KR20210064452A - Coating Material for Manufacturing Conductive film with Work Function Control - Google Patents

Abstract

The present invention relates to a coating agent capable of producing a conductive thin film that can be coated on an electrode layer such as a positive electrode in a light emitting device such as an OLED and the like, a solar cell, and the like in a UV curing method, can perform fine work function control according to the characteristics of the light emitting device, and is capable of controlling a work function without causing deterioration in the performance of the light emitting device such as the OLED and the like.

Description

Coating agent capable of manufacturing a conductive thin film capable of work function control {Coating Material for Manufacturing Conductive film with Work Function Control}

The present invention can be coated on an electrode layer such as an anode in a light emitting device such as an OLED, a solar cell, etc. in a UV curing method, and can perform fine work function control according to the characteristics of the light emitting device, and the performance of a light emitting device such as an OLED It relates to a coating agent capable of producing a conductive thin film capable of controlling a work function without causing deterioration.

In order to obtain high efficiency in various devices, including organic electronic devices such as organic thin film transistors and organic solar cells, and graphene-based electronic devices, charge injection and charge transfer must be performed smoothly.

It is the injection energy barrier between the electrode and the active layer that has the greatest effect on the charge injection, and it varies depending on the work function of the electrode or the LUMO or HOMO of the active layer. Therefore, in order to manufacture a high-efficiency device, various techniques have been proposed to change the work function of the electrode by adding a specific material to the electrode, or to reduce the energy barrier by inducing doping in the semiconductor material to activate charge injection. It still occupies a large proportion in device development.

The technology of changing the work function of the double electrode is a technology that uses the principle of coating a very thin insulating material on the electrode to enable electron tunneling to induce an interfacial dipole with the electrode, and to adjust the work function by changing the electron energy potential.

The technique for controlling the work function is generally a spin coating method suggested in Korean Patent Application Laid-Open No. 10-2012-0121065 (Prior Document 1) and Korean Patent Application Laid-Open No. 10-2013-0006050 (Prior Document 2) or Korean Patent Registration No. 10- There is a method for forming a self-assembled monolayer (Prior Document 4) suggested in No. 0945729 (Prior Document 3) or 10-0977152. However, since the spin coating method or the self-assembly single film formation method uses a solution as a liquid phase process, it is greatly affected by the surface energy of the electrode surface to induce work function control, and requires a separate surface pretreatment such as oxygen plasma treatment, and self-assembly. In the case of the single film formation method, there is a problem that it can be applied only within a limited range because it is made through a specific chemical bond.

As a method for solving this problem, Korean Patent Application Laid-Open No. 10-2015-0047840 (Prior Document 5) proposes a method of forming a work function control film on the surface of a transparent electrode by an atomic layer deposition method. However, since the atomic layer deposition method can be applied only to transparent electrodes, there is a problem in that the work functions of various electrodes cannot be adjusted.

On the other hand, Korean Patent No. 10-1718879 (Prior Document 6) discloses that when a functional polymer thin film of a monomer containing an electron donor group and/or a monomer containing an electron acceptor group is deposited on an electrode using the iCVD process, the work function is controlled. electrode is disclosed.

However, the above prior documents 1 to 6 require complicated processing such as spin coating method, self-assembled single film forming method, iCVD, etc., and also have a problem in that they cannot control the work function in various ranges in detail.

(Patent Document 0001) Patent Document 1: Korean Patent Publication No. 10-2012-0121065

(Patent Document 0002) Patent Document 2: Korean Patent Publication No. 10-2013-0006050

(Patent Document 0003) Patent Document 3: Korean Patent No. 10-0945729

(Patent Document 0004) Patent Document 4: Korean Patent No. 10-0977152

(Patent Document 0005) Patent Document 5: Korean Patent No. 10-0977152

(Patent Document 0006) Patent Document 6: Korean Patent No. 10-1718879

It is an object of the present invention to be coated on an electrode layer such as an anode in a light emitting device such as an OLED, a solar cell, etc. in a UV curing method, and can perform fine work function control according to the characteristics of the light emitting device, and a light emitting device such as an OLED An object of the present invention is to provide a coating agent capable of producing a conductive thin film with controllable work function that does not cause degradation of the performance.

