CN111438860A - Mould for manufacturing organic light-emitting diode - Google Patents

Abstract

The invention relates to a die for manufacturing an organic light-emitting diode. The mold has a flat surface and a plurality of convex portions on a main surface, wherein the average pitch of the plurality of convex portions is 50nm to 5 [ mu ] m, the average aspect ratio of the plurality of convex portions is 0.01 to 1, 80% or more of the plurality of convex portions have a specific curved surface, and when an arbitrary point of the specific curved surface is set as a 1 st point and a point 1/10 which is deviated from the 1 st point by only the average pitch is set as a 2 nd point, an inclination angle of a 2 nd tangential plane contacting the 2 nd point with respect to a 1 st tangential plane contacting the 1 st point is within 60 degrees.

Description

Mould for manufacturing organic light-emitting diode

Related information of divisional application

The scheme is a divisional application. The parent application of this division is an invention patent application having an application date of 2016, 8, 17, and an application number of 201680051921.8, entitled "mold, method for manufacturing organic light emitting diode, and organic light emitting diode".

Technical Field

The invention relates to a mold, a manufacturing method of an organic light emitting diode and the organic light emitting diode. This application claims priority based on Japanese patent application No. 2015-178324, which was filed in Japan on 9/10/2015, and the contents of which are incorporated herein by reference.

Background

An organic light emitting diode is a light emitting element utilizing organic electroluminescence. An organic light emitting diode generally has a structure in which an anode and a cathode are provided on both surfaces of an organic semiconductor layer including a light emitting layer containing an organic light emitting material. The organic semiconductor layer has an electron injection layer, an electron transport layer, a hole injection layer, and the like as necessary, in addition to the light emitting layer. The organic light emitting diode has advantages of less viewing angle dependency, less power consumption, capability of forming an extremely thin organic light emitting diode, and the like.

On the other hand, the light extraction efficiency of the organic light emitting diode is not necessarily sufficient. The light extraction efficiency is a ratio of light energy emitted into the atmosphere from a light extraction surface (for example, a substrate surface in the case of a bottom emission type) to light energy generated in the light-emitting layer.

One of the main causes of the decrease in light extraction efficiency is the influence of surface plasmon. In the organic light emitting diode, the distance between the light emitting layer and the cathode, which is a metal, is short. Therefore, a part of the near-field light generated in the light-emitting layer is converted into surface plasmon on the surface of the cathode and disappears, and the light extraction efficiency of the organic light-emitting diode is lowered. Light extraction efficiency is an index that affects the luminance of displays, illumination, and the like provided with organic light emitting diodes, and various methods for improvement have been studied.

In order to improve the light extraction efficiency, patent document 1 discloses a structure in which a two-dimensional lattice structure of convex portions or concave portions is provided on the surface of a metal layer (cathode). The two-dimensional lattice structure of the metal layer surface converts the energy of surface plasmon into light, and takes out the converted light to the outside of the element. In patent document 1, a two-dimensional lattice structure of a metal layer surface can be obtained by reflecting a two-dimensional lattice structure provided on a base. Specifically, by laminating the 1 st electrode, the organic semiconductor layer including the light-emitting layer, and the 2 nd electrode on the substrate provided with the two-dimensional lattice structure, the two-dimensional lattice structure equivalent to that of the substrate is reflected on the surface of the 2 nd electrode on the light-emitting layer side.

Generally, the organic semiconductor layer and the 1 st and 2 nd electrodes are formed by a vacuum film forming method using sputtering or vapor deposition. In contrast, patent document 2 discloses that an organic semiconductor layer in an organic thin-film solar cell is formed by an application method such as a spin coating method, an ink-jet method, or a slit coating method. The organic thin-film solar cell has the same configuration as the organic light-emitting diode, and the organic semiconductor layer of the organic light-emitting diode can also be formed by a coating method.

[ background Art document ]

[ patent document ]

[ patent document 1] International publication No. 2012/60404

[ patent document 2] International publication No. 2014/208713

Disclosure of Invention

[ problems to be solved by the invention ]

However, for example, a method of processing a two-dimensional lattice structure in a substrate, such as the method described in patent document 1, has a problem that the processing cost of the substrate becomes high. In addition, there are problems as follows: when a substrate is processed to produce a two-dimensional lattice structure, the organic semiconductor layer formed on the substrate cannot be formed by the coating method described in patent document 2. The coating method uses a liquid-phase material at the time of coating, and thus easily fills the uneven shape (two-dimensional lattice structure). Therefore, the reflectivity of the uneven shape on the surface of the substrate is lower on the surface of the metal layer than in the vacuum film formation method. If the shape is less reflective, it is difficult to provide the desired shape required for extracting surface plasmon on the 2 nd electrode.

On the other hand, forming an organic semiconductor layer by coating or the like has advantages such as reduction in manufacturing cost accompanying simplification of manufacturing equipment, improvement in yield due to shortening of time for evacuation or the like, and the like. Therefore, there is a strong demand for forming an organic semiconductor layer by a coating method.

Therefore, the present inventors have made a method of manufacturing an organic light emitting diode by sequentially performing a coating step, a stamper step for manufacturing an uneven shape, and a vacuum film forming step. In this method, first, in the coating step, at least a part of the organic semiconductor layer is formed by a coating method. Next, a mold having a shape opposite to the desired unevenness is pressed against the outermost surface of the coating layer obtained in the coating step, and the desired unevenness is formed on the outermost layer of the coating layer. Finally, the remaining layer not formed in the coating step is formed by a vacuum film-forming method. This method has an advantage that the processing cost of the substrate is reduced because the substrate does not need to be processed, an advantage that the production yield is increased because the number of layers to be formed by vacuum film formation can be reduced, and an advantage that a desired uneven shape can be reflected on the 2 nd electrode because the vacuum film formation method is used after the uneven shape is formed.

However, as a result of further studies by the inventors, the following problems were found: the organic light emitting diode manufactured by combining the coating step, the die pressing step, and the vacuum film forming step cannot obtain a sufficient light emission intensity compared to the assumed light emission intensity.

The present invention has been accomplished in view of the above circumstances. The present invention addresses the problem of providing a mold for producing an organic light-emitting diode that exhibits sufficient light-emitting characteristics even when a method is used that combines a coating step, a pressing step, and a vacuum film-forming step.

[ means for solving problems ]

The present inventors have made intensive studies to solve the above problems.

As a result, it was found that the organic light emitting diode can exhibit sufficient light emitting characteristics even when the organic light emitting diode is manufactured by combining the coating step, the press molding step, and the vacuum film forming step by forming the mold into a specific shape.

The present invention includes the following inventions.

(1) A mold according to one aspect of the present invention has a flat surface and a plurality of projections on a main surface, wherein an average pitch of the plurality of projections is 50nm to 5 [ mu ] m, an average aspect ratio of the plurality of projections is 0.01 to 1, 80% or more of the plurality of projections have a specific curved surface, and when an arbitrary point of the specific curved surface is a 1 st point and a point 1/10 which is deviated from the 1 st point by only the average pitch is a 2 nd point, an inclination angle of a 2 nd tangential plane contacting the 2 nd point with respect to a 1 st tangential plane contacting the 1 st point is 60 DEG or less.

(2) In the mold according to the above (1), an area ratio of the flat surface in the main surface may be 5 to 50%.

(3) In the mold according to any one of (1) and (2), the flat surface and the convex portion having the specific curved surface may be connected so as to satisfy the condition of the specific curved surface.

(4) In the mold according to any one of (1) to (3), the specific curved surface constituting the plurality of convex portions may have at least 1 or more inflected portions, and a closest distance from a 1 st inflected portion closest to the flat surface among the inflected portions may be 1/10 or more of an average pitch of the plurality of convex portions.

(5) In the mold according to any one of (1) to (4), the plurality of protrusions may form a honeycomb lattice, and the tops of the plurality of protrusions may be located at the vertices of hexagons constituting the honeycomb lattice in a plan view in a direction perpendicular to the flat surface.

(6) In the mold according to item (5), the convex portions located at the vertices of the hexagon may have ridge portions between the convex portions located at the vertices adjacent to the hexagon, and at least a part of the ridge portions may be present on the flat surface side of the convex portions connecting the ridge portions.

(7) In the mold according to item (6), the height of the portion of the ridge portion closest to the flat surface from the flat surface may be 50% to 90% of the height of the convex portion connecting the ridge portions from the flat surface.

