KR20220082203A - Organic/inorganic multilayer thin film encapsulation using organic monomer thin film and a preparing method of the same - Google Patents

Abstract

The present invention includes an organic thin film formed on a substrate and including a monomolecular compound, and an inorganic thin film formed on the organic thin film and including at least one of an oxide and a nitride, wherein the organic thin film includes Formula 1 To provide a multi-layer encapsulation thin film comprising at least one of the compounds represented by Formula 4 and a method for manufacturing the same.

Description

Organic/inorganic multi-layer thin film encapsulation using organic monomolecular thin film and manufacturing method thereof

The present invention relates to an organic-inorganic multi-layer thin film encapsulation using an organic mono-molecule thin film and a method for manufacturing the same, and more particularly, to an organic-inorganic multi-layer thin film using an organic mono-molecule thin film capable of improving the interfacial adhesion of an organic polymer thin film used in the past. It relates to a bag and a method for manufacturing the same.

Since the organic light emitting display is vulnerable to moisture or oxygen in the atmosphere, an encapsulation for protecting the organic light emitting device is essential. In the past, it was encapsulated by covering it with a metal can or a glass plate, but as organic light emitting displays that require flexibility have been developed, a thin film encapsulation for protection by directly depositing a thin film on top of an organic light emitting device is being used. Materials that can effectively block the permeation of moisture or oxygen are inorganic thin films, and silicon nitride or aluminum oxide thin films are mainly used. However, a thick inorganic layer is required to realize perfect thin film encapsulation by depositing only inorganic thin films. Since the thick inorganic layer has weak flexibility and is easy to break, cracks easily occur in the process of bending or folding, making it difficult to use as a thin film encapsulation for flexible organic light emitting displays. In order to solve this problem, an organic/inorganic multi-layer thin film encapsulation in which the inorganic layer is thinned and the inorganic layer and the organic layer are alternately stacked has been introduced and utilized. Here, the inorganic layer serves to block moisture, and the organic layer serves to provide flexibility. This multi-layer structure helps to improve the encapsulation properties because it serves to lengthen the path through which moisture or oxygen passes through the structure.

A polymer material has been used as a material for the organic layer. As the polymer material, an organic polymer that can be thinned by wet coating or a polymer that can be polymerized by supplying ultraviolet rays or heat can be used. In addition, a polymer deposited by plasma vapor polymerization using a dry process or vapor phase polymerization using a polymerization initiator may be used. The reason for using such an organic polymer is that thin film formation is easy and mechanical properties are good. Organic/inorganic multi-layer thin film encapsulation using an organic polymer thin film using excellent mechanical properties is being used in organic light emitting displays that require flexibility. However, even if an organic/inorganic multilayer thin film encapsulation using an organic polymer thin film is used, in the case of a foldable display with a very small folding radius of about 1 mm, the flexibility of the organic polymer thin film is not sufficient, so there is a risk of problems such as cracks in the inorganic material layer. do. When tensile or compressive deformation with a very small folding radius is applied to the encapsulation structure, cracks may occur due to the low flexibility of the inorganic layer itself, and cracks may occur in the inorganic layer as peeling occurs at the interface between the organic layer and the inorganic layer. may be In order to reduce delamination at the interface and realize a stable encapsulation structure even with a lower folding radius, it is required to use an organic material layer that is more flexible and has better interfacial adhesion.

In relation to this problem, Korean Patent Registration No. 10-1465212 discloses an organic/inorganic multi-layer encapsulation using an organic polymer obtained by plasma vapor phase polymerization. However, since the above patent has a limitation in improving interfacial adhesion with inorganic materials, it seems difficult to cover the physical properties required for various applications in this field.

Republic of Korea Patent No. 10-1465212

Samuel E. Root, Suchol Savagatrup, Adam D. Printz, Daniel Rodriquez, and Darren J. Lipomi, Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics, Chem. Rev. 2017, 117, 6467-6499.

The organic monomolecular thin film used in the organic-inorganic multi-layer thin film encapsulation of the present invention has better interfacial adhesion with inorganic substances compared to the organic polymer thin film and at the same time is more flexible, so it can be used in an encapsulation thin film that can be stable even in very small folds. do.

In addition, if an organic-inorganic multi-layer encapsulation thin film is produced using an organic monomolecular thin film, an encapsulation thin film that does not crack even with a very small folding radius of 1 mm can be realized, thereby realizing a thinner foldable display.

