JP2013008563A - Organic el device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose an organic EL device capable of suppressing irregular light emission while compensating variation of droplet discharge amounts between nozzles with high accuracy.SOLUTION: An organic EL device includes a plurality of pixels 10-1, 10-2. Each of the pixels 10-1, 10-2 has three sub-pixels corresponding to three primary colors. Each of the sub pixels has an organic EL element emitting light corresponding to each of the three primary colors. Two sub pixels 10G-1, 10G-2 corresponding to the same color of adjacent two pixels 10-1, 10-2 are surrounded by a barrier 41 having repellent property against a liquid constitutional material of the organic EL element included in each of the two sub pixels 10G-1, 10G-2. A circuit element for driving the organic EL element is formed at a position overlapping with the barrier 41 in a plane as viewed from the travelling direction of light from the organic EL element.

Description

  The present invention relates to an organic EL device for full color display and a manufacturing method thereof.

  Organic EL elements are current-driven self-luminous elements, which eliminates the need for a backlight and offers the advantages of low power consumption, high viewing angle, and high contrast ratio, and are expected in the development of flat panel displays. Has been. The organic EL element includes a light emitting layer interposed between an anode and a cathode, and when a forward bias current is supplied, holes injected from the anode and electrons injected from the cathode are recombined. Self-emission occurs due to recombination energy. As a material for forming the organic light-emitting layer, any material that can emit light according to the energy level difference between the highest occupied orbital and the lowest unoccupied orbital when the injected holes and electrons move inside and recombine. Any of low molecular materials and high molecular materials can be used. Here, a low molecule means a molecule that does not have a repeating part due to polymerization in the structure, and a polymer means a polymer that has a repeating molecular structure. Since many low molecular weight materials have a rigid skeleton and many have low solubility in an organic solvent, a vapor phase method such as a vapor deposition method is preferably used for forming a low molecular organic light emitting layer. On the other hand, since many polymer materials have relatively high solubility in an organic solvent, a liquid phase method such as a droplet discharge method is preferably used for forming a polymer organic light-emitting layer. In the droplet discharge method, a light-emitting layer can be formed by applying droplets obtained by dispersing or dissolving a constituent material of a light-emitting layer in a solvent to each pixel and drying it. For example, Patent Document 1 discloses a method in which each of a red subpixel, a green subpixel, and a blue subpixel is separately formed by a droplet discharge method.

JP 2000-208254 A

  However, when an organic EL device is manufactured by the droplet discharge method, variations in the droplet filling amount between pixels due to variations in the droplet discharge amount between nozzles occur, causing streaky shading unevenness. It was. As a method for correcting variations in droplet discharge amount between nozzles, for example, a plurality of pixels are set as one filling unit, and the total filling amount of droplets discharged from a plurality of nozzles to one filling unit There is known a method of correcting so as to be uniform. In such a correction method, the larger the number of nozzles that discharge droplets in one filling unit, the higher the correction resolution. For the same standard, the larger the panel size, the coarser the resolution and the larger the pixel size. If the pixel size is increased, the number of nozzles that can be used per pixel increases, so that correction with higher resolution becomes possible. However, in the future, with the FHD standard in the class of 30 inches or less and 3D conversion, the resolution of pixels is expected to increase, and the conventional correction method that has obtained sufficient quality in the production of large screen panels There is concern that it will be difficult to maintain its quality in the future.

  Further, in the bottom emission method in which the light emission of the organic EL element is taken out from the substrate side, in order to correct the variation in the droplet discharge amount between the nozzles, if a structure in which a plurality of pixels are surrounded by one partition is adopted, the organic EL element is Depending on the arrangement location of a circuit element such as a transistor for driving, the light from the organic EL element is shielded, resulting in a problem that irregular light emission occurs.

  Accordingly, an object of the present invention is to propose an organic EL device capable of suppressing irregular light emission and a method for manufacturing the same, while accurately correcting variations in the droplet discharge amount between nozzles.

  In order to solve the above problems, the organic EL device according to the present invention includes a plurality of pixels, each pixel has three sub-pixels corresponding to the three primary colors, and each sub-pixel corresponds to the three primary colors. The organic EL element that emits light emits light, and two sub-pixels corresponding to the same color of two adjacent pixels repel the liquid constituent material of the organic EL element included in each of the two sub-pixels. The circuit element that is surrounded by the liquid partition and drives the organic EL element is formed at a position that overlaps the partition in plan view when viewed from the traveling direction of light from the organic EL element.

