JP6492713B2 - EL display device - Google Patents

Description

  The present invention relates to an EL display device including a plurality of pixels that emit different light emission colors.

  As an example of the EL display device described above, for example, in the EL display device described in Patent Document 1, a part of the light generated by the EL element is converted into surface plasmon on the cathode surface of the EL element and consumed as heat. The Such conversion from surface plasmon to heat is one of the factors that lower the extraction efficiency of light generated by the EL element. In recent years, in the above-described EL display device, in order to increase the light extraction efficiency, it has been proposed to form a fine concavo-convex structure which is a repetition of fine concavo-convex on the cathode surface. The fine concavo-convex structure formed on the cathode surface converts surface plasmon into plasmon light and emits it from the cathode surface (see, for example, Patent Documents 2 and 3).

JP2013-118182A JP 2004-031350 A JP 2009-158478 A

  By the way, unlike an illumination device that emits light of a single color, an EL display device emits light of different colors from pixels of different light emission colors. For example, a red light emitting pixel emits red light, a green light emitting pixel emits green light, and a blue light emitting pixel emits blue light. A control unit included in the EL display device controls the luminance of light with respect to pixels having different emission colors, and expresses a full-color image on a surface from which light is extracted.

  As described above, an EL display device having a fine concavo-convex structure converts surface plasmon into plasmon light at the interface between the cathode and the EL layer. At this time, in a configuration in which adjacent pixels have one common electrode, the plasmon light converted by the fine concavo-convex structure propagates between the pixels through one common electrode between the pixels. As a result, color mixing, which is a phenomenon in which different colors are mixed, is likely to occur in a plurality of adjacent pixels.

  An object of the present invention is to provide an EL display device that can suppress color mixture between adjacent pixels in an EL display device including a plasmonic structure.

  An EL display device for solving the above-described problems is common to each of the plurality of pixels, a pixel definition wall that divides a display surface into a plurality of pixel regions, pixels located in each of the plurality of pixel regions, and A common electrode. Each of the plurality of pixels includes a lower electrode located in the pixel region and an EL layer located in the pixel region and covering the lower electrode. The common electrode covers the EL layer and the pixel definition wall, and one of the lower electrode and the common electrode is a cathode having an interface in contact with the EL layer. The interface includes a plasmonic structure in which a mode pitch is set so as to excite plasmon light included in a wavelength band of emitted light. In the height direction with respect to the lower electrode, the side surface is covered by the EL layer up to the middle of the side surface of the pixel defining wall, and the height of the pixel defining wall is higher than the height of the EL layer. large.

  In the EL display device, a portion of the side surface of the pixel definition wall covered by the EL layer may have a curved surface shape having a curvature that is convex toward the pixel definition wall.

In the EL display device, the lower electrode includes a lower electrode surface that is in contact with the EL layer, and an angle formed between a side surface of the pixel definition wall and the lower electrode surface is 30 ° or more and 60 ° or less. May be.
In the EL display device, a side surface of the pixel definition wall may be a smooth surface.

  In the EL display device, the common electrode is a cathode, the lower electrode is an anode having a periodic uneven structure, and the EL layer has an uneven shape following the uneven structure, The plasmonic structure may be a structure reflecting the uneven shape of the EL layer.

  According to the EL display device of the present invention, color mixing between adjacent pixels can be suppressed in an EL display device including a plasmonic structure.

FIG. 1 is a partial cross-sectional view showing an enlarged part of a cross-sectional structure of an EL display device in an embodiment embodying the EL display device of the present invention, in which pixel definition walls and EL between adjacent pixels are shown. It is a figure which shows the positional relationship with a layer. FIG. 2 is a partial cross-sectional view showing in detail the positional relationship between the pixel definition wall and the EL layer in the height direction in one embodiment. FIG. 3 is an operation diagram illustrating the operation of the pixel according to the embodiment. FIG. 4 is a partial cross-sectional view showing in detail the positional relationship in the height direction between the pixel definition wall and the EL layer in a modification of the EL display device according to the embodiment. FIG. 5 is an operation diagram showing the operation of the pixel in the modified example.