In order to achieve the above object, the present invention includes; an organic thin film formed on a substrate and including a monomolecular compound, and an inorganic thin film formed on the organic thin film and comprising any one or more of an oxide and a nitride It provides a multi-layer encapsulation thin film.

In addition, the present invention, (a) forming an organic thin film comprising a monomolecular compound on a substrate; and (b) forming an inorganic thin film including at least one of an oxide and a nitride on the organic thin film; It provides a method of manufacturing a multi-layer encapsulation thin film comprising a.

As in the present invention, if an organic-inorganic multi-layer encapsulation thin film is manufactured using an organic mono-molecule thin film, an organic-inorganic multi-layer encapsulation thin film that does not crack even with a very small folding radius of 1 mm can be realized, thereby creating a thinner foldable display. There are advantages to implementation.

1 is a cross-sectional view of an organic light emitting display to which a multilayer encapsulation thin film is applied.
2 is a schematic diagram illustrating a stress neutral plane of a foldable display to which a multilayer encapsulation thin film is applied.
3 is a schematic view showing the organic-inorganic multi-layer thin film encapsulation prepared in Example 1 and Comparative Examples 1 and 2 according to the present invention.
4 is a measurement result of the organic-inorganic multi-layer thin film encapsulation prepared in Comparative Example 1 according to the present invention.
5 is a measurement result of the organic-inorganic multi-layer thin film encapsulation prepared in Comparative Example 2 according to the present invention.
6 is a measurement result of the organic-inorganic multi-layer thin film encapsulation prepared in Example 1 according to the present invention.
7 is a photograph showing the crack shape of the organic-inorganic multilayer thin film encapsulation prepared in Example 1 and Comparative Examples 1 and 2 according to the present invention.
8 is a photograph of the interface of Example 1 and Comparative Example 2 according to the present invention.
9 is a schematic diagram showing the surface behavior when compressive stress is applied.
10 is a result of comparing the cracks of the organic-inorganic multi-layer thin film encapsulation prepared in Example 2 and Comparative Example 3 according to the present invention.
11 is another result of comparing the cracks of the organic-inorganic multi-layer thin film encapsulation prepared in Example 2 and Comparative Example 3 according to the present invention.
12 is a schematic diagram showing a structure of an organic-inorganic multi-layer encapsulation thin film stacked in multiple layers according to the present invention.

Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.

The terms or words used in the present specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

The present invention relates to a multilayer encapsulation thin film, comprising: an organic thin film formed on a substrate and including a monomolecular compound; and an inorganic thin film formed on the organic thin film and comprising at least one of an oxide and a nitride .

The present invention is characterized in that the multilayer encapsulation thin film utilizes an organic thin film containing an organic monomolecular compound by replacing the conventional organic polymer thin film in the organic/inorganic multilayer encapsulation film structure for a flexible organic light emitting display. The organic polymer thin film conventionally used is mainly used for manufacturing organic-inorganic multi-layer encapsulation films because, like the vapor deposition process of inorganic thin films, vapor-phase polymerization is possible using plasma or vapor-phase addition polymerization is possible using vapor-phase polymerization initiators. come. The organic monomolecular thin film presented in the present invention can be used for manufacturing an organic-inorganic multi-layer encapsulation film for flexible display because it can be coated in a liquid phase as well as in a vapor phase. Furthermore, the organic monomolecular thin film has a much lower modulus than the organic polymer thin film, so it is more flexible and has better interfacial adhesion with the inorganic thin film, so it has an advantage as a thin film encapsulation material for flexible displays that require severe deformation. .

Since the organic monomolecular material used in the present invention has a strong hydrogen bond and a ring structure at the same time, it is a material capable of pi-pi bonding (π-π interaction) and is generally present in the form of a powder at room temperature. Since this monomolecular material has a solid surface and wetting properties at a slightly high temperature near its melting point, it can be coated in a thin film form due to restructuring due to the solid surface properties. Hydrogen bonding and pi-pi bonding can play an important role when thin films are formed through surface-induced restructuring. Therefore, an appropriate structure of the organic monomolecular material may affect the process characteristics and mechanical properties of the thin film formed. Although organic semiconductor monomolecular thin films have been studied in order to utilize such organic monomolecular thin films for applications such as solar cells, there has been little research to date. In particular, as an organic material capable of imparting flexibility in the thin film encapsulation structure of an organic light emitting display, there is no conventionally used bar. The organic monomolecular material used in the present invention is expected to be utilized as an organic material for thin film encapsulation of organic light emitting devices because it has a high adhesion to a solid surface through hydrogen bonding and is more flexible than organic polymers.

