Manufacturing method of organic electroluminescent element

The present invention relates to a method for manufacturing an organic electroluminescent device.

In recent years, with the diversification of information devices, there is an increasing need for a flat display element that consumes less power than a commonly used CRT (cathode ray tube). As one of such flat surface display elements, an organic electroluminescence (hereinafter abbreviated as organic EL) element having features such as high efficiency, thinness, light weight, and low viewing angle dependence has attracted attention, and this organic EL element has been referred to. Research and development of the display used is being actively carried out.

In the organic EL element, electrons and holes are injected into the light emitting portion from the electron injection electrode and the hole injection electrode, respectively, and the injected electrons and holes are recombined at the light emitting center to excite the organic molecule, and this organic molecule is excited. Is a self-luminous element that emits fluorescence when it returns from the excited state to the ground state. This organic EL element can change the emission color by selecting a fluorescent substance as a light emitting material, and expectations for its application to display devices such as multicolor and full color are increasing.

Generally, each layer of an organic EL device is formed by using a thin-film deposition method. In this thin-film deposition method, the crucible is first filled with an organic material, and then the organic material in the crucible is heated by a heater provided outside the crucible to evaporate the organic material and form an organic layer on the substrate. is there.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-247959</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-293122</text></patcit>

<p> However, the organic material filled in the crucible may deteriorate in characteristics due to being heated by the heater. It is possible to lower the heating temperature by the heater in order to prevent this deterioration, but lowering the heating temperature lowers the vapor deposition rate. As a result, the production efficiency in the production of the organic EL device is lowered.</p><p> An object of the present invention is to provide a method for manufacturing an organic electroluminescent device capable of improving production efficiency and mass productivity while preventing deterioration of the characteristics of an organic material.</p>

<p> The method for manufacturing an organic electroluminescence element according to the present invention is a method for manufacturing an organic electroluminescence element having an organic layer made of an organic material on a substrate, and a plurality of methods extending in the first direction and arranged substantially in parallel. A step of filling at least two crucibles with the same organic material, a step of heating two crucibles, and a second direction in which a plurality of crucibles and a substrate intersect each other in a relative first direction. It is equipped with a process of moving it to.</p><p> In the method for manufacturing an organic electroluminescent element according to the present invention, at least two crucibles out of a plurality of crucibles extending in the first direction and arranged substantially in parallel are filled with the same organic material. While the two crucibles are being heated, the plurality of crucibles and the substrate are moved in a second direction in which they intersect each other in the first direction relative to each other. Thereby, the organic layer can be uniformly formed on the entire surface of the substrate.</p><p> In this case, since at least two crucibles are filled with the same organic material, even if the heating temperature of the crucible is lowered, the organic material evaporates as compared with the case where the heating temperature is set higher using one crucible. The amount can be maintained equally. As a result, it is possible to improve the production efficiency and mass productivity of the organic electroluminescence device while preventing deterioration of the characteristics of the organic material.</p><p> The plurality of crucibles eject the vapor of the organic material with a predetermined spread around the set injection direction, and the injection directions of at least two crucibles are set so that the organic material is deposited in the common area of the substrate. May be good.</p><p> In this case, since the organic material can be ejected from at least two crucibles into a common region of the substrate, the thickness of the organic layer formed on the substrate can be uniformly controlled.</p><p> The organic material may include a rubrene-based material. Here, the rubrene-based organic material is liable to be deteriorated by heat. In this case, since the heating temperature for the organic material can be lowered, deterioration of the characteristics of the rubrene-based material can be prevented.</p>

<p> According to the present invention, it is possible to improve the production efficiency and mass productivity of an organic electroluminescence device while preventing deterioration of the characteristics of an organic material.</p>

Hereinafter, a method for manufacturing an organic electroluminescence device according to the present embodiment will be described.

FIG. 1 is a perspective view for explaining a method for manufacturing an organic electroluminescence device according to an embodiment of the present invention. Hereinafter, the organic electroluminescence element is abbreviated as an organic EL element.

In FIG. 1, the three directions orthogonal to each other are the X direction, the Y direction, and the Z direction. The X and Y directions are parallel to the surface of the substrate 50 forming the organic layer, and the Z direction is perpendicular to the surface of the substrate 50.