In order to solve the above problems, the present invention provides a coating agent that is coated on an electrode layer of a solar cell or a light emitting device to form a conductive thin film capable of controlling a work function on the electrode layer by UV curing, comprising: a UV curable binder; organic solvents; dispersing aid; metal oxide powder; and a solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS), wherein the metal oxide powder and the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT) /PSS) by adjusting the content of the solid powder, to provide a coating agent, the work function of the conductive thin film is controlled.

In one embodiment of the present invention, when the coating agent is cured on the electrode layer, the conductive thin film is the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT) on the matrix made of the ultraviolet curable binder material. /PSS) may have a structure in which the particles of the solid powder and the particles of the metal oxide powder are connected to each other and dispersed.

In one embodiment of the present invention, the coating agent, 0.5 to 5% by weight of a UV curable binder; 80 to 96% by weight of an organic solvent; 0.5 to 5% by weight of a dispersing aid; 0.05 to 2% by weight of metal oxide powder; 0.1 to 2% by weight of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) solid powder; may be included.

In one embodiment of the present invention, the metal oxide powder may include aluminum doped zinc oxide (AZO) powder.

In one embodiment of the present invention, the coating agent is a state in which the solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the metal oxide powder are primarily contained in an organic solvent Dispersion and mixing by shear force by a shear mixer including two or more rotors and a stator is performed in an organic solvent, and solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and additional dispersion by a bead mill in a state in which the metal oxide powder is included.

In one embodiment of the present invention, the diameter of the particles of the metal oxide powder may be 5 to 50nm.

In order to solve the above problems, in one embodiment of the present invention, a coating agent is coated on the electrode layer of a solar cell or a light emitting device to prepare a coating agent capable of forming a conductive thin film capable of controlling the work function on the electrode layer by UV curing. As a method, the first organic solvent, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT/PSS) solid content, metal oxide powder, and preparing a first mixture in which a dispersing aid is mixed; performing stirring by a shear mixer to the first mixture; performing stirring by a bead mill to the first mixture; preparing a second mixture by mixing a second organic solvent and an ultraviolet curable binder; and, after mixing the first and second mixtures, stirring by the shear mixer described above is performed; including, the metal oxide powder and the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid ( By controlling the content of the solid powder of PEDOT / PSS), the work function of the conductive thin film is controlled, a coating agent is provided.

In one embodiment of the present invention, the conductive thin film is a solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the oxidation on a matrix made of the ultraviolet curable binder material. The particles of the metal powder may have a structure in which they are connected to each other and dispersed.

The coating agent capable of manufacturing a conductive thin film capable of controlling a work function according to an embodiment of the present invention can be stably formed on the electrode layer by a single UV curing process.

A coating agent capable of manufacturing a conductive thin film capable of controlling a work function according to an embodiment of the present invention, the poly(3,4-ethylenedioxythiophene)-polystyrene in the coating agent for optimizing a work function in a target device By adjusting the solid content powder of sulfonic acid (PEDOT/PSS) and the metal oxide powder, it is possible to exert the effect of precisely and stably controlling.

The coating agent capable of manufacturing a conductive thin film capable of controlling a work function according to an embodiment of the present invention may exhibit the effect of stably manufacturing a conductive thin film having a desired work function.

A coating agent capable of producing a conductive thin film capable of controlling a work function according to an embodiment of the present invention includes a solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the metal oxide powder. It has a stable structure disposed on this UV-curable binder matrix, and can exhibit the effect of having a homogeneous work function.

1 schematically shows a manufacturing step of a coating agent according to an embodiment of the present invention.
Figure 2 schematically shows a manufacturing step of the coating agent according to an embodiment of the present invention.
Figure 3 schematically shows the state of the coating agent in one embodiment of the present invention.
4 schematically shows the particle structure of a conductive thin film according to an embodiment of the present invention.
5 shows experimental results for measuring a work function of a conductive thin film according to embodiments of the present invention.

Various embodiments and/or aspects are now disclosed with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more aspects. However, it will also be recognized by one of ordinary skill in the art that such aspect(s) may be practiced without these specific details. The following description and accompanying drawings set forth in detail certain illustrative aspects of one or more aspects. These aspects are illustrative, however, and some of the various methods in principles of various aspects may be employed, and the descriptions set forth are intended to include all such aspects and their equivalents.