1 is a cross-sectional view of the organic light emitting display to which the multilayer encapsulation thin film according to the present invention is applied. After the organic light emitting device and the organic capping layer are deposited on the backplane on which the thin film transistor array is fabricated, the organic/inorganic multilayer thin film encapsulation may be formed. A touch screen panel (TSP) layer may be bonded to the upper portion of the organic/inorganic multi-layer thin film encapsulation. In the organic-inorganic multilayer thin film encapsulation structure, a silicon nitride thin film is mainly used as the inorganic layer, but other metal oxides or metal nitrides such as aluminum oxide may be used. In general, the inorganic layer may use a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method. As the organic layer, as described above, an organic polymer thin film that is subjected to vapor polymerization in plasma or an organic polymer thin film can be produced through an initiated-CVD method using an initiator. As the organic layer, in addition to the vapor-polymerized organic polymer thin film, an organic monomolecular layer printed by an inkjet method may be used to form an organic polymer thin film through UV curing.

In the present invention, an organic monomolecular thin film without polymerization is used instead of the conventionally used organic polymer thin film. The organic monomolecular thin film to be used may be formed by using as a material a pyridine-based organic monomolecular compound having a functional group capable of forming hydrogen bonding. After the organic monomolecular thin film is coated on a solid surface in a state of being dissolved in a solvent, a uniform thin film can be formed through heat treatment. For such wet coating, spin coating, bar coating, slot die coating, or inkjet printing may be used. In order to more easily fabricate an organic-inorganic multilayer structure, an organic monomolecular thin film may be vapor-deposited. The organic monomolecular material may be vaporized in a vacuum atmosphere, and the vaporized organic monomolecular material may be transferred to a solid surface to be deposited. In the case of vapor deposition, if a shadow mask is used, a patterned organic monomolecular thin film may be formed. In this case, the temperature of the solid surface may be 80° C. or less so as not to damage the organic light emitting device located thereunder. Therefore, the organic monomolecular material should be able to be coated on the solid surface while applying this temperature condition.

When moisture or oxygen in the air comes into contact with the organic light emitting device, the cathode of the organic light emitting device having a small work function may be oxidized to cause deterioration of device characteristics. Therefore, the role of the organic-inorganic multi-layer encapsulation thin film is to block such moisture or oxygen, and to maintain high flexibility at the same time as such blocking. In the case of the foldable display, as shown in FIG. 2 , the encapsulation thin film may be subjected to tensile or compressive stress according to its relative position with the stress neutral plane. When subjected to tensile stress, cracks may occur in the inorganic thin film, and when subjected to compressive stress, peeling may occur depending on the strength of the adhesive force at the interface between organic and inorganic materials. have. Therefore, in order to form a stable organic-inorganic multilayer encapsulation thin film that does not crack even with a very small folding radius, it is necessary to utilize an organic thin film with very high flexibility and excellent interfacial adhesion. In the present invention, the organic monomolecular material used in the present invention can be thinned by hydrogen bonding and pi-pi bonding at a temperature of 80° C. or less, and has high adhesion to inorganic thin films and high flexibility at the same time. It is suitable as an organic material for the film.

In addition to the basic conditions that flexibility and interfacial adhesion should be high, the necessary conditions for the implementation of the organic/inorganic multilayer encapsulation film for flexible displays should be able to form a thin film at 80° C. or less, pattern formation should be possible, and vapor deposition should be possible. . The pyridine-based monomolecular material having a functional group capable of hydrogen bonding used in the present invention satisfies all the above conditions and is suitable as an organic material for an organic/inorganic multilayer encapsulation film for flexible displays.

To this end, in the multilayer encapsulation thin film of the present invention, the monomolecular compound may be a pyridine-based organic monomolecular compound.

Also, according to one embodiment of the present invention, the monomolecular compound may be any one or more of the compounds represented by the following Chemical Formulas 1 to 4.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

(R1 and R2 are each independently hydrogen or a linear or branched C1-10 alkyl group)

According to one embodiment of the present invention, the inorganic thin film and the organic thin film may be stacked in a plurality of layers crossing each other.

