JP2007227289A - Electrooptic device, method of manufacturing same and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrooptic device capable of performing uniform light emission from a pixel area, to provide a method of manufacturing the electrooptic device, and to provide an electronic device. <P>SOLUTION: An EL substrate 113 of an organic EL display device 1 that is the electrooptic device comprises a plurality of pixel areas 7 with a predetermined solution applied thereto, which is surrounded by a lyophilic sidewall surface 5c of a bank 5 formed on a surface of the EL substrate 113 in a regulated height. The sidewall surface 5c has an inclination such that the area of a face parallel to the EL substrate 113 within the pixel area 7 is sequentially reduced from the EL substrate 113 side to the height direction of the bank 5. Namely, the sidewall surface 5c has a reversed tapered shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electro-optical device having a structure in which a thin film such as a light-emitting layer is formed in a pixel region surrounded by a bank, a method for manufacturing the electro-optical device, and an electronic apparatus equipped with the electro-optical device.

  2. Description of the Related Art Conventionally, an organic EL (Electro Luminescence) element used in an organic EL display device that is an electro-optical device is a droplet state of ink (solution) containing an organic EL material from an inkjet head to each of pixel regions partitioned by banks. The light emitting layer was formed by the ink jet method that is discharged in the above. At that time, the ink jet head discharges the ink to the pixel region in a plurality of times, and consideration is given to the light emitting layer in each pixel region having a uniform film thickness. Furthermore, in a plurality of times of ink ejection, the ejected ink is dried before the next ink ejection, or the size of the ejected droplet, the composition of the ink, the ink concentration, etc. The film thickness was prevented from becoming non-uniform. The hole transport layer was similarly formed by an inkjet head (for example, Patent Document 1).

  FIG. 5 is a cross-sectional view showing a conventional general organic EL display device. The organic EL display device 100 includes a glass substrate 101, a plurality of switching elements 102 formed on one surface of the glass substrate 101, an insulating layer 103 formed so as to cover the switching elements 102, and an insulating layer 103 A plurality of pixel electrodes 104 electrically connected to the switching element 102, a bank 105 including an inorganic bank 105 a and an organic bank 105 b formed between the plurality of pixel electrodes 104, and the pixel electrode 104. It has a hole transport layer 106, a light emitting layer 107 formed on the hole transport layer 106, and a counter electrode 108 provided so as to cover the light emitting layer 107 and the bank 105. Further, a sealing substrate 109 is disposed to face the counter electrode 108, and an inert gas 110 is sealed between the counter electrode 108 and the sealing substrate 109.

  In such a configuration, when the red, blue, and green light emitting layers 107 are formed in the pixel region 111 partitioned by the bank 105 by an inkjet method, the organic EL display device 100 capable of color display is obtained. In this case, the side wall surface 105 c of the bank 105 forms an obtuse angle that is perpendicular to the pixel electrode 104 or inclined outward from the pixel region 111. Further, the side wall surface 105 c is formed in ink-philicity, and the ink applied to the pixel region 111 wets and spreads to the side wall surface 105 c and spreads over the entire pixel region 111. Note that a portion constituted by the pixel electrode 104, the bank 105, the hole transport layer 106, the light emitting layer 107, and the counter electrode 108 corresponds to the organic EL element 112, and is constituted by the glass substrate 101, the switching element 102, and the insulating layer 103. An EL substrate 113 is configured.

Japanese Patent Laid-Open No. 2001-291583

  However, according to the conventional technique, due to the affinity of the bank 105, the ink spreads the side wall surface 105c of the bank 105 due to surface tension, and the ink surface is drawn near the bank 105 in the pixel region 111. Make a curve. Therefore, a phenomenon has occurred in which the ink thickness in the vicinity of the bank 105 is different from the ink thickness in the central portion of the pixel region 111. In this phenomenon, the thickness of the ink thickness in the vicinity of the bank 105 and the ink thickness in the central portion of the pixel region 111 is decreased as the amount of ink discharged each time from the inkjet head is reduced and the film thickness is reduced. The difference in thickness can be reduced, but the thickness difference has not yet been resolved. Therefore, strictly speaking, the ink thickness in the pixel region 111 becomes non-uniform, and there remains a problem that uniform light emission cannot be performed from the light emitting layer 107 in the pixel region 111.

  In order to solve the above problems, an object of the present invention is to provide an electro-optical device, a method for manufacturing the electro-optical device, and an electronic apparatus that can emit light uniformly from a pixel region.