As shown in FIG. 1, in the method for manufacturing an organic EL device according to the present embodiment, a plurality of crucibles 10, 11 and 12 are used. The plurality of crucibles 10, 11 and 12 are arranged so as to face the surface of the substrate 50 on which the organic layer is to be formed. In FIG. 1, a plurality of crucibles 10, 11 and 12 are arranged in parallel below the substrate 50.

As shown in FIG. 1, the plurality of crucibles 10, 11 and 12 have an elongated box shape extending in the Y direction. A convex portion extending in the Y direction is formed on the upper surface of the plurality of crucibles 10, and a plurality of organic material ejection holes 20 are formed on the upper surface of the convex portion. Similarly, in the crucibles 11 and 12, a convex portion extending in the Y direction is formed on the upper surface thereof, and a plurality of organic material ejection holes 21 and 22 are formed on the upper surface of the convex portion.

Next, FIG. 2 is a schematic cross-sectional view for explaining the organic material ejection hole 20 formed in the convex portion of the crucible 10 of FIG. 1, and FIG. 3 is a schematic cross-sectional view formed in the convex portion of the crucible 11 of FIG. FIG. 4 is a schematic cross-sectional view for explaining the organic material ejection hole 21, and FIG. 4 is a schematic cross-sectional view for explaining the organic material ejection hole 22 formed in the convex portion of the crucible 12.

As shown in FIG. 2, the crucible 10 is composed of a U-shaped container 1, and a lid portion 2 having an organic material ejection hole 20 is formed in the opening of the container 1. The container 1 and the lid 2 may be formed integrally or as separate bodies. The organic material ejection hole 20 formed in the lid 2 ejects the organic material within a spread angle θ1 centered on the injection direction 30 toward the ejection target point P. Here, the ejection target point P indicates the central point of the region where the organic material evaporates or sublimates from the crucible 10 and is deposited on the substrate 50. Further, the organic material ejection hole 20 formed in the lid portion 2 is provided so that the injection direction 30 is inclined by an angle θ10 with respect to the Z axis.

Similarly, the crucible 11 shown in FIG. 3 is composed of a U-shaped container 1, and a lid portion 2a having an organic material ejection hole 21 is formed in the opening of the container 1. The organic material ejection hole 21 formed in the lid portion 2a ejects the organic material within a spread angle θ1 centered on the injection direction 30 toward the ejection target point P. Further, the organic material ejection hole 21 formed in the lid portion 2a is provided so that the injection direction 30 is parallel to the Z axis, that is, perpendicular to the substrate 50.

Further, the crucible 12 shown in FIG. 4 is composed of a U-shaped container 1, and a lid portion 2b having an organic material ejection hole 22 is formed in the opening of the container 1. The organic material ejection hole 22 formed in the lid portion 2b ejects the organic material within a spread angle θ1 centered on the injection direction 30 toward the ejection target point P. Further, the organic material ejection hole 22 formed in the lid portion 2b is provided so that the injection direction 30 is inclined by an angle -θ12 with respect to the Z axis.

Next, FIG. 5 is a schematic diagram showing the positional relationship between the substrate 50 of FIG. 1 and the plurality of crucibles 10, 11 and 12.

As shown in FIG. 5, the target ejection point P indicates the central point of the length L1 of the region of the organic material deposited by the crucibles 10, 11 and 12. The above-mentioned angles θ10 and θ12 are determined by the position of the target ejection point P, the distance H between the substrate 50 and the crucible 10, 11 and 12, the distance L3 between the crucible 10 and the crucible 11, and the distance L4 between the crucible 11 and the crucible 12. Will be done.

Therefore, by setting the angles θ10 and θ12 to the optimum values, the organic material ejected from the crucibles 10, 11 and 12 is uniformly deposited in the common region of the substrate 50.

Next, a method of forming an organic layer on the surface of the substrate 50 will be described.

First, organic materials are filled inside the crucibles 10, 11 and 12 shown in FIGS. 2, 3 and 4 (not shown). Here, for example, the crucible 11 and the crucible 12 are filled with the same organic material. Details of the organic material to be filled will be described later.

