JP5141506B2 - Plasmonic crystal surface emitter, image display device, and illumination device - Google Patents

Description

The present invention relates to an organic light emitting diode (organic EL, OLED) used for a display, illumination or the like. More specifically, the present invention relates to a technique for improving the extraction efficiency of a wide range of energy from the far infrared region including the visible light region to the ultraviolet region by surface plasmon resonance.

In recent years, in order to improve the light emission efficiency of organic EL, improvement of light emitting material, lower voltage, improvement of light extraction efficiency, etc. have been studied. In particular, the improvement of light extraction efficiency has room to greatly improve the light emission efficiency. There is. So far, organic light-emitting diodes have a base glass refractive index of about 1.5, a transparent electrode (ITO) refractive index of 1.8-2.0, and organic material layers such as an electron transport layer, a light-emitting layer, and a hole transport layer. Since the refractive index is about 1.5 to 1.6 and the refractive index of air is 1.0, the emitted light is confined by repeated total reflection in the organic layer, the transparent electrode layer, and the glass substrate. There is a problem that the light extraction efficiency is reduced to about 20%.

In order to improve the light extraction efficiency, introduction of a light scattering layer or a low refractive index layer has been studied (Non-Patent Document 1, Non-Patent Document 2). In addition, this is an organic light-emitting diode device with a structure in which metal fine particles are dispersed in a dielectric layer, and the light from the light-emitting layer is extracted with high efficiency by exciting local surface plasmon resonance. Has also been devised (Patent Document 1).

Furthermore, techniques for improving the light emission efficiency through surface plasmon resonance using a one-dimensional and two-dimensional periodic grating structure have also been introduced (Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6). ). According to these, a basic structure in which an anode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially stacked on a substrate having an uneven periodic grating structure is used. A technique is described in which light produced and enhanced in a light emitting layer is enhanced by surface plasmon resonance to improve luminous efficiency.
Chemical Physics Letter, 182, p143 (1991) Synthetic Metals, 116, p145 (2001) JP 2007-35430 A JP 2002-270891 A Special table 2005-535121 JP 2005-108982 A JP 2006-259064 A JP 2004-31350 A

In these prior documents, photolithography, electron beam lithography, mechanical cutting, laser processing, two-beam interference exposure, reduced exposure, and the like are used as methods for producing a periodic grating structure. However, except for two-beam interference exposure, these methods are not suitable for producing a periodic grating structure in a large area, and thus are limited in terms of industrial use. In addition, the periodic grating structure by two-beam interference exposure can also be manufactured to a certain small area. However, in the case of a large area with a side of several centimeters or more, vibration, wind, thermal contraction / expansion for the entire optical setup, air It is extremely difficult to produce a uniform and accurate periodic grating structure due to various disturbance factors such as fluctuations in voltage, voltage fluctuations, and the like.

As a means for solving the above problem, a single particle film of a fine particle having a primary particle diameter equal to or less than the effective wavelength of emitted light is used by using the principle of the Langmuir-Blodgett method (hereinafter also referred to as LB method). By making use of the fact that a two-dimensional close-packed lattice in which the control of the particle spacing is performed with high accuracy can be obtained by making it on the surface of the base material, a wave having a constant period is obtained by gas phase etching using this as an etching mask. It was found that a high-performance surface plasmon crystal plane having a large area can be produced by producing a periodic grating structure composed of molds or pseudo-wave irregularities on the surface of a substrate.

In other words, according to the present invention, a wave in which the pitch at which the irregularities are arranged or the wavelength of the corrugated structure is less than or equal to the effective wavelength of the light emitted from the organic light-emitting diode, and A type or pseudo-wave periodic grating structure is formed on the surface of the organic light emitting diode substrate, and at least an anode conductive layer, a light emitting layer, and a cathode conductive layer are sequentially stacked on the substrate to manufacture an organic light emitting diode. The extraction efficiency of light generated in the light emitting layer is enhanced by the periodic grating structure inducing surface plasmon resonance.

(1) In an organic light emitting diode element produced by sequentially laminating at least an anode conductive layer, a light emitting layer, and a cathode conductive layer on a substrate,
Using surface plasmon resonance on the cathode surface with regular irregularities, using a substrate having a periodic grating structure with regular irregularities produced by a dry etching method using a two-dimensional crystal composed of a particle monolayer as an etching mask A plasmonic crystal surface light emitter characterized by improving the extraction efficiency of light energy.
(2) The above etching mask uses the Langmuir-Blodgett method in which particles are self-organized by the lateral capillary force when the hydrophobized particle dispersion is dropped onto the gas-liquid interface and the dispersion medium is volatilized, and transferred to the substrate. It is confirmed that the particles produced using the etching mask are two-dimensionally closely packed, and the deviation D (%) of the arrangement of the two-dimensional crystal particles defined by the following formula (1) is 10% or less. It is a characteristic plasmonic crystal surface light emitter.
D (%) = | B−A | × 100 / A (1)
(In formula (1), A represents the average particle diameter of the particles, and B represents the average pitch between the particles in the single particle film.)
(3) An injection molding method, a thermal nanoimprint method, an optical nanoimprint method, a heat using a mold, a stamper or a master disc produced using the master plate having the periodic grating structure described in any one of (1) to (2) above. This is a method for manufacturing a periodic grating structure in which the shape of the periodic grating structure is transferred by either pressing or UV embossing.
(4) The plasmonic crystal surface light emitter according to any one of (1) to (2), wherein the substrate having the periodic grating structure is replicated using a shape transfer technique.
(5) An image display device having at least a part of a plasmonic crystal surface light emitter produced by the method according to any one of (1) to (4) above.
(6) An illumination device having at least a part of a plasmonic crystal surface light emitter produced by the method according to any one of (1) to (4) above.

Here, the large area of the present invention is practically about 1 cm ² to about 3 m ² , and the effect intended by the present invention is remarkable at 10 cm ² or more, but the upper limit is particularly defined unless the effect is inhibited. It is not a thing. The reason why the method of the present invention is suitable for large-area particle coating is that other means for coating particles directly on the surface of the substrate are precisely cleaned so that there is no local variation in surface energy to avoid coating unevenness. Whereas it is difficult to obtain sufficient uniformity in a large area, in the method of the present invention, particles are spread on a uniform interface called a gas-liquid interface. This is because a highly accurate array can be stably produced. The gas-liquid interface is advantageous for realizing a uniform particle arrangement, and the present invention is suitable for further improving the arrangement accuracy by ultrasonic irradiation described later.
Since the advancement of particle arrangement by ultrasonic irradiation is very effective, the advantage of the method of the present invention increases as the area increases.

The etching mask of the present invention can be manufactured with a simple apparatus at low cost, and the size of the apparatus can be easily increased. Therefore, it is effective when it is desired to perform mask processing on a large-area substrate, or when it is desired to perform mask processing on a large number of substrate surfaces in a single operation. Moreover, since the particle arrangement according to the method of the present invention has a higher degree of crystallinity than other particle coating methods and ordinary LB methods, excellent diffracted light can be obtained. Therefore, in performing surface plasmon resonance light emission performed by resonating incident diffracted light with surface plasmons, a highly efficient light extraction effect can be obtained by using the periodic grating structure of the present invention.