  The electro-optical device of the present invention includes a bank formed on the surface of the substrate, and a pixel region defined by the bank, and the opening diameter on the bank surface side of the pixel region is equal to that of the bank on the substrate side of the pixel region. It is smaller than the opening diameter, and the side wall surface of the bank has an inclination so that the area of the surface parallel to the substrate in the pixel region becomes gradually smaller from the substrate side toward the specified height direction. It is characterized by.

  According to this electro-optical device, the side wall surface of the bank that defines the size of the pixel region is inclined toward the inner side of the pixel region at an acute angle with respect to the substrate. That is, the inclination of the side wall surface has a so-called reverse taper shape. In an electro-optical device, a predetermined solution is usually applied to a pixel region surrounded by a side wall surface. The applied solution is drawn into the acute angle portion formed by the substrate and the side wall surface of the reverse taper by the capillary phenomenon and spreads over the entire pixel region. At this time, when viewed from above, a curved portion having a film thickness due to the influence of the solution and the side wall portion is generated in the area on the side wall surface side of the reverse taper from the opening diameter on the bank surface side. However, the display by the pixel region is not affected by the curved portion because it uses the opening diameter on the bank surface side, which is a smooth surface from the central portion of the pixel region where the curved portion is subsided to the vicinity of the side wall surface. Thereby, the film of the solution applied to the opening diameter on the bank surface side of the pixel region has a uniform film thickness with respect to the substrate. Therefore, if this solution film is dried, the surface of the substrate It is possible to form a functional film having a substantially uniform thickness. For example, if the electro-optical device is of a type that transmits and transmits light that has passed through the functional film, the electro-optical device may be of a type that can obtain transmitted light that is not colored and the functional film emits a predetermined color. In this case, light of emission color having no brightness level can be obtained.

  In this case, the inclination of the side wall surface is preferably substantially uniform with respect to the substrate at any position surrounding the pixel region.

  According to this configuration, the inclination that is the reverse taper of the side wall surface is substantially the same angle in the entire peripheral region surrounding the pixel region. In the solution applied to the pixel region surrounded by such a side wall surface, the force drawn by the capillary phenomenon to the acute angle portion formed by the substrate and the side wall surface becomes uniform in any direction. Furthermore, the curved portion with respect to the side wall surface of the solution is also uniform in the entire peripheral region, and coupled with the uniform pulling force due to capillary action, the surface of the solution from the central portion of the pixel region to the vicinity of the side wall surface becomes a smoother surface. Become. Since a film of such a solution can be formed, it is possible to provide an electro-optical device having transmitted light with no colored shading and light with a luminescent color without intensity.

  The pixel region preferably includes a stack of a light emitting layer and a hole transport layer, and at least the side wall surface of the bank is preferably lyophilic.

  According to this configuration, a predetermined display can be performed by emitting light from each of the plurality of pixel regions having the light emitting layer and the hole transport layer. In addition, since the light-emitting layer emits light from the pixel region, external light is unnecessary and display that is not easily affected by external light is possible. Furthermore, since at least the side wall of the bank is lyophilic, the solution that forms the light emitting layer and the hole transport layer is attracted to the bank and easily spreads over the entire pixel region surrounded by the bank.

  The method of manufacturing an electro-optical device according to the present invention includes a step of forming a negative resist as a material for forming a bank for defining a pixel region on a substrate, and a mask alignment so that the region to be the bank is exposed. A step of exposing the negative resist, and a step of developing the negative resist with a developer. The conditions for exposing the negative resist are closer to the substrate of the negative resist than to the vicinity of the surface of the negative resist. Is characterized by being easily developed with a developer.

  According to this method of manufacturing an electro-optical device, the substrate side of the negative resist is more easily developed with the developer than the surface of the negative resist, so that the substrate side is developed more than the surface side. The Accordingly, the negative resist surface defining the bank side wall surface is formed in a taper shape. According to this method, it is possible to easily form a bank having a tapered shape only by development.

  In this case, the opening diameter on the bank surface side of the pixel region is formed so as to be smaller than the opening diameter of the bank on the substrate side of the pixel region, and the side wall surface of the bank is an area of a plane parallel to the substrate in the pixel region. Is preferably formed so as to have a slope that gradually decreases from the substrate side toward the specified height direction.

  According to this method, the side wall surface of the bank that defines the size of the pixel region is inclined toward the inner side of the pixel region at an acute angle with respect to the substrate, and has a so-called reverse taper shape. In the electro-optical device, a predetermined solution is applied to the pixel region surrounded by the side wall surface, and the solution is drawn into the acute angle portion formed by the substrate and the side wall surface of the reverse taper by a capillary phenomenon, so that the entire region of the pixel region is drawn. Spread out. In this case, when viewed from above, a curved portion having a film thickness due to the influence of the solution and the side wall portion is generated in the area of the side wall surface having a reverse taper than the opening diameter on the bank surface side. However, since the display by the pixel area uses the opening diameter on the bank surface side which is a smooth surface from the center of the pixel area where the curved part is subsided to the vicinity of the side wall surface, it is not affected by the curved part. Can provide a uniform display.

