WO2015102399A1

WO2015102399A1 - Flexible device having graphene composite layer for solution process

Info

Publication number: WO2015102399A1
Application number: PCT/KR2014/013086
Authority: WO
Inventors: 남보애; 심동훈; 조성희; 이신우; 강지연
Original assignee: 엘지디스플레이 주식회사
Priority date: 2013-12-31
Filing date: 2014-12-30
Publication date: 2015-07-09
Also published as: KR20150080381A; KR102034657B1

Abstract

The present invention relates to a flexible device and a manufacturing method therefor. A flexible display device according to the present invention comprises: a flexible substrate having an organic light-emitting device formed thereon; and a barrier layer for inhibiting gas/moisture from penetrating into the organic light-emitting device. The barrier layer has at least two layers of carbon-based fillers, having a two-dimensional flat shape, laminated thereon.

Description

Flexible device with graphene composite layer for solution process

The present disclosure relates to a flexible device and a method of manufacturing the same, and more particularly, to a flexible device and a hybrid-graphene composite layer including a hybrid-graphene composite layer that can be formed by various solution processing methods.

Graphene, a single layer composed of sp ² bonded carbon atoms, has been considered technically very important in recent years because of its excellent properties. Graphene exhibits better electrical conductivity than any other conventional material, has greater thermal conductivity than diamond, and has a physical strength of at least 200 times greater than steel at a weight of one sixth. Graphene not only provides transparency, electrical properties, gas / moisture barrier properties, but also the flexibility and mechanical strength required for flexible devices. Since it can be used, it can also be usefully used in an organic light emitting diode (OLED) display or a flexible display device which is recently attracting attention.

Initially, graphene was exfoliated through micro-mechanical cleavage of graphene called the "Scotch Tape" method. In view of the structural stability of the graphene, the graphene having the best quality can be obtained by physically peeling the graphite. For this reason, the effectiveness of the new graphene synthesis method is generally evaluated in comparison with the properties of physically exfoliated graphene. Physically exfoliated graphene has few structural defects, so it may be of interest to study graphene, but the thickness of the exfoliated graphene platelets, the length of the platelets in the plane direction, and the exfoliation Because of the inability to control the position, it is difficult to apply physical graphene stripping methods to industry. For this reason, there is a need for a graphene synthesis method that is more efficient and ensures a consistent yield.

[Related Technical Documents]

1. Manufacturing method of graphene film, manufacturing method of touch device using same (Patent Application No. 10-2011-0120656)

2. Organic light emitting device and manufacturing method thereof (Patent Application No. 10-2011- 0051871)

In general, the graphene synthesis method is divided into a bottom-up method and a top-down method. Bottom-up methods such as epitaxial growth and chemical vapor deposition (CVD) have the advantage of precisely controlling the size and thickness of graphene. For example, graphene growth technology using chemical vapor deposition can grow in the presence of metal catalysts such as nickel (Ni), copper (Cu), and platinum (Pt) on wafers of 4 inches or larger, and have a relatively large area with relatively high quality. Although graphene can be produced, defects such as wrinkles and grain boundaries exist due to the difference in thermal expansion coefficient between the metal catalyst and graphene used. In addition, chemical vapor deposition is a limitation in terms of industrial applications, as well as low yield and high manufacturing costs, as the process of moving graphene from a grown substrate to a substrate to which graphene is actually deposited is a very complex and additional source of defects. There is this.

In order to overcome these limitations, development of graphene synthesis technology using a top-down method such as graphene oxidation and interlayer compound exfoliation has been actively conducted. In particular, the liquid-phase separation and oxidation method in which the graphite is peeled off from the liquid phase and obtained in a liquid form in which graphene is dispersed is not only able to manufacture a large amount of graphene at a low cost but also a costly vacuum technology. It can be coated on the target substrate through a variety of solution process without using a coating method, it is a graphene synthesis method is very likely to use in industrial. In a common liquid phase reduction method, graphite becomes a graphite oxide by a strong acid and an oxidant, and the graphene oxide plate is composed of a single layer and / or a multilayer (2-20 layer) sheet by exfoliating the graphite oxide in a liquid phase. Get the letts. The oxygen functionalities of graphene oxide platelets make graphene oxide platelets easily soluble in water. The colloidal solution of the graphene oxide platelet is subjected to several chemical treatments, filtration, dehydration process, and re-dispersion, and reduced graphene oxide platelets in which the graphene oxide platelets are partially restored. A dispersion is obtained.

This liquid phase reduction method has several advantages but also several disadvantages. Graphene oxide platelets reduced by chemical methods in the liquid phase cannot be completely restored in structure. In addition, even if the chemical structure or functional group is modified to improve the dispersion of the graphene oxide platelet or reduced graphene oxide platelet in the solution, it is inevitable to generate defects in the graphene structure, so the chemical reduction method in the liquid phase The reduced graphene oxide platelet obtained as a problem is difficult to use in the field requiring high electrical properties or moisture permeation prevention functions. For example, the electrical properties of chemically reduced reduced graphene oxide in the liquid phase may be two orders of magnitude lower (eg, 100 times) than raw graphene. Furthermore, the chemical treatment, filtration, drying and re-dispersion steps repeated several times until reduction in the liquid phase by chemical methods to obtain a reduced graphene oxide platelet solution may be achieved by re-agglomeration of the reduced graphene oxide platelets and Re-stacking can be caused to significantly reduce the effectiveness of graphene for solution processing.

By dispersing the graphene in a solvent, various solution processes such as spin-coating, inkjet, dipping, etc. can be used for a wider range of applications in a simpler, less expensive and more efficient manner. It can be said that there is a sufficient advantage because it allows. For this reason, various efforts have been made to obtain graphene for the solution process with the above-mentioned problems improved. However, the improvements proposed so far have focused mainly on the use or types of chemical agents or surfactants to reduce the graphene platelets or to improve dispersibility in solvents. Satisfactory results have not been obtained.

The inventors of the embodiments disclosed herein, in the process of making the graphene for the solution process: 1) it is unnecessary to chemically reduce the graphene oxide in the liquid phase to create a defect in the structure of the reduced graphene oxide platelet; 2) Re-agglomeration / re-stacking of the reduced graphene oxide platelets is a method of reducing graphene oxide platelets rather than factors such as the type of reducing agent, the type of solvent or the use of a surfactant in the solvent, It was recognized that it is further due to the state of the reduced graphene oxide platelets and the timing of dispersion.

Accordingly, the problem to be solved by the present invention is to provide a new method for synthesizing the graphene usable in a solution process method with fewer defects without re-aggregation / re-stacking problems. Another problem to be solved by the present invention is a new method to synthesize a solution-processable hybrid-graphene composite that provides better optical, physical, thermal, electrical and gas / moisture barrier properties than existing graphene composites. To provide.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

The flexible display device according to the exemplary embodiment of the present invention includes a flexible substrate on which the organic light emitting diode is formed, and a barrier layer that suppresses penetration of gas / moisture of the organic light emitting diode. The barrier layer is formed by stacking at least two layers of carbon-based fillers having a two-dimensional planar shape.

A hybrid-graphene layer comprising a substrate or polymer matrix and a plurality of reduced graphene oxide platelets in accordance with one embodiment of the present invention. The reduced graphene oxide platelets included in the hybrid graphene layer are oriented horizontally.

In the method for producing a hybrid-graphene composite for solution processing according to an embodiment of the present invention, a dispersion solution containing graphene oxide platelets is produced. In addition, the carbon nanoparticles are dispersed in a dispersion solution to produce a precursor solution. In addition, the precursor solution is aerosolized to convert it into aerosol droplets with graphene oxide platelets and carbon nanoparticles. Pyrolysis is also performed on the aerosol droplets to reduce the graphene oxide platelets.

The reduced graphene oxide platelets of graphene for solution processing prepared by the above method have hydrophobic properties, but are compatible with various kinds of organic solvents and polymers. High-quality reduced graphene oxide platelets made from the manufacturing method of the present invention and excellent dispersibility in various kinds of solvents, as well as the development of new graphene-based composites, as well as the ability to provide multi-functions in electronic devices, and biomedical It enables the production of hybrid-graphene composites that can be applied even to the field.

Specific details of other embodiments are included in the detailed description and drawings.

1 is a flow chart illustrating an exemplary method for synthesizing graphene that can be used in a solution process.

2 is a flow chart illustrating an exemplary method for synthesizing a hybrid-graphene composite that can be used in a solution process.

3 is a table showing a comparison of sheet resistance values of samples obtained by the exemplary methods disclosed in the present invention.

4 is a high magnification SEM image showing the plate and single phase structure of the samples obtained by the exemplary methods disclosed herein.

5A is a plan view illustrating an exemplary touch screen panel using a hybrid-graphene layer in accordance with one embodiment of the present invention.

FIG. 5B is a cross-sectional view taken along Vb-Vb of FIG. 5A.