Next, the crucibles 10,11,12 are heated by a heater (not shown) provided in the crucibles 10,11,12. The heat evaporates or sublimates the organic material filled in the crucibles 10, 11 and 12.

At this time, the crucibles 10, 11 and 12 reciprocate in the X direction at a constant speed with respect to the substrate 50. The moving speed is preferably 5 mm / sec or more and 10 mm / sec or less. As a result, the evaporated or sublimated organic material is uniformly deposited on the substrate 50, and an organic layer is formed on the surface of the substrate 50.

In this case, since the crucibles 11 and 12 are filled with the same organic material, even if the heating temperature of the heater is lowered, the organic material evaporates as compared with the case where the heating temperature is set higher using one crucible. The amount can be maintained equally. As a result, it is possible to improve the production efficiency and mass productivity of the organic electroluminescence device while preventing deterioration of the characteristics of the organic material.

In the present embodiment, the crucibles 10, 11 and 12 are moved with respect to the substrate 50 at a constant speed, but the present invention is not limited to this, and the crucibles 10, 11 and 12 are moved at a constant speed only in one direction. It may be moved by, or the crucibles 10, 11 and 12 may be moved and stopped intermittently.

Further, in the present embodiment, the crucibles 10, 11 and 12 are moved, but the present invention is not limited to this, and the substrate 50 may be moved with the crucibles 10, 11 and 12 fixed. ..

Next, FIG. 6 is a schematic structural diagram of the organic EL device formed by the manufacturing method according to the present embodiment.

As shown in FIG. 6, the organic EL element 600 includes a substrate 50, an anode (hole injection electrode) 51, a hole injection layer 52, a hole transport layer 53, a light emitting layer 54, an electron transport layer 55, and a cathode (electron injection electrode) 56. It has a laminated structure containing in order.

A transparent anode 51 is formed on the substrate 50. Indium tin oxide (hereinafter abbreviated as ITO) is used as the material for the anode 51. In addition to ITO, tin oxide (SnO)₂) Or indium oxide (In₂O₃) Etc. are used. A hole injection layer 52 made of an organic material and a hole transport layer 53 made of an organic material are formed so as to cover the anode 51.

As a material for the hole injection layer 52, 4,4'4 "-tris (N- (2-naphthyl) -N-phenyl-amino) -triphenylamine (4,) having a molecular structure represented by the following formula (1) 4'4 "-Tris (N- (2-naphthyl) -N-phenyl-amino) -triphenylamine: hereinafter abbreviated as 2TNATA) is used.

<chemistry num="1"><img file="JP2005293968A_D0001.tif" /></chemistry>

Further, as a material for the hole transport layer 53, N, N'-di (naphthalene-1-yl) -N, N'-diphenyl-benzidine (N, N'-) having a molecular structure represented by the following formula (2) Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: hereinafter abbreviated as NPB) and the like are used.

<chemistry num="2"><img file="JP2005293968A_D0002.tif" /></chemistry>

A light emitting layer 54 made of an organic material is formed on the hole transport layer 53. The material of the light emitting layer 54 is NPB, which is a host material and has a molecular structure represented by the above formula (2), and 5,12-bis (4- (4- (4-( 6-Methylbenzothiazol-2-yl) phenyl) -6,11-diphenylnaphthacene (5,12-Bis (4- (6-methylbenzothiazol-2-yl) phenyl) -6,11-diphenylnaphthacene: hereafter, DBzR (Abbreviated as) etc. are used. Here, DBzR is a rubrene derivative (rubrene-based material).

<chemistry num="3"><img file="JP2005293968A_D0003.tif" /></chemistry>

Further, an electron transport layer 55 is formed on the light emitting layer 54. As a material for the electron transport layer 55, Tris (8-hydroxyquinolinato) aluminum having a molecular structure represented by the formula (4) (hereinafter abbreviated as Alq) or the like is used.

<chemistry num="4"><img file="JP2005293968A_D0004.tif" /></chemistry>

Further, as the material of the cathode 56, MgIn alloy (ratio 10: 1) or the like is used.

The crucibles 10, 11 and 12 described above are used for forming the light emitting layer 54 of the organic EL element 600 described above. In this case, the crucible 10 is filled with NPB, and the crucibles 11 and 12 are filled with DBzR. Here, the rubrene-based organic material is liable to be deteriorated by heat.