Hereinafter, embodiments of the electro-optical device according to the invention will be described with reference to the drawings. In the embodiment, an organic EL (Electro Luminescence) display device capable of color display will be described as an example of the electro-optical device.
(Embodiment)

  FIG. 1 is a cross-sectional view showing a substrate structure of an organic EL display device of the present invention. In the part of the reference numerals in FIG. 1, the same reference numerals are assigned to the parts common to the conventional organic EL display device shown in FIG. Further, FIG. 1 mainly shows an organic EL element portion which is a point of the present invention. As shown in FIG. 1, the organic EL display device 1 includes a plurality of pixel electrodes 104 formed on the surface of an EL substrate (substrate) 113, and an inorganic bank 5 a and an inorganic bank formed between the plurality of pixel electrodes 104. And a bank 5 composed of an organic bank 5b formed so as to overlap with 5a. The bank 5 is formed so as to surround each of the pixel electrodes 104, and a region surrounded by the bank 5 is a pixel region 7.

  The organic EL display device 1 includes a hole transport layer 2 formed over the pixel electrode 104 in the pixel region 7, a light emitting layer 3 formed over the hole transport layer 2, and a light emitting layer 3. And the counter electrode 4 provided so as to cover both the organic bank 5 b of the bank 5. Further, a sealing substrate 109 is disposed at a position facing the counter electrode 4, and the light emitting functions of the light emitting layer 3 and the hole transport layer 2 are deteriorated by adsorption of moisture or the like between the counter electrode 4 and the sealing substrate 109. In order to prevent this, an inert gas 110 is enclosed.

Note that a portion constituted by the pixel electrode 104, the bank 5, the hole transport layer 2, the light emitting layer 3, and the counter electrode 4 is the organic EL element 6. In detail, as shown in FIG. 5, the EL substrate 113 is formed so as to cover the glass substrate 101, a plurality of switching elements 102 formed on one surface of the glass substrate 101, and the switching elements 102. is a an insulating layer 103 of S _i O _2, a was, the switching element 102 is electrically connected to the pixel electrode 104 formed on the insulating layer 103 of the EL substrate 113.

  In the organic EL display device 1 having such a configuration, the pixel electrode 104 is a transparent electrode serving as an anode formed of ITO (Indium Tin Oxide), and the counter electrode 4 includes aluminum (Al), silver (Ag), The cathode is formed of a metal such as calcium (Ca), magnesium (Mg), and lithium (Li). Here, Ca / Al is used to form Ca with a thickness of 20 nm and Al with a thickness of 150 nm. Both the pixel electrode 104 and the counter electrode 4 were formed by vapor deposition. A glass substrate was used as the sealing substrate 109.

The inorganic bank 5a formed between the pixel electrodes 104 is formed to a thickness of 40 nm using T _i O ₂ , S _i O ₂ or the like. In the organic EL display device 1, T _i O ₂ was formed on the EL substrate 113 and the pixel electrode 104 by vapor deposition, and only the portion of the pixel electrode 104 forming the hole transport layer 2 was removed by etching. . The thickness (height) of the bank 5 was formed to 2 μm together with the organic bank 5b.

  The side wall surface 5c of the organic bank 5b forms an acute angle with respect to the EL substrate 113, and is inclined toward the inner side of the pixel region 7 in a so-called reverse taper shape. That is, in the pixel region 7, the EL substrate 113 of the light emitting layer 3 stacked on the hole transport layer 2 is larger than the area parallel to the EL substrate 113 of the hole transport layer 2 positioned on the EL substrate 113 side. The area parallel to is smaller. The formation of the organic bank 5b will be described later with reference to FIG.

  Each pixel region 7 of the organic EL display device 1 has a configuration capable of emitting any one of red, green, and blue by the hole transport layer 2 and the light emitting layer 3. Therefore, as a constituent material (hole transport material) of the hole transport layer 2, in this case, in any pixel region 7, polytetrahydrothiophenylphenylene was used and formed to a thickness of 90 nm. The constituent material (organic EL material) of the light emitting layer 3 is cyanopolyphenylene vinylene that emits red light when excited to the pixel region 7 that emits red light, and polyphenylene that emits green light when excited to the pixel region 7 that emits green light. Using vinylene, a pixel region 7 that emits blue light was formed to a thickness of 40 nm using a mixed material of polyalkylphenylene and polyphenylene vinylene that emits blue light when excited.