The present invention is described in detail below.
The particles constituting the single particle film etching mask comprising the particle single layer film of the present invention refer to particles having a particle diameter of about the effective wavelength or less of the emitted light of the organic light emitting diode. This is because the period of the periodic grating structure is defined by the particle diameter of the fine particles.
The particles constituting the single particle film etching mask preferably have a particle diameter variation coefficient (a value obtained by dividing the standard deviation by an average value) of 15% or less, more preferably 10% or less, and more preferably 5% or less. Are more preferred. When particles having a small variation coefficient of the particle diameter, that is, a particle diameter variation is used in this way, in the manufacturing process of a single particle film etching mask described later, it is difficult to generate a defective portion where the particle does not exist, and the deviation D of the arrangement is caused. It is easy to obtain a single particle film etching mask of 10% or less. In order to efficiently induce surface plasmon resonance, it is necessary for the periodic grating structure to efficiently generate diffracted light, and for this purpose, it is preferable to use a single particle film etching mask with little misalignment.

Particle materials include metals such as Al, Au, Ti, Pt, Ag, Cu, Cr, Fe, Ni, and Si, and metal oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , MgO ₂ , and CaO ₂ . In addition to organic polymers such as polystyrene and polymethyl methacrylate, one or more of semiconductor materials and inorganic polymers can be employed.

The single particle film etching mask of the present invention is arranged on at least one surface of a substrate which is an object to be etched, and is formed on the substrate by a method utilizing a so-called LB method (Langmuir-Blodget method). Can be formed. Specifically, a dropping step of dropping a dispersion in which particles are dispersed in a solvent onto the liquid surface in the water tank, a single particle film forming step of forming a single particle film made of particles by volatilizing the solvent, And a transfer step of transferring the particle film onto the substrate.

A preferred method for producing a single particle film etching mask will be specifically described below with an example.
First, a dispersion liquid is prepared by adding particles having a hydrophobic surface to a hydrophobic organic solvent composed of one or more of volatile solvents such as chloroform, methanol, ethanol, methyl ethyl ketone, and hexane. On the other hand, a water tank (trough) is prepared, and water is added thereto as a liquid for developing particles on the liquid surface (hereinafter sometimes referred to as lower layer water).
Next, a dispersion liquid is dripped at the liquid level of lower layer water (drip process). As a result, the solvent as the dispersion medium is volatilized, and the particles are developed in a single layer on the liquid surface of the lower layer water to form a two-dimensional close packed single particle film (single particle film formation). Process).
Thus, when a hydrophobic particle is selected as the particle, it is necessary to select a hydrophobic particle as the solvent. On the other hand, in that case, the lower layer water needs to be hydrophilic, and water is usually used as described above. By combining in this way, as will be described later, self-organization of particles proceeds and a two-dimensional close packed single particle film is formed. However, hydrophilic particles and solvents may be selected. In that case, a hydrophobic liquid is selected as the lower layer water.

  The particle concentration of the dispersion dropped into the lower layer water is preferably 1 to 10% by mass. Further, the dropping rate is preferably 0.001 to 0.01 ml / second. If the concentration of the particles in the dispersion and the amount of dripping are in such a range, the particles are partially agglomerated in a cluster to form two or more layers, defective portions where no particles are present, and the pitch between particles is A tendency of spreading and the like is suppressed, and a single particle film in which each particle is two-dimensionally closely packed with high accuracy is more easily obtained.

  As the particles having hydrophobic surfaces, among the previously exemplified particles, particles made of organic polymers such as polystyrene and having a hydrophobic surface may be used. It may be used after making it hydrophobic with an agent. As the hydrophobizing agent, for example, a surfactant, a metal alkoxysilane, or the like can be used.

The method of using a surfactant as a hydrophobizing agent is effective for hydrophobizing a wide range of materials, and is suitable when the particles are made of metal, metal oxide, or the like.
As the surfactant, cationic surfactants such as brominated hexadecyltrimethylammonium and brominated decyltrimethylammonium, and anionic surfactants such as sodium dodecyl sulfate and sodium 4-octylbenzenesulfonate can be suitably used. Moreover, alkanethiol, a disulfide compound, tetradecanoic acid, octadecanoic acid, etc. can also be used.

Such a hydrophobizing treatment using a surfactant may be performed in a liquid by dispersing particles in a liquid such as an organic solvent or water, or may be performed on particles in a dry state.
When performed in a liquid, for example, a volatile organic solvent composed of one or more of chloroform, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethyl ethyl ketone, toluene, n-hexane, cyclohexane, ethyl acetate, butyl acetate, etc. What is necessary is just to add and disperse | distribute the particle | grains to be hydrophobized, and to mix surfactant then, and to disperse | distribute it further. If the particles are dispersed in advance in this way and then a surfactant is added, the surface can be more uniformly hydrophobized. Such a hydrophobized dispersion can be used as it is as a dispersion for dripping onto the surface of the lower layer water in the dropping step.

If the particles to be hydrophobized are in the form of an aqueous dispersion, a surfactant is added to the aqueous dispersion, the surface of the particles is hydrophobized with an aqueous phase, and then an organic solvent is added to make the hydrophobized treatment. An oil phase extraction method is also effective. The dispersion thus obtained (a dispersion in which particles are dispersed in an organic solvent) can be used as it is as a dispersion for dropping onto the liquid surface of the lower layer water in the dropping step. In order to improve the particle dispersibility of this dispersion, it is preferable to appropriately select and combine the type of organic solvent and the type of surfactant. By using a dispersion having a high particle dispersibility, the particles can be prevented from agglomerating in clusters, and a single particle film in which each particle is two-dimensionally closely packed with high accuracy can be obtained more easily. For example, when chloroform is selected as the organic solvent, it is preferable to use brominated decyltrimethylammonium as the surfactant. In addition, a combination of ethanol and sodium dodecyl sulfate, a combination of methanol and sodium 4-octylbenzenesulfonate, a combination of methyl ethyl ketone and octadecanoic acid, and the like can be preferably exemplified.
The ratio of the particles to be hydrophobized and the surfactant is preferably such that the mass of the surfactant is 1/3 to 1/15 times the mass of the particles to be hydrophobized.
In addition, in such a hydrophobizing treatment, it is effective in terms of improving particle dispersibility to stir the dispersion during the treatment or to irradiate the dispersion with ultrasonic waves.

The method of using metal alkoxysilane as a hydrophobizing agent is effective when hydrophobizing particles such as Si, Fe, and Al, and oxide particles such as AlO ₂ , SiO ₂ , and TiO _2. The present invention is not limited and can be applied basically to particles having a hydroxyl group on the surface.
As the metal alkoxysilane, monomethyltrimethoxysilane, monomethyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxy Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3methacryloxy Propyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (amino Ethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyl Examples include trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

When using a metal alkoxysilane as a hydrophobizing agent, the alkoxysilyl group in the metal alkoxysilane is hydrolyzed to a silanol group, and the silanol group is dehydrated and condensed to a hydroxyl group on the particle surface to effect hydrophobicity. That is, the hydrophobization using metal alkoxysilane is preferably carried out in water.
Thus, when hydrophobizing in water, it is preferable to stabilize the dispersion state of the particles before hydrophobization by using a dispersant such as a surfactant, for example. Since the hydrophobizing effect of the alkoxysilane may be reduced, the combination of the dispersant and the metal alkoxysilane is appropriately selected.