  According to such a pixel structure, two sub-pixels corresponding to the same color of two adjacent pixels are surrounded by the partition as one filling unit of the liquid constituent material of the organic EL element. The number of nozzles of the droplet discharge device that can be used per filling unit can be increased, and variations in droplet discharge amount between nozzles can be corrected with high resolution. In addition, since the circuit element for driving the organic EL element is formed at a position overlapping with the partition in plan view when viewed from the light traveling direction of the organic EL element, the light from the organic EL element is shielded by the circuit element. Can be prevented, and irregular light emission can be suppressed.

  The organic EL device preferably further includes a thin film for filling a step between adjacent pixel electrodes of two subpixels corresponding to the same color of two adjacent pixels. As a result, it is possible to prevent the light emitting layer of the organic EL element formed by the droplet discharge method from being cut off at the stepped portion and causing an electrical short circuit or being thinned and causing a decrease in light emission luminance.

  In the method for manufacturing an organic EL device according to the present invention, the liquid constituent material is ejected by a droplet ejection method to form a film.

  According to the organic EL device of the present invention, it is possible to suppress irregular light emission while correcting the variation in the droplet discharge amount between the nozzles with high accuracy.

1 is a circuit configuration diagram of an organic EL device according to Example 1. FIG. 3 is a plan view of a pixel structure according to Example 1. FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. 3 is a cross-sectional view of a pixel structure according to Example 1. FIG. 6 is a plan view of a pixel structure according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 7 is a cross-sectional view of a pixel structure according to Example 2. FIG. FIG. 10 is an explanatory diagram of an electronic device according to a third embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings. The same reference numerals denote the same members, and duplicate explanations are omitted.

  FIG. 1 is a circuit configuration diagram of an organic EL device 11 for full color display according to the first embodiment. The organic EL device 11 includes a plurality of scanning lines 12 connected to the scanning line driving circuit 16, a plurality of signal lines 13 connected to the signal line driving circuit 15 and extending in a direction intersecting each scanning line 12. A plurality of power supply lines 14 extending in parallel with each signal line 13 are wired. At the intersection of the scanning line 12 and the signal line 13, the switching transistor 21 to which the scanning signal from the scanning line 12 is supplied to its gate terminal is connected via the switching transistor 21 when the switching transistor 21 is on. A storage capacitor 22 that holds a pixel signal supplied from the signal line 13, a drive transistor 23 to which the potential of the storage capacitor 22 is supplied to its gate terminal, and the drive transistor 23 via the drive transistor 23 when the drive transistor 23 is on. An organic EL element 27 connected to the power line 14 is disposed. The organic EL element 27 includes a functional layer 26 between a pixel electrode (anode) 24 and a common electrode (cathode) 25. The functional layer 26 has a stacked structure of an electron transport layer / a light emitting layer / a hole transport layer / a hole injection layer.

  With the above circuit configuration, when the scanning signal is supplied from the scanning line 12 to the gate terminal of the switching transistor 21 and the switching transistor 21 is turned on, the pixel signal is supplied from the signal line 13 to the storage capacitor 22. The on / off state of the drive transistor 23 is determined according to the potential of the storage capacitor 22. When the drive transistor 23 is turned on, a drive current flows from the power supply line 14 to the organic EL element 27 through the channel of the drive transistor 23. . The organic EL element 27 emits light with a luminance corresponding to the drive current.

  Next, the pixel structure of the organic EL device 11 according to the first embodiment will be described with reference to FIGS. 2 is a plan view of the pixel structure, FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2, and FIG. 4 is a cross-sectional view of the pixel structure. However, for convenience of explanation, illustration of the functional layer 26 and the common electrode 25 is omitted in FIGS. 2 and 3. In Example 1, the organic EL device 11 employs a bottom emission method in which light emitted from the organic EL element 27 is extracted from the substrate side. The functional layer 26 of the organic EL element 27 is formed by a known droplet discharge method using the droplet discharge device 60.