According to an embodiment of the present invention, as the oxide or nitride, aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zinc oxide, silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), Silicon carbide (SiC), silicon oxynitride (Si ₂ N ₂ O), silicon carbonate (SiOC), and may include, but may not be limited thereto.

According to one embodiment of the present invention, a polymer thin film may be additionally formed on one side of both surfaces of the organic thin film on which the inorganic thin film is not formed.

According to one embodiment of the present invention, the polymer may include one selected from the group consisting of plasma polymers, acrylic polymers, and combinations thereof, but may not be limited thereto. For example, the plasma polymer is hexamethyl disiloxane (hereinafter referred to as 'HMDSO'), 1,4-epoxy-1,3-butadiene (1,4-epoxy-1,3-butadiene, hereinafter 'HMDSO'). Furan '), hexane, and may include one selected from the group consisting of combinations thereof, but may not be limited thereto. For example, the acrylic polymer may include one selected from the group consisting of acrylates, urethane acrylates, polyacrylates, polyalkyl acrylates, polyacrylamides, ethylene-acrylic acid copolymers, and combinations thereof. However, it may not be limited thereto.

According to one embodiment of the present invention, the single layer of the inorganic thin film may have a thickness of about 0.1 nm to about 20 nm, but may not be limited thereto. For example, about 0.1 nm to about 20 nm, about 1 nm to about 20 nm, about 2.5 nm to about 20 nm, about 5 nm to about 20 nm, about 10 nm to about 20 nm, about 0.1 nm to about 10 nm, about 1 nm to about 10 nm, about 2.5 nm to about 10 nm, about 5 nm to about 10 nm, about 0.1 nm to about 5 nm, about 1 nm to about 5 nm, about 2.5 nm to about 5 nm, It may be about 0.1 nm to about 2.5 nm, about 1 nm to about 2.5 nm, or about 0.1 nm to about 1 nm, but may not be limited thereto.

According to one embodiment of the present invention, the single layer of the organic thin film may have a thickness of about 20 nm to about 2 μm, but may not be limited thereto. For example, the organic thin film may be about 20 nm to about 2 μm, about 50 nm to about 2 μm, about 100 nm to about 2 μm, about 300 nm to about 2 μm, about 500 nm to about 2 μm, about 700 nm to about 2 μm, about 900 nm to about 2 μm, about 1 μm to about 2 μm, about 20 nm to about 1 μm, about 50 nm to about 1 μm, about 100 nm to about 1 μm, about 300 nm to about 1 μm, about 500 nm to about 1 μm, about 700 nm to about 1 μm, about 900 nm to about 1 μm, about 20 nm to about 900 nm, about 50 nm to about 900 nm, about 100 nm to about 900 nm, about 300 nm to about 900 nm, about 500 nm to about 900 nm, about 700 nm to about 900 nm, about 20 nm to about 700 nm, about 50 nm to about 700 nm, about 100 nm to about 700 nm, about 300 nm to about 700 nm, about 500 nm to about 700 nm, about 20 nm to about 500 nm, about 50 nm to about 500 nm, about 100 nm to about 500 nm, about 300 nm to about 500 nm, about 20 from about 300 nm to about 300 nm, from about 50 nm to about 300 nm, from about 100 nm to about 300 nm, from about 20 nm to about 100 nm, from about 50 nm to about 100 nm, or from about 20 nm to about 50 nm, This may not be limited.

According to an embodiment of the present invention, the plastic substrate is polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polyimide It may include a plastic substrate selected from the group consisting of de (PI), polyethylene (PE), and combinations thereof, but is not limited thereto.

When the multilayer encapsulation thin film according to the present invention is positioned on a neutral plane in which tensile and compressive forces can be offset, the probability that defects may occur due to bending may be lowered, but may not be limited thereto. For example, when the same material is used for upper and lower portions of the multilayer thin film, the multilayer encapsulation thin film may be positioned on the neutral plane, but the present invention may not be limited thereto. Theoretically, in the case of perfect vertical symmetry, the occurrence of defects can also be prevented because tensile and/or compressive forces are not applied to the neutral plane. However, since perfect vertical symmetry cannot be obtained in an actual process, a certain level of tensile force and/or compressive force may occur, but may not be limited thereto.

The multilayer encapsulation thin film according to the present invention may be used in one or more devices selected from an electric device, a magnetic device, an optical device, and a sensor device, but is not necessarily limited thereto. Specifically, the multilayer encapsulation thin film may be used in devices such as an organic light emitting diode display, an organic solar cell, a perovskite solar cell, a touch screen, and a secondary battery.