6 is a cross-sectional view illustrating an exemplary thin film transistor using a hybrid-graphene layer in accordance with an embodiment of the present invention.

7 is a cross-sectional view illustrating an exemplary organic light emitting display device using a hybrid graphene layer according to an exemplary embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

When an element or layer is referred to as “on” another element or layer, it encompasses both the case where another layer or other element is interposed over or in the middle of another element.

Although the first, second, etc. are used to describe various components, it is only used to distinguish a particular component among a plurality of components corresponding to the first and second components. Therefore, of course, the first component mentioned below may be a second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout.

The size and thickness of each component shown in the drawings are shown for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated configuration.

Each of the features of the various embodiments of the present invention may be combined or combined with each other in part or in whole, various technically interlocking and driving as can be understood by those skilled in the art, each of the embodiments may be implemented independently of each other It may be possible to carry out together in an association.

As used herein, “graphene” may collectively refer to both graphene oxide (GO) and reduced graphene oxide (rGO) as well as pristine graphene. Theoretically graphene consists of a single layer structure, but the graphene platelets used in the examples herein include not only graphene of a single layer structure but also multilayer structures (for example, 2-20 layers). Therefore, in this specification, the graphene oxide platelet or the reduced graphene oxide platelet used in the embodiments using the expression “platelet” is not only a single layer structure but also a plurality of layers stacked. Emphasis was placed on including structure.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flow diagram illustrating an exemplary method 100 for obtaining a colloidal dispersion in which reduced graphene oxide platelets are dispersed, suitable for depositing on a desired surface in various solution based processes.

As shown in FIG. 1, the method 100 for obtaining a reduced graphene oxide platelets dispersion solution may include preparing a solution in which graphene oxide platelets having a single layer structure and / or a multilayer structure are dispersed in a liquid phase (S110). ). The dispersion solution of graphene oxide can be obtained through various conventional methods known in the art. For example, Brodie, Stademaier and Hummers methods and their various variations can be prepared.

In the case of oxidizing graphite, the inherent 0.34 nm interlayer spacing can be extended to about 0.7 nm and includes hydroxyl, epoxide, carbonyl and carboxylic functional groups. Graphite oxides with oxyfunctionals can be produced. The functional groups also make the graphene sheets hydrophillic and facilitate the retention of water molecules between layers in the graphite oxide. Accordingly, it is much easier to obtain graphene platelets by exfoliating graphite oxide than to exfoliate graphite directly to obtain graphene platelets.

In order to produce a dispersion solution of graphene oxide platelets, graphite oxide can be stripped in the solution by sonication and centrifugation. Unexfoliated graphite oxide can be removed from the solution through filtration.

Graphene for solution processing can be used to produce a large amount of graphene to form a graphene composite, a layer (Layer) or a film (Film). In this case the size of the graphene platelets has a decisive influence on the properties of the final structure formed from them, so it may be important to obtain platelets of sufficient size. For example, the Lateral Length of graphene platelets may be greater than or equal to a particular micron (eg, greater than or equal to 0.5 μm) to obtain the desired physical properties from the graphene composite. In general, the sheet resistance of the graphene film formed using platelets of longer length has a lower value than that of the graphene film formed using platelets of relatively short size. This results in more junctions between the plates when forming films using smaller platelets, so that the electrical conductivity throughout the network of these platelets is dependent on the contact resistance between the platelets. It is bound to be limited.

It has also been generally considered in the industry that membranes formed using platelets with larger aspect ratios have longer torsional paths and therefore better gas / moisture barrier properties. However, the inventors of the embodiments described herein have found that using platelets with larger aspect ratios does not lead to membranes with better gas / moisture barrier properties. In other words, the lateral length of graphene platelets and the gas / moisture barrier properties of the films formed therefrom are not necessarily proportional. Sometimes when the average size of platelets exceeds a certain size, the gas / moisture barrier properties of the final graphene film may be rather deteriorated.

Accordingly, in embodiments for obtaining the reduced graphene oxide platelets dispersion solution, the step of controlling the size of the graphene oxide platelets may be performed. Size selection of graphene oxide platelets may be accomplished by chromatography, but such methods are typically limited in the amount obtainable. Thus, in some embodiments of the present invention, the size of the graphene platelets is controlled by adjusting the centrifugation rate.

The maximum size of the graphene oxide platelets is limited by the size of the source from which the graphene is first peeled off, but the average lateral length of the graphene oxide platelets dispersed in the solution is in the preparation of the graphene oxide platelet dispersion. Increasing centrifugal turnover can even control nanoscale units. The average transverse length of the scattered platelets decreases with increasing centrifugal turnover. In other words, higher centrifugation turns can be separated into relatively short length platelets left dispersed in the colloidal solution in the form of precipitates and longer platelets remaining in the form of precipitates. This precipitate can be redispersed, which leads to dispersions in which platelets of different average lengths are dispersed.

In general, the process of obtaining a graphene oxide plate dispersion by peeling from the sonicated graphite oxide includes a portion of unpeeled graphite crystals (Crystallite) to be removed from the aqueous solution through a centrifugation step. For example, a centrifugal turnover of 500 rpm may be suitable for removing graphite crystals while keeping the graphene oxide platelets dispersed. When redispersing the precipitate, the average length of graphene oxide platelets can be controlled by adjusting the centrifugation turnover. For example, if centrifuged at 500 rpm to remove only graphite crystals, an initial supernatant with small flakes, a precipitate with all different lengths of redispersed solution and a precipitate containing graphite crystals are obtained. do. Here, if the precipitated solution is centrifuged at a higher rotation rate, the graphite crystals and the relatively longer platelets are removed, and only the medium length platelets are dispersed to obtain a dispersion solution. In this case, the first supernatant contains only small platelets of small length, and the precipitate is redispersed so that medium length platelets are dispersed in the centrifuged solution. And large platelets and graphite crystals remain as precipitates. Through this mechanism it is possible to control the length of the graphene oxide platelets, and further reduced graphene oxide platelets. Note that if you centrifuge at the same turn rate in each step, you will only get sediments of the same length. Therefore, in order to obtain samples in which graphene oxide platelets of various average lengths are separated, centrifugation should be performed sequentially at a lower rotation rate.

The solvent for preparing the graphene oxide platelets dispersion is not particularly limited. Preferred solvents are water, but additives that can improve the wetting of co-solvents or hydrophobic graphene platelets can be used together. Solvents and / or additives may be used alone or in combination. Preferred additives include surfactants such as alcohols, such as methanol, ethanol, butanol, propanol, glycols, water soluble esters and ethers, nonionic ethylene oxide, propylene oxide and their copolymers, tergitol ( tergitol) surfactants, or alkyl surfactants such as Triton-based surfactants, or surfactants having ethylene oxide and propylene oxide or butylene oxide units. Such examples include the Pluronic or Tetronic series of surfactants. Cosolvents and surfactants may be included in the solution at 0.0001 to 10% by weight. Cosolvents and surfactants are in solution, in particular 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7 , 7.5, 8, 8.5, 9 and 9.5 weight percent, and may be included as a sub-value between these values.

The method 100 for obtaining the reduced graphene oxide platelets dispersion solution includes converting the graphene oxide platelets dispersion solution into an aerosol droplet (S120). As a step of transforming into an aerogel dropplets, for example, an ultrasonic nebulizer may be used to spray by transforming the precursor solution into an aerosol droplet having a diameter of several tens of microns.

The method 100 for obtaining the reduced graphene oxide platelets dispersion solution includes passing the airgel droplets through a furnace to evaporate water molecules and reduce the graphene oxide platelets (S130). As an example of a furnace, a tubular furnace may be used. The sprayed airgel droplets can be transferred to the furnace using gas. In this case, as the gas used, one or other various reducing gases such as argon gas and nitrogen (N ₂ ) gas may be mixed and used. You can also use an additional fan for faster movement.

The temperature of the furnace may range from 300 ° C to 2000 ° C. The temperature of the furnace may be a temperature capable of simply reducing the graphene oxide platelets in the aerosol droplets, but the temperature of the furnace may be determined in consideration of various factors in order to facilitate the reduction of the graphene oxide platelets. For example, the temperature of a furnace may vary within the furnace structure of the furnace, the volume and rate of aerosol droplets passing through the furnace in a particular section, and the aerosol droplets determined by these. It can be determined according to the residence time of. The higher the temperature of the furnace, the shorter the time that the aerosol droplets must remain in the furnace. The residence time in the furnace of the aerosol droplets may be from about 0.1 seconds to about 10 minutes, preferably from 1 second to 5 minutes. Retention time may include, in particular, 5, 10, 20, 30, 40, 50 seconds, 1 minute, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 minutes, including sub-values between these values. Can be. As an example, the furnace may be heated to a temperature between 300 ° C. and 600 ° C. to sufficiently reduce graphene oxide platelets with a residence time of 0.1 seconds to 10 minutes.

