, but the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and equivalent arrangements included in the spirit and scope of the claims are all included in the scope of the present invention.

Claims

An ink composition comprising:

A hole injection layer material, which is 0.1 to 30% by weight of the ink composition;

An organic solvent, 10 to 99.9% by weight of the ink composition;

A morphology modifier comprising several ellipsoidal particles, the morphology modifier is 0.5 to 10% by weight of the ink composition;

A surface tension modifier, which is 0.1 to 5% by weight of the ink composition; and

A viscosity modifier is 0.1 to 5% by weight of the ink composition.
The ink composition of claim 1, wherein the organic solvent is an alcohol.
The ink composition of claim 1, wherein the boiling point of the organic solvent is greater than 200°C.
8. The ink composition of claim 1, wherein the aspect ratio of the ellipsoidal particles is greater than 1.2.
The ink composition of claim 1, wherein the ellipsoidal particles are electrically conductive.
8. The ink composition of claim 1, wherein the viscosity modifier is one or more of alcohols, ethers, esters, phenols and amines.
5. The ink composition of claim 1, wherein the viscosity of the ink composition is 1 to 10 cps.
The ink composition of claim 1, wherein the surface tension of the ink composition is 30 to 40 dynes/cm.
An ink composition comprising:

A hole injection layer material, which is 0.1 to 30% by weight of the ink composition;

An organic solvent, 10 to 99.9% by weight of the ink composition;

A morphology modifier comprising several ellipsoidal particles, the morphology modifier is 0.5 to 10% by weight of the ink composition;

A surface tension modifier, which is 0.1 to 5% by weight of the ink composition; and

A viscosity modifier, which is 0.1 to 5% by weight of the ink composition,

The ellipsoidal particles are conductive and have an aspect ratio greater than 1.2.
9. The ink composition of claim 9, wherein the ellipsoidal particle is a metal particle or a metal oxide particle.
9. The ink composition of claim 9, wherein the organic solvent is an alcohol.
The ink composition of claim 9, wherein the boiling point of the organic solvent is greater than 200°C.
9. The ink composition of claim 9, wherein the viscosity modifier is one or more of alcohols, ethers, esters, phenols, and amines.
9. The ink composition of claim 9, wherein the viscosity of the ink composition is 1 to 10 cps.
9. The ink composition of claim 9, wherein the surface tension of the ink composition is 30 to 40 dynes/cm.