  In the pixel electrode 104, the hole transport layer 2, the light emitting layer 3, and the counter electrode 4 formed in the pixel region 7, when charge is applied by the switching element 102 so that the pixel electrode 104 becomes an anode and the counter electrode 4 becomes a cathode, Holes are injected into the light emitting layer 3 from the hole transport layer 2 on the anode side, and electrons are injected into the light emitting layer 3 from the cathode side. In the light emitting layer 3, the injected holes and electrons are combined, and the organic molecules of the light emitting layer 3 are excited by the binding energy generated when the holes are combined to emit one of red, green, and blue. The emitted light is emitted from the organic EL display device 1 through the EL substrate 113 from the light emitting region 8 formed in the pixel electrode 104 after the inorganic bank 5a is removed by etching. In this case, the emitted light becomes more uniform as the hole transport layer 2 and the light emitting layer 3 have a uniform thickness, with no color shading and brightness.

  Therefore, it is desirable that the hole transport layer 2 and the light emitting layer 3 which are the main components of the light emission are formed by discharging a solution containing a constituent material from the ink jet head of the ink jet apparatus to the pixel region 7 and drying after the discharge. . The ink jet apparatus can discharge the solution from the ink jet nozzle in a fine droplet state, and can uniformly arrange the solution in accordance with any shape of the pixel region 7. Therefore, once the solution is applied to the pixel region 7 and the bank 5 and the unnecessary portion is removed, the solution is not consumed wastefully, and the expensive solution can be used efficiently. . Regarding the formation of the hole transport layer 2 and the light emitting layer 3 by the ink jet device, the case of the bank 5 having the reverse tapered side wall surface 5c and the bank 105 having the non-reverse tapered side wall surface 105c of the present invention is compared. Next, a description will be given.

  FIG. 2A is a cross-sectional view showing film formation of a solution in a reverse taper bank. FIG. 2B is a cross-sectional view showing the film formation of the solution in the non-inverted taper bank. As shown in FIG. 2A, the organic bank 5b has a reverse-tapered side wall surface 5c and a sealing surface 5d. The side wall surface 5c is subjected to lyophilic treatment and sealed. The stop surface 5d is subjected to a liquid repellent treatment. FIG. 2A shows a case where the hole transport layer 2 is formed in the pixel region 7 surrounded by the side wall surface 5 c of the bank 5 by the inkjet device 10. The hole transport layer 2 must be uniformly formed in the opening 20 (opening diameter of the bank on the substrate side) 20 of the pixel electrode 104 from which the inorganic bank 5a has been removed by etching. Here, the opening 20 defines the size of the light emitting region 8.

  The hole transport layer 2 is formed by first moving the ink jet head 11 of the ink jet apparatus 10 to the position of the pixel region 7 and ejecting fine droplets 12 of the solution forming the hole transport layer 2 from the ink jet head 11. To do. The ejected liquid droplets 12 land on the inorganic bank 5a and the opening 20 of the pixel electrode 104, and spread over the entire pixel region 7 after landing. The solution (droplet) that has reached the side wall surface 5c is drawn in by a pulling force 15 due to capillary action in the direction of the bank base portion 14 formed by the side wall surface 5c and the inorganic bank 5a at an acute angle. Therefore, the solution can easily spread and fill in the vicinity of the side wall surface 5 c of the pixel region 7 which is difficult to fill, and the hole transport layer 2 can be filled in the entire region of the pixel region 7.

  In addition, since the solution is wetted along the lyophilic side wall surface 5c, the contact portion of the solution with the side wall surface 5c becomes curved due to surface tension, and the contact portion becomes thick. However, since the side wall surface 5c has a reverse taper, the distance from the bank base 14 on the inorganic bank 5a to the opening 20 can be set longer than in the case of the side wall surface 105c that is not a reverse taper. In addition, the curved portion can be prevented from being applied to the opening 20. Then, the solution is drawn into the side wall surface 5c by capillary action, so that the pixel region 7 is sufficiently filled with the solution, and the surface 13 of the solution at the center of the opening 20 becomes a stable and smooth surface. That is, the hole transport layer 2 formed in the opening 20 has a uniform thickness.