  As a specific method for hydrophobizing with a metal alkoxysilane, first, particles are dispersed in water, and this is mixed with a metal alkoxysilane-containing aqueous solution (an aqueous solution containing a hydrolyzate of metal alkoxysilane), and from room temperature. The reaction is carried out for a predetermined time, preferably 6 to 12 hours, with appropriate stirring in the range of 40 ° C. By carrying out the reaction under such conditions, the reaction proceeds moderately and a dispersion of sufficiently hydrophobized particles can be obtained. When the reaction proceeds excessively, the silanol groups react with each other to bond the particles, the particle dispersibility of the dispersion decreases, and the resulting single particle film has particles partially agglomerated in clusters 2 It tends to be more than a layer. On the other hand, when the reaction is insufficient, the surface of the particles is not sufficiently hydrophobized, and the resulting single particle film tends to have a wide pitch between the particles.

Moreover, since metal alkoxysilanes other than amines are hydrolyzed under acidic or alkaline conditions, it is necessary to adjust the pH of the dispersion to acidic or alkaline during the reaction. Although there is no restriction | limiting in the adjustment method of pH, Since the effect of silanol group stabilization is acquired besides the acceleration | stimulation of hydrolysis according to the method of adding 0.1-2.0 mass% concentration acetic acid aqueous solution, it is preferable. .
The ratio of the particles to be hydrophobized and the metal alkoxysilane is preferably in the range where the mass of the metal alkoxysilane is 1/10 to 1/100 times the mass of the particles to be hydrophobized.

  After the reaction for a predetermined time, one or more of the above-mentioned volatile organic solvents are added to the dispersion, and the particles hydrophobized in water are subjected to oil phase extraction. At this time, the volume of the organic solvent to be added is preferably in the range of 0.3 to 3 times the dispersion before addition of the organic solvent. The dispersion thus obtained (a dispersion in which particles are dispersed in an organic solvent) can be used as it is as a dispersion for dropping onto the liquid surface of the lower layer water in the dropping step. In this hydrophobization treatment, it is preferable to carry out stirring, ultrasonic irradiation, etc. in order to improve the particle dispersibility of the dispersion during the treatment. By increasing the particle dispersibility of the dispersion, it is possible to suppress the aggregation of particles in a cluster shape, and it becomes easier to obtain a single particle film in which each particle is two-dimensionally closely packed with high accuracy.

  In order to further improve the accuracy of the formed single particle film, the dispersion before dropping onto the liquid surface is microfiltered with a membrane filter or the like, and aggregated particles (from a plurality of primary particles) present in the dispersion are used. Secondary particles) are preferably removed. If the microfiltration is performed in advance as described above, it is difficult to generate a portion where two or more layers are formed or a defective portion where particles are not present, and it is easy to obtain a single particle film with high accuracy. Assuming that a defect portion having a size of several to several tens of μm exists in the formed single particle film, a surface pressure sensor that measures the surface pressure of the single particle film in a transition step described later in detail, Even if an LB trough device having a movable barrier that compresses the single particle film in the liquid surface direction is used, it is difficult to detect such a defective part as a difference in surface pressure. It becomes difficult to obtain an etching mask.

  Furthermore, such a single particle film forming step is preferably performed under ultrasonic irradiation conditions. When the single particle film formation process is performed while irradiating ultrasonic waves from the lower layer water to the water surface, the close packing of particles is promoted, and a single particle film in which each particle is two-dimensionally close packed with high accuracy is obtained. It is done. At this time, the ultrasonic output is preferably 1 to 1200 W, and more preferably 50 to 600 W. Moreover, although there is no restriction | limiting in particular in the frequency of an ultrasonic wave, For example, 28 kHz-5 MHz are preferable, More preferably, they are 700 kHz-2 MHz. In general, when the vibration frequency is too high, energy absorption of water molecules starts and a phenomenon in which water vapor or water droplets rise from the surface of the water occurs, which is not preferable for the LB method of the present invention. In general, when the frequency is too low, the cavitation radius in the lower layer water is increased, bubbles are generated in the water, and rise toward the water surface. When such bubbles accumulate under the single particle film, the flatness of the water surface is lost, which is inconvenient for the implementation of the present invention. In addition, standing waves are generated on the water surface by ultrasonic irradiation. If the output is too high at any frequency, or if the wave height of the water surface becomes too high due to the tuning conditions of the ultrasonic transducer and the transmitter, the single particle film may be destroyed by the water surface wave.

From the above, if the ultrasonic frequency is set appropriately, close-packing of particles can be effectively promoted without destroying the single particle film being formed. However, since the natural frequency becomes very high when the particle diameter is small, for example, 100 nm or less, it is difficult to give ultrasonic vibration as calculated.
In such a case, the calculation is performed assuming that the natural vibration corresponding to the mass of the particle dimer, trimer,... Can be reduced. Even when ultrasonic vibration corresponding to the natural frequency of the aggregate of particles is applied, the effect of improving the particle filling rate is exhibited. The ultrasonic irradiation time may be sufficient to complete the rearrangement of particles, and the required time varies depending on the particle diameter, ultrasonic frequency, water temperature, and the like. However, under normal production conditions, it is preferably performed for 10 seconds to 60 minutes, more preferably 3 minutes to 30 minutes.
Advantages obtained by ultrasonic irradiation include the effect of destroying the soft agglomerates of particles that tend to occur when preparing a nanoparticle dispersion, in addition to the closest packing of particles (to make the random array 6-way closest) This also has the effect of repairing some of the point defects, line defects, or crystal transitions.

The formation of the single particle film described above is due to self-organization of particles. The principle is that when the particles are aggregated, surface tension acts due to the dispersion medium existing between the particles, and as a result, the particles do not exist randomly but have a two-dimensional close packed structure. It forms automatically. In other words, the close-packing by surface tension is also referred to as arrangement by lateral capillary force.
In particular, when three particles, such as colloidal silica, which are spherical and have a highly uniform particle diameter, come together in a floating state on the water surface, the surface of the particle group is minimized so that the total length of the waterline of the particle group is minimized. As shown in FIG. 1, if the tension is applied and the three particles are stabilized in an arrangement based on an equilateral triangle, if the water line is at the top of the particle group, that is, the particles are submerged below the liquid level. In some cases, such self-organization does not occur and a single particle film is not formed. Therefore, when one of the particles and the lower layer water is hydrophobic, it is important to make the other hydrophilic so that the particles do not dive under the liquid surface.
As the lower layer water, it is preferable to use water as described above. When water is used, relatively large surface free energy acts, and the close-packed arrangement of particles once generated is stable on the liquid surface. It becomes easy to sustain.