It may further include the step (S125) of further adding a reducing gas having hydrogen (H ₂ ) or other active or volatile characteristics in the furnace to create a more efficient reducing atmosphere. In this case, the ratio of the active gas and the inert gas in the reducing atmosphere in the furnace may be 50%, respectively. For example, the ratio of H ₂ and N ₂ in the reducing atmosphere in the entire furnace may be 50:50, respectively. However, there may be various limitations in using a high proportion of reducing gas such as H ₂ having high volatile characteristics. Even when a volatile reducing gas such as H _{2 is} used, the ratio of H ₂ in the reducing atmosphere in the heating furnace can be used at 50% or less, more preferably at 25% or less. As such, nitrogen in the reducing atmosphere in the furnace The proportion of argon or the same inert reducing gas may be 50% or more, and more preferably 75% or more.

In addition, an exfoliating gas such as carbon monoxide, methane or mixtures thereof may be further added to the furnace. When such stripping gas is added, when the graphene oxide platelets are heated at a very high rate, the release of gas (eg, CO ₂ ) by chemical decomposition of oxygen-containing groups in the graphene oxide Overheating and volatilization of the solvents (eg, water and / or water soluble solvents) that have been absorbed into the graphene oxide platelets, and intercalants can occur.

These processes may evaporate water molecules, reduce graphene oxide platelets to reduced graphene oxide platelets, and may further exfoliate graphene oxide plates having a multilayer structure.

By reducing the graphene oxide platelets in the manner described above, it is possible to obtain reduced graphene oxide platelets having significantly fewer defects than the graphene oxide platelets chemically reduced in the liquid phase. In particular, the reducing atmosphere in the furnace reacts with the oxygen functionalities of the graphene oxide platelets to obtain high quality reduced graphene oxide platelets with substantially all remaining functional groups removed.

However, even when using the above-mentioned aerosol pyrolysis reduction method, the process of collecting the reduced graphene oxide platelets using a common filtration membrane such as a Teflon filtration membrane and dispersing it into a solution again to make the graphene for solution process, such processes Van der Waals binding forces at can cause reaggregation / relamination between the reduced graphene oxide platelets. This results in the phenomenon that the reduced graphene oxide platelets are not uniformly dispersed in the hybrid-graphene composite, resulting in a reduction of the gas / moisture barrier and electrical properties of the hybrid-graphene layer.

Accordingly, the method 100 for obtaining the reduced graphene oxide platelets dispersion solution is to re-aggregate the vapor in which the reduced graphene oxide platelets are dispersed through the heating furnace between the reduced graphene oxide platelets. Passing directly through an aqueous solution (eg, an organic solvent) mixed with a surfactant having an inhibitory function, and directly collecting the solution (S140) using the solution. Collecting the reduced graphene oxide platelets in the gas directly using an aqueous solution containing a surfactant causes re-agglomeration and re-lamination of the reduced graphene oxide platelets such as filtration, drying process and re-dispersion. Reduction of graphene oxide platelets can be obtained with a much lower frequency of reaggregation / relamination. As an example, the aqueous solution may be DI mixed with 1% to 5% of a surfactant having the ability to inhibit aggregation of reduced graphene oxide platelets, and the temperature of the aqueous solution may be between 20 ° C and 100 ° C. .

The aqueous solution may comprise alcohols such as methanol, ethanol, butanol, propanol, glycols, water soluble esters and ethers. The surfactants mixed in the aqueous solution are alkyl surfactants such as nonionic ethylene oxide, propylene oxide and their copolymers, tergitol group surfactants, or triton based surfactants, or ethylene oxide and propylene oxide or butylene oxide It may also comprise surfactants with units. Examples of these include the Pluron or Tetronic series of surfactants. Cosolvents and surfactants may be included in the solution at 0.0001 to 10% by weight. Cosolvents and surfactants are in solution, in particular 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7 , 7.5, 8, 8.5, 9 and 9.5% by weight, and may be included as a sub-value between these values.

While the reduced graphene oxide platelets are floating in the vapor, there is less chance of re-agglomeration and / or re-stacking between the reduced graphene oxide platelets. It is also involved in the methods used in the preparation of reduced graphene for conventional liquid processes by permeating vapor directly into an aqueous solution mixed with a surfactant to cause re-aggregation and re-stacking of the reduced graphene platelets. It is possible to obtain graphene for solution processing without going through process steps such as filtration, drying and redispersion of the platelets.

하이브리드-그래핀 복합물Hybrid-Graphene Complex

The method described with reference to FIG. 1 is also very suitable for producing hybrid-graphene composites, which is another aspect of the present invention. The novel hybrid-graphene composites described herein have improved optical properties as the reduced graphene platelets, which are fillers in two-dimensional planes, and the fillers in particle form, which have three-dimensional shapes, are dispersed in the polymer matrix. , Physical properties (strength, ductility, Modulus, crack-resistant, abrasion and scratch resistance) and electrical / thermal conductivity and gas / moisture barrier properties.

Some of these properties are highly dependent on the uniform distribution of platelets in the composite, the interconnections between the platelets, and the formation of gas / moisture penetration inhibition pathways within the hybrid-graphene composite. In embodiments of hybrid-graphene composites, some or all of these properties may be improved by methods of synthesis and composition of specific configurations.

It is known that most gas and water particles cannot penetrate through reduced graphene oxide platelets. As such, a network made by connecting reduced graphene oxide platelets in a polymer matrix can also be used as an excellent barrier to prevent gas and moisture ingress. In order for gas and moisture particles to penetrate through the hybrid-graphene layer formed of the hybrid-graphene composite, the particles must first enter through a defect site on the upper surface of the hybrid-graphene layer. After entry, it must enter through the path between the polymer matrices along the surface of the graphene platelets spread inside the polymer matrix. Graphene oxide is hydrophilic in the various oxygen functional groups on the surface thereof, as compared with the reduced graphene oxide from which most of the oxygen functional groups are removed, the water particles can move better through the path in the polymer matrix, and thus, Most or all of the graphene platelets included in the hybrid-graphene composite and hybrid-graphene layer are preferably reduced graphene oxide platelets. However, the hybrid-graphene composite and hybrid-graphene layer of the embodiments herein may include a small number of unreduced graphene oxide platelets due to process variations.

As noted above, gas / moisture molecules can migrate along the relatively permeable polymer channels around the incapable reducing graphene oxide platelets and penetrate through the hybrid-graphene layer. Therefore, it may be the most important point to improve the gas / moisture barrier property of the hybrid-graphene layer formed of the hybrid-graphene composite to establish the longest path so that gas / water particles are difficult to penetrate. In this regard, the factors that greatly influence the gas / moisture intrusion properties of the hybrid-graphene composite are the aspect ratio, defined as the ratio of the longest dimension to the shortest dimension of the reduced graphene oxide platelet. ), The dispersion rate of the reduced graphene oxide platelets in the composite and the alignment of the platelets, the interface bond between the reduced graphene oxide platelets and the polymer matrix, and the crystallinities of the polymer matrix. The stacking direction of the reduced graphene oxide platelets and the self-aggregation between the reduced graphene oxide platelets in the polymer matrix are also considered as important factors affecting the gas / moisture penetration properties of the hybrid-graphene composite. Should be.

Considering all of the above factors, the very large aspect ratio and two-dimensional planar shape of the reduced graphene oxide platelets are very suitable materials to combine with the polymer matrix and build a long path therein.

Reducing graphene oxide platelets of hybrid-graphene composites not only provide good gas / moisture barrier properties, but also combine with the polymer matrix to provide physical properties such as tensile and compression stresses required in flexible devices. It also provides a strong tolerance to withstand phosphorus stresses. In ordinary composites, the interface bonding force between the filler and the surrounding polymer matrix plays an important role in the transfer of stress from the polymer matrix to the filler through shear-activated mechanisms. The higher the shear force of the interface, the greater the load it can withstand before interfacing failures occur. If the bond / shear force between the polymer matrix and the fillers is weak, the strength of the interfacing between them decreases and eventually defects may occur. Therefore, the strong bonding / shearing force between the polymer matrix and the filler is important for improving the physical properties of the hybrid-graphene layer formed of the hybrid-graphene composite.

Reduced graphene oxide platelets are very suitable fillers for improving the tensile modulus and strength of hybrid-graphene composites. In contrast to many other types of fillers that have smooth surfaces that do not aid in mechanical interlocking, reduced graphene oxide platelets have a rough, corrugated surface that can make the bonds with the polymer chains stronger. It has a topology. The reduced graphene oxide platelets have a larger interfacing contact area in the polymer matrix as compared to other one-dimensional fillers such as carbon nanotubes (CNTs). In addition, polymer chains with large molecules cannot penetrate the inside of the tube through the inner holes of the carbon nanotubes, and only the outer surface of the carbon nanotubes contacts the polymer matrix. However, planar reduced graphene oxide platelets are well suited to improve tensile modulus and strength because both sides can interface with the polymer and have a larger interface contact area. In addition, because it has a two-dimensional planar shape, the reduced graphene oxide platelets support the physical loads in both the longitudinal and transverse bidirectional directions, so the reduced graphene oxide platelets serve as a conventional gas / moisture barrier even in flexible devices. Can be done.