  An EL display device according to an embodiment will be described with reference to FIGS. The EL display device according to an embodiment is an EL display device including EL layers for three colors different from each other, and includes a plurality of red light emission pixels and a plurality of green colors as pixels for three colors having different light emission colors. A light emission pixel and a plurality of blue light emission pixels are provided. The red light emitting pixel emits red light, the green light emitting pixel emits green light, and the blue light emitting pixel emits blue light.

  As shown in FIG. 1, the red light emission pixel 10 </ b> R includes a red driving unit 20 </ b> R positioned on the base material 11 and a red EL structure 30 </ b> R positioned on the red driving unit 20 </ b> R. The red driving unit 20R and the red EL structure 30R are electrically connected.

  The red driving unit 20R supplies a driving current for causing the red light emitting pixel 10R to emit light to the EL structure 30R for red. The insulating layer 12 is sandwiched between the red driving unit 20R and the red EL structure 30R. The insulating layer 12 restricts electrical contact between the red driving unit 20R and the red EL structure 30R, and insulates pixel circuits adjacent to each other. The surface in contact with the red EL structure 30R in the insulating layer 12 is a flat surface.

  The red EL structure 30R includes a red anode layer 14R and a red EL layer 15R. The red anode layer 14R is an example of a lower electrode that is an electrode close to the substrate 11 among the two electrodes sandwiching the EL layer. The red anode layer 14R is connected to the red driving unit 20R through the plug 13R penetrating the insulating layer 12, and the red driving unit 20R supplies a driving current to the red anode layer 14R. The red EL structure 30 </ b> R is covered with the cathode layer 16. The cathode layer 16 is an example of a common electrode that is an electrode common to the EL structure 30R for red, the EL structure 30G for green, and the EL structure 30B for blue.

  When current flows between the cathode layer 16 and the red anode layer 14R, holes are injected from the red anode layer 14R into the red EL layer 15R, and the cathode layer 16 has a function as a cathode. Electrons are injected into the EL layer 15R for red. The red EL layer 15R generates red light by the combination of holes and electrons injected into the red EL layer 15R. Red light has a spectrum different from that of green light and blue light, and shows a broad peak between, for example, 620 nm and 750 nm.

  The cathode layer 16 may have a function of reflecting colored light or may have a function of transmitting colored light. When the cathode layer 16 has a function of reflecting colored light, the red anode layer 14 </ b> R has a light-transmitting property of transmitting colored light, and the EL display device functions as a bottom emission type. When the cathode layer 16 has a function of transmitting colored light, the red anode layer 14R has light reflectivity for reflecting colored light, and the EL display device functions as a top emission type. When the cathode layer 16 reflects colored light, the cathode layer 16 may be composed of one layer that reflects colored light, or a layer that has a function of transmitting colored light, and reflects colored light. It may be a multilayer structure including a reflective layer. When the red anode layer 14R reflects red light, the red anode layer 14R may be composed of one layer that reflects red light, or a layer having a function of transmitting red light; A multilayer structure including a reflective layer that reflects red light may be used.

  The cathode layer 16 has a red cathode surface 16RS that constitutes an interface between the red EL layer 15R and the cathode layer 16. The cathode surface 16RS for red has a fine concavo-convex structure for red, which is composed of a plurality of steps repeated on the cathode surface 16RS for red. The fine concavo-convex structure for red is a plasmonic structure, and in the plasmonic structure for red, the interval between adjacent step portions is a pitch for red, and the size of each step is a step for red It is. In the red plasmonic structure, the red pitch is a periodic length in which the stepped portion is repeated on the red cathode surface 16RS.

  The pitch for red is set to a size that allows surface plasmons generated when red light is generated to be extracted into the air as red light. The mode pitch, which is the mode value of the red pitch, is set to such a size that the plasmonic structure for red excites plasmon light when the EL layer 15R for red light is emitted. The wavelength of the plasmon light excited by the plasmonic structure is determined by the interval between the step portions adjacent to each other. The wavelength of the plasmon light generated by the red plasmonic structure is included in the wavelength band corresponding to the half width of the peak in the emission spectrum, which is the spectrum of the light emitted from the red emission pixel 10R. Note that, in the light emission peak of the red light emission pixel 10R, the maximum luminance value is determined as the maximum luminance, and the interval between the two wavelengths indicating the half value of the maximum luminance is determined as the half width of the red peak. Then, a wavelength band corresponding to the half-value width of the red peak is defined between the two wavelengths indicating half the maximum luminance.