  As shown in FIG. 2, two adjacent sets of pixels 10-1 and 10-2 are arranged at a constant pitch along two directions (in the example shown in FIG. 2, the X direction and the Y direction). Yes. The pixel 10-1 includes a green subpixel 10G-1, a red subpixel 10R-1, and a blue subpixel 10B-1 as subpixels corresponding to the three primary colors. Similarly, the pixel 10-2 includes a green subpixel 10G-2, a red subpixel 10R-2, and a blue subpixel 10B-2 as subpixels corresponding to the three primary colors. Each subpixel includes an organic EL element 27 that emits light corresponding to the three primary colors. Reference numerals 24G-1, 24R-1, and 24B-1 denote a pixel electrode of the green subpixel 10R-1, a pixel electrode of the red subpixel 10G-1, and a pixel electrode of the blue subpixel 10B-1, respectively. Similarly, reference numerals 24G-2, 24R-2, and 24B-2 denote a pixel electrode of the green subpixel 10R-2, a pixel electrode of the red subpixel 10G-2, and a pixel electrode of the blue subpixel 10B-2, respectively. . The pixel electrodes 24R-1, 24G-1, 24B-1, 24R-2, 24G-2, and 24B-2 are simply referred to as pixel electrodes 24 when it is not necessary to distinguish them.

  The droplet discharge device 60 forms the functional layer 26 by discharging droplets obtained by dispersing or dissolving the constituent material of the functional layer 26 in a solvent from each nozzle 61 and drying the droplets. According to the droplet discharge method, fine patterning can be performed easily and in a short time. In addition, the light emission ability such as the color balance and the luminance can be controlled easily and freely by adjusting the film thickness by adjusting the discharge amount or by adjusting the density. The droplet discharge device 60 is preferably capable of discharging minute droplets with high resolution by, for example, an electromechanical conversion method, a charge control method, a pressure vibration method, an electrothermal conversion method, or an electrostatic suction method.

  Two sub-pixels corresponding to the same color of two adjacent pixels 10-1 and 10-2 are grouped as one unit filled with the liquid constituent material of the functional layer 26, and the surrounding area is surrounded by the partition wall 41. Is enclosed. Specifically, a pair of green subpixels 10G-1 and 10G-2, a pair of red subpixels 10R-1 and 10R-2, and a pair of blue subpixels 10B-1 , 10B-2 are set as one unit for filling the liquid constituent material of the functional layer 26 for green, red, and blue, respectively. Further, in order to paint each pixel separately by the droplet discharge device 60, the sub-pixels of the same color of adjacent pixels are arranged in one direction (X direction in the example shown in FIG. 2). In this way, two sets of sub-pixels are combined into one unit that is filled with the liquid constituent material of the functional layer 26, so that one sub-pixel is used as a filling unit. Thus, the number of nozzles that can be used per filling unit can be increased, so that the correction resolution can be increased.

  For example, as shown in FIG. 3, a pair of green subpixels 10 </ b> G- 1 and 10 </ b> G- 2 is surrounded by a partition wall 41 as one filling unit. A pair of pixel electrodes 24G-1 and 24G-2 are exposed on the surface of the opening 41A surrounded by the partition wall 41. Each of the pixel electrodes 24G-1 and 24G-2 is formed on the surface of the interlayer insulating film 52 formed on the light transmissive substrate 51, and through the contact hole 52A opened in the interlayer insulating film 52, the interlayer insulating film 52 is formed. Are connected to a circuit element such as a driving transistor 23 embedded in the substrate. Assuming that the traveling direction of light from the organic EL element 27 is the −Z direction, the contact hole 52A is formed at a position overlapping the partition wall 41 in plan view when viewed from the ± Z direction. Although not shown in FIG. 3, circuit elements other than the drive transistor 23 (for example, the switching transistor 21, the storage capacitor 22, the scanning line 12, the signal line 13, and the power supply line 14) are also embedded in the interlayer insulating film 52. Similarly, these circuit elements are also formed at positions overlapping the partition walls 41 when viewed from the ± Z direction. With such a structure, the light from the organic EL element 27 can be prevented from being blocked by the circuit element.

  Referring to FIG. 2, the two contact holes 52A formed in the two subpixels corresponding to the same color of the two adjacent pixels 10-1 and 10-2 are formed between the two adjacent subpixels. It is arranged at a symmetrical position as the center.