(8) A method for manufacturing an organic light-emitting diode according to an aspect of the present invention includes a coating step and a subsequent vacuum film-forming step, wherein an organic semiconductor layer including a light-emitting layer and a 2 nd electrode are formed on a surface of an electrode-carrying substrate having a transparent 1 st electrode on a substrate, on which the 1 st electrode is formed, and a press-molding step is provided between the coating step and the vacuum film-forming step, wherein a mold according to any one of the above (1) to (7) is pressed against an outermost surface of a coating layer formed in the coating step, and a shape of a principal surface of the mold is inverted on the outermost surface of the coating layer.

(9) An organic light emitting diode according to an aspect of the present invention includes a substrate, a transparent 1 st electrode, an organic semiconductor layer including a light emitting layer, and a 2 nd electrode in this order, the surface of the 2 nd electrode on the organic semiconductor layer side has a flat surface and a plurality of projections projecting from the flat surface toward the base, the average pitch of the plurality of projections is 50nm to 5 μm, the average aspect ratio of the plurality of projections is 0.01 to 1, wherein 80% or more of the plurality of convex portions have a specific curved surface, and the specific curved surface is defined as a 1 st point at an arbitrary point of the specific curved surface, and a point 1/10 which is deviated from the 1 st point toward the center point of the convex portion by the average pitch is set as the 2 nd point, the 2 nd tangential plane connected with the 2 nd point is within 60 degrees of the inclination angle of the 1 st tangential plane connected with the 1 st point.

(10) In the organic light-emitting diode according to the above (9), an area ratio of the flat surface in a surface of the 2 nd electrode on the organic semiconductor layer side may be 5 to 50%.

[ Effect of the invention ]

The mold according to an aspect of the present invention can exhibit sufficient light emission characteristics even when an organic light emitting diode is manufactured by combining a coating step, a press molding step, and a vacuum film forming step.

An organic light emitting diode according to an aspect of the present invention has desired light emitting characteristics and can efficiently extract generated surface plasmon.

The method for manufacturing an organic light emitting diode according to an aspect of the present invention can manufacture an organic light emitting diode capable of efficiently extracting surface plasmon at low cost.

Drawings

Fig. 1 is a perspective view of a mold according to an aspect of the present invention.

Fig. 2 is a schematic sectional view of a mold according to an aspect of the present invention, cut along a plane passing through a center point of a convex portion and a center point of a flat surface formed on the mold.

Fig. 3 is a schematic top view of a mold according to an aspect of the invention.

Fig. 4 is a view of a mold according to an aspect of the present invention, cut along a plane passing through the center point of the convex portion formed in the mold, and is an enlarged cross-sectional view of one convex portion.

Fig. 5 is a schematic sectional view of a mold according to an aspect of the present invention pressed against a surface of a laminate formed by coating.

Fig. 6 is a schematic sectional view when a mold having no specific curved surface is pressed against the surface of a laminate formed by coating.

Fig. 7 is a schematic sectional view when a mold according to another aspect of the present invention is pressed against the surface of a laminate formed by coating.

Fig. 8 is a schematic cross-sectional view in the case of forming a layer on the transfer shown in fig. 7 by a vacuum film-forming method.

Fig. 9 is a schematic sectional view cut along the adjacent convex portions of the mold according to an aspect of the present invention.

Fig. 10 is a perspective view of a mold according to another aspect of the present invention.

Fig. 11 is a perspective view of a mold according to another aspect of the present invention.

Fig. 12 is a schematic cross-sectional view of an organic light emitting diode device according to an aspect of the present invention.

Fig. 13 is a view of a main part of the mold according to the present embodiment, viewed from a direction perpendicular to the flat surface.

Fig. 14(a) to (e) are schematic diagrams showing a method for manufacturing a mold.

Fig. 15(a) to (b) are views schematically showing a dropping step and a single particle film forming step in the process of manufacturing a mold.

Detailed Description

Hereinafter, each configuration will be described with reference to the drawings. In the drawings used in the following description, a portion to be a feature may be enlarged for convenience of understanding the feature, and the dimensional ratio of each component is not necessarily the same as the actual one. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to such materials and dimensions, and can be implemented by appropriately changing the materials and dimensions within the scope not changing the gist thereof.

Mould

Fig. 1 is a perspective view schematically showing a mold according to an aspect of the present invention. In a mold 10 according to an aspect of the present invention, a plurality of flat surfaces 1a to 1n and a plurality of convex portions 2a to 2n are provided on a main surface 10A. The plurality of flat surfaces 1a to 1n are arranged in a region surrounded by the most adjacent convex portion among the plurality of convex portions 2a to 2 n. In fig. 1, if the center points of the most adjacent convex portions are connected, a planar surface is arranged in the central region of the hexagonal shape in a plan view. The plurality of projections 2a to 2n are connected at a part thereof.

Fig. 2 is a cross-sectional view taken along a plane connecting a center point of a convex portion and a center point of a flat surface of a mold according to an embodiment of the present invention. The cross section shown in fig. 2 is obtained as an AFM (Atomic Force microscope) image or a microscope image obtained by observing a cut sample with an electron microscope.

The cross section of the AFM image is obtained by taking the cross section information of a cross section passing through the center point 2An of the projection 2n and the center point 1An of the flat surface 1n from An AFM image obtained by photographing a square region 30 to 40 times the average pitch P of the projections 2a to 2 n.

The cross section is obtained by cutting a cross section passing through the center point 2An of the convex portion 2n with FIB (Focused Ion Beam) or the like of the mold 10. The microscopic image of the cross section is obtained by observing the cross section with an optical microscope. When there is a possibility that the cross-sectional shape of the mold is deformed by cutting, it is preferable to cover the surface of the convex portion with a material that can withstand cutting, or to embed the convex portion with a resin or the like and cut it.

In the case where both the cross section measured by AFM imaging and the cross section observed by microscopic imaging are available, the cross section measured by AFM imaging is preferred. This is because a measured surface of a specific cut surface can be easily obtained in a cross section measured by AFM imaging, and the cross sectional shape can be easily confirmed. When the convex portions 2a to 2n are regularly arranged, it is preferable that the cutting direction for obtaining the cross section is a direction along the arrangement direction of the convex portions 2a to 2 n.

The center points 2Aa to 2An of the projections 2a to 2n are set based on the measurement result of AFM. Specifically, a plurality of contour lines are drawn parallel to the reference plane for each of the convex portions 2a to 2n at intervals of 20nm, and the center of gravity (a point determined by the x coordinate and the y coordinate) of each contour line is determined. The average position of each of these gravity points (a bit value determined by the average value of each x coordinate and the average value of each y coordinate) is set as the center points 2Aa to 2An of the respective convex portions 2a to 2 n. The reference surface is a measurement surface obtained by correcting the inclination from image information having the inclination measured by AFM.

The center points 1Aa to 1An of the flat surfaces 1a to 1n are set based on the measurement result of the AFM. Specifically, an inscribed circle is provided on each of the plurality of flat surfaces 1a to 1n, which is inscribed in a plan view. The center of the inscribed circle is set to center points 1Aa to 1An of the flat surfaces 1a to 1 n.

The convex portions 2a to 2n are portions protruding from the flat surfaces 1a to 1 n. The flat surfaces 1a to 1n are regions having a slope within ± 5 ° with respect to a surface parallel to the reference plane of the AFM and passing through the center of gravity point of the region connecting the most adjacent projections.

The projections 2a to 2n are two-dimensionally arranged on one surface of the mold 10. The "two-dimensional arrangement" refers to a state in which a plurality of projections are arranged on the same plane. The two-dimensional structure in which the plurality of projections are arranged two-dimensionally may be periodic or aperiodic.

The mold 10 can be preferably used when a concave-convex shape is formed in an electrode containing metal of an organic light emitting diode. The concave-convex shape contributes to extraction of surface plasma generated on the electrode surface. When the organic light emitting diode manufactured using the mold 10 emits light in a narrow band, the two-dimensional arrangement of the plurality of projections is preferably periodic.

Preferred specific examples of the periodic two-dimensional structure include those having 2 directions of the straight lines connecting adjacent convex portions and a crossing angle of 90 ° (tetragonal lattice), those having 3 directions of the straight lines connecting adjacent convex portions and a crossing angle of 120 ° (hexagonal lattice, honeycomb lattice), and the like.

First, a line segment L1 having a length equal to the average pitch P is drawn from 1 center point 2Aa toward the adjacent center point 2Ab, then, a line segment L2 having a length equal to the average pitch P is drawn from the center point 2Aa toward the line segment L1, and if the center point adjacent to the center point 2Aa is within 15% of the average pitch P from the end point of each line segment L1 opposite to the center point 2Aa, the intersection angle is 120 °, and the positional relationship of the intersection angle of 90 ° is defined by replacing the description of "120 °" with 90 ° ".