  The mode value of the red pitch is obtained as follows. That is, in the cathode surface 16RS formed with the red plasmonic structure, a square measurement target region that is approximately 30 to 40 times the most frequent pitch of the red pitch is randomly extracted. Next, an atomic force microscope image for the measurement target region is obtained. For example, when the most frequent pitch is 10 μm, an atomic force microscope image is obtained for a measurement target region of 300 μm × 300 μm to 400 μm × 400 μm. In addition, the atomic force microscope image obtained here is an image obtained by planar view of the plasmonic structure. Subsequently, the atomic force microscope image is waveform-separated by fast Fourier transform to obtain a fast Fourier transform image. Then, the distance from the zero-order peak to the first-order peak in the profile of the fast Fourier transform image is obtained, and the reciprocal of the distance thus obtained is handled as the most frequent pitch in the measurement target region.

  By the same method as described above, the most frequent pitch is obtained for each of 25 different measurement target regions. The average value of the most frequent pitches in the 25 measurement objects is handled as the most frequent pitch in the red plasmonic structure. At this time, it is preferable that at least 1 mm is selected as the measurement target regions, and it is more preferable that the measurement target regions be selected as 5 mm or more and 1 cm or less.

  Regarding the degree to which the surface plasmon generated when red light is generated is converted into red radiation light, the contribution of the red step is smaller than the contribution of the red pitch. In the configuration in which the step for red is less than 12 nm, it is difficult to generate the surface plasmon diffracted wave itself, and therefore it is difficult to extract the surface plasmon as radiant light. In the configuration where the step for red exceeds 180 nm, the surface plasmon is localized, and therefore it is difficult to extract the surface plasmon as radiation light. Further, in the configuration in which the red step exceeds 180 nm, the cathode layer 16 and the red anode layer 14R are easily short-circuited in the portion where the red EL layer 15R is excessively thin due to the large step.

  The red EL layer 15R includes a red light emitting layer. The red light emitting layer combines the electrons sent from the cathode layer 16 and the holes sent from the red anode layer 14R to generate red light. The red EL layer 15R may include a functional layer other than the red light-emitting layer in order to generate red light. The red EL structure 30 </ b> R preferably includes a functional layer other than the red light emitting layer in order to increase the generation efficiency of red light. The red EL structure 30 </ b> R may be configured by only the red light-emitting layer, omitting other functional layers. The material constituting the EL structure 30R for red is not particularly limited as long as it is a material that generates red light, and may be a low molecular weight organic material, a high molecular organic material, or an inorganic material. Good materials can be used.

  The red plasmonic structure is a step structure in which a plurality of step portions are repeated on the red cathode surface 16RS. The red plasmonic structure may be a one-dimensional periodic structure in which a plurality of stepped portions are repeated along the one-dimensional direction, but a two-dimensional periodic structure is preferable in terms of increasing light extraction efficiency.

  The red plasmonic structure is, for example, a two-dimensional lattice structure in which stepped portions are arranged at lattice points periodically located in the two-dimensional direction. The two-dimensional lattice structure is a structure in which stepped portions are arranged along at least two directions. One example of the two-dimensional lattice structure is a square lattice structure in which stepped portions are arranged along two different directions, and an angle formed by the two directions of the stepped portions is 90 °. One example of the two-dimensional lattice structure is a hexagonal lattice structure in which stepped portions are arranged along three different directions, and an angle formed by two directions among the three directions in which the stepped portions are arranged is 60 °.