  Thus, the hole transport layer 2 is formed by discharging droplets of the solution that forms the hole transport layer 2 to the pixel region 7 surrounded by the side wall surface 5c having the reverse taper, thereby forming a uniform thickness. Hole transport layer 2 is obtained. If the ejection of the solution by the inkjet device 10 is divided into a plurality of times and the amount of the solution ejected at one time is reduced, the influence of the curved portion is reduced and the hole transport layer 2 having a more uniform thickness can be obtained. . Similarly, the light emitting layer 3 can be uniformly formed by being laminated on the hole transport layer 2. Since the hole transport layer 2 and the light emitting layer 3 are formed to have a uniform thickness in the opening 20, the light emitted from the opening 20 has no color shade and brightness intensity. The thickness of each part of the hole transport layer 2 and the light emitting layer 3 could be formed with an error within ± 5%.

  As a reference, the case where the side wall surface 5c of the bank 5 is not reversely tapered will be briefly described. The bank 105 shown in FIG. 2B is the one of the organic EL display device 100 shown in FIG. In the same manner as described with reference to FIG. 2A, first, the droplet 12 of the solution that forms the hole transport layer 106 is discharged from the inkjet head 11 to the pixel region 111. The discharged liquid droplet 12 lands on the opening 115 of the pixel electrode 104, and after landing, spreads over the entire region of the pixel region 111 and gets wet along the lyophilic side wall surface 105c. The contact portion becomes curved due to surface tension. At this time, the side wall surface 105c is not reversely tapered like the side wall surface 5c described with reference to FIG. 2A, and therefore, the wetting and spreading to the side wall surface 105c due to surface tension is greater than when the side wall surface 105c is reversely tapered. Accordingly, the curvature of the curved portion increases. As a result, the surface 16 of the solution in the opening 115 is also likely to be curved, and it is difficult to obtain a smooth solution surface 16.

  This tendency is caused by dividing the discharge of the solution by the ink jet apparatus 10 into a plurality of times, and even if the amount of the solution discharged at one time is reduced, the influence of the curved portion cannot be eliminated, and the uniform thickness can be corrected. It is difficult to obtain the hole transport layer 106. Similarly, it is difficult to uniformly form the light-emitting layer 107 formed by being stacked on the hole transport layer 106. Therefore, the light emitted from the opening 115 is likely to be non-uniform in which color shades and brightness levels are generated.

  Next, a method of forming the organic bank 5b having the reverse tapered side wall surface 5c will be described. In the present embodiment, the organic bank 5b is formed using a photolithography method. FIG. 3 is a cross-sectional view showing a process of forming a reverse-tapered bank, and FIG. 3A is a cross-sectional view showing formation of a negative resist in the process of forming a reverse-tapered bank. FIG. 3B is a cross-sectional view showing an exposure process for a reverse taper bank, and FIG. 3C is a cross-sectional view showing a development process for a reverse taper bank. The organic bank 5b having the side wall surface 5c is formed to overlap the inorganic bank 5a after the pixel electrode 104 and the inorganic bank 5a are formed on the surface of the EL substrate 113.

  The organic bank 5b having the side wall surface 5c is formed by first applying a negative resist 21 by spin coating so as to be laminated on the pixel electrode 104 and the inorganic bank 5a as shown in FIG. Baked in (step of forming a negative resist). Here, as the negative resist 21, TELR-N101PM manufactured by Tokyo Ohka Kogyo Co., Ltd. having propylene glycol and monoethyl ether acetate was used.

  Next, as shown in FIG. 3B, a glass mask (mask) 22 is set so as to cover the negative resist 21, and the negative resist 21 is exposed to ultraviolet rays (exposure step). The glass mask 22 has a light shielding part 22a and a transmission part 22b. The light shielding part 22a blocks exposure light, and the transmission part 22b transmits exposure light. The negative resist 21 undergoes a cross-linking reaction in the transmitting portion 22b exposed to ultraviolet rays, and is polymerized and cured. This is the exposure part 23 of the negative resist 21. On the other hand, no crosslinking reaction occurs in the blocking part 22a where the ultraviolet rays are not exposed. The negative resist 21 is dissolved by development with a developer described later, but the exposed portion 23 cured by exposure is not dissolved by development. That is, the exposure part 23 becomes the organic bank 5b. Before the exposure, it is necessary to adjust the alignment of the glass mask 22 so that the transmission portion 22b of the glass mask 22 is positioned on the portion of the negative resist 21 where the organic bank 5b is formed (mask alignment). Process).