If the convex portions 2a to 2n are periodically arranged so as to satisfy the above-described relationship, the period of arrangement of the convex portions 2a to 2n resonates with the period of the surface plasmon, and the extraction efficiency of light of a specific frequency band improves. In addition, when the convex portions 2a to 2n are arranged in a honeycomb lattice pattern, the strength of the mold 10 is increased, and the durability when repeatedly used is particularly improved. In other words, the honeycomb lattice pattern can be a relationship in which the tops of the plurality of convex portions 2a to 2n are located at the vertices of a hexagon in a plan view viewed from a direction perpendicular to the flat surfaces 1a to 1 n.

In contrast, when the organic light emitting diode manufactured using the mold 10 emits light in a wide frequency band or light in a plurality of different frequency bands, the two-dimensional arrangement of the plurality of convex portions 2a to 2n is preferably aperiodic. The "aperiodic arrangement" refers to a state in which the intervals between the centers of the projections 2a to 2n and the arrangement direction are not fixed.

Here, the average pitch P is a distance between adjacent convex portions, and can be specifically obtained as follows. Here, the adjacent convex portions refer to the case of the convex portions adjacent to each other without interposing a flat surface therebetween in fig. 1.

First, AFM images are obtained for a region of a square having a side 30 to 40 times the average pitch P in randomly selected regions on the main surface 10A of the mold 10. for example, when the design pitch is about 300nm, an image is obtained for a region of 9 μm × 9 μm to 12 μm × 12 μm, the distances between adjacent projections in the obtained region are measured, and the measured distances between adjacent projections are averaged to obtain the average pitch P in the region₁. This process is similarly performed for the randomly selected regions having the same area at 25 or more points in total, and the average pitch P in each region is obtained₁～P₂₅. Thus obtained average pitch P in the region of 25 or more₁～P₂₅Is the average pitch P. In this case, the regions are preferably selected at least 1mm apart from each other, more preferably 5mm to 1cm apart.

The average pitch P of the projections 2a to 2n is 50nm to 5 μm, preferably 50nm to 500 nm. If the average pitch of the projections 2a to 2n is within this range, surface plasmon can be efficiently extracted from the metal electrode in the organic light emitting diode manufactured using the mold 10.

The projections 2a to 2n are formed with Ca to Cn in each region in a periodic structure. The respective regions Ca to Cn may have a non-periodic structure as a whole in a macroscopic view. The regions Ca to Cn shown in fig. 3 are arranged in a positional relationship in which the intersection angle of the center point of each convex portion with respect to the center point of the flat surface is 120 °. In fig. 3, for convenience, the position of the center point of each of the convex portions 2a to 2n is represented by a circle u having the center point as its center.

The most frequent area Q (the most frequent value of the area of each region) of each region Ca to Cn is preferably in the following range.

When the average pitch P is less than 500nm, the area Q of the most frequent region in the AFM image measuring range of 10 μm × 10 μm is preferably 0.026 μm²～6.5μm²。

When the average pitch P is 500nm or more and less than 1 μm, the maximum frequency area Q in the AFM image measurement range of 10 μm × 10 μm is preferably 0.65 μm²～26μm²。

When the average pitch P is 1 μm or more, the maximum frequency area Q in the AFM image measurement range of 50 μm × 50 μm is preferably 2.6 μm²～650μm²。

If the maximum frequency area Q is within the preferred range, the periodic structure becomes a polycrystal having a macroscopically random lattice orientation, and therefore, when surface plasmon is converted into propagating light on the metal surface and radiated, it is possible to suppress the emission angle of the radiated light in the planar direction from becoming random and to make the emitted light extracted from the element have anisotropy.

As shown in FIG. 3, the areas, shapes and lattice orientations of the regions Ca to Cn are random.

Specifically, the degree of irregularity of the area is preferably satisfied as follows.

First, an ellipse having the largest area circumscribed by the boundary line of one region is drawn, and this ellipse is expressed by the following formula (1).

X²/a²+Y²/b²＝1···(1)

When the average pitch P is less than 500nm, the standard deviation of π ab in the measurement range of 10 μm × 10 μm AFM image is preferably 0.08 μm²The above.

When the average pitch P is 500nm or more and less than 1 μm, the standard deviation of π ab in the AFM image measurement range of 10 μm × 10 μm is preferably 1.95 μm²The above.

When the average pitch P is 1 μm or more, the standard deviation of π ab in the AFM image measurement range of 50 μm × 50 μm is preferably 8.58 μm²The above.

If the standard deviation of pi ab is within a preferable range, the effect of averaging the emission angles in the planar direction of surface plasmons emitted from the metal surface to the outside of the element at a specific angle is excellent, and anisotropy of emitted light can be suppressed.

Specifically, the degree of irregularity in the shape of each of the regions Ca to Cn is preferably 0.1 or more in the ratio of a to b and the standard deviation of a/b in the formula (1). The randomness of the lattice orientation of each of the regions Ca to Cn is specifically preferably satisfied with the following conditions.

First, a straight line K0 connecting the center points of arbitrary adjacent 2 projections in an arbitrary region (I) is drawn. Next, 1 region (II) adjacent to this region (I) was selected, and 3 straight lines K1 to K3 connecting any convex portion in this region (II) and the center points of 3 convex portions adjacent to this convex portion were drawn. When the straight lines K1 to K3 all have an angle different by 3 degrees or more from 6 straight lines rotated by 60 ° each time with reference to the straight line K0, it is defined that the lattice orientations of the region (I) and the region (II) are different.

In the region adjacent to the region (I), the number of regions having lattice orientations different from that of the region (I) is preferably 2 or more, preferably 3 or more, and more preferably 5 or more.

In this case, the projections are polycrystalline structures whose lattice orientations are uniform in the respective regions Ca to Cn but are not uniform macroscopically. The randomness of the macroscopic lattice orientation can be evaluated by the ratio of the maximum to minimum of the FFT (Fast Fourier Transform) fundamental. The ratio of the maximum value to the minimum value of the FFT fundamental wave is obtained by obtaining an AFM image, obtaining a 2-dimensional fourier transform image thereof, drawing a circle of wave numbers of the fundamental wave from the origin, selecting a point having the maximum amplitude and a point having the minimum amplitude on the circle, and obtaining the ratio of the amplitudes.

It is considered that when the ratio of the maximum value and the minimum value of the FFT fundamental wave is large, the lattice orientations of the projections match, and the crystallinity is high when the projections are regarded as 2-dimensional crystals. On the contrary, it is considered that when the ratio of the maximum value and the minimum value of the FFT fundamental wave is small, the lattice orientations of the projections do not match, and the projections are in a polycrystalline structure when they are regarded as 2-dimensional crystals.

The average aspect ratio of the plurality of projections 2a to 2n is 0.01 to 1, preferably 0.05 to 0.5. The average aspect ratio is an average height H of the convex portions 2a to 2n relative to an average width D of the convex portions 2a to 2 n. If the average aspect ratio of the mold 10 is 0.01 or less, the effect of extracting surface plasmon as radiation light cannot be sufficiently obtained in the organic light emitting diode manufactured using the mold 10. On the other hand, if the average aspect ratio is 1 or more, it is difficult to form the convex portion with a specific curved surface described below. In addition, it is difficult to perform transfer of the shape using the mold 10 when manufacturing the organic light emitting diode.

The average aspect ratio of the projections 2a to 2n was measured by AFM.

First, the main surface 10A of the mold 10 is randomly selected to have a thickness of 25 μm²An AFM image was obtained in the region of 1 position (5 μm × 5 μm), then, a line was drawn in the diagonal direction of the obtained AFM image, and the height and width of each of the plurality of projections 2a to 2n intersecting the line were measured, the height of the projection was the distance from the flat surfaces 1a to 1n to the top of the projection, and the width of the projection was the diameter of an inscribed circle having the center point of the projection as the center in a plan view, then, the average values of the height and width of the projection in the region were obtained, the same processing was performed for the total 25 regions randomly selected, then, the average values of the height and width of the projection in each of the 25 regions obtained were further averaged to obtain an average height and an average width, and then, the average height was divided by the average width to obtain an average aspect ratio.

At least 80% of the projections 2a to 2n are formed of a specific curved surface. The ratio of the convex portion having a specific curved surface among the plurality of convex portions is more preferably 90% or more, and still more preferably 95% or more. The specific curved surface is defined in the following manner.