As used herein, “embodiment”, “example”, “aspect”, “exemplary”, etc. may not be construed as an advantage or advantage in any aspect or design described above over other aspects or designs. .

In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise specified or clear from context, "X employs A or B" is intended to mean one of the natural implicit substitutions. That is, X employs A; X employs B; or when X employs both A and B, "X employs A or B" may apply to either of these cases. It should also be understood that the term “and/or” as used herein refers to and includes all possible combinations of one or more of the listed related items.

Also, the terms "comprises" and/or "comprising" mean that the feature and/or element is present, but excludes the presence or addition of one or more other features, elements, and/or groups thereof. should be understood as not

In addition, it will be understood that singular expressions such as "above" and "above" include plural expressions, unless explicitly indicated otherwise in this specification. Thus, as an example, a “component surface” includes one or more component surfaces.

Also, terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

In addition, the terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, are generally understood by those of ordinary skill in the art to which the present invention belongs. have the same meaning as Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the embodiment of the present invention, an ideal or excessively formal meaning is not interpreted as

Structure of conductive thin film

The conductive thin film of the present invention is formed on an anode corresponding to an electrode layer of a solar cell device or a light emitting device. Preferably, the anode corresponds to a reflective electrode using Ag, the coating agent according to the present invention is applied on the reflective electrode, and a conductive thin film may be formed on the anode as the coating agent is UV-cured.

In the present invention, by controlling the content of PEDOT:PSS and metal oxide in the coating agent for producing such a conductive thin film, the work function can be controlled. For example, in the case of an OLED light emitting device, electrical properties related to the movement of charges are determined according to the properties of the hole transport layer and the light emitting layer. If the work function of the anode is controlled, the electrical efficiency can be optimized. However, electrical characteristics related to the movement of charges of the light emitting device may be different for each device, and thus the value of the optimized work function changes.

The present invention provides a coating agent having the effect of controlling the work function by simply adjusting the components of the coating agent to have a target work function, but through a single process called UV curing after coating, and a conductive thin film using the same.

Method for manufacturing a coating agent

The coating agent according to embodiments of the present invention is a coating agent that is coated on an electrode layer of a solar cell or a light emitting device to form a conductive thin film capable of controlling a work function on the electrode layer by UV curing, comprising: a UV curable binder; organic solvents; dispersing aid; metal oxide powder; and a solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS).

In the coating agent of the present invention, by controlling the content of the solid powder of the metal oxide powder and the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS), the coating agent is UV-cured to form the conductive thin film. The work function can be controlled.

The coating agent is 0.5 to 5% by weight of a UV-curable binder; 80 to 96% by weight of an organic solvent; 0.5 to 5% by weight of a dispersing aid; 0.05 to 2% by weight of metal oxide powder; 0.1 to 2% by weight of a solids powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS).

Preferably, the coating agent includes a photoinitiator, and preferably, the photoinitiator includes 0.03 g to 0.5 g per 100 g of the UV curable binder.

The UV-curable binder included in the coating agent preferably includes an acrylic binder material. Such an acrylic binder can stably form a matrix in which the solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the particles of metal oxide powder can be located.

More preferably, an acrylic binder having a trifunctional group or more is preferable. In an embodiment of the present invention, the UV-curable binder includes 30 to 50% by weight of a 9-functional acrylic oligomer, 30 to 50% by weight of a 6-functional acrylic oligomer, 5 to 15% by weight of a silane coupling agent, and a phosphate-based adhesion improving agent 5 to 15% by weight.

Such a UV curable binder is preferably 0.5 to 5% by weight of the total weight of the coating agent. When the UV curable binder is less than 0.5 wt%, it is difficult to implement a binder matrix in which particles of PEDOT:PSS and metal oxide are evenly dispersed, and when it exceeds 5 wt%, the manufacturing process becomes difficult due to high viscosity, and the amount of metal powder used There is a problem that the economic feasibility decreases as the number increases.

Meanwhile, in the present invention, a special dispersing aid is used to further promote the dissolution of the PEDOT/PSS powder and the metal oxide powder. Specifically, the dispersing aid may include: a first dispersing aid to aid in the dispersion of the metal powder in the form of a solid powder; and a second dispersing aid for improving conductivity when the coating agent is coated. Such a dispersing aid preferably accounts for 0.5 to 5 wt% with respect to the total coating solution.