The single particle film formed on the liquid surface by the single particle film forming step is transferred onto the organic light emitting diode substrate, which is an object to be etched, in a single layer state (transfer step).
There is no particular limitation on the specific method for transferring the single particle film onto the substrate. For example, while maintaining the hydrophobic substrate substantially parallel to the single particle film, the single particle film is lowered from above to form the single particle film. A method of transferring and transferring the single particle film to the substrate by the affinity between the single particle film and the substrate, both of which are hydrophobic, and the substrate; before the single particle film is formed, the substrate is approximately horizontal in the lower water of the water tank in advance. There is a method of transferring the single particle film onto the substrate by arranging the single particle film in the direction and gradually lowering the liquid level after forming the single particle film on the liquid surface. According to these methods, the single particle film can be transferred onto the substrate without using a special apparatus, but even in the case of a single particle film having a larger area, its two-dimensional close-packed state It is preferable to employ the so-called LB trough method in that it can be easily transferred onto the substrate while maintaining the above.

  FIG. 2 schematically shows an outline of the LB trough method. In this method, the substrate 4 is dipped in the vertical direction in advance in the lower layer water 2 in the water tank, and the above-described dropping step and single particle film forming step are performed in this state to form the single particle film 3 (FIG. 2 (A)). Then, after the single particle film forming step, the single particle film 3 can be transferred onto the substrate 4 by pulling the substrate 4 upward (FIG. 2B). Here, since the single particle film 3 is already formed in a single layer state on the liquid surface by the single particle film forming step, the temperature condition of the transition step (temperature of the lower layer water), the pulling speed of the substrate 4, etc. Even if it fluctuates somewhat, there is no fear that the single particle film 3 collapses and becomes multilayered in the transfer step. In addition, the temperature of lower layer water is normally about 10-30 degreeC depending on the environmental temperature which fluctuates with a season or weather.

At this time, as a water tank, a surface pressure sensor based on the principle of an unillustrated Wilhelmy plate or the like for measuring the surface pressure of the single particle film 3, and an unillustrated for compressing the single particle film 3 in a direction along the liquid surface. When the LB trough apparatus having the movable barrier is used, the single particle film 3 having a larger area can be transferred onto the substrate 4 more stably. According to such an apparatus, the single particle film 3 can be compressed to a preferable diffusion pressure (density) while measuring the surface pressure of the single particle film 3, and is moved toward the substrate 4 at a constant speed. be able to. Therefore, the transition from the liquid surface of the single particle film 3 to the substrate 4 proceeds smoothly, and troubles such as that only the single particle film 3 having a small area can move to the substrate 4 are unlikely to occur. A preferable diffusion pressure is 5 to 80 mNm ⁻¹ , more preferably 10 to 40 mNm ⁻¹ . With such a diffusion pressure, it is easy to obtain a single particle film 3 in which each particle is two-dimensionally closely packed with higher accuracy. The speed at which the substrate 4 is pulled up is preferably 0.5 to 20 mm / min.

The material of the substrate of the organic light emitting diode is basically a transparent material. For example, various glass, artificial quartz, mica, metal oxides such as sapphire (Al ₂ O ₃ ), polyethylene terephthalate (PET), polyethylene naphthalate, Examples thereof include polymer materials such as triacetyl cellulose. Further, if necessary, the surface of the substrate may be coated with another material or chemically altered.
In addition, as described later, a master (master) is first prepared, a master replica mold is manufactured, and actually, using this mold, an injection molding method, a thermal nanoimprint method, an optical nanoimprint method, a hot press method, In the case of producing a resin molded product by any method of the UV embossing method, the substrate for producing the single particle film does not need to be transparent. In this case, specifically, compounds such as silicon, silicon carbide and gallium arsenide, and various metals such as copper and aluminum can be used.

  By such a transfer process, a single particle film etching mask can be formed on the substrate. However, after the transfer process, a fixing process for fixing the formed single particle film etching mask on the substrate is performed. Also good. By fixing the single particle film on the substrate, it is possible to suppress the possibility that particles move on the substrate during an etching process described later, and it is possible to perform etching more stably and with high accuracy. In particular, such a possibility increases when the final stage of the etching process in which the diameter of each particle gradually decreases.

As a method of the fixing step, there are a method using a binder and a sintering method.
In the method using a binder, a binder solution is supplied to the single particle film side of the substrate on which the single particle film etching mask is formed, and this is infiltrated between the single particle film etching mask and the substrate.
The amount of the binder used is preferably 0.001 to 0.02 times the mass of the single particle film etching mask. In such a range, the particles can be sufficiently fixed without causing the problem that the binder is too much and the binder is clogged between the particles, and the accuracy of the single particle film etching mask is adversely affected. If a large amount of the binder solution has been supplied, after the binder solution has permeated, the excess of the binder solution may be removed by using a spin coater or tilting the substrate.
As the type of binder, metal alkoxysilanes, general organic binders, inorganic binders, etc., previously exemplified as hydrophobizing agents can be used. After the binder solution has permeated, heat treatment is appropriately performed according to the type of binder. Just do it. When using a metal alkoxysilane as a binder, it is preferable to heat-process at 40-80 degreeC on the conditions for 3 to 60 minutes.

  In the case of employing the sintering method, the substrate on which the single particle film etching mask is formed may be heated to fuse each particle constituting the single particle film etching mask to the substrate. The heating temperature may be determined according to the material of the particle and the material of the substrate, but particles having a particle diameter of 1 μmφ or less start an interfacial reaction at a temperature lower than the original melting point of the material, and thus are heated on a relatively low temperature side. The result is complete. If the heating temperature is too high, the fusion area of the particles increases, and as a result, the shape as a single particle film etching mask may change, which may affect the accuracy. Moreover, since it may oxidize a board | substrate and each particle | grain when heating is performed in air, it is preferable to carry out in inert gas atmosphere. When sintering is performed in an atmosphere containing oxygen, it is necessary to set conditions in consideration of an oxide layer in an etching process described later.

  Thus, the method for producing a single particle film etching mask includes a dropping step of dropping a dispersion liquid in which particles are dispersed in a solvent onto a liquid surface in a water tank, and a single particle film made of particles by volatilizing the solvent. Since it has a single particle film formation process to be formed and a transfer process to transfer the formed single particle film onto the substrate, the accuracy of single layering, ease of operation, response to large area, and reproduction Compared to the so-called particle adsorption method described in, for example, the liquid thin film method described in Nature, Vol. 361, 7 January, 26 (1993), and Japanese Patent Application Laid-Open No. 58-120255. It is very good and can cope with industrial production level.

A periodic grating structure can be formed on one side of the substrate by subjecting the substrate with the single-particle film etching mask provided on one side as described above to surface processing (etching process) by vapor phase etching. Specifically, when the gas phase etching is started, first, as shown in FIGS. 3A, 3B, and 3C, gaps between the particles 6 constituting the single particle film are formed. The etching gas passes through and reaches the surface of the substrate 7, a groove is formed in that portion, and a convex portion appears at a position corresponding to each particle 6. When the gas phase etching is continued, the particles 6 on the respective convex portions are gradually etched and become smaller, and at the same time, the groove of the substrate 7 becomes deeper. Finally, each particle 6 disappears by etching, and at the same time, many irregularities are formed on one side of the substrate 7. The shape of the unevenness may be a wave shape as shown in FIG. 3 and rounded peaks and valleys, a comb shape as shown in FIG. 4, or a saw-like shape such as peaks and valleys as shown in FIG. It may be sharp and sharp. The shape of the periodic grating structure can be adjusted by manipulating various conditions such as bias, gas flow rate, and type and amount of deposition gas during dry etching.