First, An arbitrary 1 point is selected from the curved surface 2B constituting the convex portion 2n as the 1 st point p1., a tangent plane to the 1 st point p1 is defined as the 1 st tangent plane t1, a point 1/10 which is deviated from the 1 st point p1 toward the center point 2An of the convex portion 2n by only the average pitch is defined as the 2 nd point p2., the point 1/10 which is deviated only by the average pitch is defined as a distance L which is moved from the 1 st point p1 in parallel to the flat surface 1 toward the center point 2An, a tangent plane to the 2 nd point p2 is defined as the 2 nd tangent plane t2, and in this case, An inclination angle of the 2 nd tangent plane t2 to the 1 st tangent plane t1 is defined as θ.

Even in any portion of the curved surface 2B of the convex portion 2n, when the relationship that the inclination angle θ of the 2 nd tangential plane t2 with respect to the 1 st tangential plane t1 is within 60 ° is satisfied, the convex portion 2n is considered to be a specific curved surface. The inclination angle θ is preferably within 45 °, and more preferably within 30 °.

Fig. 5 is a schematic sectional view of a mold according to an aspect of the present invention pressed against a surface of a laminate formed by coating. The multilayer body 20 includes a 1 st layer 21, a 2 nd layer 22, and a 3 rd layer 23. If the mold 10 is pressed against the 3 rd layer 23 of the laminate 20, the convex portions 2a to 2n of the mold 10 are initially pressed against the laminate 20. Therefore, force F1 is applied to each layer constituting laminate 20 from the top portions of projections 2a to 2n toward the outer peripheral portion. The material constituting each layer is also supplied to the space between the plurality of projections 2a to 2n of the mold 10 by the force F1. As a result, the respective layers constituting the laminate 20 are deformed into a shape corresponding to the mold 10.

The force F1 applied to each layer of the laminate 20 does not concentrate in stress and spreads from the top portions of the pressed convex portions 2a to 2n toward the outer peripheral portion. This is because the convex portions 2a to 2n of the mold 10 have a gentle shape including a specific curved surface. If the force F1 is not stress concentrated, each of the 1 st, 2 nd, and 3 rd layers 21, 22, and 23 is uniformly diffused in the in-plane direction. Therefore, the thickness of each can be prevented from becoming extremely thin.

In general, the material of each layer is sufficiently supplied along the specific curved surface 2B to the boundary 3 between the plurality of convex portions 2a to 2n and the flat surface of the mold 10, which is a portion where voids are likely to occur. That is, the generation of voids in the boundary portion 3 can also be prevented.

In contrast, fig. 6 is a schematic sectional view when a mold having no specific curved surface is pressed against the surface of the laminated layer formed by coating. The convex portion 152n of the mold 15 shown in fig. 6 has a corner portion 155 whose shape is drastically changed. The corner 155 is such that the 2-point tangent plane across the corner 155 does not satisfy the relationship of a specific curved surface. Therefore, the force F2 applied to each layer constituting the multilayer body 20 is not uniformly dispersed along the shape of the convex portion 152n, but the stress is concentrated near the corner portion 155. As a result, the 1 st layer 21, the 2 nd layer 22, and the 3 rd layer 23 cannot be uniformly diffused in the in-plane direction. Therefore, the layers may be cut near the corner 155, or the layer thickness may be extremely thin.

In addition, a sufficient amount of material cannot be supplied to the boundary 153 between the convex portion 152n and the flat surface, and voids are likely to be generated.

The layer constituting the laminate 20 corresponds to any one of the layers constituting the organic light emitting diode. If a part of each layer constituting the organic light emitting diode is cut, the organic light emitting diode does not emit light or does not exhibit sufficient light emitting characteristics in the cut part. That is, by using the mold 10 of the present embodiment, it is possible to avoid the problem that the organic light emitting diode does not emit light or does not exhibit sufficient light emitting characteristics.

Returning to fig. 5, in order to avoid a gap between the mold 10 and the multilayer body 20, the boundary portion 3 is preferably gentle. That is, in any of the connecting portions between the convex portions 2a to 2n and the flat surface, it is preferable that the inclination angle of the tangent plane at a point 1/10 which is deviated from the average pitch from any 1 point with respect to the tangent plane at any 1 point is within 60 °.

Fig. 7 is a schematic sectional view when a mold according to another aspect of the present invention is pressed against the surface of a laminate formed by coating. The mold 30 shown in fig. 7 has a plurality of convex portions and a flat surface 31, and boundary portions 33 between the plurality of convex portions and the flat surface 31 are connected by a specific curved surface. That is, in the connecting portion between the flat surface 31 and the convex portion 32n, a relationship is satisfied in which the inclination angle of the tangent plane at the point 1/10 deviated from the average pitch from the arbitrary 1 point with respect to the tangent plane at the arbitrary 1 point is within 60 °. That is, the boundary portion 33 becomes gentle.

If the mold 30 shown in fig. 7 is pressed against the laminate 20, neither the force F1 applied from the top of the convex portion 32n toward the outer peripheral portion nor the force F3 applied to the vicinity of the boundary portion 33 is stress-concentrated. Therefore, the material constituting each layer smoothly diffuses along the main surface of the mold 30. As a result, it is possible to avoid the occurrence of voids between the mold 10 and the layered product 20, and to make the thicknesses of the layers of the layered product 20 uniform in the in-plane direction.

In the mold 30, the boundary 33 between the flat surface 31 and the plurality of convex portions is gentle, and the mold can have at least 1 or more reverse curved portions p by satisfying the specific curved portions constituting the convex portions at the same time_inAnd the reverse curvature p_inThe 1 st reverse curvature p1 on the side closest to the flat surface 31_inThe curved surface connected to the flat surface 31 is implemented to be convex downward. Reverse curve p_inThe aggregate of the points of inflection in the cross section of the convex portion is a portion that changes from an upwardly convex curved surface to a downwardly convex curved surface or a portion that changes from a downwardly convex curved surface to an upwardly convex curved surface. If looking down on the inflection part p_inThen, the linear shape is formed along the convex portion 32 n.

From 1 st inflection point p1_inThe closest distance to the flat surface 31 is preferably 1/10 or more, more preferably 1/5 or more, of the average pitch P of the plurality of projections. The closest distance is the 1 st inflection point p1 in the plan view of the convex portion 32n_1nAnd the narrowest part of the width between the flat surfaces 31. If p1 is reversed from 1 st curve_inWhen the closest distance to the flat surface 31 is equal to or greater than 1/10, which is the average pitch P of the plurality of convex portions, the inclination of the boundary portion 33 can be made more gradual.

Further, if the boundary 33 of the mold 30 is made gentle, the layer formed by the vacuum film forming method is more reflective of the shape of the transferred object when the layer is formed by the vacuum film forming method on the transferred object manufactured by using the mold 30.

Fig. 8 is a schematic cross-sectional view in the case where a layer is formed on the transfer shown in fig. 7 by a vacuum film forming method. In the mold 30 shown in fig. 7, the boundary 33 between the flat surface 31 and the convex portion 32n is gentle. Therefore, the boundary portion 23A of the curved surface 20A formed on the outermost surface of the multilayer body 20 by using the mold 30 is also gentle. In general, the portion where the shape changes sharply often changes greatly in the dispersion of film-forming particles during vacuum film formation. On the other hand, if the shape of the curved surface 20A including the boundary portion 23A is gentle, the dispersion of the film forming particles does not change greatly, and a uniform layer can be formed. The transfer product shown in fig. 8 has a gentle main surface (outermost surface) 20A of the laminate 20. Therefore, the outer surface 26B of the layer 26 formed by vacuum deposition can sufficiently reflect the shape of the main surface 20A. Here, "sufficiently reflecting" means that the shape formed in the press molding step is not necessarily completely reflected. If the average pitch of the projections constituting the outer surface 26B of the vacuum-formed layer 26 is within ± 10% of the average pitch of the projections constituting the main surface 20A, and the average height of the projections constituting the outer surface 26B of the vacuum-formed layer 26 is within ± 10% of the average height of the projections constituting the main surface 20A, the outer surface 26B of the vacuum-formed layer 26 can be said to sufficiently reflect the shape of the main surface 20A. The method for measuring the average pitch P can be applied to the measurement of the average pitch mentioned here. In addition, the method for measuring the average height H can be applied to the measurement of the average height.