In this case, since the crucibles 11 and 12 are filled with the same rubrene-based organic material (DBzR), even if the heating temperature of the heater is lowered, compared with the case where the heating temperature is set higher using one crucible. Therefore, the amount of evaporation of the rubrene-based organic material can be maintained at the same level. As a result, it is possible to improve the production efficiency and mass productivity of the organic electroluminescence device while preventing deterioration of the characteristics of the rubrene-based material.

In the present embodiment, the organic EL element 600 having a back emission structure that extracts light from the anode 51 has been described, but the present invention is not limited to this, and the present invention is an organic EL device having a top emission structure that extracts light from the cathode 56 side. It can also be applied to elements.

Further, in the present embodiment, the case where the crucibles 10, 11 and 12 are used has been described, but the present invention is not limited to this, and any plurality of crucibles may be used.

Further, in the present embodiment, the organic material ejection holes 20 of the crucible 10 and the organic material ejection holes 22 of the crucible 12 are inclined at angles θ10 and θ12, but the present invention is not limited to this, and the crucible 10 and the crucible 12 itself are not limited to this. May be tilted at angles θ10 and θ12.

(Other examples of the positional relationship between the board and the plurality of crucibles) Next, as another configuration example of the positional relationship between the substrate 50 and the plurality of crucibles 10, 11, 12, crucible 13 was used instead of the crucible 10. An example will be described. FIG. 7 is a schematic cross-sectional view of the crucible 13, and FIG. 8 is a schematic view showing the positional relationship between the substrate 50 and the plurality of crucibles 11, 12 and 13.

In FIGS. 7 and 8, the three directions orthogonal to each other are the X direction, the Y direction, and the Z direction. The X and Y directions are parallel to the surface of the substrate 50 forming the organic layer, and the Z direction is perpendicular to the surface of the substrate 50.

As shown in FIG. 7, the crucible 13 is composed of a U-shaped container 1, and a lid portion 2c having an organic material ejection hole 23 is formed in the opening of the container 1. The organic material ejection hole 23 formed in the lid portion 2c ejects the organic material within a spread angle θ1 with respect to the ejection target point P. Further, the organic material ejection hole 23 formed in the lid portion 2c is provided so as to be inclined by an angle -θ13 with respect to the Z axis.

Then, as shown in FIG. 8, the target ejection point P indicates the central point of the length L1 of the region of the organic material deposited by the crucibles 11, 12 and 13. The above-mentioned angles θ12 and θ13 are determined by the position of the target ejection point P, the distance H between the substrate 50 and the crucibles 11, 12 and 13, the distance L4 between the crucible 11 and the crucible 12, and the distance L5 between the crucible 12 and the crucible 13. Will be done.

Therefore, by setting the θ12 and θ13 to the optimum values, the organic materials ejected from the crucibles 11, 12 and 13 are uniformly deposited in the common area of the substrate 50.

Hereinafter, in the examples, the organic EL device shown in FIG. 6 was manufactured by using the method for manufacturing the organic EL device according to the present embodiment. Further, in the comparative example, the organic EL device was manufactured by using the conventional method for manufacturing the organic EL device. Hereinafter, details of Examples and Comparative Examples will be described.

(Example) In the example, a substrate 50 having a size of 500 mm × 350 mm was used. A plurality of crucibles 10, 11 and 12 were provided at positions 200 mm below the substrate 50.

The distance L3 between the crucible 10 and the crucible 11 in the embodiment is 100 mm, the distance L4 between the crucible 11 and the crucible 12 is 100 mm, the length L2 in the X direction of the substrate 50 is 500 mm, and the angle θ10 of the crucible 10 is 45 degrees. The angle θ12 of the crucible 12 was set to -45 degrees. The length L1 of the region is 400 mm.

First, the anode 51 was formed on the glass substrate 50 by the sputtering method. The substrate 50 on which the anode 51 was formed was washed with a neutral detergent and pure water, and then baked at a predetermined temperature for a predetermined time. Then, UV / 03 cleaning was performed, and the mixture was set in a reduced vacuum vapor deposition apparatus.