Here, the first dispersion aid includes at least one of amines (amines), acrylates (Acrylates), and polyols (Polyols), and the second dispersion aid includes carbonate, diethylene glycol (Diethylene glycol), propylene glycol, tetramethylene glycol, sorbitol, N,N-dimethylformamide, ethylene glycol, N,N -Dimethylacetamide (N,N-dimethylacetamide), acetonitrile, dimethylsulfoxide, glycerol, ethylene cyanide, formic acid, propylene carbonate , ethylene carbonate (ethylene carbonate), 2,6-difluoropyridine (2,6-difluoropyridine), formamide (formamide), and N- methylformamide (N-methylformamide) is preferred to include at least one of.

More preferably, the first dispersing aid includes a tertiary amine-based additive, and the second dispersing aid includes a carbonate-based additive.

Preferably, the organic solvent is an amide solvent, nitromethane, ketone solvent, alcohol solvent, acetate solvent, aromatic solvent, glycol ether solvent, acrylate monomolecular solvent, amide solvent, acrylate oligomer (Acrylate) oligomer), urethane acrylate polymer, or a mixed solvent of the organic solvent.

More preferably, the organic solvent is ethanol, N,N-dimethylacetamide (DMA), nitromethane, methyl ethyl ketone (MEK (Methyl ethyl ketone)), isopropyl alcohol (Isopropyl alcohol), ethyl alcohol (Ethyl alcohol), n-butyl acetate, toluene, PGME (Propylene glycol methyl ether, 1-METHOXY-2-PROPANOL), PGMEA (Propylene glycol methyl ether acetate), HEMA (Hydroxyethyl methacrylate) ), HEA (Hydroxyethy acrylate), and N,N-dimethylformamide (N,N-dimethylform amide (DMF)), or a mixed solvent of the organic solvent.

Most preferably, the organic solvent may be propylene glycol methyl ether (PGME) or propylene glycol methyl ether acetate (PGMEA). In the case of PGME, the metal oxide powder and the solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) can be more homogeneously dispersed. Or most preferably, the organic solvent may be used by mixing DMA and ethanol.

However, despite the selection of the organic solvent as described above, since there is a problem in that, due to the nature of the PEDOT/PSS powder material, it is not completely dissolved in the organic solvent, in the present invention, additional Agitation takes place.

On the other hand, as the metal oxide powder, various metal oxide powders may be used depending on the purpose of the work function control, but in the present invention, as a result of experimenting with various materials, AZO (Aluminum doped zinc oxide), Fe ₃ O ₄ Nanoparticle powder It was derived that the work function was adjusted linearly and stably according to this content control.

or Co, Fe ₂ O ₃ , Fe ₃ O ₄ , FeOFe ₂ O ₃ , NiOFe ₂ O ₃ , CuOFe ₂ O ₃ , MgOFe ₂ O ₃ , MnBi, Ni, MnSb, MnOFe ₂ O ₃ , Y ₃ Fe ₅ O ₁₂ , CrO ₂ , MnAs, Gd, Dy, EuO and the like nanoparticles may correspond to the metal oxide powder.

The metal oxide powder preferably has a weight of 10% to 50% of the UV-curable acrylic binder. Nanoparticle particles of metal oxide powder may be uniformly disposed on the matrix formed by the acrylic binder at the above content.

Preferably, the particle diameter of the metal oxide powder is 5 to 50 nm. As described above, since the metal oxide powder has the form of nanoparticles, the conductive particles of the metal oxide powder and the PEDOT:PSS powder are connected to realize a uniformly controlled work function.

The poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) has an ethylenedioxy group in the form of a ring in the structure of thiophene, and excellent stability to air or heat has a

In addition, it has a lower optical band gap (760 nm to 780 nm or 1.6 eV to 1.7 eV) than thiophene due to the electron donating effect by the ethylenedioxy group substituted at positions 3 and 4, and depending on the potential difference of oxidation/reduction It is possible to change color, and in the oxidation state, the absorption band exists in the infrared region, so it is possible to secure transparency.

Preferably, PEDOT / PSS is in the form of a solid powder, and pallets (trade name: Orgacon Dry) provided by AGFA of Belgium can be used.