When the layer 26 formed by vacuum deposition is an electrode, the outer surface 26B does not need to have a shape that sufficiently reflects the shape of the main surface 20A. In this case, the main surface 20A is gentle, so that the thickness of the layer 26 is not reduced or cut.

Examples of a method for confirming the shape of curved surface 22B or outer surface 26B include cross-sectional observation with a Scanning Electron Microscope (SEM) or a Transmission Electron Microscope (TEM), and observation with a three-dimensional electron microscope or AFM after removing a layer covering the observed surface.

Returning to fig. 1, the area ratio of the flat surfaces 1a to 1n in the main surface 10A is preferably 5 to 50%, and more preferably 5 to 30%. If the area ratio of the flat surfaces 1a to 1n in the main surface 10A is 5% or more, the aspect ratio of the irregularities that can be used to extract the surface plasmon in the organic light emitting diode manufactured using the mold becomes small. On the other hand, if the area ratio of the flat surfaces 1a to 1n in the main surface 10A is 50% or less, the surface plasmon can be suppressed from being trapped in the flat surfaces in the organic light emitting diode manufactured using the mold.

Fig. 9 is a schematic sectional view of a mold according to an embodiment of the present invention, which is cut by connecting surfaces between centers of adjacent projections. More specifically, the cross-sectional view is taken on a plane connecting the center points of the adjacent convex portions in fig. 1. The broken line in fig. 9 is an approximate curve of the convex portions 2a to 2 n. The approximate curve can be obtained by approximating the center points 2Aa to 2An of the convex portions 2a to 2n with a normal distribution with the vertices. The boundaries between the convex portions 2a to 2n and the ridge portion 4 are approximate curves. The adjacent convex portions are connected by the ridge portion 4. The convex portions 2a to 2n are located closer to the center points 2Aa to 2An than the approximate curve, and the ridge portion 4 is located on the opposite side.

Preferably, the connection portions between the ridge portion 4 and the convex portions 2a to 2n and the connection portions between the ridge portion 4 and the flat surfaces 1a to 1n are connected so as to satisfy a condition of a specific curved surface. By connecting these connecting portions so as to satisfy the condition of a specific curved surface, the force generated when the mold 10 is pressed against the laminate can be more uniformly dispersed. That is, the layers constituting the laminate against which the mold 10 is pressed can be suppressed from being cut.

As shown in fig. 9, at least a part of the ridge portion 4 is preferably present on the flat surface 1n side of the convex portion 2n connecting the ridge portion 4. That is, it is preferable that the height H from the flat surface 1n of the portion closest to the flat surface 1n of the ridge portion 4 is lower than the height H from the flat surface 1n of the convex portion 2n connecting the ridge portion 4.

Fig. 13 is a view of a main part of the mold according to the present embodiment, viewed from a direction perpendicular to the flat surface. If the height H of the ridge portion 4 is lower than the height H of the convex portion 2n, air interposed between the mold and the object to be transferred is removed through this portion when the mold is pressed against the object to be transferred (arrow in fig. 13). That is, air can be prevented from being mixed into the transfer object, and uniform transfer can be performed.

As shown in fig. 13, when the tops of the plurality of projections 2a to 2n are located at the vertices of the hexagons constituting the honeycomb lattice (hexagonal lattice) in a plan view in a direction perpendicular to the flat surface 1n, the diffusion of the resin or the like when the mold is pressed against the transfer object becomes uniform, and the pressure can be applied uniformly to the transfer object. If the pressure can be applied uniformly, for example, even in the case where the transferred material is a thin layer, the layer can be prevented from being cut or the layer thickness can be made extremely thin.

In addition, the height H from the flat surface 1n of the portion closest to the flat surface 1n of the ridge portion 4 shown in fig. 9 is preferably 50% to 90%, and more preferably 60% to 85%, relative to the height H from the flat surface 1n of the convex portion 2n connecting the ridge portions 4. If the height h of the ridge line portion 4 is too low, the strength of the mold is reduced, and if the height h of the ridge line portion 4 is too high, the escape path of air becomes small.

The mold 10 of fig. 1 is used as an example to describe an embodiment of the present invention, but the shape of the mold is not limited to this configuration.

Fig. 10 is a perspective view of a mold according to another aspect of the present invention. The mold 40 shown in fig. 10 is different from the mold 10 and the like in that the convex portions 42a to 42n are arranged to be spaced apart from each other and include 1 flat surface 41.

For example, the structure shown in fig. 11 may be used. Fig. 11 is a perspective view of a mold according to another aspect of the present invention. As shown in fig. 11, the mold 50 has a plurality of convex portions 52a to 52n and a plurality of flat surfaces 51a to 51 n. The positional relationship between the convex portion and the flat surface is reversed between the mold 10 shown in fig. 1 and the mold 50 shown in fig. 11. That is, in the mold 50, the plurality of convex portions 52a to 52n are arranged in a region surrounded by the most adjacent flat surface among the plurality of flat surfaces 51a to 51 n. In fig. 11, if the center points of the most adjacent flat surfaces are connected, a hexagonal shape is drawn in a plan view, and a convex portion is disposed in the central region thereof. Even in the case where the positional relationship of the plurality of convex portions 52a to 52n and the flat surfaces 51a to 51n is reversed like the mold 50, the respective convex portions 52a to 52n are formed by specific curved surfaces, so that the layers constituting the laminate can be suppressed from being cut in the press molding step of pressing against the mold 50.

One aspect of the present invention is a mold having a convex portion having a specific curved surface. Therefore, the organic light emitting diode manufactured using the mold 10 does not have a portion with a small layer thickness or a portion without a layer formed, and surface plasmon can be efficiently extracted.

Method for manufacturing mold

The mold can be formed by electron beam lithography, mechanical machining, laser lithography, laser thermal lithography, interference exposure, reduction exposure, aluminum anodization, a method using a particle mask, or the like. Among them, it is preferable to manufacture a mold by using a method using a particle mask. The method using a particle mask is a method in which a particle single-layer film is formed as an etching mask on a flat surface of a base material of a mold, and then etching treatment is performed. In the method using the particle mask, the base material directly under the particles is not etched to become the projections.

A specific example of the method using the particle mask will be described below. Fig. 14 is a view schematically showing a method of manufacturing a mold.

First, a single particle film etching mask 62 containing a plurality of particles M is formed on a substrate 61 (FIG. 14(a)), and a method of forming the single particle film etching mask 62 on the substrate 61, for example, a method using a scheme called L B method (L angmuir-Blodgett method) can be used.

(dropping step and Single particle film formation step)

First, particles having a hydrophobic surface are added to a hydrophobic organic solvent containing 1 or more kinds of solvents having a high volatility such as chloroform, methanol, ethanol, and methyl ethyl ketone to prepare a dispersion. As shown in fig. 15, a water tank (tank) V is prepared, and water W is added as a liquid for spreading the particles on the liquid surface (hereinafter, also referred to as "lower layer water").

Then, the dispersion was dropped to the liquid surface of the lower layer water (dropping step). Then, the solvent as the dispersion medium is volatilized, and the particles spread in a single layer on the liquid surface of the lower layer water, thereby forming a single particle film F which is two-dimensionally densely packed (single particle film forming step).

In this way, when the particles are hydrophobic, the solvent must be hydrophobic. On the other hand, in this case, the lower layer water must be hydrophilic, and usually, water is used as described above. By combining these, self-assembly of particles is promoted as described below, and a two-dimensionally closest packed single particle film F is formed. However, the particles and the solvent may be hydrophilic, and in this case, a hydrophobic liquid is selected as the lower water layer.

(step of moving)

As shown in fig. 15, the single particle film F formed on the liquid surface by the single particle film forming step is transferred onto the substrate 61 as the etching object while maintaining a single layer state (transfer step). The substrate 61 may be planar, or may include a part or all of a non-planar shape such as a curved surface, an inclination, a step, or the like.

The specific method of transferring the single particle film F to the substrate 61 while maintaining the two-dimensional closest-packed state even if the substrate 61 is not flat is not particularly limited, and for example, as the 1 st method, the hydrophobic substrate 61 may be brought into contact with the single particle film F while being kept in a substantially parallel state with respect to the single particle film F, and the single particle film F may be transferred to the substrate 61 by moving the single particle film F to the substrate 61 by the affinity between the single particle film F, which is both hydrophobic, and the substrate 61 while being lowered from above, and as the 2 nd method, the substrate 61 may be disposed in a substantially horizontal direction in the bottom water of the water tank before the formation of the single particle film F, and the single particle film F may be transferred to the substrate 61 after the formation of the single particle film F on the liquid surface, and according to these methods, the single particle film F may be transferred to the substrate 61 without using a special device, and the so-called L B may be employed for transferring the single particle film F to the substrate 61 while maintaining its secondary closest-packed state even if it is a larger area.