The improved elastic modulus of these hybrid-graphene composites also leads to improved buckling stability at compression loads. Buckling is a very difficult structural instability in the structural design of flexible devices. The improved buckling stability of the hybrid-graphene composites described herein is a two-dimensional planar form of the reduced graphene oxide platelets used in each example and the majority of the reduced graphene oxide platelets consist of a plurality of sheets. It is related to all structural features. As such, the reduced graphene oxide platelet, which consists of a plurality of sheets, combines the polymer matrix with only the outer ones of the multiple sheets it contains so as to transfer the stress of tensile stress that the hybrid-graphene layer receives. Contribute. On the other hand, the load of compressive stress is equally distributed not only to the outer sheets but also between the outer sheets, contributing to the load transfer.

Each sheet in the reduced graphene oxide platelet can be buckled and bent when subjected to compressive stress due to their atomic scale thickness. The buckling or bending of the sheet in the reduced graphene oxide platelet then increases the friction between the adjacent sheets, resulting in better load transfer between the sheets in the reduced graphene oxide platelet. As such, hybrid-graphene composites made using reduced graphene oxide platelets consisting of one or more sheets improve both tensile and compressive load transfer properties, which are important considerations in implementing flexible electronic devices.

The above-described properties provided by the reduced graphene platelets are the hybrid-graphene composite when the reduced graphene platelets are re-aggregated and / or re-stacked during the reduction process or during the formation of the hybrid-graphene composite. May not be expressed in. In the present invention, however, hybrid-graphene composites are prepared by directly trapping high-quality reduced graphene platelets obtained by reducing graphene oxide platelets in an aerosolized droplet state with an aqueous solution so that there is no reaggregation / re-stacking. can do. The hybrid-graphene composite can be used to form a hybrid-graphene layer with uniformly dispersed reduced graphene platelets, thereby exhibiting excellent electrical, physical and / or gas / moisture barrier properties suitable for a variety of applications. .

예시적인 하이브리드-그래핀 복합물들 및 방법들Exemplary Hybrid-Graphene Composites and Methods

Example 1

The three-dimensional particle-shaped filler included in some embodiments of the hybrid-graphene composite is carbon nanoparticles (Carbon Nanoparticles). Hybrid-graphene composites formed of mixed-reduced graphene platelets and carbon nanoparticles in a polymer matrix exhibit significantly lower sheet resistance compared to hybrid-graphene layers without carbon nanoparticles.

2 is a flow chart illustrating an exemplary method 200 for forming a hybrid-graphene composite. As shown in FIG. 2, the method 200 for forming the hybrid-graphene composite may include preparing a precursor solution (S210). In one embodiment, the carbon nano particle powder is mixed with graphene oxide solution to prepare a precursor solution. The graphene oxide solution may be formed with DI water mixed with DI water and / or organic solvents. Graphene oxide platelets in the precursor solution may be included in the precursor solution at about 0.05%. Similarly, carbon nano particle powder may be included in the precursor solution at about 0.05%. As one example, 40 ml of the precursor solution may include 0.20 g of graphene oxide platelets and 0.20 g of carbon nano particle powder mixed inside the precursor solution. Carbon nano particles are graphite particles that are essentially nano-sized with horizontal / lateral length of less than 50 nm. In addition, the precursor solution may comprise an acid such as HNO ₃ and / or HCl.

Carbon nanoparticles can be formed by commonly used methods such as grinding or ball-milling to make graphite into particles of nano size. It should be noted that the carbon nanoparticles used in the precursor solution are graphite, not graphite oxide. As described above, the maximum size of the graphene oxide platelets and the maximum size of the reduced graphene oxide obtained by reducing the same may be determined according to the size of the base material, ie, graphite, to which the graphene oxide platelets are initially peeled off. Also, as described above, since the difference in size between the two end fillers such as the transverse length and thickness between the reduced graphene oxide platelets and the carbon nanoparticles is important, the graphene oxide platelets dispersed in the precursor solution and Carbon nanoparticles may be obtained from different graphites.

In order to improve the electrical and gas / moisture barrier properties of the hybrid-graphene layer, sufficient size and structural differences between the filler having a two-dimensional planar shape, that is, the reduced graphene oxide platelet and the carbon nanoparticle having a three-dimensional shape Should be. Thus, reduced graphene oxide platelets having a two-dimensional planar shape have an average transverse length of 0.5 μm to 5 μm, more preferably at least 1 μm, more preferably at least 2.5 μm, more preferably about Have an average transverse length of at least 3 μm. Also, reduced graphene oxide platelets having a two-dimensional planar shape have an average thickness of about 0.5 nm to about 7 nm, more preferably about 0.5 nm to about 3.5 nm, even more preferably about 0.5 nm to It has an average thickness of about 1.7 nm or less.

The carbon nanoparticles have an average diameter of about 1 nm to about 50 nm. Carbon nanoparticles, which are graphite, have a much larger thickness than graphene oxide platelets. As the difference between the reduced graphene platelet and the size increases, the gap between the reduced graphene platelets is more closely filled, and the Van Der Walls bonds with the reduced graphene platelets and carbon nanoparticles. It is possible to form a hybrid-graphene layer in a complementary form. When the average diameter of the carbon nanoparticles used in the precursor solution exceeds 50 nm, the sheet resistance value of the hybrid-graphene layer formed of the hybrid-graphene composite of this embodiment cannot be obtained.

When preparing the precursor solution, a ball mill process can be used to disperse the graphene oxide platelets and carbon nano particle powder. For example, a ball mill process may be performed on the precursor solution for about 12 hours to about 24 hours. The ball mill process may use zirconia beads having a size of 1.0Φ. Smaller size beads (eg, 0.5Φ) can be used to control the average size of the carbon nanoparticles.

It should be noted that each of the graphene oxide platelets included in the precursor solution can be formed in a different number of layers. Because of this, the reduced graphene oxide platelets included in the hybrid-graphene composite do not have to have only a certain number of reduced graphene oxide layers, for example reduced graphene in a single layer, double layer, or triple layer. And may include fin oxide platelets. For example, reduced graphene platelets consisting of 1 to 20 layers may be included in the hybrid-graphene composite, thus the average number of layers of reduced graphene platelets included in the hybrid-graphene composite is 2 to 20. 10 layers, more preferably between 2 and 5 layers. As described above, the sheet having two or more layers is suitable for improving the physical properties of the hybrid-graphene layer, but if the average number of layers included in each reduced graphene platelet is too large, transparency may be reduced.

Furthermore, although three-dimensional carbon nanoparticles have a shorter length in the transverse direction than two-dimensional reduced graphene oxide platelets, since the carbon nanoparticles are graphite particles, graphite is peeled off and thus two-dimensional. It may have more layers than reduced graphene oxide platelets. However, because carbon nanoparticles have a small surface area, they are not sufficient for physical interfacing or interlocking with the surrounding polymer in the hybrid-graphene layer. It may not contribute significantly to improving the relevant characteristics.

In addition, the precursor solution may include other fillers and / or other additives, and other additives may include a dispersant comprising an ionic surfactant and / or a non-ionic surfactant and a binder such as a silane binder, an emulsifier, a stabilizer, or the like. You may.

The method 200 of forming the hybrid-graphene composite includes converting the precursor solution into aerosol droplets (S220). As illustrated in FIG. 1 above, the aerosolized precursor droplets are conveyed to the furnace with an inert gas such as argon and / or N ₂ .

The method 200 of forming a hybrid-graphene composite includes thermally decomposing aerosolized precursor droplets in a furnace (S230). The furnace may be heated to about 300 ° C to 1900 ° C. However, the heating furnace is preferably heated to 900 ℃. The rate at which the aerosolized precursor flows through the furnace may be from about 0.1 m / sec to about 5 m / sec. As mentioned above, the time for which the precursor droplets remain in the furnace can be determined by various factors.

The pyrolysis process evaporates water molecules and reduces graphene oxide platelets to reducing graphene oxide platelets. During the reduction of graphene oxide platelets, the carbon nanoparticles are incorporated into the reducing graphene platelets or otherwise synthesized with the reducing graphene platelets, thus reducing graphene platelets without mixing of the carbon nanoparticles. It shows a significantly smaller defect rate compared to reduced graphene platelets subjected to the same pyrolysis process.

The method 200 of forming a hybrid-graphene composite includes a step (S240) of directly passing an aqueous solution mixed with a surfactant and gases from a steam and a furnace including reducing graphene platelets. The surfactant here serves to inhibit re-aggregation and re-stacking of the reduced graphene platelets in aqueous solution. The vapor leaves the aqueous solution, but carbon nanoparticles that are not synthesized with the reduced graphene platelets and even reduced graphene platelets are collected by the aqueous solution. As described above, this process can form a hybrid-graphene composite for solution processing with less re-agglomeration / re-stacking between the reduced graphene platelets. As the aqueous solution for capturing the reduced graphene platelets and carbon nanoparticles, a solvent and a surfactant described above with reference to S140 of FIG. 1 may be used.