Preferably, the coating agent is a solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the metal oxide powder in an organic solvent before UV curing. Dispersion and mixing by shear force by a shear mixer including two or more rotors and stators are performed, and secondarily, the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) in an organic solvent is Further dispersion by a bead mill is performed in a state in which the solid powder and the metal oxide powder are included.

Such a coating agent can form a conductive thin film on the anode layer by UV curing to a thickness of 1 μm or less.

1 schematically shows a manufacturing step of a coating agent according to an embodiment of the present invention.

In step S100, a first mixture is prepared in which the first organic solvent, PEDOT:PSS solid powder, metal oxide powder, and dispersing aid are mixed. The first mixture prepared in this way may be agitated in general.

The first organic solvent may correspond to an embodiment of the above-described organic solvent.

In step S200, stirring may be made by the shear mixer of the above-described method with respect to the first mixture. In this case, the temperature is preferably maintained between 5 and 12 degrees Celsius, preferably between 6 and 10 degrees Celsius.

As an example of a high shear mixer, a high shear force may be generated by using a high rotational force, and the like may be a device composed of two or more rotors and a stator. Such a high shear mixer can be prepared as a second mixed solution by making the mixed solution more homogeneous by using the cavitation phenomenon. Preferably, with respect to the mixed solution, the high shear mixer performs dispersion and mixing for 1 hour or more at a rotation speed of about 6,000 rpm or more. At this time, cooling is additionally performed so that the temperature of the mixed solution maintains the temperature range.

In step S300, agitation by the bead mill in the above-described manner is performed with respect to the first mixed solution in which S200 is performed. In general, PEDOT:PSS is known as a material that does not dissolve in organic solvents, and most of them are prepared in the form of an aqueous solution. It can be evenly dispersed by additional special stirring of the aforementioned shear mixer and bead mill.

Preferably, the bead mill is in the form of a bead mill capable of nano-dispersion. By such a bead milling step, the mixed solution can be made more homogeneous by the beads and the dispersibility can be improved.

As an example of the bead mill, pulverization and dispersion are applied by applying an impact force to the target powder using an efficient bead, for example, a zirconia-containing bead in wet dispersion and wet pulverization, and thus the second mixed solution by such a bead mill step The silver beads can make it more homogeneous and improve dispersibility.

In addition, the beads preferably have a particle diameter of 50 μm to 200 μm, and more preferably, beads having a particle diameter in the range of 80 μm to 120 μm. The rotational speed of the rotating body of the bead mill is preferably used in a frequency range of about 30 to 60 Hz.

In step S400, a second mixture is prepared by mixing an ultraviolet curable binder with a second organic solvent. The second mixture may contain a photoinitiator. The second organic solvent may be an organic solvent different from the first organic solvent. This second mixture is stirred in a general manner.

In step S500, after mixing the above first mixed solution and the second mixed solution, stirring by the aforementioned shear mixer is performed.

The coating agent thus prepared should be stored in a refrigerated storage unit at 10° C. or less. When stored for a long time at room temperature of 20℃ or higher, the particles of PEDOT/PSS and metal powder may agglomerate and the conductivity may decrease rapidly.

In this way, PEDOT:PSS and metal oxide powder are primarily dispersed in an organic solvent, and after preparing a UV curable binder solution, the two solutions are mixed and further stirred by a shear mixer. In this case, it was confirmed that the work function control according to the content control of the PEDOT:PSS powder and the metal oxide powder had a more regular shape than the steps as in FIG. 2 to be described later. This is because PEDOT:PSS particles and metal oxide particles may be more homogeneously dispersed in the coating solution.

Figure 2 schematically shows a manufacturing step of the coating agent according to an embodiment of the present invention.

In step S110, an organic solvent, PEDOT:PSS solid powder, metal oxide powder, dispersion aid, additives such as photoinitiator, and a mixture of a UV curable binder is prepared. The mixed solution prepared in this way may be subjected to general stirring.

The organic solvent may correspond to an embodiment of the organic solvent described above.

In step S210, the mixture may be stirred by the shear mixer of the above-described method. In this case, the temperature is preferably maintained between 5 and 12 degrees Celsius, preferably between 6 and 10 degrees Celsius.

In step S310, the stirring by the bead mill in the above-described manner is made with respect to the first mixed solution in which S210 is performed. In general, PEDOT:PSS is known as a material that does not dissolve in organic solvents, and most of them are prepared in the form of an aqueous solution. It can be evenly dispersed by additional special stirring of the aforementioned shear mixer and bead mill.