  The step portion in the red plasmonic structure may be formed by a plurality of protrusions protruding from the red cathode surface 16RS, or may be formed by a plurality of recesses recessed in the red cathode surface 16RS. Good. When the step portion in the red plasmonic structure is constituted by a protrusion, the shape of the protrusion is not particularly limited as long as it is a shape protruding at the cathode surface 16RS for red. It may be a shape, a hemispherical shape, a pyramid shape, a prism shape, a truncated cone shape, a truncated pyramid shape, or a shape derived from one of these. When the stepped portion in the red plasmonic structure is constituted by a dent, the shape of the dent is not particularly limited as long as it is a shape that dents on the red cathode surface 16RS. The shape of the dent may be, for example, a circular hole shape, a square hole shape, a circular hole shape whose diameter is reduced along the depth direction, or a square hole shape whose diameter is reduced along the depth direction.

  The red plasmonic structure reflects a periodic uneven structure formed on the surface of the red anode layer 14R. The periodic uneven structure formed on the surface of the red anode layer 14R is a structure for forming a plasmonic structure on the red cathode surface 16RS through the red EL layer 15R. The red EL layer 15R has a concavo-convex shape following the concavo-convex structure formed on the surface of the red anode layer 14R, and a plasmonic structure for emitting red light into the space is formed on the cathode surface 16RS. ing.

  When the red light emitting layer generates light, near-field light is generated in the vicinity of the red light emitting layer. Since the distance between the red light emitting layer and the cathode layer 16 is so short that surface plasmons are generated on the red cathode surface 16RS, the near-field light is on the surface of the red cathode surface 16RS. Converted to plasmon.

  Here, the surface plasmon generated on the cathode surface 16RS for red is one in which the density wave of free electrons generated by near-field light is accompanied by a surface electromagnetic field. When the red cathode surface 16RS is a flat surface, the surface plasmon dispersion curve generated on the flat metal surface and the red light dispersion curve do not intersect, so the surface plasmon energy is not extracted as light. Is generally consumed as heat.

  In contrast, when the red cathode surface 16RS has a red plasmonic structure, the dispersion curve of light diffracted by the red plasmonic structure and the surface plasmon generated on the red cathode surface 16RS. Intersects with the dispersion curve. As a result, the energy of the surface plasmon generated when red light is generated is extracted as red radiant light.

  As the distance between the red cathode surface 16RS and the red light emitting layer is shorter, the light generated by the red light emitting layer is more easily converted to surface plasmons at the red cathode surface 16RS. The red EL layer 15R may include a functional layer other than the red light emitting layer in order to generate red light, but the distance between the red light emitting layer and the red cathode surface 16RS is The shorter it is, the higher the effect of extracting red radiation light.

  The green light output pixel 10G includes a green drive unit 20G and a green EL structure 30G located on the green drive unit 20G on the base material 11 common to the red light output pixel 10R. The green driving unit 20G and the green EL structure 30G are electrically connected. The green EL structure 30G includes a green anode layer 14G, which is an example of a lower electrode, and a green EL layer 15G. The green anode layer 14G is connected to the green driving unit 20G through a plug 13G penetrating the insulating layer 12, and the green driving unit 20G supplies a driving current to the green anode layer 14G.

  When a current flows between the cathode layer 16 and the green anode layer 14G, the green EL layer 15G generates green light. Green light has a spectrum different from that of red light and blue light, and shows a broad peak between, for example, 495 nm and 570 nm.

  The cathode layer 16 has a green cathode surface 16GS that constitutes an interface between the green EL layer 15G and the cathode layer 16. The green cathode surface 16GS has a fine concavo-convex structure for green composed of a plurality of stepped portions that are repeated on the green cathode surface 16GS. The fine concavo-convex structure for green is a plasmonic structure like the fine concavo-convex structure for red, and in the plasmonic structure for green, the interval between the adjacent step portions is a green pitch, The size of the step is a green step. In the green plasmonic structure, the green pitch is a periodic length in which the stepped portion is repeated on the green cathode surface 16GS.

  The green pitch is set to a size that allows surface plasmons generated when green light is generated to be taken out into the air as green light. The mode pitch, which is the mode value of the green pitch, is set to such a size that the green plasmonic structure excites plasmon light when the green EL layer 15G emits light. The mode value of the green pitch is obtained in the same manner as the mode value of the red pitch.