Depending on the use of the hybrid-graphene composite and the particular solution-based processing method to be used for its use, various types of polymers may be included in the aqueous solution which permeates the vapor from the furnace in liquid form. For example, if lowering the sheet resistance in a layer formed of a hybrid-graphene composite is prioritized, an electrically conductive polymer such as PETDOT may be mixed in the aqueous solution. In addition, polymers exhibiting gas / moisture barrier properties such as PVA-co-ethylene may be mixed into the aqueous solution if better gas / moisture barrier properties are prioritized in the layer formed of the hybrid-graphene composite. .

It should be noted that the polymer in the hybrid-graphene composite is not limited to the examples described above, and that various other forms of polymer may be mixed in the aqueous solution to achieve the desired function. The amount and shape of the polymer may affect the viscosity of the final hybrid-graphene composite and further limit the solution based processing method to be used for depositing / coating onto the desired surface with the desired hybrid-graphene composite. In addition, the polymer may be mixed into the aqueous solution prior to permeation of the vapor from the furnace, or the polymer may be mixed into the aqueous solution after permeating the vapor from the furnace to collect the reduced graphene platelets and the remaining carbon nanoparticles. have. Accordingly, the aqueous solution for permeating vapor from the heating furnace may include an organic solvent capable of dissolving the polymer mixed in the aqueous solution. It is also preferred that the organic solvent has a low BP in order to reduce bubbles in the hybrid-graphene layer formed of the hybrid-graphene composite. For example, when the PVA-co-ethylene polymer is mixed in an aqueous solution, the aqueous solution may be mixed with an organic solvent, which may be propanol, DMAC, tetra butyl alcohol, or pyridine. ) And formic acid, but are not necessarily limited thereto.

Example 2

As mentioned above, the sheet resistance of the layer formed from the hybrid-graphene composite can be improved by adding nanoparticles into the hybrid-graphene composite. In some embodiments, the three-dimensional particle shaped filler included in the hybrid-graphene composite is an oxidizable metal nanoparticle. Hybrid-graphene composites comprising oxidizable metal nanoparticles can be formed using processes similar to those described above with reference to FIG. 2.

In short, a precursor solution comprising graphene oxide platelets and metal nanoparticles can be used to form the hybrid-graphene composite. The precursor solution may be formed from DI water mixed with DI water and / or organic solvent. Graphene oxide platelets in the precursor solution may be included in the precursor solution at about 0.05%. Similarly, the metal nanoparticle powder in the precursor solution may be included at about 0.05% in the precursor solution. For example, 40 ml of the precursor solution may include 0.20 g of graphene oxide platelets and 0.20 g of metal nano particle powder mixed therein. Examples of the metal used as the metal nanoparticles may include platinum (Pt), nickel (Ni), copper (Cu), silver (Ag), gold (Au), or mixtures thereof.

The precursor solution is aerosolized and subjected to a pyrolysis process of the aerosolized aerosol droplets in a manner similar to that described above. The pyrolysis process evaporates water molecules and reduces the graphene oxide platelets to reduced graphene oxide platelets. The reducing atmosphere in the furnace can reduce graphene oxide platelets, but the metal nanoparticles are not oxidized in this reducing atmosphere. Thus, during the reduction of graphene oxide platelets, some of the metal nanoparticles will simply flow in the vapor and some of the metal nanoparticles are attached to the surface of the reduced graphene platelet.

Metal nanoparticles adhering to the surface of the reduced graphene platelets not only allow more tight coupling of the interface between the reduced graphene platelets and the surrounding polymer matrix in the hybrid-graphene layer, but furthermore between the reduced graphene platelets. Serves to make it easier to form electrical networks. However, when the temperature of the furnace and the residence time of the aerosol droplets are excessive, metal nanoparticles may be formed in a form surrounding the reduced graphene platelets. In this case, the phenomenon of losing the characteristics of the reduced graphene platelet may be caused. Since the temperature and residence time at which the above-described phenomena occur may vary depending on the type of the metal nanoparticles, in some embodiments in which the metal nanoparticles are included in the aerosol droplets, the temperature and the aerosol of the heating furnace depend on the type of the metal nanoparticles included. The residence time of the droplets can be adjusted. For example, when including one of the metal nanoparticles mentioned above, it is preferable that the temperature of a heating furnace is 1500 degreeC or less.

Steam with reduced graphene platelets and metal nanoparticles flowing inside the vapor pass directly through the mixed aqueous solution with a surfactant that prevents re-aggregation and re-stacking of the reduced graphene platelets. Although the vapor will escape from the aqueous solution, the reduced graphene platelets and metal nanoparticles will be collected by the aqueous solution, so for solution processing where re-agglomeration / re-stacking between the reduced graphene platelets is significantly less likely to occur. Hybrid-graphene complexes are formed.

FIG. 3 shows 1) a layer formed with a reduced graphene solution, 2) a layer formed with a hybrid-graphene composite with carbon nanoparticles, and 3) a hybrid with metal nanoparticles, obtained by the disclosed embodiments of the present invention. Tables compare the surface resistance values of the layers formed of graphene composites. The table also shows the differences in the sheet resistance of the layer with the temperature of the furnace during the pyrolysis step.

Among the experimental results, the surface resistance of the reference layer formed of the colloidal solution of the reduced graphene platelets according to the examples discussed herein was measured to be about 700 Ω / square, which was formed by conventional chemical reduction or thermal expansion methods. It is much lower than the sheet resistance of the layer formed of the colloidal solution of the reduced graphene platelets. In addition, the layer formed of the hybrid-graphene composite mixed with the copper nanoparticles exhibited a sheet resistance as low as about 600 Ω / □. In addition, the sheet resistance of the layer formed of the hybrid-graphene composite mixed with carbon nanoparticles was only about 15 Ω / square, which was particularly low.

As shown in the table of FIG. 3, pyrolysis temperature plays an important role in synthesizing hybrid-graphene composites with carbon nanoparticles. A layer formed of a hybrid-graphene composite subjected to a pyrolysis process at a relatively low temperature (eg, 80 ° C.) is a hybrid-graphene composite subjected to a pyrolysis process at a higher temperature (eg 300 ° C.). It showed a larger sheet resistance than the layer formed by. It was observed that when the pyrolysis process was carried out at 500 ° C., a layer with a sheet resistance value as low as 15 Ω / □ could be formed.

FIG. 4 shows 1) a layer formed with a reduced graphene solution, 2) a layer formed with a hybrid-graphene composite with carbon nanoparticles, and 3) a hybrid with metal nanoparticles, obtained by the disclosed embodiments of the present invention. Show the plate and cross-sectional structures of layers formed of graphene composites. As shown in FIG. 4, carbon nanoparticles cannot be observed on a plate of a hybrid graphene layer formed of a hybrid-graphene composite including carbon nanoparticles. On the other hand, the metal nanoparticles are observed on the plate of the hybrid graphene layer formed of the hybrid-graphene composite including the metal nanoparticles. In addition, the cross-sectional structure of the hybrid graphene layer formed of the hybrid-graphene composite including carbon nanoparticles can be observed that the sheets of the reduced graphene platelets included are deformed evenly and evenly oriented. This is because the carbon nanoparticles contained in the furnace together with the graphene oxide platelet were combined with the graphene oxide platelet while the graphene oxide platelet was reduced in the furnace. Is converted into a. The sheet resistance of the hybrid-graphene layer formed of the hybrid-graphene composite including the reduced graphene platelets obtained by synthesizing with the carbon nanoparticles is 45 times higher than the sheet resistance of the film formed only with the reduced graphene platelets. Shows low values.

Although the hybrid-graphene composite including carbon nanoparticles as shown in the table in FIG. 3 exhibited lower sheet resistance compared to the hybrid-graphene layers including metal nanoparticles, the hybrid-graphene composite with metal nanoparticles was also present. It has been observed to have lower surface resistance than simple reduced graphene platelet-polymer composites. However, the use of oxidizable metal nanoparticles provides a special function in that an optional portion of the layer formed of the hybrid-graphene composite may exhibit a different sheet resistance than the other portions of the layer. It can be used as.

More specifically, optional regions of the layer formed of hybrid-graphene may be treated with an acid or laser so that metal nanoparticles within the treated region may be oxidized. Regions of the layer with oxidized metal nanoparticles will exhibit higher surface resistance than regions with non-oxidized metal nanoparticles. In other words, layers formed of the same hybrid-graphene composite can be patterned into two different regions exhibiting different surface resistance while substantially maintaining gas / moisture barrier properties. This unique feature of the hybrid-graphene composite of the present invention allows the fabrication of a true multi-functional layer that can function as both an encapsulation layer and an electrical pathway in a variety of electrical devices.