By this traveling step, the plurality of particles M are aligned in a substantially single layer on the flat surface 61a which is one surface of the base 61. That is, the single particle film F of the particles M is formed on the flat surface 61 a.

(etching step)

The single particle film F thus formed functions as the single particle etching mask 62. The substrate 61 having the single particle etching mask 62 provided on one surface thereof is subjected to vapor etching to be surface-processed (etching step).

Specifically, if the vapor phase etching is started, first, as shown in fig. 14(b), the etching gas reaches the surface of the base body 61 through the gaps of the particles M constituting the etching mask 62, and a groove is formed in this portion. Then, the columns 63 appear at positions corresponding to the respective particles M. Groove portions 61m are formed between the columns 63. The groove 61M is formed in the center of the 3 particles M arranged on the regular triangle by closest packing. Therefore, the groove 61m is positioned at the vertex of the regular hexagon with the column 63 as the center.

The particles M constituting the single particle film etching mask 62 are not particularly limited, and, for example, gold particles, colloidal silica particles, or the like can be used. In addition, as the etching gas, a gas generally used can be used. For example, Ar and SF can be used₆、F₂、CF₄、C₄F₈、C₅F₈、C₂F₆、C₃F₆、C₄F₆、CHF₃、CH₂F₂、CH₃F、C₃F₈、Cl₂、CCl₄、SiCl₄、BCl₂、BCl₃、BC₂、Br₂、Br₃、HBr、CBrF₃、HCl、CH₄、NH₃、O₂、H₂、N₂、CO、CO₂And the like.

These particles M and the etching gas may be changed according to the substrate 61 to be etched. For example, in the case where gold particles are selected as the particles M constituting the single particle film etching mask 62, and a glass substrate is selected as the substrate 61 and these are combined, if CF is used as the etching gas₄、CHF₃And the gas reactive with the glass, the etching rate of the gold particles is relatively reduced, and the glass substrate is selectively etched.

The desired shape can be obtained by changing the dry etching conditions for the molds having various shapes as shown in fig. 1, 10, and 11. In addition, wet etching may be used in order to make the surface shape of the convex portion more gentle.

The conditions of the dry etching include the material of the particles constituting the particle mask, the material of the original plate, the type of etching gas, bias power, power supply, the flow rate and pressure of the gas, and the etching time. The flat surface can be obtained by increasing the flow rate of the initial etching gas and gradually decreasing the flow rate. In addition, when the ridge line portion remains like the mold 10 shown in fig. 1, it can be obtained by increasing the hardness of the particles used in the particle mask.

The average pitch of the projections and the like can be freely changed by changing the particle diameter of the particles to be used. In the case of forming an aperiodic structure by a particle monolayer, it can be produced by using a plurality of particles having different particle diameters.

(transfer printing step odd number of times)

Subsequently, the substrate 61 shown in fig. 14(b) is transferred odd number of times. The transfer body 71 shown in fig. 14(c) is obtained by odd number of transfers. Specifically, first, the manufactured substrate 61 is transferred with a resin. The surface of the obtained resin transfer product is coated with a metal plating such as Ni by electroforming or the like. The hardness of the transfer body 71 is increased by the metal plating coating, and the following shape adjustment and the like can be performed.

The top of the column 63 of the substrate 61 is a flat surface since it is coated with the particles M. Therefore, a flat surface 71n is formed in the transfer body 71 at a position corresponding to the columnar post 63 of the base body 61. In addition, the transfer body 71 is formed with a convex portion 72n at a position corresponding to the groove portion 61m of the base body 61. Therefore, the convex portion 72 is positioned at the vertex of the regular hexagon with the flat surface 71n as the center. That is, a shape corresponding to fig. 1 is obtained.

(shape adjusting step)

However, a specific curved surface may not be formed on the surface of the transfer body 71. For example, the corner 72a may be formed at the top of the projection 72 n. The corner portion 72a is a portion that does not satisfy a specific curved surface. Therefore, the corner portion 72a is removed to make the outer surface of the convex portion 72n a specific curved surface. The further etching may be performed by wet etching or dry etching. Hereinafter, the case of dry etching will be specifically described.

In order to remove the corner portion 72a, as shown in fig. 14(d), the transfer 71 is irradiated with plasma P generated by a plasma etching apparatus to perform physical etching.

The physical etching is different from the reactive etching used in the etching step. The reactive etching is etching that advances by reaction of the plasmatized chemical species with the transfer body 71. In contrast, the physical etching is etching by a physical force by which the plasmatized chemical species collide with the transfer body 71. Therefore, in the physical etching, there is a variation in etching rate between a portion where the probability of collision of the plasma chemical species is high and a portion where the probability is low, and the etching is anisotropic as compared with the reactive etching. Physical etching is a process similar to the ashing process.

In the plasma etching apparatus, plasma chemical species are used between an upper electrode and a lower electrode. Specifically, the transfer body 71 is electrically charged by electrically connecting the lower electrode having a low potential to the transfer body 71. The plasmatized chemical species between the upper electrode and the lower electrode are attracted by the transfer body 71 having a low potential and collide with the transfer body 71 at a high speed.

At this time, there is a property that if there is a sharp portion like the corner portion 72a in the charged transfer body 71, the electric charge is concentrated in this portion. Therefore, most of the plasmatized chemical species are attracted by the sharp portion. That is, the sharp portion has an increased probability of colliding with the plasmatized chemical species than the other portions. If the chance of collision with the plasmatized species increases, that portion is etched faster than the other portions. That is, the corner 72a of the convex portion 72 is gradually cut off, and the convex portion 2n having a specific curved surface is formed (fig. 14 (e)).

As an etching gas used for physical etching, for example, a rare gas such as argon, oxygen, or the like can be used. These gases lack reactivity to drive physical etching.

In addition, as an etching gas used for physical etching, an etching gas having reactivity may also be used. For example, CF can be used₄、CHF₃Etc. with reactive gases. In this case, etching by physical collision with chemical reactivity of ion species becomes more remarkableThe etching conditions are adjusted in a known manner. For example, the etching conditions are adjusted so that the potential difference between the upper electrode and the lower electrode becomes large. If the potential difference between the upper electrode and the lower electrode is increased, the collision rate of the plasmatized chemical species increases, and the effect of the physical etching becomes more remarkable than the effect of the reactive etching.

Preferably, the physical etching is performed using argon or oxygen at a low pressure and high bias. Specific conditions vary depending on the apparatus and cannot be determined in general, and for example, in the case of dry etching using Inductively Coupled Plasma (ICP), it is preferable to apply a pressure of 0.5 to 1.5W/cm at a pressure of 0.5 to 1.0Pa²To the bias voltage of (1). Even when other dry etching gas is used, the processing time is preferably shortened, although the processing time does not largely deviate from the above range. The reason for this is that there are cases where the etching rate is high, and the corner portion 62a is etched as expected.

As described above, only the corner portion 72a may be formed with a sharp portion at a ridge portion (see fig. 1 and 9) between adjacent convex portions 72n, for example. Even in this case, the sharp portions of the ridge line portion can be removed simultaneously with the corner portions 72a by physical etching.

(replication step)

The mold produced by the above method may be used as it is, or a replica produced from the produced mold as an original may be used as a mold to be actually used. The replica can be produced by transferring the produced mold an even number of times. Specifically, first, the manufactured mold is transferred with a resin. The surface of the obtained odd-numbered transfer product is coated with metal plating such as Ni by electroforming. The hardness of the odd-numbered transfers can be increased by metal plating to further transfer. Then, the odd-numbered transfer products are further transferred to produce even-numbered transfer products. The even-numbered transfer product has the same shape as the mold to be produced. Finally, a metal such as Ni is plated on the surface of the even-numbered transfer body by electroforming or the like, thereby completing the transfer of the mold.

The die 30 shown in fig. 7, in which the boundary portions 33 between the plurality of convex portions 32n and the flat surface 31 are also connected by a specific curved surface, can be manufactured by the following method.

For example, as a first method, there is a method of performing physical etching between the etching step and the odd number of transfer steps. By performing physical etching between the etching step and the odd-numbered transfer step, the top of the cylinder 63 becomes gentle, and the shape of the concave portion of the transfer body 71n becomes gentle.