  The material of the partition wall 41 is preferably an insulating film having appropriate heat resistance and solvent resistance. For example, the partition wall 41 is made of an organic or organic polymer containing polysilazane, polysiloxane, etc. An inorganic hybrid material or the like is preferable. As a method for forming the partition wall 41, an arbitrary method such as a lithography method or a printing method can be used. For example, when a lithography method is used, a layer made of the constituent material of the partition wall 41 is formed by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, and then patterned by etching, ashing, or the like. Good.

  FIG. 4 shows a cross-sectional structure in which the functional layer 26 and the cathode 25 are formed in the pixel structure shown in FIG. The functional layer 26 has a structure in which a hole injection layer 31, a hole transport layer 32, a light emitting layer 33, and an electron transport layer 34 are stacked. The light emitting layer 33 is preferably a high molecular organic compound or a low molecular organic compound made of an organic compound. By using an organic compound, surface emission with high luminance and low voltage can be enabled. In addition, the light emitting layer 33 can be rationally designed by a wide selection of light emitting materials. As the organic light emitting layer material, a polymer organic compound itself, a precursor of a conjugated polymer organic compound conjugated by heating or the like, a low molecular compound, or the like is used. In the case where a precursor or a low molecular weight compound before conjugation is used as a light emitting material, it is easy to adjust the surface tension, viscosity, etc. as the discharge liquid of the droplet discharge device 60, and precise patterning is possible. The light emission characteristics and film properties of 33 can be easily controlled.

  Examples of the organic compound that can form the light emitting layer 33 include PPV (poly (para-phenylene vinylene)) or a derivative thereof, polyalkylthiophene such as PTV (poly (2,5-thienylene vinylene)), PFV (poly ( 2,5-furylene vinylene)), polyarylene vinylene such as polyparaphenylene, polyalkylfluorene, pyrazoline dimer, quinolidinecarboxylic acid, benzopyrylium perchlorate, benzopyranoquinolidine, rubrene, phenanthroline europium complex These may be used, and these may be used alone or in combination of two or more.

  Further, PEDOT-TSS, TFB, and PBD may be used as the hole injection layer 31, the hole transport layer 32, and the electron transport layer 34, respectively. In addition, the surface of the partition wall 41 is provided with liquid repellency to the liquid material of the functional layer 26 by, for example, fluorine plasma treatment or the like, or is provided with liquid repellency when formed by photolithography. It is preferable that it is a partition wall. On the other hand, the surface of the pixel electrode 24 is preferably lyophilic with respect to the liquid material of the functional layer 26 by, for example, oxygen plasma treatment or UV ozone treatment. As a result, the landing performance of droplets on the subpixels grouped in pairs can be improved, and color mixing and filling defects can be suppressed. Liquid repellency means a property having a relatively large contact angle with the droplet, and lyophilic property means a property having a relatively small contact angle with the droplet. The contact angle can be adjusted by the applied voltage, applied frequency, processing time, processing gas partial pressure, etc. during plasma processing, oxygen partial pressure, processing time, UV type and illuminance during UV ozone processing.

  According to the first embodiment, two sub-pixels corresponding to the same color of two adjacent pixels 10-1 and 10-2 are surrounded by the partition wall 41 as one filling unit of the liquid constituent material of the functional layer 26. Therefore, the number of nozzles of the droplet discharge device 60 that can be used per one filling unit can be increased, and variations in the droplet discharge amount among the nozzles 61 can be corrected with high resolution. For example, when the resolution of the nozzle 61 of the droplet discharge device 60 is 360 ppi and the pixel pitch is higher than 60 ppi, the nozzle that can be used for one filling unit in the conventional technology in which one subpixel is one filling unit. However, according to the first embodiment, the number of nozzles that can be used per one filling unit is reduced to the number of nozzles that can be used. Since the number of droplet discharge amounts can be sufficient for high-resolution correction, variation in droplet discharge amount between nozzles can be corrected with high resolution.

  Further, according to the first embodiment, the circuit element for driving the organic EL element 27 is formed at a position overlapping the partition wall 41 in plan view as viewed from the traveling direction of the light from the organic EL element 27. The light from the organic EL element 27 can be prevented from being shielded by the circuit element, and irregular light emission can be suppressed.