To this end, it is preferable that the electrically conductive polymer is not included in the hybrid-graphene composite, which type of polymer has a plane between the region with oxidized metal nanoparticles and the region with non-oxidized metal nanoparticles. This is because the amount of difference in resistance is reduced. When metal nanoparticles are used in hybrid-graphene composites to achieve different surface resistance between selective regions of the hybrid-graphene layer, a gas such as PVA-co-ethylene to achieve better gas / moisture barrier properties Polymers exhibiting moisture barrier properties can be mixed in an aqueous solution.

Another advantage of using metal nanoparticles over carbon nanoparticles is that metal nanoparticles adhering to the surface of the reduced graphene platelets provide a rough and corrugated surface topology that provides stronger physical bonding with the polymer chain. This topology contrasts with reduced graphene platelets synthesized with carbon nanoparticles having flat surfaces that may have relatively lower interfacial bonds with the polymer chain. Stronger interfacial bonding of the reduced graphene platelets with the surrounding polymer matrix provides strong resistance to physical stress, which can make the hybrid-graphene layer very useful for applying to flexible devices.

As noted above, the reduced graphene solution and hybrid-graphene composites are various solution-based methods including, but not limited to, spin coating, slot coating, spray coating, screen printing, dip coating, and the like. It is very suitable for forming layers or films using. With good sheet resistance and gas / moisture barrier properties, the reduced graphene solutions and hybrid-graphene composites disclosed herein can be used to make multi-functional hybrid-graphene layers for a variety of applications.

5A is a plan view illustrating an exemplary touch screen panel using a hybrid-graphene layer in accordance with one embodiment of the present invention. 5B is a cross-sectional view taken along line Vb-Vb 'of FIG. 5A. 5A and 5B illustrate a touch screen panel 500 as an electronic device of the present invention. 5A and 5B, in the touch screen panel 500, the hybrid-graphene layer 510, the first touch detector 520, the second touch detector 530, and the insulating layer 540 are formed of a substrate ( 550). In FIG. 5A, the insulation layer 550 is not illustrated for convenience of description, and hatching of the hybrid graphene layer 510 is illustrated.

5A and 5B, a hybrid graphene layer 510 is formed on the substrate 550. The hybrid-graphene layer 510 was formed of a hybrid-graphene composite composed of reduced graphene oxide platelets and metal nanoparticles dispersed in a polymer matrix. The hybrid-graphene layer 510 is composed of one or more first regions 512, which are conductive regions, and one or more second regions 514, which are non-conductive regions. In the present specification, the conductive region and the non-conductive region are expressed by relative sheet resistance values between the two regions. In other words, the non-conductive region has a relatively high sheet resistance value compared to the conductive region, and thus refers to a region having a relatively low electrical conductivity compared to the conductive region. The hybrid graphene layer 510 may implement the touch screen panel 500 by using the difference between the sheet resistance values of the first region 512 and the second region 514. The difference in the sheet resistance value between the first region 512 and the second region 514 is sufficiently different so that the first region 512 and the second region 514 can be distinguished by the device, respectively.

It is determined by the oxidation state of the metal nanoparticles in the hybrid-graphene composite located at the specific portion of the hybrid-graphene layer 510 to have a specific sheet resistance value different from the other portions of the hybrid-graphene layer 510. In the first region 512 of the hybrid graphene layer 510, reduced graphene oxide platelets and non-oxidized metal nanoparticles are dispersed in a polymer matrix. On the other hand, in the second region 514 of the hybrid-graphene layer 510, reduced graphene oxide platelets and oxidized metal nanoparticles are dispersed in a polymer matrix.

An insulating layer 540 is formed on the hybrid graphene layer 510. The insulating layer 540 has an opening that opens a portion of each first region 512 of the hybrid-graphene layer 510. The insulating layer 540 is configured to insulate the first region 512 of the hybrid graphene layer 510 from the first touch sensing unit 520. The insulating layer 540 is formed of an insulating material and may be formed of a flexible transparent insulating material. Can be.

The first touch sensing unit 520 is formed on the insulating layer 540. The first touch sensing unit 520 is formed of a conductive material. For example, the first touch sensing unit 520 may be formed of a transparent conductive material such as ITO or may be formed of a metal material having a mesh structure. The first touch sensing unit 520 has a plurality of sensing electrodes, and the plurality of sensing electrodes of the first touch sensing unit 520 are connected to each other in a first direction. For example, as illustrated in FIG. 5A, the plurality of sensing electrodes of the first touch sensing unit 520 are formed to be connected to each other in a vertical direction on a plane, and the first touch sensing unit 520 also extends in the vertical direction. .

The second touch sensing unit 530 is formed on the hybrid graphene layer 510 and the insulating layer 540. The second touch sensing unit 530 may be formed of a conductive material and may be formed of the same material as the first touch sensing unit 520. The second touch sensing unit 530 has a plurality of sensing electrodes, and the plurality of sensing electrodes of the second touch sensing unit 530 are formed to be separated from each other in a second direction. Although the plurality of sensing electrodes of the second touch sensing unit 530 are formed to be separated from each other, as illustrated in FIG. 5B, the sensing electrodes of the second touch sensing unit 530 adjacent to each other are the openings of the insulating layer 540. Contact the same first region 512 of the hybrid-graphene layer 510, and are electrically connected to each other through the first region 512 of the hybrid-graphene layer 510. Therefore, all of the sensing electrodes of the second touch sensing unit 530 positioned in the same row are electrically connected.

The touch screen panel 500 detects a touch input from a user by using the first touch detector 520 and the second touch detector 530. For example, one of the first touch sensing unit 520 and the second touch sensing unit 530 may be a first direction sensing electrode pattern, and the other may be a second direction sensing electrode pattern. The first direction sensing electrode pattern is a sensing electrode pattern for sensing a first direction (eg, Y-axis direction) coordinates of the user's touch input, and the second direction sensing electrode pattern is a second for the user's touch input. A sensing electrode pattern for sensing a direction (eg, X-axis direction) coordinate. Therefore, when a user's touch occurs at a predetermined position of the touch screen panel 500, the touch screen panel 500 detects the first direction coordinates and the second direction sensing electrode pattern detected by the first direction sensing electrode pattern. The touched position of the user may be sensed by combining the second direction coordinates.

Meanwhile, in the present specification, although both the first touch detector 520 and the second touch detector 530 are described as including sensing electrodes, the first touch detector 520 and the second touch detector 530 are described. One may be a sensing electrode pattern for sensing a change in capacitance, and the other may be a driving electrode pattern for supplying a sensing signal for detecting a touch position. In this case, when the detection signal for detecting the touch position is applied to the driving electrode pattern near the position where the user's touch actually occurred, the amount of change in capacitance generated in the sensing electrode pattern near the position where the user's touch actually occurred is the most. It can be measured largely. Therefore, the touch screen panel 500 may detect the touch position of the user based on the sensing signal supplied by the driving electrode pattern and the amount of change in capacitance sensed in the sensing electrode pattern.

In FIGS. 5A and 5B, although the first touch detector 520 and the second touch detector 530 are separated from each other and formed of a conductive material, the first touch detector 520 and the second touch detector are illustrated. 530 may also be formed using a hybrid-graphene layer. For example, the areas corresponding to the first touch sensor 520 and the second touch sensor 530 as shown in FIGS. 5A and 5B are conductive areas, and the first touch sensor 520 and the first touch sensor 520 are formed. In the space between the two touch sensing units 530, the hybrid-graphene layer, which is a non-conductive region, may be formed on the insulating layer 560 having an opening.

In the touch screen panel 500 according to the exemplary embodiment of the present invention, the hybrid graphene layer 510 is used as a sensing electrode for sensing a user's touch input. As described above, since the solution process is used to form the hybrid-graphene layer 510 on the substrate 550, a process such as vacuum deposition for forming a conventional conductive material may not be performed, thereby processing costs. This has the effect of being reduced. In addition, the hybrid graphene layer 510 used as the sensing electrode in the touch screen panel 500 may function as an excellent gas / moisture barrier layer as described above. Accordingly, the touch screen panel 500 performs not only a user's touch input sensing function but also a barrier function, thus eliminating the use of a separate barrier film to prevent the penetration of gas or moisture, thereby simplifying the manufacturing process and the final product. There is an effect of reducing the thickness of. In addition, the flexible electronic device may be implemented by replacing the ITO material of the touch screen panel 500 with the hybrid graphene layer 510. The touch screen panel 500 may further include another hybrid graphene layer that does not require patterning, such as the hybrid graphene layer 510, and the hybrid graphene layer that does not require patterning may use carbon nanoparticles. It may be a layer formed of a hybrid-graphene composite. In another embodiment, the hybrid-graphene layer formed of the hybrid-graphene composite using the carbon nanoparticles without the hybrid-graphene layer including the metal nanoparticles may be formed.