  The green EL layer 15G includes a green light emitting layer. The green light emitting layer combines the electrons sent from the cathode layer 16 and the holes sent from the green anode layer 14G to generate green light. Similarly to the red EL layer 15R, the green EL layer 15G may include other functional layers other than the green light emitting layer in order to generate green light.

  The blue light output pixel 10B includes a blue drive unit 20B and a blue EL structure 30B located on the blue drive unit 20B on the base material 11 common to the red light output pixel 10R and the green light output pixel 10G. It has. The blue driving unit 20B and the blue EL structure 30B are electrically connected. The blue EL structure 30B includes a blue anode layer 14B, which is an example of a lower electrode, and a blue EL layer 15B. The blue anode layer 14B is connected to the blue drive unit 20B through a plug 13B penetrating the insulating layer 12, and the blue drive unit 20B supplies a drive current to the blue anode layer 14B.

  When a current flows between the cathode layer 16 and the blue anode layer 14B, the blue EL layer 15B generates blue light. Blue light has a spectrum different from that of red light and green light, and shows a broad peak between, for example, 450 nm and 495 nm.

  The cathode layer 16 has a blue cathode surface 16BS that constitutes an interface between the blue EL layer 15B and the cathode layer 16. The blue cathode surface 16BS has a fine concavo-convex structure for blue composed of a plurality of stepped portions that are repeated on the blue cathode surface 16BS. The fine concavo-convex structure for blue is a plasmonic structure, like the fine concavo-convex structure for red, and in the plasmonic structure for blue, the interval between adjacent step portions is a blue pitch, The size of the step is a blue step. In the blue plasmonic structure, the blue pitch is a periodic length in which the stepped portion is repeated on the blue cathode surface 16BS.

  The blue pitch is set to a size that allows surface plasmons generated when blue light is generated to be taken out into the air as blue light. The mode pitch, which is the mode value of the blue pitch, is set to such a size that the plasmonic structure for blue excites plasmon light when the blue EL layer 15G emits light. The mode value of the blue pitch is obtained in the same manner as the mode value of the red pitch.

  The blue EL layer 15G includes a blue light emitting layer. The blue light emitting layer combines the electrons sent from the cathode layer 16 and the holes sent from the blue anode layer 14B to generate blue light. Similarly to the red EL layer 15R, the blue EL layer 15B may include a functional layer other than the blue light-emitting layer in order to generate blue light.

  Each of the plurality of EL structures 30R, 30G, and 30B including the EL structure 30R for red, the EL structure 30G for green, and the EL structure 30B for blue is compared to the other EL structures. Are defined by the pixel definition wall 40. The pixel definition wall 40 is a structure protruding from the surface of the insulating layer 12, and divides the display surface, which is a surface on which a plurality of pixels are arranged, into a plurality of pixel regions where the pixels are located. In addition, the pixel defining wall 40 increases the distance between the edges of the anode layers 14R, 14G, and 14B and the cathode layer 16, and suppresses the phenomenon that the electric field concentrates at the edges of the anode layers 14R, 14R, and 14B. Short circuit between 14R, 14R, 14B and the cathode layer 16 is suppressed.

  The pixel definition wall 40 may be formed from an organic material or an inorganic material. As the organic material forming the pixel defining wall 40, for example, polystyrene resin, polyacrylonitrile resin, polyamide resin, polyimide resin, fluorine resin, epoxy resin, siloxane resin, or the like is used. As the inorganic material forming the pixel defining wall 40, amorphous silicon, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or the like is used.

  Next, the relative positional relationship between the EL layers 15R, 15G, and 15B and the pixel definition wall 40 will be described below with reference to FIGS. The relative positional relationship between the green EL layer 15G and the pixel definition wall 40 and the relative positional relationship between the blue EL layer 15B and the pixel definition wall 40 are red. This corresponds to the relative positional relationship between the EL layer 15 </ b> R for use and the pixel definition wall 40. Therefore, in the following, the relative positional relationship between the red EL layer 15R and the pixel definition wall 40, and the relative positional relationship between the green EL layer 15G and the pixel definition wall 40 Will be described in detail.