An object of the present invention is to improve the light emission efficiency of an organic light emitting diode by radiation from a propagation surface plasmon. For this purpose, it is necessary to efficiently generate diffracted waves with a periodic grating structure and continue to supply energy to propagating surface plasmons. When the periodic grating structure is one-dimensional (line / space periodic structure), the two-dimensional case (uneven structure on the surface) has a higher effect on the generation of diffracted waves. Even when the periodic grating structure is two-dimensional, the arrangement having a periodic structure in three directions (lattice crossing angle = 60 degrees) is more diffracting than the arrangement having a periodic structure in two directions (lattice crossing angle = 90 degrees). Since there are many conditions for obtaining light, surface plasmon resonance can be induced with high efficiency.
That is, in the case of the two-dimensional six-way close packed lattice arrangement produced by the present invention, since the periodic structure is created in three directions, the lattice arrangement is the most excellent in the efficiency of resonating the diffracted light with the surface plasmon, and the light emission High efficiency improvement effect.

The pitch of the periodic grating structure is set to be less than or equal to the effective wavelength of the emitted light generated in the light emitting layer of the organic light emitting diode, and the relationship between the wavelength λ ₀ of the emitted light in the medium and the period d is expressed by d <λ ₀ . Is done. This has the same meaning as that in the case of localized surface plasmon resonance on the surface of the metal fine particle, the wavelength λ ₀ of the incident light and the diameter d of the metal fine particle are d <λ ₀ . Therefore, the grating period in the present invention is approximately in the range of 150 to 1000 nm, and is selected according to the wavelength of the emitted light. Since the single particle film etching mask of the present invention has high crystallinity and the pitch of the periodic grating structure can be determined by the diameter of the particles used for the single particle film, the periodic grating structure can be obtained by using a predetermined particle diameter. Control the pitch of

The height of the periodic grating structure is about 5 to 100 nm, preferably about 10 to 40 nm. When the height of the periodic grating structure is too high, surface plasmons are localized and are not preferable because they are not of a propagation type.

Examples of the etching gas used for the vapor phase etching include Ar, SF ₆ , F ₂ , CF ₄ , C ₄ F ₈ , C ₅ F ₈ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , and CHF. ₃ , CH ₂ F ₂ , CH ₃ F, C ₃ F ₈ , Cl ₂ , CCl ₄ , SiCl ₄ , BCl ₂ , BCl ₃ , BC ₂ , Br ₂ , Br ₃ , HBr, CBrF ₃ , HCl, CH ₄ , NH ₃ , O ₂ , H ₂ , N ₂ , CO, CO _{2 and the} like can be mentioned, but are not limited to these as long as the effects of the present invention are not impaired. One or more of these can be used depending on the particles constituting the single particle film etching mask, the material of the substrate, and the like.

  As an etching apparatus that can be used, a reactive ion etching apparatus, an ion beam etching apparatus, or the like that can perform anisotropic etching and can generate a bias electric field of about 20 W at the minimum can generate plasma. There are no particular restrictions on specifications such as system, electrode structure, chamber structure, and frequency of the high-frequency power source.

In order to perform the etching according to the present invention, each etching condition (single particle) is performed so that anisotropic etching with an etching selectivity (substrate etching rate / single particle film etching rate) of 1.0 or less is performed. The material of the particles constituting the film etching mask, the material of the substrate, the type of etching gas, the bias power, the antenna power, the gas flow rate and pressure, the etching time, etc. are set.

For example, when colloidal silica particles are selected as the particles constituting the single particle film etching mask, a quartz substrate is selected as the substrate, and these are combined, by using a gas such as Ar or CF ₄ as the etching gas, Low aspect ratio etching can be performed.
When the electric field bias is set to several tens to several hundreds W, the positively charged particles in the etching gas in the plasma state are accelerated and incident on the substrate at a high speed almost vertically. Therefore, when a gas having reactivity with the substrate is used, the reaction rate of the physicochemical etching in the vertical direction can be increased.
Depending on the combination of the material of the substrate and the type of etching gas, isotropic etching by radicals generated by plasma also occurs in parallel in gas phase etching. Etching with radicals is chemical etching, and isotropically etches in any direction of the object to be etched. Since radicals have no electric charge, the etching rate cannot be controlled by setting the bias power, and the operation can be performed with the concentration of the etching gas in the chamber. In order to carry out anisotropic etching with charged particles, a certain level of gas pressure must be maintained, so as long as a reactive gas is used, the influence of radicals cannot be made zero. However, a method of slowing the reaction rate of radicals by cooling the substrate is widely used, and since there are many devices equipped with the mechanism, it is preferable to use them. Further, in this etching process, a periodic grating structure formed with gentle irregularities having a low aspect ratio can be obtained by mainly adjusting the bias power and using a so-called deposition gas depending on the situation.

For the periodic grating structure thus obtained, the average pitch C of the array of the periodic grating structures is obtained in the same manner as the above-described method for obtaining the average pitch B between the grains in the single particle film etching mask. C is almost the same value as the average pitch B of the used single particle film etching mask. Further, when an alignment shift D ′ (%) defined by the following formula (2) is obtained for this fine structure, the value is also 10% or less.
D ′ [%] = | C−A | × 100 / A (2)
However, in Formula (2), A is an average particle diameter of the particle | grains which comprise the used single particle film | membrane etching mask.

Even if the single particle film of the present invention has non-planar elements such as irregularities, slopes, and steps on the coating surface, it is possible to sufficiently follow the shape and coat the surface. Therefore, if necessary, it is possible to coat the surface of a material having a non-planar surface using such a property, and to create a periodic grating structure by the subsequent etching process. Due to such characteristics, the light emitting surface of the organic light emitting diode is not necessarily flat.

The periodic grating structure of the present invention can be replicated and produced by a nanoimprint method, a hot press method, an injection molding method, or a UV embossing method. In order to create a mold (mold or stamper) used in these replication techniques, for example, a metal layer is formed on the surface of the lattice structure by electroforming, and then the periodic lattice structure is made into a metal by peeling the metal layer. Create a negative mold transferred to the layer. If the shape is transferred using this mold by the nanoimprint method, the hot press method, the injection molding method, or the UV embossing method, the replica of the periodic grating structure of the present invention can be mass-produced efficiently.

  In the mold production process, as a method of forming the metal layer on the surface of the periodic grating structure, electroforming is preferable. Specifically, first, nickel, tungsten, copper, gold, silver, platinum, titanium, cobalt, tin, Electroless plating with one or more metals selected from zinc, chromium, gold / cobalt alloy, gold / nickel alloy, solder, copper / nickel / chromium alloy, tin / nickel alloy, nickel / palladium alloy, nickel / cobalt / phosphorus alloy, etc. Alternatively, a vacuum film forming method (sputtering or vapor deposition) is performed to form a conductive layer, and then an electrode is connected to the conductive layer, and electrolytic plating is performed with one or more metals selected from these metals, and the thickness of the metal layer is reduced. A method of increasing is preferable.