6 is a cross-sectional view illustrating an exemplary thin film transistor using a hybrid-graphene layer according to an embodiment of the present invention. 6 illustrates a thin film transistor 600 as an electronic device of the present invention. Referring to FIG. 6, the thin film transistor 600 includes a gate electrode 630, an active layer 620, and a hybrid graphene layer 610. In FIG. 6, the thin film transistor 600 is a thin film transistor having an inverted staggered structure.

The gate electrode 630 is formed on the substrate 690. The gate electrode 630 is formed of a conductive material, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) And copper (Cu), or an alloy thereof. A gate insulating layer 691 is formed on the gate electrode 630 to insulate the gate electrode 630 and the active layer 620. The gate insulating layer 691 may be formed of a silicon oxide film, a silicon nitride film, or a multilayer thereof. The active layer 630 is formed on the gate insulating layer 691 so as to overlap the gate electrode 620. The active layer 630 is a layer in which a channel is formed when the thin film transistor 600 is driven and may be formed of an oxide semiconductor.

The hybrid graphene layer 610 is formed on the gate insulating layer 691 in which the active layer 630 is formed. Hybrid-graphene layer 610 has a

first region

640, 650 and a second region 660. The second region 660 of the hybrid graphene layer 610 has a higher sheet resistance value than the

first regions

640 and 650 of the hybrid graphene layer 610. The

first regions

640 and 650 and the second region 660 are used as electrodes and the second regions 660 as the insulating portions of the hybrid-graphene layer 610. The difference in electrical characteristics between them is large enough. The hybrid-graphene composite constituting the

first region

640, 650 and the second region 660 of the hybrid-graphene layer 610 is the first of the hybrid-graphene layer 510 described in FIGS. 5A and 5B. It is identical to the hybrid-graphene composite that makes up region 512 and second region 514, respectively.

In order for the second region 660 of the hybrid-graphene layer 610 to have a higher sheet resistance value than the

first regions

640 and 650, the second region 660 of the hybrid-graphene layer 610 as described above. Acid treatment methods can be used for the present invention. In this case, the acid treatment of the second region 660 of the hybrid graphene layer 610 may be performed after the hybrid graphene layer 610 is coated on the active layer 620 and the gate insulating layer 691. After the acid treatment is first performed, the hybrid graphene layer 610 may be coated. In addition, as described above, the second region 660 of the hybrid-graphene layer 610 may be oxidized using the laser treatment method to oxidize the metal nanoparticles embedded in the second region 660.

Each of the

first regions

640 and 650 of the hybrid-graphene layer 610 is in contact with the active layer 620, and the second region 660 of the hybrid-graphene layer 600 is the first region 640 and the first region. Insulate region 660. One of the

first regions

640 and 650 of the hybrid graphene layer 610 serves as a source electrode of the thin film transistor 600, and the other serves as a drain electrode of the thin film transistor 600.

In the case of a thin film transistor including an active layer formed of an oxide semiconductor, a crystallization process through high temperature heat treatment of 200 ° C. or more is required to improve oxide characteristics. However, in the process of performing the high temperature heat treatment, the source layer and the drain electrode, which are generally formed of metal, and the active layer formed of the oxide semiconductor may be oxidized, thereby causing difficulty in high temperature heat treatment. However, in the thin film transistor 600 according to the exemplary embodiment of the present invention, the hybrid-graphene layer 610 is used instead of the metal electrode as the source electrode and the drain electrode, and thus may occur during high temperature heat treatment to improve the oxide characteristics. Electrode oxidation may be prevented, and thus stable electrical characteristics of the thin film transistor 600 may be secured, and stable ohmic contact between the active layer 620 and the source electrode and the drain electrode may also be secured.

In addition, when forming a source electrode and a drain electrode of a thin film transistor including an active layer formed of an oxide semiconductor, a deposition method such as sputtering a metal material used as the source electrode and the drain electrode is used. The active layer may be damaged. Therefore, in order to prevent damage to the active layer, a method of forming a source electrode and a drain electrode after forming an etch stopper on the active layer is generally used. However, in the thin film transistor 600 according to an embodiment of the present invention, instead of using a metal electrode as a source electrode and a drain electrode formed through deposition, a hybrid-graphene layer 610 coated using a solution process is used. Therefore, it is not necessary to form an etch stopper, thereby reducing manufacturing cost and manufacturing process time.

In addition, a passivation layer formed on the thin film transistor is generally used to protect each of the electrodes and the active layer of the thin film transistor from gas and moisture from the outside. However, in the thin film transistor 600 according to the exemplary embodiment of the present invention, since the hybrid-graphene layer 610 used as the source electrode and the drain electrode has the excellent gas / moisture barrier characteristics as described above, the hybrid-graphene layer 610 may perform the same function as the passivation layer. Therefore, since a separate passivation layer does not need to be formed, it is possible to reduce additional costs required for forming the passivation layer.

In FIG. 6, only the source electrode and the drain electrode are illustrated as being formed of the hybrid graphene layer 610, but the gate electrode may also be formed of the hybrid graphene layer. In addition, although the thin film transistor 600 is illustrated as an inverted staggered thin film transistor in FIG. 6, the hybrid-graphene layer 610 may be used when forming the electrode in the thin film transistor having the coplanar structure. In addition, the active layer 620 may be formed of a material such as amorphous silicon, polycrystalline silicon, and the like instead of an oxide semiconductor.

The device using the hybrid-graphene layer according to the embodiment of the present invention replaces the conventional semiconductor process of fabricating an electric device by doping silicon impurities at a high temperature through a diffusion process. In addition, since a graphene electric device can be embedded in a hybrid-graphene layer without a high temperature process, it can be applied to various fields such as a transparent and flexible display field. The manufacturing method of such a transparent polymer structure is also applicable to the field of polymer MEMS.

The thin film transistor 600 may further include another hybrid graphene layer that does not require patterning, such as the hybrid graphene layer 610, and the hybrid graphene layer that does not require patterning may use carbon nanoparticles. It may be a layer formed of a hybrid-graphene composite. In another embodiment, the hybrid-graphene layer formed of the hybrid-graphene composite using the carbon nanoparticles without the hybrid-graphene layer including the metal nanoparticles may be formed. Hybrid-graphene layers made of hybrid-graphene composites formed using carbon nanoparticles can be used as layers to protect the active layer while helping to shorten the channel between the source and the drain.

7 is a cross-sectional view illustrating an exemplary organic light emitting display device using a hybrid graphene layer according to an exemplary embodiment of the present invention. 7 illustrates an organic light emitting display 700 as an electronic device of the present invention. Referring to FIG. 7, the organic light emitting diode display 700 includes an organic light emitting diode 750 including an anode 751, an organic emission layer 752, and a cathode 753, an auxiliary electrode 740, and a partition 760. Include. In FIG. 7, only the organic light emitting diode 750, the auxiliary electrode 740, and the partition wall 760 formed on the planarization layer 711 are illustrated for convenience of description, and may be a thin film transistor required to drive the organic light emitting display 700. The illustration is omitted. In the present specification, the organic light emitting diode display 700 is a top emission type organic light emitting diode display.

An organic light emitting device 750 including an anode 751, an organic light emitting layer 752, and a cathode 753 is formed on the planarization layer 711. The anode 751 formed on the planarization layer 711 is formed on the reflective layer 755, which is a conductive layer having excellent reflectance, and the reflective layer 755, and has a work function for supplying holes to the organic light emitting layer 752. And a transparent conductive layer 754 made of a highly conductive material. An organic light emitting layer 752 is formed on the anode 751. The cathode 753 formed on the organic light emitting layer 752 is formed on the metal layer 756 and the metal layer 756 made of a conductive material having a low work function to supply electrons to the organic light emitting layer 752. Hybrid-graphene layer 710.

The hybrid-graphene composite constituting the hybrid-graphene layer 710 may use a hybrid-graphene composite including metal nanoparticles or carbon nanoparticles, or both nanoparticles. Although two organic light emitting diodes 750 are illustrated in FIG. 7, for convenience of description, reference numerals are shown only to the organic light emitting diodes 750 positioned on the right side of FIG. However, when the patterning of the electrode is not required as shown in FIG. 7, it may be more preferable to use only carbon nanoparticles for the convenience of the process.

The auxiliary electrode 740 is formed between the two organic light emitting diodes 750 on the planarization layer 711. The auxiliary electrode 740 is an electrode to compensate for voltage drop that may occur in the top emission type organic light emitting diode display and is formed of the same material as the anode 751. In detail, the auxiliary electrode 740 is formed of the transparent conductive layer 741 and the reflective layer 742.

The bank 720 is formed on the planarization layer 711. As shown in FIG. 7, the bank 720 is formed to cover one side of the auxiliary electrode 740 and one side of the anode 751 of the organic light emitting element 750.