  As shown in FIG. 2, the pixel definition wall 40 that partitions the red light emission pixel 10R and the green light emission pixel 10G covers the edge of the red anode layer 14R and the edge of the green anode layer 14G. The pixel defining wall 40 that partitions the red light emitting pixel 10R and the green light emitting pixel 10G has a thickness of the anode layers 14R and 14G from the edge of the red anode layer 14R and the edge of the green anode layer 14G. It protrudes along the direction.

  The pixel defining wall 40 has a trapezoidal shape in a cross section orthogonal to the edge of the red anode layer 14R and the edge of the green anode layer 14G. The pixel definition wall 40 has a red side surface 40S that rises from the edge of the red anode layer 14R, and the red side surface 40S forms the trapezoidal oblique side described above. The pixel definition wall 40 has a green side surface 40S that rises from the edge of the green anode layer 14G, and the green side surface 40S also forms the trapezoid-shaped oblique side described above.

  The thickness direction of the red anode layer 14R is a height direction with respect to the surface of the red anode layer 14R. In this height direction, the side surface 40S is red up to the middle of the red side surface 40S. The EL layer 15R is covered. Then, with reference to the surface of the red anode layer 14R, the height HP of the pixel definition wall 40 is greater than the height HE of the red EL layer 15R.

  The thickness direction of the green anode layer 14G is a height direction with respect to the surface of the green anode layer 14G. In this height direction, the side surface 40S is green up to the middle of the green side surface 40S. The EL layer 15G is covered. Then, with reference to the surface of the green anode layer 14G, the height HP of the pixel definition wall 40 is larger than the height of the green light emitting layer. The angle θ formed between the surface of the red anode layer 14R and the side surface 40S for red is preferably 30 ° or more and 60 ° or less.

  If the angle θ is 30 ° or more, it is easy to suppress the light generated at the edge of the red light output pixel 10R from entering the green light output pixel 10G adjacent to the red light output pixel 10R. If the angle θ is 60 ° or less, the red EL layer 15R can easily cover the side surface 40S up to the middle of the red side surface 40S in the height direction. In particular, the occurrence of distortion between the portion covering the red side surface 40S and the portion covering the red anode layer 14R is suppressed. Further, if the angle θ is 60 ° or less, it is easy to ensure an allowable range of error regarding the positional accuracy of the red EL layer 15R in the direction along the surface of the red anode layer 14R.

  The angle formed between the surface of the green anode layer 14G and the side surface 40S for green is preferably 30 ° or more and 60 ° or less. According to such a green side surface 40S, an effect similar to the effect obtained in the red light emission pixel 10R described above can be obtained also in the green light emission pixel 10G.

  As shown in FIG. 3, according to the relative positional relationship between the pixel definition wall 40 and the light emitting layer, the pixel definition wall 40 has a side surface 40S that rises further from the red EL layer 15R. Plasmon light generated on the cathode surface 16RS is reflected or refracted on the side surface 40S for red before propagating to the green light output pixel 10G. Then, the plasmon light reflected or refracted on the side surface 40S of the pixel definition wall 40 increases the probability of being emitted from the red light emitting pixel 10R to which it belongs instead of the green light emitting pixel 10G.

  In other words, when the line connecting the upper end of the red EL layer 15R and the upper end of the red side surface 40S is a virtual line L, the light generated in the red EL layer 15R and Plasmon light, which is converted light, increases the luminance in the region S inside the red light-emitting pixel 10R with respect to the virtual line L.

  Further, according to the relative positional relationship between the pixel definition wall 40 and the light emitting layer, the side surface 40S further rising from the green EL layer 15G also has the pixel definition wall 40, so that it is generated on the green cathode surface 16GS. The transmitted plasmon light is reflected or refracted on the green side surface 40S before propagating to the red light output pixel 10R. Then, the plasmon light reflected or refracted on the side surface 40S of the pixel definition wall 40 increases the probability of being emitted from the green light emitting pixel 10G to which it belongs instead of the red light emitting pixel 10R.

  In other words, when the line connecting the upper end of the green EL layer 15G and the upper end of the green side surface 40S is a virtual line L, the light generated in the green EL layer 15G and Plasmon light, which is converted light, increases the luminance in the region S inside the green light-emitting pixel 10G with respect to the virtual line L.