In addition, as another method, there is a method of performing physical etching in a transfer process in a replication step. By performing physical etching, the shape of the portion that becomes the convex portion after transfer can be made gentle.

Organic light emitting diode

Fig. 12 is a schematic cross-sectional view of an organic light emitting diode device 100 according to an aspect of the present invention. The organic light emitting diode device 100 includes a substrate 110, a 1 st electrode 120, an organic semiconductor layer 130 including a light emitting layer 133, and a 2 nd electrode 140 in this order.

The organic semiconductor layer 130 shown in fig. 12 includes a hole injection layer 131 and a hole transport layer 132 between the 1 st electrode 120 and the light-emitting layer 133, and an electron transport layer 134 and an electron injection layer 135 between the light-emitting layer 133 and the 2 nd electrode 140, in addition to the light-emitting layer 133. The hole injection layer 131, the hole transport layer 132, the electron transport layer 134, and the electron injection layer 135 are not necessarily provided, and may not be provided. The organic light emitting diode element 100 of the present invention may further include other layers within a range not impairing the effects of the present invention.

The 1 st electrode 120 and the 2 nd electrode 140 of the organic light emitting diode apply a voltage to the organic semiconductor layer 130. When a voltage is applied between the 1 st electrode 120 and the 2 nd electrode 140, electrons and holes are injected into the light emitting layer 133, and these are coupled to generate light. The generated light is directly extracted to the outside of the device through the 1 st electrode 120, or is extracted to the outside of the device after being reflected once by the 2 nd electrode 140.

The 2 nd electrode 140 has a two-dimensional structure in which a plurality of projections 142a to 142n are two-dimensionally arranged on the surface 140A on the light-emitting layer 133 side. The two-dimensional structure is either periodic or aperiodic, as in the case of the mold described above.

The average pitch of the plurality of projections 142a to 142n is 50nm to 5 μm, preferably 50nm to 500 nm. The average pitch can be determined by the same method as the average pitch in the mold. If the average pitch of the convex portions 142a to 142n is within this range, the energy trapped on the surface 140A of the 2 nd electrode as the metal electrode in the form of surface plasmon can be efficiently radiated and extracted as light.

The average aspect ratio of the plurality of projections 142a to 142n is 0.01 to 1, preferably 0.05 to 0.5. The average aspect ratio can be determined by the same method as the average aspect ratio in the mold. If the average aspect ratio of the convex portions 142a to 142n on the surface of the 2 nd electrode 140 on the light-emitting layer side is within this range, the energy trapped as surface plasmon on the surface 140A of the 2 nd electrode as a metal electrode can be efficiently radiated and extracted as light.

The trapping of surface plasmons occurs in a process as follows. When the light-emitting layer 133 emits light from the light-emitting molecules, near-field light is generated in the very vicinity of the light-emitting point. Since the distance between the light-emitting layer 133 and the 2 nd electrode 140 is very short, the near-field light is converted into energy of propagation type surface plasmon on the surface of the 2 nd electrode 140.

The propagating surface plasmon on a metal surface is generated by an incident electromagnetic wave (near-field light or the like) and a surface electromagnetic field is generated by a dilatational wave of electrons. In the case of surface plasmon existing on a flat metal surface, the dispersion curve of the surface plasmon does not intersect with the dispersion straight line of light (spatially propagating light). Therefore, the energy of the surface plasmon cannot be extracted as light. On the other hand, if the metal surface has a two-dimensional periodic structure, the dispersion curve of the surface plasmon diffracted by the two-dimensional periodic structure intersects with the dispersion curve of the spatially propagating light. As a result, the energy of the surface plasmon can be extracted as the radiation light to the outside of the element.

Thus, if a two-dimensional periodic structure is provided, the energy of the light lost in the form of surface plasmon is extracted. The extracted energy is radiated as spatially propagating light from the surface of the 2 nd electrode 140. At this time, the directivity of the light radiated from the 2 nd electrode 140 is high, and most of the light is directed toward the extraction surface. Therefore, high-intensity light is emitted from the extraction surface, and the extraction efficiency is improved.

At least 80% of the plurality of projections 142a to 142n have a specific curved surface. The specific curved surface is defined identically to the specific curved surface in the mold.

A flat surface 141 is formed on the surface 140A of the 2 nd electrode between the plurality of projections 142a to 142 n. The area ratio of the flat surface 141 is preferably 5 to 50%, and more preferably 5 to 30%. If the area ratio of the flat surface 141 on the surface 140A of the 2 nd electrode is 5% or more, the aspect ratio of the unevenness for extracting the surface plasma can be reduced. On the other hand, if the area ratio of the flat surface 141 in the surface 140A of the 2 nd electrode is 50% or less, the surface plasmon trapped by the surface 140A of the 2 nd electrode can be efficiently converted into light.

The 2 nd electrode 140 is preferably a material having a negative value such that the absolute value of the real part of the complex permittivity is large, and is preferably a metal material selected to have a high plasma frequency advantageous for the extraction of surface plasma. Examples of the material include a single material such as gold, silver, copper, aluminum, and magnesium, an alloy of gold and silver, and an alloy of silver and copper. In consideration of light extraction from the organic light emitting diode, a metal material having a resonance frequency in the entire visible light region is preferable, and silver or aluminum is particularly preferably used. The 2 nd electrode 140 may have a laminated structure of 2 or more layers.

The thickness of the 2 nd electrode 140 is not particularly limited. For example, 20 to 2000nm, preferably 50 to 500 nm. When the thickness is smaller than 20nm, the reflectance is lowered and the front luminance is lowered, and when the thickness is larger than 500nm, heat or damage due to radiation at the time of film formation or mechanical damage due to film stress is accumulated in a layer including an organic material such as the organic light-emitting layer 133.

The organic semiconductor layer 130 includes an organic material. In fig. 12, a concave-convex shape is formed at the interface between the light-emitting layer 133 and the electron transport layer 134 of the organic semiconductor layer 130 and at the interface between the electron transport layer 134 and the electron injection layer 135. The concave-convex shape is a reverse shape of the main surface 10A of the mold 10. The uneven shape does not necessarily need to be formed at the interface between the light-emitting layer 133 and the electron transport layer 134 and at the interface between the electron transport layer 134 and the electron injection layer 135 of the organic semiconductor layer 130. As will be described in detail later in a method of manufacturing an organic light emitting diode, the concave-convex shape may be formed on the surface of any one of the layers constituting the organic semiconductor layer on the 2 nd electrode 140 side. The layer on the 2 nd electrode 140 side has a shape that reflects the entire shape of the irregularities, as compared with the layer on which the irregularities are formed.

The light emitting layer 133 includes an organic light emitting material. Examples of the organic light-emitting material include pigment compounds such as tris [ 1-phenylisoquinoline-C2, N ] iridium (III) (Ir (piq)3), 1, 4-bis [4- (N, N-diphenylaminostyrylbenzene) ] (DPAVB), and bis [2- (2-benzoxazolyl) phenol ] zinc (II) (ZnPBO). In addition, a substance obtained by doping a fluorescent dye compound or a phosphorescent material with another substance (host material) may be used. In this case, the host material may be a hole transporting material, an electron transporting material, or the like.

As materials constituting the hole injection layer 131, the hole transport layer 132, the electron transport layer 134, and the electron injection layer 135, organic materials are generally used, respectively.

Examples of the material (hole injection material) constituting the hole injection layer 131 include compounds such as 4,4',4 ″ -tris [ 2-naphthylphenylamino ] triphenylamine (2-TNATA).

Examples of the material (hole transport material) constituting the hole transport layer 132 include aromatic amine compounds such as N, N '-diphenyl-N, N' -bis (1-naphthyl) - (1,1 '-biphenyl) -4,4' -diamine (NPD), copper phthalocyanine (CuPc), and N, N '-diphenyl-N, N' -bis (m-methylphenyl) aminobiphenyl (TPD).

Examples of the material (electron-transporting material) constituting the electron-transporting layer 134 and the material (electron-injecting material) constituting the electron-injecting layer 135 include oxadiazole compounds such as 2, 5-bis (1-naphthyl) -1,3, 4-oxadiazole (BND) and 2- (4-tert-butylphenyl) -5- (4-biphenyl) -1,3, 4-oxadiazole (PBD), and metal complex compounds such as tris (8-quinolinyl) aluminum (Alq).

The thickness of the entire organic semiconductor layer including the light-emitting layer 133 is usually 30 to 500 nm.

The 1 st electrode 120 is a transparent conductor that transmits visible light.