The thickness of the metal layer formed by electroless plating or vacuum film formation is preferably 10 nm to 100 nm, but generally about 50 nm. When the film thickness is set in this way, the uneven current density in the surface to be plated can be suppressed in the subsequent electrolytic plating process, and a mold having a uniform thickness can be easily obtained.
In the subsequent electrolytic plating, the thickness of the metal layer is finally increased to 10 to 5000 μm, generally about 300 μm, and then the metal layer is peeled off from the original plate. Although there is no restriction | limiting in particular in the current density in electroplating, Since generation | occurrence | production of a bridge | bridging can be suppressed and a uniform metal layer can be formed, and such a metal layer can be formed in a comparatively short time, it is 0.03-10A. / M ² is preferred.
Also, from the viewpoint of wear resistance as a mold and reworkability at the time of peeling / bonding, the material of the metal layer is preferably nickel, both for electroless plating or vacuum film formation performed first, and subsequent electrolytic plating It is preferable to employ nickel.
Actually, the mold is re-created from the first mold by electroforming, and this process is repeated to transfer the mold 2-3 times to mass-produce the mold for use in production. It is preferable.

  According to the structure transfer apparatus having the mold used in the nanoimprint method, the hot press method, the injection molding method, and the UV embossing method manufactured in this way, the shape of the periodic grating structure of the present invention is reproduced with high accuracy, and the dry etching method is used. A structural transfer body with inferior performance compared to the one directly processed is obtained. Of these four methods, nanoimprint method, hot press method, injection molding method, UV embossing method, and electroforming method, the nanoimprint method is most suitable for transferring a fine structure. The hot press method, injection molding method, and UV embossing method are characterized by high productivity. By combining the features of the above methods, it is possible to mass-produce replicas of the periodic grating structure of the present invention.

Of the four methods used for shape transfer, the nanoimprint method is particularly excellent for transferring a fine structure.
The basic operation of thermal imprinting was to maintain the high pressure, a process in which a softened resin follows the mold shape by bringing a thermoplastic resin into contact with the mold surface on which the periodic lattice structure is formed at a high temperature and high pressure higher than the Tg of the resin. The process consists of a step of cooling the thermoplastic resin to Tg or less as it is, a step of returning the pressure to normal pressure after cooling, and peeling the thermoplastic resin from the mold having a periodic lattice structure.
The basic operation of optical imprinting is a process in which a highly fluid photocurable resin is brought into contact with the mold surface on which the periodic grating structure is formed at room temperature and normal pressure to reduced pressure to cause the resin to follow the mold shape. It consists of a step of curing the resin by irradiating ultraviolet rays or ionizing radiation while maintaining the state following the mold shape, and a step of peeling the cured photocurable resin from the mold having a periodic lattice structure.
The basic operation of thermal + optical imprint is normal pressure to reduced pressure under a heating condition (a degree of fluidity of the resin) of a photocurable resin having low fluidity on the mold surface on which the periodic lattice structure is formed. The process of making the resin follow the mold shape by making contact with the resin, the step of curing the resin by irradiating the resin with ultraviolet rays or ionizing radiation while maintaining the state where the resin follows the mold shape, and the period of curing the photocurable resin It consists of a step of peeling from the mold having a lattice structure.

Since the plasmonic crystal of the present invention has a small aspect ratio, any of the above-described four methods can be used in practice for shape transfer. Among them, an injection molding method can be used as a highly productive method.
The basic operation of the injection molding method is to form a space with a molding die using a mold (stamper) with a periodic grating structure in part, and to inject and inject molten resin into the space at high speed and pressure. It consists of a step of following the resin to the mold shape, a step of cooling the injected resin together with the mold to lose fluidity, and developing a part of the mold to take out the molded product.

The anode conductive layer and hole injection layer are formed on the substrate regardless of whether the master of the periodic grating structure that is directly provided with a particle mask and produced by a dry etching process or the replica of the periodic grating structure that is produced by transferring the shape of the master is used. An organic light emitting diode element is fabricated by sequentially laminating a multilayer including at least three layers of an anode conductive layer, a light emitting layer, and a cathode conductive layer among a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode conductive layer. I can do it.
Regarding the hole injection layer, hole transport layer, light emitting layer, electron transport layer, and electron injection layer, one layer may serve two or more functions, or the hole transport layer and the electron transport layer may be omitted. . A light emitting layer is necessary as a place where holes and electrons meet. The simplest system need only have a light emitting layer sandwiched between an anode conductive layer and a cathode conductive layer.

A method for producing the anode conductive layer, hole injection layer, hole transfer layer, light emitting layer, electron transfer layer, electron injection layer, and cathode conductive layer used in the present invention is not particularly limited, but a general top emission organic light emitting diode is exemplified. The explanation is as follows. That is, the anode conductive layer and the cathode conductive layer are formed by a vacuum vapor deposition method or a sputtering method, and the hole injection layer, the hole transfer layer, the light emitting layer, the electron transfer layer, and the electron injection layer are formed by an organic vapor deposition method or a thin film coating method.
Since lamination of each layer is performed in order from a layer close to the base material, an anode conductive layer is first formed. In the case of a top emission organic EL, the anode conductive layer must be transparent, and therefore, a transparent conductive material such as ITO (Indium Tin Oxide), ZnO (Zinc Oxide), or ZTO (Zinc Tin Oxide) is selected.
Next, an aromatic amine compound or the like is formed as a hole injecting / moving layer. Aromatic amine compounds such as α-NPD and CuPc are most often used as hole transport materials because they have appropriate ionization potential and hole transport properties and are electrochemically reversible. Next, a light emitting layer is laminated. Examples of the material used alone for the light emitting layer include fluorescent dye compounds such as BBA and DTE, but holes and electron transport compounds may be doped with the fluorescent dye compound. It is preferable to use a phosphorescent material instead of a fluorescent material because the theoretical conversion efficiency is improved from about 25% to about 100%.
Next, an electron transport layer is laminated. As the electron transport layer, an oxadiol type (such as PBD) or a triazole type (such as TAZ) is used. Use of a metal complex (such as Alq3) substance is convenient because it can serve as both an electron transport layer and a light emitting layer.
Finally, a cathode conductive layer is laminated. The material for the cathode conductive layer is generally formed by laminating Al, Ag, an Al / Ag alloy or the like after adding a very small amount of LiF or Li-based compound.

  In the present invention, the periodic grating structure fabricated on the substrate generates diffracted light of the light emitted by EL, and creates a resonance state with the surface plasmon of the cathode. The light emitted from the organic EL element is directed toward the base material, which is the extraction surface, and the light emitted from the metal surface of the cathode, which cannot be extracted, but the light is temporarily transferred to the surface plasmon energy by the plasmonic crystal on the cathode surface. And then emitted as high-intensity radiation from the cathode surface toward the extraction surface. Radiant light emitted from the cathode surface has high directivity and can improve light extraction efficiency. For this purpose, the material of the cathode conductive layer is preferably a material having a high electron transport number and a low loss (a material having a low work function). Therefore, Ag, Au, or the like is selected, or Al or the like, which is generally selected. However, the material selection is not necessarily limited to these.