The partition wall 760 is formed on the auxiliary electrode 740. The partition wall 760 is formed in an inverse taper shape, and the organic light emitting layer 751 of the organic light emitting element 750 shown on the right side and the organic light emitting layer of the organic light emitting element shown on the left side of the partition wall 760 are formed. Disconnect 752). Specifically, a method of depositing an organic light emitting material on the entire surface of the planarization layer 711 is used to form the organic light emitting layer 752. Since the organic light emitting material has poor step coverage, the organic light emitting device 750 may be formed. The organic light emitting layer 752 is disconnected by the inverse tapered partition wall 760, and the organic light emitting layer 762 is formed on the partition wall 760. In addition, in the case of metal materials, which are materials used as the metal layer 756 of the cathode 753, the step coverage is generally poor, so that the metal layer 756 of the cathode 753 is also formed by the inverse tapered partition wall 760. Disconnected.

In the organic light emitting diode display 700 according to the exemplary embodiment, the cathode 753 includes a hybrid graphene layer 710, and the hybrid graphene layer 710 is formed by a solution process. Step coverage of the hybrid-graphene layer 710 may be determined according to the viscosity of the hybrid-graphene composite forming the hybrid-graphene layer 710. Thus, to add the desired step coverage of the hybrid-graphene layer 710, a polymer added in the manufacture of the hybrid-graphene composite, a filler with three-dimensional particle enhancement, and reduced graphene with a two-dimensional planar structure The viscosity can be controlled by adjusting the composition ratio of the platelets. It is also possible to further add a binder to obtain viscosity. Thus, as shown in FIG. 7, the hybrid-graphene layer 710 is not disconnected by the partition wall 760, but the auxiliary electrode 740 exposed between the partition wall 760 and the bank 720 under the partition wall 760. ) And provide an electrical connection between the metal layer 756 of the cathode 750 and the auxiliary electrode 740.

In addition, since the materials constituting the organic light emitting layer 752 are very vulnerable to moisture and oxygen, a configuration for minimizing moisture and oxygen penetration from the outside to the organic light emitting layer 752 is required. Thus, a separate encapsulation unit such as a thin film encapsulation (TFE) may be used in the organic light emitting display device 700, but in order to additionally form such an encapsulation unit, additional equipments are required and additional equipment costs are generated and manufacturing time is also increased. Since there is a problem in using a separate encapsulation. In addition, currently used encapsulation such as TFE, glass encapsulation, metal encapsulation does not have enough flexibility required for the flexible device. In the organic light emitting diode display 700 according to the exemplary embodiment, the hybrid-graphene layer 710 included in the cathode 753 has excellent gas / moisture barrier characteristics as described above. 710 may perform the same function as the encapsulation unit. Therefore, there is no advantage in terms of manufacturing process, since the separate sealing portion does not have to be formed. In addition, the hybrid graphene layer may be used on the upper and lower portions of the organic light emitting layer, respectively, to further strengthen the role of protecting the organic light emitting layer.

In FIG. 7, the cathode 753 is described as including a metal layer 756 and a hybrid-graphene layer 700. However, the cathode 753 is formed of only the metal layer 756 that provides electrons to the organic emission layer 752. The hybrid-graphene layer 700 may be defined as not included in the cathode 753.

Hereinafter, various features of the flexible display device according to an exemplary embodiment will be described.

According to another feature of the present invention, the carbon-based fillers having a two-dimensional planar shape included in the barrier layer may include a plurality of reduced graphene oxide platelets.

According to another feature of the invention, the average transverse length of the plurality of reduced graphene platelets may be from about 0.5 μm to about 10 μm.

According to another feature of the invention, the average number of reduced graphene oxide platelets included in the barrier layer may be 2 to 10 layers.

According to another feature of the present invention, the flexible display device further includes at least one or more conductive layers, and the conductive layer may be formed by stacking at least two layers of carbon-based fillers having a two-dimensional planar shape.

According to another feature of the present invention, the carbon-based filler having a two-dimensional planar shape included in the conductive layer may include a plurality of reduced graphene oxide platelets.

According to another feature of the invention, the average transverse length of the plurality of reduced graphene platelets may be 0.5 μm to 10 μm.

According to another feature of the invention, the average number of reduced graphene oxide platelets included in the conductive layer may be 2 to 10 layers.

According to another feature of the invention, the sheet resistance value of the conductive layer may be 15 kW / square or less.

Hereinafter, various features of an electronic device according to an embodiment of the present invention will be described.

According to another feature of the invention, the average number of reduced graphene platelets included in the hybrid-graphene layer may be 2 to 10 layers.

According to another feature of the invention, the hybrid-graphene layer can function as a barrier layer of an electronic device.

According to another feature of the invention, the hybrid-graphene layer can function as an electrode layer of an electronic device.

Hereinafter, various features of a method of manufacturing a hybrid-graphene composite for solution processing according to an embodiment of the present invention will be described.

According to another feature of the invention, the pyrolysis of the droplets can be carried out at a temperature of 300 ℃ to 2000 ℃.

According to another feature of the invention, the average diameter of the carbon nanoparticles may be 50 nm or less and the average lateral length of the graphene oxide platelets may be 0.5 μm to 10 μm.

According to another feature of the invention, the step of performing pyrolysis on the aerosol droplets may be carried out in a furnace with a reducing atmosphere.

According to another feature of the invention, the reducing atmosphere may further include a gas for stripping.

According to another feature of the invention, the step of preparing a dispersion solution, the step of exfoliating graphite oxide by sonication and centrifugation, to obtain a graphene oxide platelet; And adjusting the rotation rate of the centrifugation to control the transverse length of the graphene oxide platelet.

According to another feature of the invention, the aqueous solution may comprise a polymer, and an organic solvent capable of maintaining the polymer in a liquid state.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

A flexible substrate on which an organic light emitting element is formed; And

In the flexible display device comprising a barrier layer for suppressing the penetration of gas / moisture of the organic light emitting device,

The barrier layer may be formed by stacking at least two layers of carbon-based fillers having a two-dimensional planar shape.
The method of claim 1,

The carbon-based filler having a two-dimensional planar shape included in the barrier layer comprises a plurality of reduced graphene oxide platelets.
The method of claim 2,

And wherein the average transverse length of the plurality of reduced graphene platelets is between about 0.5 μm and about 10 μm.
The method of claim 2,

And the average number of the reduced graphene oxide platelets included in the barrier layer is 2 to 10 layers.
The method of claim 1,

The flexible display device further includes at least one conductive layer,

The conductive layer is a flexible display device, characterized in that formed by stacking at least two layers of carbon-based filler having a two-dimensional planar shape.
The method of claim 5,

The carbon-based filler having a two-dimensional planar shape included in the conductive layer includes a plurality of reduced graphene oxide platelets.
The method of claim 6,

And a mean transverse length of said plurality of reduced graphene platelets is between 0.5 μm and 10 μm.
The method of claim 6,

And an average number of layers of the reduced graphene oxide platelets included in the conductive layer is 2 to 10 layers.
The method of claim 5,

The sheet resistance value of the said conductive layer is 15 kV / square or less, The flexible display device.
Substrate or polymer matrix; And

In an electronic device comprising a hybrid-graphene layer comprising a plurality of reduced graphene oxide platelets,

The reduced graphene oxide platelets included in the hybrid-graphene layer are oriented horizontally.
The method of claim 10,

The average number of reduced graphene platelets included in the hybrid-graphene layer is 2 to 10, characterized in that the electronic device.
The method of claim 10,

And wherein said hybrid-graphene layer functions as a barrier layer of said electronic device.
The method of claim 10,

And wherein said hybrid-graphene layer functions as an electrode layer of said electronic device.
Generating a dispersion solution containing graphene oxide platelets;

Dispersing carbon nanoparticles in the dispersion solution to form a precursor solution;

Aerosolizing the precursor solution to convert it into an aerosol droplet having graphene oxide platelets and carbon nanoparticles;

Performing pyrolysis on the aerosol droplets to reduce graphene oxide platelets; And

And collecting the reduced graphene oxide platelet by passing the vapor containing the reduced graphene oxide platelet through an aqueous solution containing a surfactant. Manufacturing method.
The method of claim 14,

The pyrolysis of the droplets is characterized in that it is carried out at a temperature of 300 ℃ to 2000 ℃, a method for producing a hybrid-graphene composite for a solution process.
The method of claim 15,

And the average diameter of the carbon nanoparticles is 50 nm or less and the average lateral length of the graphene oxide platelets is 0.5 μm to 10 μm.
The method of claim 16,

The pyrolysis of the aerosol droplets is characterized in that it is carried out in a furnace with a reducing atmosphere, a method for producing a hybrid-graphene composite for a solution process.
The method of claim 17,

The reducing atmosphere is characterized in that it further comprises a gas for peeling, a method for producing a hybrid-graphene composite for a solution process.
The method of claim 18,

Preparing the dispersion solution,

Exfoliating graphite oxide by sonication and centrifugation to obtain the graphene oxide platelet; And

And adjusting the rotation rate of the centrifugation to control the transverse length of the graphene oxide platelet.
The method of claim 14,

The aqueous solution comprises a polymer, and an organic solvent capable of maintaining the polymer in a liquid state, the method of producing a hybrid-graphene composite for a solution process.