In addition, the present invention comprises the steps of (a) forming an organic thin film including a monomolecular compound on a substrate; and (b) forming an inorganic thin film including at least one of an oxide and a nitride on the organic thin film.

In the characteristics of each configuration of the method for manufacturing the multilayer encapsulation thin film of the present invention, all of the characteristics of each configuration described in the multilayer encapsulation thin film of the present invention described above may be applied.

In the method of manufacturing the multilayer encapsulation thin film of the present invention, step (a) may be performed by spin coating, bar coating, slot die coating, or inkjet printing.

In addition, step (a) may be performed using a coating solution for forming an organic thin film containing 0.1 to 3.0 wt% of a monomolecular compound, and preferably, an organic thin film containing 0.5 to 2.5 wt% of a monomolecular compound A coating solution for forming may be used, and most preferably, a coating solution for forming an organic thin film containing 1.5 to 2.5 wt% of a monomolecular compound may be used.

In step (a), a coating solution for forming an organic thin film is applied on a substrate, and the coated organic monolayer has a thin and dense layer having strong adhesion at the interface with the substrate, but has a weak binding force and low density on the top thereof. A molecular layer is present. When silicon nitride is deposited on the organic monomolecular film in vacuum, the organic monomolecules with low density on the top are removed in the vapor phase or mixed with the silicon nitride thin film to greatly improve the adhesion between organic-inorganic interfaces. For this reason, the thickness of the organic monomolecular thin film layer in the prepared organic-inorganic thin film encapsulation varies depending on the silicon nitride coating conditions, but when the concentration of the coating solution is high, a slightly thicker organic monomolecular thin film is formed.

In addition, step (b) may be performed by a chemical vapor deposition method or an atomic layer deposition method. When the inorganic thin film is formed by using the atomic layer deposition method or the chemical vapor deposition method, an inorganic thin film having a thin thickness of about 20 nm or less may be formed, but the present invention may not be limited thereto. For example, the inorganic thin film may be about 20 nm or less, about 18 nm or less, about 16 nm or less, about 14 nm or less, about 12 nm or less, about 10 nm or less, about 8 nm or less, about 6 nm or less, about 4 nm or less nm or less, about 2 nm or less, about 1 nm or less, or about 0.5 nm or less, but may not be limited thereto.

Hereinafter, preferred examples are presented to help the understanding of the present invention, but the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, It goes without saying that changes and modifications fall within the scope of the appended claims.

Example: Preparation of organic-inorganic multi-layer thin film encapsulation

[Example 1]

Using a 50 micron thick polyimide (PI) film as a substrate, 0.5 wt.% of a 4-aminopyridine (4-AP) coating solution (using isopropyl alcohol as a solvent) was bar-coated on the top. After drying, a semi-transparent monomolecular organic thin film was formed. This film was heat-treated at a temperature of 80° C. to form a transparent organic monomolecular thin film layer with a thickness of 50 nm.

Thereafter, a silicon nitride (Si ₃ N ₄ ) thin film was vapor-deposited to a thickness of 100 nm through CVD on the organic monomolecular thin film layer to prepare an organic/inorganic multilayer thin film encapsulation.

[Comparative Example 1]

It was prepared in the same manner as in Example 1, except that silicon nitride having a thickness of 100 nm was deposited on a polyimide film without forming an organic monomolecular thin film layer.

[Comparative Example 2]

Instead of an organic monomolecular thin film layer, a plasma vapor-polymerized organic polymer thin film using n-hexane as a raw material is deposited to a thickness of 50 nm, and then a silicon nitride (Si ₃ N ₄ ) thin film is deposited thereon to a thickness of 100 nm through CVD. Except for vapor deposition, it was prepared in the same manner as in Example 1. In the plasma gas phase polymerization, a raw material was supplied using an argon (Ar) transport gas into a plasma of 50 W, and the raw material radicals generated in the plasma were radically polymerized on the surface of the substrate to form a polymer.

Experimental Example 1: Mechanical stability test of organic-inorganic multi-layer thin film encapsulation-1

With respect to the organic-inorganic multilayer thin film encapsulation prepared in Example 1 and Comparative Examples 1 and 2, it was tested whether the mechanical stability of the inorganic thin film was improved in the folding deformation. The structures of Example 1 and Comparative Examples 1 and 2 are shown in FIG. 3 .