  In the case of a top-emitting organic light-emitting diode, an anode conductive layer is first formed on the structural surface side of a transparent substrate provided with a periodic lattice structure, followed by a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer. Then, an electron injection layer and a cathode conductive layer are sequentially laminated to complete. By this operation, the shape of the fine irregularities of the periodic grating structure is transmitted to the cathode conductive layer, and the cathode conductive layer has the shape of a plasmonic crystal. In order for the shape to be transmitted, the thickness of each layer needs to be as thin as possible. However, these layers of the organic light emitting diode are usually formed with a thickness of about 20 to 100 nm, and there is no problem.

Propagation type surface plasmon on a metal surface is a surface in which a polarization wave of free electrons generated by electromagnetic waves (such as visible light) incident on a conductor surface such as metal forms a transverse wave electric field on the surface. In the case of propagating surface plasmons existing on a flat metal surface, the propagating light cannot directly excite the plasmons because the propagating light dispersion line does not intersect the plasmon dispersion curve. However, if the metal surface has a periodic grating structure, the diffracted wave reflected by the grating crosses the dispersion curve of the plasmon, so the incident electromagnetic wave and the polarization wave of free electrons on the metal surface create a resonance state. be able to.
At this time, the wave number vector of the surface plasmon has the same value as the wave number of light, and the exciton (electron) and light are coherently coupled to form a state of exciton polariton. Therefore, polaritons are a state where free electron polarization waves and electromagnetic waves exchange energy by resonance. Since the surface plasmon has one wave vector when the pitch of the periodic grating structure is constant, the periodic grating structure is required to have high crystallinity.

The incident light energy is comparable to the excited plasmon. Thereafter, radiation occurs at an angle corresponding to the wave number vector of the surface plasmon. The width of the emission angle becomes narrower as the emission spectrum width becomes smaller. Therefore, the effect of improving the luminance of the organic light emitting diode by the surface plasmon includes an effect of extracting light emission energy that cannot be extracted by the surface plasmon mode, and an effect of obtaining radiation light having a fixed emission angle with respect to incident light at various angles. The latter effect helps to avoid the situation where the light emission energy is lost due to total reflection at the interface, such as the thin film mode and the substrate mode. Therefore, if the emission angle is controlled accurately, it greatly contributes to the improvement of extraction efficiency.

As described above, the single-particle film etching mask of the present invention is one in which the particles constituting the single-particle film are two-dimensionally closely packed and arranged with high precision. An accurate periodic grating structure can be manufactured, diffracted light can be obtained with high efficiency, and a high-luminance element can be obtained.
In order to improve the accuracy of the periodic grating structure, in the present invention, (1) using spherical particles, (2) making the particle size distribution as narrow as possible, and (3) super-monolayering on the water surface. The device is devised to promote close-packing by applying sonic irradiation, and (4) use the Langmuir-Blodgett method for particle coating on the substrate. Even if any of these elements is lost, it is difficult to create a highly accurate two-dimensional crystal mask, and the accuracy of the periodic grating structure cannot be increased.

An example of the embodiment of the present invention will be described below. As long as the concept of the present invention is used, the structure, configuration, and system of the target organic light emitting diode are not necessarily limited.
[Example 1]
A 5.0% by mass aqueous dispersion (dispersion) of spherical colloidal silica having an average particle size of 520.2 nm and a particle size variation coefficient of 3.2% was prepared. The average particle size and the coefficient of variation of the particle size were determined from the peak obtained by fitting the particle size distribution obtained by the particle dynamic light scattering method with Zetasizer Nano-ZS manufactured by Malvern Instruments Ltd to a Gaussian curve.
Next, this dispersion was filtered through a membrane filter having a pore size of 1.2 μmφ, and an aqueous solution of a hydrolyzate of phenyltriethoxysilane having a concentration of 1.0 mass% was added to the dispersion that passed through the membrane filter, and the mixture was heated at about 40 ° C. for 3 hours. Reacted. At this time, the dispersion and the aqueous hydrolysis solution were mixed so that the mass of phenyltriethoxysilane was 0.02 times the mass of the colloidal silica particles.
Subsequently, methyl ethyl ketone having a volume 5 times the volume of the dispersion was added to the dispersion after completion of the reaction, and the mixture was sufficiently stirred to extract the hydrophobized colloidal silica in the oil phase.

The thus obtained hydrophobized colloidal silica dispersion having a concentration of 1.05% by mass includes a surface pressure sensor for measuring the surface pressure of the single particle film, and a movable barrier for compressing the single particle film in a direction along the liquid surface. Was added dropwise at a dropping rate of 0.01 ml / sec to the liquid surface (water used as the lower layer water, water temperature 25 ° C.) in the water tank (LB trough device). In addition, a quartz substrate (4 inches in diameter, double-sided mirror polishing) for use as a transparent substrate of an organic light emitting diode was previously immersed in the lower layer water of the water tank in a substantially vertical direction.
Thereafter, ultrasonic waves (output 100 W, frequency 1500 kHz) are irradiated from the lower layer water toward the water surface for 10 minutes to promote the two-dimensional closest packing of the particles, while volatilizing methyl ethyl ketone, which is the solvent of the dispersion, A single particle film was formed.
Next, the single particle film was compressed by a movable barrier until the diffusion pressure became 22 to 29 mNm ⁻¹ , the quartz substrate was pulled up at a speed of 5 mm / min, and the single particle film on the water surface was transferred onto one surface of the substrate.
Next, a 0.4 mass% monomethyltrimethoxysilane hydrolyzate as a binder is infiltrated onto the quartz substrate on which the single particle film is formed, and then the excess hydrolyzate is treated with a spin coater (3000 rpm) for 1 minute. And removed. Then, this was heated at 100 degreeC for 10 minute (s), the binder was made to react, and the quartz substrate with the single particle film | membrane etching mask which consists of colloidal silica was obtained.

On the other hand, for this single particle film etching mask, a region of 10 μm × 10 μm is selected at random, and an atomic force microscope image of that portion is obtained. Then, this image is subjected to waveform separation by Fourier transform, and FFT is performed. I got a statue. Next, the distance from the 0th order peak to the 1st order peak in the profile of the FFT image was obtained, and the reciprocal thereof was also obtained. The inverse is the average pitch B ₁ between the particles in this region.
Such a process is similarly performed for a total of 25 regions of 10 μm × 10 μm, average pitches B _{1 to} B ₂₅ in each region are obtained, and an average value thereof is calculated as average pitch B in Formula (1). . At this time, each region was set so that adjacent regions were separated from each other by about 5 mm to 1 cm.
The calculated average pitch B was 527.3 nm as shown in Table 1.
Therefore, when the average particle diameter A = 520.2 nm and the average pitch B = 527.3 nm are substituted into the equation (1), the deviation D of the particle arrangement in the single particle film etching mask of this example is shown in Table 1. As shown in the figure, it was 1.36%.