  At this time, the exposure conditions are set so that the shape of the exposure portion 23 of the negative resist 21 is a so-called reverse tapered shape. In order to change the shape of the exposed portion 23 to an inversely tapered shape, the exposed portion of the negative resist 21 on the glass mask 22 side has an exposure amount sufficient to sufficiently bridge the negative resist 21, and the inorganic bank 5a. On the other hand, the degree of cross-linking of the negative resist 21 is lowered to some extent. In other words, the negative resist 21 in the vicinity of the transmissive portion 22b is exposed to the entire width in the direction parallel to the EL substrate 113 to become the exposed portion 23, but the portion closer to the inorganic bank 5a side of the negative resist 21 is exposed. It is hard to be done and the degree of cross-linking is lowered. Furthermore, on the inorganic bank 5a side of the exposure part 23, the closer to the non-exposure part of the light shielding part 22a than the central part of the transmission part 22b, the smaller the amount of exposure and the lower the degree of crosslinking. That is, the general shape of the exposure part 23 is a substantially inverted triangle with the transmission part 22b portion of the glass mask 22 as the base and the inorganic bank 5a side as the apex direction.

  After the predetermined exposure part 23 is obtained, as shown in FIG. 3C, the unexposed negative resist 21 is developed and removed (developing step). As the developer, NMD-W alkaline developer manufactured by Tokyo Ohka Kogyo Co., Ltd. was used. Thus, the shape of the organic bank 5b having the reverse-tapered side wall surface 5c by the negative resist 21 is formed. In this state, since the hardness and strength of the bank 5 are not sufficient, the negative resist 21 can be exposed (post-exposure) and main baking, and can be used as the bank 5 in terms of hardness and strength. Organic bank 5b is obtained.

  A pixel region 7 is formed by the bank 5 having the inversely tapered side wall surface 5c formed in this manner, and a solution for forming the hole transport layer 2 and the light emitting layer 3 in the pixel region 7 is formed by the ink jet device 10 respectively. Is done. At that time, the solution that forms the hole transport layer 2 or the light emitting layer 3 can be attracted to the side wall surface 5c by the capillary phenomenon generated by the reverse-tapered side wall surface 5c, and can be uniformly arranged over the entire pixel region 7. It is. For this reason, the solution can be easily disposed even in a corner portion of the bank 5 where the solution is difficult to be filled, and it is not necessary to restrict the shape of the pixel region 7.

  Specifically, FIG. 4A is a plan view showing the shape of a pixel region in a reverse-tapered bank. This plan view shows the pixel region 7 shown in FIG. It is a thing. As shown in FIG. 1, the bank 5 shown in FIG. 4A has a side wall surface 5 c having a reverse taper shape, and the corner portion of the pixel region 7 can be easily filled with the solution, and is surrounded by the bank 5. The shape of the pixel region 7 is almost free of restrictions. Therefore, as shown in FIG. 4A, the shape of the pixel region 7 can make the corner portion R extremely small so that the opening 20 is maximized. Along with this, the opening 20 can also be set large, and the organic EL display device 1 having the pixel region 7 has a large amount of light emitted from the light emitting region 8 and has a bright display.

  On the other hand, FIG. 4B is a plan view showing the shape of the pixel region in the non-inverse tapered bank. In this plan view, the pixel region 111 shown in FIG. 5 is viewed from the direction of the sealing substrate 109. In the bank 105 shown in FIG. 4B, as shown in FIG. 5, the side wall surface 105c has a non-inverted taper shape, and it is difficult to fill the solution in the vicinity of the side wall surface 105c, and the thickness of the solution is not uniform. It is easy to become. Therefore, the shape of the pixel region 111 surrounded by the bank 105 is desirably a round shape as much as possible. At least, the corner portion R of the pixel region 111 needs to be sufficiently rounded as shown in FIG. With such consideration, the pixel region 111 can be filled with a solution. In this case, the area of the pixel region 111 becomes smaller and the opening 115 becomes smaller as the shape of the pixel region 111 with the rounded corner portion R becomes larger. The organic EL display device 100 having the pixel region 111 has a light emitting region due to the small opening 115 and the non-uniform emission due to the nonuniform thickness of the hole transport layer 106 and the light emitting layer 107. The amount of light radiated from 114 is small and the display becomes dark.

  Therefore, in the organic EL display device 100 having the pixel region 111, if a similar brightness is to be displayed, an excessive charge is applied to the hole transport layer 106 and the light emitting layer 107 to give a load of 120%, for example. It is necessary to emit light. In this case, problems such as a short emission lifetime occur. In the organic EL display device 1 having the pixel region 7 formed by the inversely tapered side wall surface 5c of the present invention, the hole transport layer 2 and the light emitting layer 3 are uniform in thickness, and charge is applied without load. Since the predetermined light emission is possible, there is an advantage that uniform light emission of the light emitting portion can be performed, the total light emission efficiency is good, and the light emission life is long.

  The embodiment of the present invention has been described above. Below, the effect of embodiment is described collectively.