In this way, PEDOT:PSS, metal oxide powder, and UV-curable binder are dispersed in an organic solvent at once to prepare a coating solution, and the advantage of being able to prepare a coating solution more easily than the method shown in FIG. 1 is have.

Figure 3 schematically shows the state of the coating agent according to an embodiment of the present invention.

The part denoted by reference numeral 121 corresponds to a solvent including an organic solvent, an additive, and a UV binder, the part denoted by reference numeral 122 corresponds to metal oxide powder particles, and the part denoted by reference numeral 123 corresponds to poly (3 ,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) particles.

3(A) is a shear mixer in the form of a mixture of UV-curable acrylic binder, organic solvent, and metal oxide powder without solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and a stirred state with a bead mill or the like. Since the metal oxide powder has a property of cohesive to each other and has a high density, most of it is stirred and settled on the bottom after a certain period of time. In the case of UV curing of the coating agent in such a state, the metal oxide powder particles are not uniformly distributed, and accordingly, there is a problem that the work function may vary in the local area of the conductive thin film.

On the other hand, (B) of Figure 3 is a shear mixer and a shear mixer in the form in which the solid content of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS), UV-curable acrylic binder, organic solvent, and metal oxide powder are mixed. It corresponds to a stirred state with a bead mill or the like. The metal oxide powder has the property of aggregating with each other, but it is bound to the PEDOT:PSS particles and is homogeneously distributed. In particular, since PEDOT:PSS has a low specific gravity, it becomes suspended in an organic solvent, thereby preventing agglomeration of metal oxide powder particles. Therefore, in the state of the coating agent, the particles of the metal oxide powder and the particles of the PEDOT:PSS powder are homogeneously dispersed, which can exert the effect of forming a conductive thin film having more homogeneous electrical properties in the area.

Figure 4 schematically shows the particle structure of the conductive thin film formed by the coating agent according to an embodiment of the present invention.

The part denoted by reference numeral 124 corresponds to the matrix formed by the UV binder, the part denoted by reference numeral 122 corresponds to metal oxide powder particles, and the part denoted by reference numeral 123 corresponds to poly(3,4-ethylene). deoxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) particles.

As shown in FIG. 4 , the conductive thin film has a form in which particles of metal oxide powder and particles of PEDOT:PSS powder are atypically connected to each other on a matrix of a UV binder material. The UV curing acrylic binder stably fixes the particles of the metal oxide powder and the PEDOT:PSS particles, and the particles of the metal oxide powder and the PEDOT:PSS powder are uniformly distributed, but may have a structure connected to each other.

In such a structure, the connection between the metal oxide powder and the PEDOT:PSS powder is stably maintained, and thus, a stable work function control can be achieved.

5 shows experimental results for measuring a work function of a conductive thin film according to embodiments of the present invention.

Manufacturing method A-1

1. Ethanol (EtOH) 344.5g, Dimethylacetamide (DMA) 125g, Carbonate-based additive 20g, Tertiary amine-based additive 5g all mixed together to make a . A mixture is prepared by stirring for 60 minutes.

2. After mixing 5 g of PEDOT:PSS solid powder with the above mixture, stir for 60 minutes.

3.PEDTO: After mixing 0.5 g of aluminum doped zinc oxide (AZO) [average particle size of 15nm, aluminum 2wt% doped] to the above mixture to which PEDTO:PSS solid powder is added, stir for 60 minutes.

4.PEDOT: High shear mixing is performed for the above mixed solution with PSS and AZO added for 60 minutes. At this time, the temperature of the mixed solution is maintained at 8℃.

5.Disperse the above mixed solution with high shear mixing by bead mill for 60 minutes

Manufacturing method A-2

1. A mixed solution is prepared in the same manner as in Preparation Method A-1 except that 343.5 g of EtOH and 1.5 g of AZO are used.

Manufacturing method A-2

1. A mixed solution is prepared in the same manner as in Preparation Method A-1, except that 342 g of EtOH and 3 g of AZO are used.

Example B-1

1. After mixing 1g of UV-curable binder mixture, 13g of 1-methoxy-2-propanol, and 0.1g of polyol, completely dissolve the UV-curable binder.