The transparent conductor constituting the 1 st electrode 120 is not particularly limited, and a known transparent conductive material can be used. Examples thereof include Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Zinc Oxide (ZnO), and Zinc Tin Oxide (ZTO). The thickness of the 1 st electrode 120 is usually 50 to 500 nm.

The substrate 110 uses a transparent body that transmits visible light. The material constituting the substrate 110 may be an inorganic material, an organic material, or a combination thereof. Examples of the inorganic material include various glasses such as quartz glass, alkali-free glass, and white plate glass, and transparent inorganic minerals such as mica. Examples of the organic material include resin films such as cycloolefin films and polyester films, and fiber-reinforced plastic materials obtained by mixing fine fibers such as cellulose nanofibers into the resin films.

Generally, the substrate 110 has a high visible light transmittance, although the use is also possible depending on the application. The transmittance is 70% or more, preferably 80% or more, and more preferably 90% or more in the visible light range (wavelength 380nm to 800nm) without spectral bias.

The thickness of each layer constituting the organic light emitting diode 100 can be measured by a spectroscopic ellipsometer, a contact level difference meter, an AFM, or the like.

Method for manufacturing organic light emitting diode

A method for manufacturing an organic light-emitting diode according to an aspect of the present invention is a method for manufacturing an organic light-emitting diode in which an organic semiconductor layer including a light-emitting layer and a 2 nd electrode are formed by a coating step and a subsequent vacuum film forming step on a surface of an electrode-carrying substrate having a transparent 1 st electrode on a substrate, on which the 1 st electrode is formed. Between the coating step and the vacuum film-forming step, there is a press-molding step of pressing the mold against the outermost surface of the coating layer formed in the coating step, and forming a reverse shape of the main surface of the mold on the outermost surface of the coating layer.

< preparation of substrate with electrode >

The substrate with electrode is formed with a transparent 1 st electrode on a transparent substrate. The substrate and the 1 st electrode can be used as described above.

A method for forming the 1 st electrode on the substrate can use a known method. For example, a material for a transparent electrode such as ITO can be formed on the base by sputtering. In addition, commercially available substrates with electrodes are also available.

< coating step >

In the coating step, a part of the layers constituting the organic semiconductor layer, or all of the layers, is formed by coating. In general, in the coating step, it is necessary to select a solvent of the coating liquid so as not to intrude into each layer formed in the previous step, and therefore, it is difficult to select an appropriate solvent as the number of layers formed by coating increases. Therefore, in the coating step, it is preferable to form the organic semiconductor layer up to the light-emitting layer in the layers constituting the organic semiconductor layer.

The coating method may be a known method, and for example, spin coating, bar coating, slit coating, die coating, spray coating, an inkjet method, or the like can be used. The coating method does not require vacuum atmosphere in the lamination and does not require a large-scale facility. In addition, since time such as evacuation is not required, the yield of manufacturing the organic light emitting diode can be improved.

< pressing step >

The stamper step is a method of forming a concave-convex shape by a so-called imprint method. If the mold is pressed against the coating layer formed in the coating step, the coating liquid constituting the coating layer follows along the shape of the mold. The coating liquid maintains its shape even after the mold is removed, since it has a viscosity of such an extent that the shape can be maintained.

In addition, even when the material forming the film formation layer has a glass transition point after the coating liquid is dried and evaporated, the shape can be imparted by pressing against the mold in a state where the film formation layer is heated to the glass transition point or more.

In the press molding step, a mold according to an aspect of the present invention is pressed against the outermost layer of the coating layer formed in the coating step. The outermost layer is the last layer formed in the coating step and is the layer farthest from the substrate at the end of the coating step. For example, in the case where the luminescent layer 133 in fig. 12 is formed by coating, the reverse shape of the mold is transferred by pressing the mold against the surface of the luminescent layer 133 on the 2 nd electrode 140 side.

As described above, the mold according to one aspect of the present invention has a plurality of projections having a specific curved surface and a flat surface. Therefore, when the mold is pressed against the light emitting layer 133, the force applied to the light emitting layer 133 is dispersed along a specific curved surface. As a result, it is possible to avoid a case where the layer thickness of the light-emitting layer 133 becomes extremely thin, a case where the light-emitting layer 133 is cut, or the like.

< vacuum film formation step >

In the vacuum film formation step, among the layers constituting the organic semiconductor layer, a layer not formed in the coating step and the 2 nd electrode are formed by a vacuum film formation method.

As the vacuum film formation method, a vacuum deposition method, a sputtering method, CVD (chemical vapor deposition), or the like can be used. In order to reduce damage to the organic layer, it is preferable to use a vacuum deposition method as the vacuum film formation method.

The vacuum film forming method is more highly reflective of the shape of the substrate than the coating method. Therefore, the shapes of the convex portions and the flat surfaces formed on the outermost layer of the coating layer in the press molding step are also reflected on the layer laminated on the outermost layer of the coating layer.

In the concave portion formed in the outermost layer of the coating layer by pressing against the die, it is preferable that the concave portion and the flat surface are connected by a specific curved surface. That is, the boundary between the concave portion and the flat surface is preferably gentle. The thickness unevenness of the layer formed by vacuum deposition can be further suppressed.

By forming the recessed portion and the flat surface in the outermost layer of the coating layer, a shape reverse to the outermost layer of the coating layer is formed on the surface of the 2 nd electrode on the light-emitting layer side as shown in fig. 12. The shape is a shape reflecting the shape of the mold pressed against in the press molding step.

In the method of manufacturing an organic light emitting diode according to an aspect of the present invention, since the step of pressing the substrate using the mold having the specific shape is provided, a desired unevenness can be easily formed on the light emitting layer side of the 2 nd electrode. The organic light emitting diode manufactured by the method can extract surface plasma, so that high light emitting characteristics can be obtained.

[ description of symbols ]

10. 30, 40, 50 mould

10A Main surface

1 a-1 n, 41, 51 a-51 n flat surface

2 a-2 n, 32n, 42 a-42 n, 52 a-52 n convex parts

2 Aa-2 An central point

1 Aa-1 An central point

2B curved surface

20 laminated body

21 layer 1

22 layer 2

23 layer 3

26 layers of

26B outer surface

3. 33 boundary portion

4 ridge line part

100 organic light emitting diode

110 base body

120 st electrode

130 organic semiconductor layer

131 hole injection layer

132 hole transport layer

133 light emitting layer

134 electron transport layer

135 electron injection layer

140 nd electrode

142 a-142 n convex parts

Claims (7)

1. A mold for manufacturing an organic light emitting diode, having a flat surface and a plurality of projections on a main surface,

the average pitch of the plurality of projections is 50nm to 5 μm, the average aspect ratio of the plurality of projections is 0.01 to 1,

more than 80% of the plurality of convex parts have a specific curved surface,

when an arbitrary point of the specific curved surface is defined as a 1 st point and a point 1/10 which is deviated from the 1 st point by the average pitch is defined as a 2 nd point,

the 2 nd tangential plane connected with the 2 nd point is within 60 degrees of the inclination angle of the 1 st tangential plane connected with the 1 st point.

2. The mold for manufacturing an organic light-emitting diode according to claim 1, wherein an area ratio occupied by the flat surface in the main surface is 5 to 50%.

3. The mold for manufacturing an organic light-emitting diode according to claim 1, wherein the flat surface and the convex portion having the specific curved surface are connected so as to satisfy a condition of the specific curved surface.

4. The mold for manufacturing an organic light-emitting diode according to claim 3, wherein the specific curved surface constituting the plurality of convex portions has at least 1 or more reverse curved portions,

the closest distance from the 1 st inflection portion closest to the flat surface among the inflection portions is equal to or greater than 1/10 which is the average pitch of the plurality of convex portions.

5. The mold for manufacturing an organic light emitting diode according to any one of claims 1 to 4, wherein the plurality of protrusions form a honeycomb lattice,

the top portions of the plurality of convex portions are located at the vertices of hexagons constituting the honeycomb lattice in a plan view in a direction perpendicular to the flat surface.

6. The mold for manufacturing an organic light-emitting diode according to claim 5, wherein the convex portion at the vertex of the hexagon has a ridge line portion between the convex portions at the adjacent vertices of the hexagon,

at least a part of the ridge portion is present on the flat surface side of the convex portion connecting the ridge portions.

7. The mold for manufacturing an organic light-emitting diode according to claim 6, wherein the height of the portion of the ridge line portion closest to the flat surface from the flat surface is 50% to 90% of the height of the convex portion connecting the ridge line portion from the flat surface.

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