  (1) Since the bank 5 of the organic EL display device 1 has the side wall surface 5c having a reverse taper, the amount of wetting of the solution with respect to the side wall surface 5c is reduced, and the solution is applied to the side wall surface 5c which is difficult to fill. Coupled with the force drawn by capillary action, the solution can be formed with a uniform thickness over the entire pixel region 7. Thereby, if the film of this solution is dried, it is possible to form the hole transport layer 2 or the light emitting layer 3 having a uniform thickness. The organic EL display device 1 has the intensity of brightness and brightness. Light emission without any is possible.

  (2) By discharging the solution to the pixel region 7 by the ink jet device 10, the solution can be uniformly applied to the entire region of the pixel region 7, and discharged by the action of the bank 5 having the reverse tapered side wall surface 5 c. In combination with the smoothing of the surface 13 of the solution, the hole transport layer 2 or the light emitting layer 3 having a more uniform thickness can be formed.

  (3) The organic bank 5b is formed by applying, exposing, developing, and baking the negative resist 21, so that the organic bank 5b having the reverse tapered side wall surface 5c is substantially the same as the conventional non-reverse tapered bank 105. It can be easily formed by a simple process.

  (4) The side wall surface 5c of the organic bank 5b has a reverse taper, and can easily be filled into a square-shaped portion that is difficult to fill with a solution by capillary action. It can be formed into a shape. Therefore, the opening 20 can be set as large as possible, and bright light emission with a large amount of light from the light emitting region 8 is possible.

  (5) In the organic EL display device 1, the thicknesses of the hole transport layer 2 and the light emitting layer 3 in the opening 20 are uniform over the entire region, and uniform light emission is possible from the entire region of the opening 20. When the hole transport layer 2 and the light-emitting layer 3 have non-uniform thickness and dark light emission, the load transport layer 2 and the light-emitting layer 3 are subjected to measures such as increasing the load of charges and obtaining bright light emission. The device 1 has the advantages that predetermined light emission is possible by applying an electric charge without overload, the light emission part can emit light uniformly, the total light emission efficiency is good, and the light emission life is long.

  (6) The side wall surface 5c of the organic bank 5b is subjected to a lyophilic process, and the sealing surface 5d is subjected to a liquid repellent process. Accordingly, even when the droplet 12 is discharged on the sealing surface 5d by the inkjet device 10, the droplet 12 is reliably applied to the pixel region 7 without remaining due to the liquid repellency of the sealing surface 5d. The solution discharged from the inkjet device 10 as the droplet 12 is not disposed wastefully outside the pixel region 7, and an expensive solution can be effectively used.

  Further, the present invention is not limited to the above-described embodiment, and the same effects as those of the embodiment can be obtained even in the form of the following modification.

  (Modification 1) The pixel region 7 is not limited to the structure having the light emitting function by the hole transport layer 2 and the light emitting layer 3 of the organic EL display device 1, but has a light emitting function such as a color filter used in a liquid crystal display device or the like. A filter layer that does not have a filter layer may be formed. The aperture of the filter layer can be set large, and a bright filter layer with good light transmittance can be obtained.

  (Modification 2) The pixel electrode 104 is not limited to the configuration in which the pixel electrode 104, the hole transport layer 2, the light emitting layer 3, and the counter electrode 4 are formed in this order from the EL substrate 113 side in the pixel region 7, but the pixel electrode 104 is a reflective electrode. Alternatively, light may be emitted in the direction of the sealing substrate 109 by forming the pixel electrode 104, the hole transport layer 2, the light emitting layer 3, and the counter electrode 4 in this order from the sealing substrate 109 side. It is possible to provide the organic EL display device 1 that can flexibly cope with the device to be incorporated.

  (Modification 3) The material which comprises the positive hole transport layer 2 and the light emitting layer 3 is not limited to the constituent material as described in embodiment. For example, as another example, 1,1-bis-cyclohexane is used as the hole transport layer 2 to the pixel region 7 that emits red light, and 2-13,4-dihydroxy that emits red light when excited as the light emitting layer 3. Phenyl-3,5,7-trihydroxy-1-benzobililium perchlorate is used. To the pixel region 7 that emits green light, 1,1-bis-cyclohexane is used as the hole transport layer 2 and 2,3,6,7-tetrahydro-11 oxo-, which emits green light when excited as the light-emitting layer 3. 1H, 5,11H-benzopyrano-quinolizine-10-carboxylic acid is used. Then, to the pixel region 7 that emits blue light, 8-hydroxyquinolinol aluminum is used as the hole transport layer 2, and 2,3,6,7-tetrahydro-9-methyl that emits blue light when excited as the light emitting layer 3. -11-oxo-1H, 5H, 11H-benzopyrano-quinolidine may be used. The constituent material is not limited to this example.