2.UV-curable binder mixture (The UV-curable binder mixture is a mixture of 40wt% of 9-functional acrylic oligomer, 38% of 6-functional acrylic, 12wt% of silane coupling agent, and 10wt% of phosphate-based adhesion improving agent.)

3. Mix 31 g of the dispersion prepared by Preparation Method A-1 with the above mixture and stir for 30 minutes.

4. Perform high shear mixing to the above mixture for 60 minutes. At this time, the temperature of the mixed solution should be maintained at 8℃.

5. After mixing the photoinitiator and other additives in the above mixture, stir for 30 minutes.

Example B-2

1. Same as Example B-1,

2. Prepare a mixed solution by using only the dispersion prepared by Preparation Method A-2 as the dispersion.

Example B-3

1. Same as Example B-1,

2. Prepare a mixed solution by using only the dispersion prepared by Preparation Method A-3 as the dispersion.

Example B-4

1. Mix 24g of UV curable binder, 551.64g of Ethanol, and 551.64g of 1-methoxy-2-propanol and dissolve completely.

A. As a UV-curable binder mixture, a mixture of 46wt% of 9-functional acrylic oligomer, 46wt% of 6-functional aromatic acrylic oligomer, and 8wt% of phosphate-based adhesion improving agent is used.

2. Mix 48 g of carbonate-based additive and 12 g of tertiary amine-based additive with the above mixture and dissolve it completely.

3. Mix 12 g of PEDOT:PSS solid powder with the above mixture and stir for 60 minutes.

4. After mixing 0.72g of AZO with the above mixture, stir for 60 minutes.

5. High shear mixing is performed on the above mixture. At this time, the temperature of the mixed solution should be maintained at 8°C.

6. Execute “Police’s unique milling technique” for 60 minutes in the above mixture.

7. Mix other additives (photoinitiator and additive) with the above mixture and use it as a coating agent.

Example B-5

1. Same as Example B-4,

2. Prepare a mixed solution by using only EtOH 550.8g, 1-methoxy-2-propanol 550.8g, and AZO 2.4g.

Example B-6

1. Same as Example B-4,

2. Prepare a mixed solution by only using Fe3O4 [average particle size 15~20nm] as metal particles.

Example B-7

1. Same as Example B-5

2. Prepare a mixed solution by only using Fe3O4 [average particle size 15~20nm] as metal particles.

Example B-8

1. Mix 17.14g of UV-curable binder and 1140g of 1-methoxy-2-propanol and dissolve completely.

A. As a UV-curable binder mixture, a mixture of 50wt% of 9-functional acrylic oligomer and 50wt% of 6-functional aromatic acrylic oligomer is used.

2. Mix 17.14 g of carbonate-based additive and 4.29 g of tertiary amine-based additive with the above mixture and dissolve completely.

3. Mix 17.14 g of Fe3O4 nanoparticles in the above mixture and stir for 60 minutes.

4. Mix 12 g of PEDOT:PSS solid powder with the above mixture and stir for 60 minutes.

5. Perform high shear mixing on the above mixture. At this time, the temperature of the mixture should be maintained at 8℃.

6. Execute “Police’s unique milling technique” for 60 minutes in the above mixture.

7. Mix other additives (photoinitiator and additive) with the above mixture and use it as a coating material.

Formation of conductive thin film

1. A conductive electrode using Ag as a reflective electrode is formed on the glass surface.

2. On the surface of the electrode above, spin coating the coating solution prepared according to recipe B-1, B-2, B-3, B-4, B-5, B-6, B-7, B-8 as shown below. enforced on condition.

1) Spin coating at 10000rpm for 20 seconds

2) Dry the above coated specimen in a convection oven at 90℃

3) UV curing of the above coated specimen with a light quantity of 400mJ/cm2

3.Measurement

1) The work function of the electrode surface was measured by the Kelvin probe measurement method for the surface of the coated specimen prepared in the above example.

2) The Kelvin probe measurement method was used by KP Technology of the UK.

3) After 50 measurements per point, the average was calculated, and the measurement was performed at 3 points per specimen, and the average was calculated again.