As shown in FIG. 4 , in Comparative Example 1 without an organic layer between the polyimide film and the silicon nitride thin film, cracks occurred as the inorganic layer was rolled with a rod having a diameter of 3 mm to receive tensile or compressive stress. When the silicon nitride thin film is rolled inward, compressive stress is generated in the nitride thin film, and when the polyimide film is rolled inward, tensile stress is generated in the nitride thin film. In addition, when tensile stress occurs, cracks occur directly due to the force pulling the nitride on both sides, but when compressive stress occurs, delamination occurs at the interface between the silicon nitride thin film and the polyimide, and cracks occur. .

5, in the case of Comparative Example 2, in which a plasma vapor-polymerized organic polymer thin film was inserted between the polyimide film and the silicon nitride thin film, cracks occurred in both compression and tensile deformation when rolled with a rod having a diameter of 3 mm. Did not do it. From this fact, it can be confirmed that when the organic thin film is inserted, the mechanical stability of the upper inorganic thin film is improved. In the case of this sample, rolling with a rod with a diameter of 2 mm begins to crack under both tensile and compressive strains. The average spacing between cracks was found to be smaller than that of Comparative Example 1 in FIG. 4 .

As shown in FIG. 6 , in the case of Example 1, in which a 4-AP organic monomolecular thin film was inserted between the polyimide film and the silicon nitride thin film, no cracks occurred when rolling with a 3 mm diameter rod, and a 2 mm diameter rod Even in the case of rolling with , cracks occurred for both tensile and compressive stresses, but the average interval between cracks was smaller than that of Comparative Example 2 of FIG. 5 .

7 shows the shape of cracks that occurred when compressive stress was applied to Examples 1 and 1 and 2 above. As shown in FIG. 7 , the average spacing between cracks was the smallest in Example 1 in which the 4-AP organic monomolecular thin film was inserted. In addition, in each case, cracks generated due to compressive stress showed different degrees of cracking, and in Comparative Example 1 in which an organic thin film was not inserted or Comparative Example 2 in which a plasma vapor-polymerized organic polymer thin film was inserted, cracks occurred. appeared to be large. In the case of Example 1 in which the 4-AP organic monomolecular thin film was inserted, the average spacing between cracks was small, but the size of the cracks was also weak.

8 shows a photograph taken with an electron microscope at the interface of Example 1 (right) and Comparative Example 2 (left). As shown in FIG. 8, in Comparative Example 2 using the plasma vapor-polymerized organic polymer thin film, peeling from the polyimide substrate was severe after rolling deformation and cracking occurred significantly, but in Example 1 using the 4-AP organic monomolecular thin film In the case of , the degree of peeling was small and cracks were also small.

In addition, when compressive stress is applied, wrinkles are generated in the inorganic thin film having a large strain coefficient as shown in FIG. 9 . The strain coefficient of the silicon nitride thin film is about 300 GPa, which is much larger than 3 GPa, which is the strain coefficient of polyimide.

When analyzed theoretically, when the thickness of the silicon nitride thin film is 100 nm, the interfacial adhesion between silicon nitride and polyimide is very high, and assuming that delamination does not occur, the period of wrinkles is expected to be about 2 microns. As a result of the actual experiment, cracks occurred in the compressive deformation, which is because the interfacial adhesion is not strong enough. When the average distance between cracks is large or the size of the cracks is large, interfacial peeling occurred at a lower compressive stress, which can be interpreted as a larger crack. It can be seen that the interfacial adhesive force is greater in the case of 1 than in the case of Comparative Example 2 in which the plasma vapor-polymerized organic polymer thin film is inserted.

[Example 2]

An organic-inorganic multilayer thin film encapsulation was prepared in the same manner as in Example 1, except that the silicon nitride (Si ₃ N ₄ ) thin film was formed to a thickness of 25 nm.

[Comparative Example 3]

An organic-inorganic multilayer thin film encapsulation was prepared in the same manner as in Comparative Example 2, except that the silicon nitride (Si ₃ N ₄ ) thin film was formed to a thickness of 25 nm.