Next, vapor phase etching was performed on the substrate with a single particle film etching mask using a mixed gas of CF ₄ : CH ₂ F ₂ = 25: 75 to 75:25. Etching conditions were an antenna power of 1500 W, a bias power of 50 to 300 W (13.56 MHz), and a gas flow rate of 30 to 50 sccm. The shape of the obtained fine structure was corrugated as shown in FIG. 3C. The average height h of the periodic lattice structure actually measured from the atomic force microscope image is 75.8 nm, and the average pitch C of the arrangement of the periodic lattice structure obtained by the same method as that used for the single particle film etching mask (the circular bottom surface) The average diameter d) was 524.5 nm and the aspect ratio calculated from these was 0.145. The average height h of the periodic grating structure was determined as follows. First, an atomic force microscope image is obtained for one 5 μm × 5 μm region randomly selected in the microstructure, then the diagonal of the image is drawn, and the average value of the maximum height of the protrusions where the diagonals intersect is calculated. Asked. Such a process was similarly performed on a total of 25 randomly selected 5 μm × 5 μm regions, and an average value in each region was obtained. An average height h was obtained by further averaging the average values in the 25 regions thus obtained.

On the side of the periodic grating structure surface of this quartz substrate, ITO was formed into a film having a thickness of 160 nm by a vacuum evaporation method as an anode conductive layer, and sintered in an electric furnace at 350 ° C. for 1 hour to obtain a transparent film. The surface resistance of the ITO film was 99Ω / cm. Next, α-NPD (manufactured by Chemipro Kasei Co., Ltd., melting point: 281.6 ° C.) as a hole transport material is formed into a film with a thickness of 40 nm by an organic vapor deposition method, and AlQ ₃ (manufactured by Chemipro Kasei Co., Ltd., melting point) as an electron transfer / light emitting layer. 420.4 ° C.) with a thickness of 70 nm by an organic vapor deposition method. Finally, Al / Ag was deposited as a cathode conductive layer with a thickness of 500 nm by vacuum vapor deposition to complete a top emission organic light emitting diode device.

When the obtained top-emitting organic light-emitting diode element was made to emit light at a voltage of 9.8 V, the average value of the emission intensity in the vertical direction ± 30 ° was measured with Genesia Co., Ltd., a scattering / light source measuring instrument GENESISA / GONIO However, ADU (Analog to Digital Unit) values as shown in Table 1 were obtained. The ADU is a coefficient of how many electrons are counted in one count when converting the amount of electrons accumulated in the CCD pixel into a digital amount, and is defined as ADU = Ns / Nc. However, the number of photoelectrons detected by the CCD is Ns, and the number of counts after AD conversion is Nc.

[Comparative Example 1]
An organic light-emitting diode element produced by exactly the same operation as in Example 1 was prepared except that the periodic grating structure was not produced on the quartz substrate. Therefore, the surface of the substrate of this element is flat. As in Example 1, when the average value of the emission intensity in the vertical direction ± 30 ° when light was emitted at a voltage of 9.8 V was measured, the ADU values shown in Table 1 were obtained.

[Comparative Example 2]
Organic light-emitting diode fabricated in exactly the same manner as in Example 1 except that the average pitch B of particles obtained by Fourier transform is 586.2 nm and the deviation D of the arrangement of particles is 12.71% (Table 1). An element was prepared. As in Example 1, when the average value of the emission intensity in the vertical direction ± 30 ° when light was emitted at a voltage of 9.8 V was measured, the ADU values shown in Table 1 were obtained.

以上の実施例1および比較例１、２の結果から、周期格子構造を高精度で作製した実施例１の方法による素子は、周期格子構造を持たない比較例１による素子に比べて、正面発光強度(垂直方向±３０°)において３倍以上の改善効果が得られた。
また、周期格子構造を持つがその配列精度が低いもの（比較例２）は、発光強度が低いことも確認された。したがって、本発明による周期格子構造を持つ基材上に作製した有機発光ダイオード素子は、外部量子効率の著しい改善効果があることが実証された。

From the results of Example 1 and Comparative Examples 1 and 2 described above, the element according to the method of Example 1 in which the periodic grating structure was manufactured with high accuracy was compared with the element according to Comparative Example 1 having no periodic grating structure. An improvement effect of 3 times or more was obtained in the strength (vertical direction ± 30 °).
It was also confirmed that the light emission intensity of the one having a periodic grating structure but low alignment accuracy (Comparative Example 2) was confirmed. Therefore, it was demonstrated that the organic light-emitting diode device manufactured on the base material having the periodic grating structure according to the present invention has a remarkable improvement effect on the external quantum efficiency.

The top view which shows typically a single particle film etching mask. Schematic which shows an example of the manufacturing method of a single particle film etching mask. An example (wave type) of the schematic diagram explaining the mode of periodic grating structure preparation by an etching. An example (comb shape) of the schematic diagram explaining the mode of periodic grating structure preparation by an etching. An example (saw shape) of the schematic diagram explaining the mode of periodic grating structure preparation by an etching.

Explanation of symbols

1 particle 2 lower layer water 3 single particle film 4 substrate 5 lower layer water 6 single particle film 7 substrate 8 moisture evaporation 9 particle 10 substrate

Claims (5)

At least an anode conductive layer on the substrate, the light emitting layer, the organic light emitting diode element fabricated by sequentially stacking a cathode conductive layer, Ri Do a particle monolayer, was added dropwise to a hydrophobic particle dispersion into the air-liquid interface dispersant The particles are self-organized by the transverse capillary force when volatilizing the particles and transferred to the substrate. The particles having the average particle diameter A are two-dimensionally packed 2 Light energy extraction efficiency using surface plasmon resonance on the surface of the cathode conductive layer with regular irregularities, using a substrate with a periodic grating structure with regular irregularities created by a dry etching method using a three- dimensional crystal as an etching mask characterized in that to improve, a plasmonic crystal surface-emitting body, a regular uneven created on the substrate which is defined by the following formula (2) Deviation D '(%) is plasmonic crystal surface-emitting material is not more than 10% of the sequence of the periodic grating structure that.
D ′ [%] = | C−A | × 100 / A (2)
(In the formula (2), A represents the average particle diameter of the particles, and C represents the average pitch of the array of periodic grating structures formed on the substrate.) In an organic light emitting diode device fabricated by sequentially laminating at least an anode conductive layer, a light emitting layer, and a cathode conductive layer on a substrate, it is composed of a particle single layer film, and a dispersion of hydrophobic particles is dropped onto a gas-liquid interface. A two-dimensional crystal in which particles with an average particle size of A, which are produced using the Langmuir-Blodgett method, self-assembled by transverse capillary force during volatilization and transferred to a substrate, are two-dimensionally packed closely. A periodic grating structure with regular irregularities created by dry etching using the body as an etching mask has a periodic grating structure replicated by any method selected from nanoimprinting, hot pressing, injection molding, and UV embossing Using a substrate to improve light energy extraction efficiency using surface plasmon resonance on the surface of the cathode conductive layer with regular irregularities A plasmonic crystal surface light emitter, characterized in that the deviation D ′ (%) of the periodic lattice structure due to the regular irregularities formed on the substrate defined by the following formula (2) is 10% or less A plasmonic crystal surface emitter.
D ′ [%] = | C−A | × 100 / A (2)
(In the formula (2), A represents the average particle diameter of the particles, and C represents the average pitch of the array of periodic grating structures formed on the substrate.) The plasmonic crystal surface light emitter according to claim 1 or 2, wherein the self-organization is performed under ultrasonic irradiation conditions. The image display apparatus which has at least one part the plasmonic crystal surface light-emitting body of any one of Claims 1-3. The illuminating device which has at least one part the plasmonic crystal surface light-emitting body of any one of Claims 1-3.

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