  (Modification 4) The bank 5 is not limited to the configuration of the inorganic bank 5a and the organic bank 5b, but only the configuration of the organic bank 5b having a reverse taper or the configuration of only the inorganic bank 5a having a reverse taper. There may be.

  (Modification 5) The hole transport layer 2 and the light emitting layer 3 are most effective when the solution is ejected by the ink jet apparatus 10, but the solution may be applied by a dispenser or the like.

  An organic EL display device that emits light only when the pixel region 7 is necessary does not need to always irradiate the entire pixel region with a light source, including a pixel region that is not displayed like a liquid crystal display device, and is very energy saving. The organic EL display device having a reverse-tapered bank of the present invention can display brighter and better in color, and is optimal for display units of electronic devices such as mobile phones, electronic dictionaries, digital cameras, and electronic watches. It has a wide range of applications.

Sectional drawing which shows the board | substrate structure of the organic electroluminescence display of this invention. (A) Cross-sectional view showing film formation of solution in bank with reverse taper, (b) Cross-sectional view showing film formation of solution in non-reverse taper. 5A is a cross-sectional view showing the formation of a negative resist in a reverse-tapered bank forming process, FIG. 5B is a cross-sectional view showing the reverse-tapered bank exposure process, and FIG. 5C is a cross-sectional view showing the reverse-tapered bank development process. (A) The top view which shows the shape of the pixel area in the bank of reverse taper, (b) The top view which shows the shape of the pixel area in the bank of non-inverse taper. Sectional drawing which shows the conventional common organic electroluminescent display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Organic EL display device as an electro-optical device, 2 ... Hole transport layer, 3 ... Light emitting layer, 4 ... Counter electrode, 5 ... Bank, 5c ... Side wall surface, 6 ... Organic EL element, 7 ... Pixel region, 8 DESCRIPTION OF SYMBOLS ... Light-emitting region, 11 ... Inkjet head, 12 ... Droplet, 13 ... Solution surface, 14 ... Bank base, 15 ... Retraction force, 20 ... Opening as opening diameter of bank on substrate side, 21 ... Negative resist, 22 DESCRIPTION OF SYMBOLS ... Glass mask, 23 ... Curing part, 101 ... Glass substrate, 102 ... Switching element, 103 ... Insulating layer, 104 ... Pixel electrode, 105 ... Bank, 106 ... Hole transport layer, 107 ... Light emitting layer, 108 ... Counter electrode, DESCRIPTION OF SYMBOLS 109 ... Sealing substrate, 110 ... Inert gas, 111 ... Pixel region, 113 ... EL substrate as a substrate, 114 ... Light emission region, 115 ... Opening part.

Claims (9)

A bank formed on the surface of the substrate;
A pixel region defined by the bank,
An electro-optical device, wherein an opening diameter of the pixel area on the bank surface side is smaller than an opening diameter of the bank on the substrate side of the pixel area. The electro-optical device according to claim 1,
A side wall surface of the bank has an inclination such that an area of a surface parallel to the substrate in the pixel region is gradually reduced from the substrate side toward the specified height direction. An electro-optical device. The electro-optical device according to claim 2,
The electro-optical device according to claim 1, wherein the inclination of the side wall surface is substantially uniform with respect to the substrate at any position surrounding the pixel region. The electro-optical device according to any one of claims 1 to 3,
The electro-optical device, wherein the pixel region has a stack of a light emitting layer and a hole transport layer. The electro-optical device according to any one of claims 2 to 4,
At least the side wall surface of the bank is lyophilic.   An electronic apparatus comprising the electro-optical device according to any one of claims 1 to 5. Forming a negative resist as a material for forming a bank for defining a pixel region on a substrate;
Aligning the mask so that the area to be the bank is exposed;
Exposing the negative resist;
Developing the negative resist with a developer,
The method for manufacturing an electro-optical device is characterized in that the negative resist exposure condition is such that the vicinity of the negative resist substrate is more easily developed with the developer than the vicinity of the negative resist surface. A method for manufacturing the electro-optical device according to claim 7,
An electro-optical device manufacturing method, wherein an opening diameter of the pixel area on the bank surface side is smaller than an opening diameter of the bank on the substrate side of the pixel area. A method for manufacturing the electro-optical device according to claim 7,
A side wall surface of the bank is formed so as to have an inclination such that an area of a plane parallel to the substrate in the pixel region gradually decreases from the substrate side toward the specified height direction. A method for manufacturing an electro-optical device.

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