Experimental Example 2: Mechanical stability test of organic-inorganic multi-layer thin film encapsulation-2

For the organic-inorganic multi-layer thin film encapsulation prepared in Example 2 and Comparative Example 3, the occurrence of cracks after folding the two samples with a folding radius of 2.5 mm was compared. The sample was manufactured in a size of 1 inch in width and length and both ends in the folding direction were fixed. The width of the folded portion of the sample was 2 cm, and the encapsulation layer was placed on the inside of the folded surface so that the thin film encapsulation layer could be subjected to compressive tension. When folded, the radius of the folded sample was set to the desired radius. As shown in FIG. 10, in Comparative Example 3, in which the organic polymer thin film was inserted after folding, very many cracks occurred on the surface of the inorganic thin film, but in Example 2, in which the organic monolayer thin film was inserted, a very small number of cracks were observed. was confirmed to have occurred.

In addition, after folding at a slightly larger folding radius of 2.8 mm, as shown in FIG. 11 , in Comparative Example 3 in which an organic polymer thin film was inserted, a large number of cracks still occurred on the surface of the inorganic thin film, but an organic monomolecular thin film was inserted In the case of Example 2, cracks hardly occurred.

Through the comparison of Examples 1 to 2 and Comparative Examples 1 to 3, the organic monomolecular thin film such as 4-AP is replaced with the conventional organic polymer thin film, thereby improving the mechanical stability of the organic-inorganic multilayer thin film against folding deformation. It was confirmed that it can be done.

[Example 3]

An organic-inorganic multilayer thin film encapsulation was prepared in the same manner as in Example 1, except that the silicon nitride was deposited to a thickness of 20 nm.

[Example 4]

Instead of 0.5 wt.% 4-aminopyridine (4-AP) coating solution, 1 wt.% 4-aminopyridine coating solution was used to coat at 200 nm, and silicon nitride was deposited to a thickness of 20 nm, except for the case Then, an organic-inorganic multi-layer thin film encapsulation was prepared in the same manner as in Example 1.

[Example 5]

Instead of 0.5 wt.% of 4-aminopyridine (4-AP) coating solution, 2 wt.% of 4-aminopyridine coating solution was used to coat at 350 nm, except that silicon nitride was deposited with a thickness of 20 nm Then, an organic-inorganic multi-layer thin film encapsulation was prepared in the same manner as in Example 1.

[Example 6]

Instead of 0.5 wt.% of 4-aminopyridine (4-AP) coating solution, 2 wt.% of 2,2-Bipyridyl coating solution was used to coat at 350 nm, and silicon nitride was deposited to a thickness of 20 nm. An organic-inorganic multi-layer thin film encapsulation was prepared in the same manner as in Example 1, except that.

Experimental Example 3: Mechanical stability test of organic-inorganic multi-layer thin film encapsulation-3

For the organic-inorganic multi-layer thin film encapsulations prepared in Examples 3 to 6 and Comparative Example 2, the mechanical stability against folding deformation was compared. The folding deformation test was tested in the same manner as in Experimental Example 2.

organic thin film Bending radius (mm) number of repeated bends 1.5mm 2mm Episode 20 100 times Comparative Example 2 F F F F Example 3 F O F F Example 4 F O F F Example 5 O O O O Example 6 O O O O

As shown in Table 1 above, in the case of Example 3 coated using a composition of 0.5 wt.%, when bending once with a bending radius of 2 mm, there was no cracking and stable, but bending 20 times and 100 times It was found that cracks occurred when the number of times was increased. At this bending radius, it was confirmed that the plasma vapor-polymerized organic polymer thin film, Comparative Example 2, always cracked, indicating that the mechanical stability was inferior to that of the organic monomolecular thin film. In addition, even in the case of Example 4 in which the concentration of 4-AP was increased to 1 wt.%, it was found to be stable to one bending at a bending radius of 2 mm, but cracks were confirmed when the number of bendings was increased.

However, in the case of Example 5, in which the concentration of 4-AP was increased to 2 wt.%, not only at a bending radius of 2 mm, but also at a bending radius of 1.5 mm smaller than this, and even when the number of bending was increased to 100 or more It was confirmed that it was always mechanically stable without occurrence of cracks.

In addition, the improvement of these mechanical properties is not limited to 4-AP organic monomolecular materials. In the case of Example 6, which was coated with a composition of 2 wt.% using a 2,2-bipyridyl organic monomolecular material capable of thin film deposition in the same process, similar to the 4-AP organic monomolecular material, mechanical stability against bending deformation showed improvement.