Ingredient content of each example

BB1 BB2 B3 B4 B5 ethanol 21.359 21.297 21.122 ethanol 551.64 550.8 DMA 7.75 7.75 7.75 CARBONATE ADDITIVES 1.24 1.24 1.24 CARBONATE ADDITIVES 48 48 TERTIARY AMINE ADDITIVES 0.31 0.31 0.31 TERTIARY AMINE ADDITIVES 12 12 PEDOT:PSS 0.31 0.31 0.31 PEDOT:PSS 12 12 AZO 0.031 0.093 0.186 AZO 0.72 2.4 UV curable binder One One One UV curable binder 24 24 1-METHOXY-2-PROPANOL 13 13 13 1-METHOXY-2-PROPANOL 551.64 550.8 POLYOL 0.1 0.1 0.1

BB6 BB7
BB8 ethanol 551.64 550.8 CARBONATE ADDITIVES 48 48 17.14 TERTIARY AMINE ADDITIVES 12 12 4.29 PEDOT:PSS 12 12 12 Fe3O4 0.72 2.4 17.14 UV curable binder 24 24 17.14 1-METHOXY-2-PROPANOL 551.64 550.8 1140

Work function measurement results for the prepared conductive thin film

As shown in Fig. 5, which is the work function test result of Examples 1 to 8, according to the coating agent of the present invention, the work function in various ranges was stably implemented by adjusting the type and content of the metal oxide powder. .

In particular, in the case of Examples 1 to 5, it was confirmed that the work function changed with a certain relationship according to the change in the content of AZO, which is the metal oxide powder, and in the case of Examples 6 to 8, the type of the metal oxide powder was changed to Fe3O4 In this case, a wider range of work functions could be stably implemented. That is, in one embodiment of the present invention, by selecting any one of AZO and Fe3O4 as the metal oxide powder and controlling their content, the effect of precisely controlling the work function in a wide range of 4.34 to 5.28 eV is obtained. It was confirmed that it can be performed.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments presented herein, but is to be construed in the widest scope consistent with the principles and novel features presented herein.

Claims (8)

A coating agent that is coated on the electrode layer of a solar cell or light emitting device to form a conductive thin film capable of controlling a work function on the electrode layer by UV curing,
UV curable binder;
organic solvents;
dispersing aid;
metal oxide powder; and
Poly (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT / PSS) solid powder;
The work function of the conductive thin film is controlled by adjusting the content of the solid powder of the metal oxide powder and the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS).
The method according to claim 1,
When the coating agent is cured on the electrode layer, the conductive thin film is a solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) on a matrix made of the ultraviolet curable binder material. And, a coating agent having a structure in which the particles of the metal oxide powder are connected to each other and dispersed.
The method according to claim 1,
The coating agent,
0.5 to 5% by weight of an ultraviolet curable binder;
80 to 96% by weight of an organic solvent;
0.5 to 5% by weight of a dispersing aid;
0.05 to 2% by weight of metal oxide powder;
A coating agent comprising a; 0.1 to 2% by weight of a solid powder of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS).
The method according to claim 1,
The metal oxide powder is AZO (Aluminum doped zinc oxide) powder or Fe ₃ O ₄ A coating agent comprising a powder.
The method according to claim 1,
The coating agent,
A shear mixer including two or more rotors and a stator in a state where the solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the metal oxide powder are primarily contained in an organic solvent Dispersion and mixing by shear force is performed, and the solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the metal oxide powder are secondarily included in the organic solvent In which additional dispersion by a bead mill is performed, the coating agent.
The method according to claim 1,
The diameter of the particles of the metal oxide powder is 5 to 50nm, the coating agent.
A method of manufacturing a coating agent that is coated on the electrode layer of a solar cell or light emitting device to form a conductive thin film capable of controlling a work function on the electrode layer by UV curing,
A first organic solvent, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT/PSS) solid content, metal oxide powder, and preparing a first mixture in which a dispersing aid is mixed;
performing stirring by a shear mixer to the first mixture;
performing stirring by a bead mill to the first mixture;
preparing a second mixture by mixing a second organic solvent and an ultraviolet curable binder; and
After mixing the first mixture and the second mixture, stirring by the shear mixer described above is performed; including;
The work function of the conductive thin film is controlled by adjusting the content of the solid powder of the metal oxide powder and the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS).
8. The method of claim 7,
In the conductive thin film, the particles of the solid powder of the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT/PSS) and the particles of the metal oxide powder are connected to each other on the matrix made of the ultraviolet curable binder material. A method of forming a conductive thin film having a dispersed structure.

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