  Next, the pixel structure of the organic EL device 11 according to the second embodiment will be described with reference to FIGS. 5 shows a plan view of the pixel structure, FIG. 6 shows a sectional view taken along line 6-6 in FIG. 5, and FIG. 7 shows a sectional view of the pixel structure. However, for convenience of explanation, illustration of the functional layer 26 and the common electrode 25 is omitted in FIGS. 5 and 6. FIG. 7 shows a cross-sectional structure in which the functional layer 26 and the cathode 25 are formed in the pixel structure shown in FIG. The organic EL device 11 according to the second embodiment includes a thin film 42 for filling a step between adjacent pixel electrodes 24 of two subpixels corresponding to the same color of two adjacent pixels 10-1 and 10-2. It differs from the organic EL device 11 according to the first embodiment in that it is provided, and is common in the remaining points. The thin film 42 is obtained, for example, by patterning an inorganic insulating film such as a silicon oxide film by a lithography method, and its surface is given lyophilicity to the liquid material of the functional layer 26 by, for example, oxygen plasma treatment. ing. By forming the thin film 24 for filling the step between the two adjacent pixel electrodes 24, the light emitting layer 33 formed by the droplet discharge method is cut off at the step portion, causing an electrical short circuit, Or it can suppress that it becomes thin and causes the fall of light-emitting luminance.

The electronic apparatus according to the third embodiment includes the organic EL device 11 according to the first and second embodiments as a display unit 500. Examples of electronic devices include a mobile phone 530, a video camera 540, a television 550, a roll-up television 560, as shown in FIG.
As shown in FIG. 9A, the cellular phone 530 includes an antenna portion 531, an audio output portion 532, an audio input portion 533, an operation portion 534, and a display portion 500.
As shown in FIG. 9B, the video camera 540 includes an image receiving unit 541, an operation unit 542, an audio input unit 543, and a display unit 500.
As illustrated in FIG. 9C, the television 550 includes a display portion 500.
As shown in FIG. 9D, the roll-up television 560 includes a display portion 500.

  In addition to the above, examples of the electronic apparatus according to the third embodiment include, for example, a fax machine with a display function, a digital camera finder, a portable TV, an electronic notebook, an electronic bulletin board, and an advertisement display.

10-1 ... Pixel area 10-2 ... Pixel area 10R-1 ... Red subpixel 10R-2 ... Red subpixel 10G-1 ... Green subpixel 10G-2 ... Green subpixel 10B-1 ... Blue subpixel 10B-2 ... Blue sub-pixel 11 ... Organic EL device 12 ... Scanning line 13 ... Signal line 14 ... Power supply line 15 ... Signal line driving circuit 16 ... Scanning line driving circuit 21 ... Switching transistor 22 ... Retention capacitor 23 ... Drive transistor 24R-1 ... Pixel Electrode 24R-2 ... Pixel electrode 24G-1 ... Pixel electrode 24G-2 ... Pixel electrode 24B-1 ... Pixel electrode 24B-2 ... Pixel electrode 25 ... Common electrode 26 ... Functional layer 27 ... Organic EL element 31 ... Hole injection layer 32 ... Hole transport layer 33 ... Light emitting layer 34 ... Electron transport layer 41 ... Partition wall 41A ... Opening 42 ... Thin film 51 ... Substrate 52 ... Interlayer insulating film 52A ... Contact 60: Droplet discharge device 61 ... Nozzle 500 ... Display unit 530 ... Mobile phone 531 ... Antenna unit 532 ... Audio output unit 533 ... Audio input unit 534 ... Operation unit 540 ... Video camera 541 ... Image receiving unit 542 ... Operation unit 543 ... voice input unit 550 ... television 560 ... roll-up television

Claims (3)

An organic EL device including a plurality of pixels,
Each pixel has three subpixels corresponding to the three primary colors,
Each sub-pixel has an organic EL element that emits light corresponding to the three primary colors,
Two subpixels corresponding to the same color of two adjacent pixels are surrounded by a liquid-repellent partition wall with respect to the liquid constituent material of the organic EL element included in each of the two subpixels.
The organic EL device, wherein the circuit element for driving the organic EL element is formed at a position overlapping with the partition in plan view when viewed from a traveling direction of light from the organic EL element. The organic EL device according to claim 1,
An organic EL device further comprising a thin film for filling a step between adjacent pixel electrodes of two subpixels corresponding to the same color.   3. The method of manufacturing an organic EL device according to claim 1, wherein the liquid constituent material is ejected by a droplet ejection method to form a film. Device manufacturing method.

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