[Example 7]

Using a 50 micron thick polyimide (PI) film as a substrate, 0.5 wt.% of a 4-aminopyridine (4-AP) coating solution (using isopropyl alcohol as a solvent) was bar-coated on the top. After drying, a semi-transparent monomolecular organic thin film was formed. This film was heat-treated at a temperature of 80°C to form a transparent organic monomolecular thin film layer with a thickness of 50 nm.

Thereafter, a HMDSO (hexamethyl disiloxane) plasma polymer layer was vapor-polymerized on the organic monomolecular thin film layer. For gas phase polymerization of the HMDSO plasma polymer layer, HMDSO (hexamethyl disiloxane) as an organic monomer was used to supply a raw material using an argon (Ar) transport gas into a plasma of 50 W, and raw material radicals generated in the plasma A polymer was formed by radical polymerization on the surface of the substrate. The plasma polymer formed was transparent and was deposited at a rate of about 50 nm per minute. After the plasma polymer deposition was finished, an organic monomolecular thin film layer was again formed on the plasma polymer layer in the same manner.

Thereafter, a silicon nitride (Si ₃ N ₄ ) thin film is deposited on the organic monomolecular thin film layer to a thickness of 100 nm through plasma vapor polymerization to complete an organic-inorganic layer of one cycle. The organic-inorganic multilayer thin film could be obtained by repeating the organic-inorganic deposition as many times as desired.

As shown in FIG. 12 , the organic-inorganic multilayer encapsulation thin film structure has an advantage in that a very thin layer of organic monomolecular material improves adhesion at the interface, thereby increasing the mechanical stability of the encapsulating thin film when bending deformation occurs. Since the presence or absence of an organic monolayer can increase mechanical stability while hardly affecting the moisture permeation prevention properties, a foldable organic light emitting diode that requires extreme mechanical stability is the structure of a rollable organic light emitting diode encapsulation thin film. very suitable

In the above, although the present invention has been described with reference to limited examples and drawings, the present invention is not limited thereto, and it is described below with the technical idea of the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims.

Claims (14)

An organic thin film formed on a substrate and comprising a monomolecular compound, and
A multilayer encapsulation thin film comprising a; an inorganic thin film formed on the organic thin film and comprising at least one of an oxide and a nitride.
The method of claim 1,
The monomolecular compound is a pyridine-based organic monomolecular compound, a multilayer encapsulation thin film.
The method of claim 1,
The monomolecular compound is at least one of the compounds represented by the following Chemical Formulas 1 to 4, Multilayer encapsulation thin film.
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

(R1 and R2 are each independently hydrogen or a linear or branched C1-10 alkyl group)
The method of claim 1,
The inorganic thin film and the organic thin film cross each other and are stacked in a plurality of layers, the multilayer encapsulation thin film.
The method of claim 1,
wherein any one of the oxides and nitrides is selected from the group consisting of aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, silicon nitride, silicon carbide, silicon nitride, silicon carbonate, and combinations thereof, Multi-layer encapsulation thin film.
The method of claim 1,
A multi-layer encapsulation thin film of which a polymer thin film is additionally formed on one surface on which an inorganic thin film is not formed among both surfaces of the organic thin film.
7. The method of claim 6,
Wherein the polymer comprises one selected from the group consisting of plasma polymers, acrylic polymers, and combinations thereof.
The method of claim 1,
The single layer of the inorganic thin film will have a thickness of 0.1 nm to 20 nm, a multilayer encapsulation thin film.
The method of claim 1,
The single layer of the organic thin film will have a thickness of 20 nm to 2 ㎛, a multi-layer encapsulation thin film.
According to claim 1,
The multilayer encapsulation thin film is to be used in one or more devices selected from the group consisting of an organic light emitting diode display, an organic solar cell, a perovskite solar cell, a touch screen and a secondary battery, the multilayer encapsulation thin film.
(a) forming an organic thin film including a monomolecular compound on a substrate; and
(b) forming an inorganic thin film including at least one of an oxide and a nitride on the organic thin film;
A method of manufacturing a multi-layer encapsulation thin film comprising a.
12. The method of claim 11,
Wherein the step (a) is performed by spin coating, bar coating, slot die coating, or inkjet printing.
13. The method of claim 12,
The step (a) is a method for producing a multi-layer encapsulation thin film that is performed using a coating solution for forming an organic thin film containing the monomolecular compound in an amount of 0.1 to 3.0 wt%.
12. The method of claim 11,
The step (b) is a method of manufacturing a multilayer encapsulation thin film that is performed by a chemical vapor deposition method or an atomic layer deposition method.

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