Next, the crucible (not shown) was filled with 2TNATA. Then, the hole injection layer 52 was formed on the anode 51 by heating the crucible. Next, the inside of the crucible (not shown) was filled with NPB. Then, by heating the crucible, the hole transport layer 53 was formed on the hole injection layer 52.

Subsequently, the inside of the crucible 10 in FIG. 1 was filled with NPB, which is a host material, and the inside of the crucibles 11 and 12 was filled with DBzR, which is a red light emitting dopant.

Then, the crucibles 10, 11 and 12 were heated by the heater while moving in one direction (X direction) at a constant speed (10 mm / sec). In the examples, the heating temperature by the heater was set to about 320 ° C. Then, the light emitting layer 54 was formed on the hole transport layer 53.

The crucible (not shown) was then filled with Alq. Then, the electron transport layer 55 was formed on the light emitting layer 54 by heating the crucible. Further, Al was formed as a cathode to prepare an organic EL device.

(Comparative Example) In the comparative example, at the time of forming the light emitting layer, the inside of the crucible 10 was filled with NPB which is a host material, and the inside of the crucible 11 was filled with DBzR which is a red light emitting dopant. In this case, crucible 12 is not used.

In addition, the heating temperature by the heater was set to 340 ° C. Regarding other conditions, an organic EL device was produced in the same manner as in the examples.

(Evaluation) Luminous efficiency, CIE (Comission International d'Eclairage) chromaticity coordinate CIE, drive voltage and luminance half-life of the organic EL element produced in Examples and Comparative Examples were measured. The measurement results are shown in Table 1.

In Table 1, the measurement results of each characteristic of the organic EL device of the example and the comparative example were standardized with each measurement result of the comparative example as 1, and each standardized measurement result is shown.

<tables num="1"><img file="JP2005293968A_D0005.tif" /></tables>

In addition, x is the horizontal axis of the CIE chromaticity coordinates, and y is the vertical axis of the CIE chromaticity coordinates.

As shown in Table 1, the luminous efficiency of the organic EL element produced in the example was 2.14 times the luminous efficiency of the organic EL element produced in the comparative example.

Further, in the organic EL device manufactured in the comparative example, light having a target chromaticity was not generated due to deterioration of the organic material constituting the organic EL device. On the other hand, in the organic EL device produced in the examples, light having a target chromaticity was generated.

The drive voltage of the organic EL element produced in the example was 1.05 times the drive voltage of the organic EL element produced in the comparative example.

The brightness half-life of the organic EL device manufactured in the examples was 10 times the brightness half-life of the organic EL device manufactured in the comparative example.

Based on the above, when the same organic material is filled in the crucibles 11 and 12 and the heating temperature of the crucibles 11 and 12 is set low, when one crucible is filled with the organic material and the heating temperature of the crucible is set high. Compared with, the light emitting characteristics of the organic EL element were improved.

The present invention can be used for various display devices, various light sources, and the like.

<figref num="1">It is a perspective view for demonstrating the manufacturing method of the organic electroluminescence element which concerns on this embodiment.</figref><figref num="2">It is a schematic cross-sectional view for demonstrating the organic material ejection hole formed in the convex part of the crucible of FIG.</figref><figref num="3">It is a schematic cross-sectional view for demonstrating the organic material ejection hole formed in the convex part of the crucible of FIG.</figref><figref num="4">It is a schematic cross-sectional view for demonstrating the organic material ejection hole formed in the convex part of a crucible.</figref><figref num="5">It is a schematic diagram which shows the positional relationship between the substrate of FIG. 1 and a plurality of crucibles.</figref><figref num="6">It is a schematic structural drawing of the organic EL element formed by the manufacturing method which concerns on this embodiment.</figref><figref num="7">It is a schematic cross-sectional view of a crucible.</figref><figref num="8">It is a schematic diagram which shows the positional relationship between a substrate and a plurality of crucibles.</figref>

Code description

10, 11, 12 Crucibles 20, 21, 22 Organic material ejection holes 50 Substrate 51 Anode (hole injection electrode) 52 Hole injection layer 53 Hole transport layer 54 Light emitting layer 55 Electron transport layer 56 Cathode (electron injection electrode) 600 Organic EL element