  In the configuration in which the red EL layer 15R covers the entire red side surface 40S, the light generated on the red side surface 40S is likely to be emitted toward the green light emitting pixel 10G. In particular, in the configuration in which plasmon light is generated on the red cathode surface 16RS that is the interface between the red EL layer 15R and the cathode layer 16, the plasmon light generated at the edge of the red EL layer 15R. Is easily emitted directly onto the green light emitting pixel 10G. In this regard, with the above-described configuration, the red side surface 40S is positioned between the edge of the red EL layer 15R and the green light output pixel 10G, so that the light generated in the red light output pixel 10R is green. The light emitted toward the light output pixel 10G is suppressed.

  On the other hand, in a configuration in which the red EL layer 15R does not cover the red side surface 40S, the position of the edge in the red EL layer 15R and the red side surface 40S in the direction in which the red anode layer 14R spreads. It is necessary to ensure alignment with the position of the edge. In this regard, with the configuration described above, the edge of the red EL layer 15R may be positioned on the red side surface 40S in the direction in which the red anode layer 14R spreads. Therefore, it is possible to ensure an allowable range for the positional accuracy in the red EL layer 15R in the direction in which the red anode layer 14R spreads.

  As a result, plasmon light propagates through the cathode layer 16 that secures an allowable range of positional accuracy in the red EL layer 15R and the green EL layer 15G and is common to the red light emission pixel 10R and the green light emission pixel 10G. The color mixture between the red light output pixel 10R and the green light output pixel 10G is suppressed.

  The relative positional relationship between the height of the side surface 40S on the pixel definition wall 40 and the height of the EL layer covering a part of the side surface 40S is the same in all the EL layers 15R, 15G, and 15B. Therefore, the suppression of the propagation of plasmon light means that the red light emission pixel 10R and the green light emission light are also emitted between the red light emission pixel 10R and the blue light emission pixel 10B and between the green light emission pixel 10G and the blue light emission pixel 10B. This is the same as that between the pixel 10G. Therefore, in the above-described EL display device, color mixture can be suppressed among all pixels having different light emission colors.

As mentioned above, according to the said embodiment, the effect listed below is acquired.
(1) The EL layer 15R for red covers the side surface 40S halfway in the height direction with respect to the side surface 40S of the pixel definition wall 40 that partitions the red light emission pixel 10R. Therefore, the light generated in the red light emitting pixel 10R is mixed with the light emitted from the green light emitting pixel 10G, including the excited plasmon light, while ensuring an allowable range for the positional accuracy error of the EL layer 15R. It can be suppressed.

  (2) With respect to the side surface 40S of the pixel definition wall 40 that partitions each of the plurality of pixels, the EL layer constituting the pixel covers the side surface 40S halfway in the height direction. For this reason, the light generated in one pixel is mixed with the light emitted from the other pixel between adjacent pixels while ensuring an allowable range with respect to the positional accuracy error of the EL layer for each color. It can be suppressed.

  (3) The angle θ formed by the surfaces of the anode layers 14R, 14G, 14G and the side surface 40S rising from the edges of the anode layers 14R, 14G, 14B is 30 ° or more and 60 ° or less. Therefore, the effects described in (1) and (2) are more easily obtained.

  (4) The cathode layer 16 including a plasmonic structure is a common electrode common to adjacent pixels and covers the pixel definition wall 40 that partitions two adjacent pixels. As described above, in the configuration in which the common electrode includes a plasmonic structure, color mixing between adjacent pixels is likely to occur, and thus the above-described color mixing suppression becomes more remarkable.

In addition, the said embodiment can be changed and implemented as follows.
[Pixel definition wall 40]
The portion covered with the EL layer on the side surface 40 </ b> S of the pixel definition wall 40 may have a curved surface shape having a curvature that is convex toward the pixel definition wall 40.
For example, as shown in FIG. 4, the side surface 40S for red has a curvature R that is convex toward the pixel definition wall 40 in a cross section orthogonal to the direction in which the edge of the anode layer 14R for red extends. Yes. The side surface 40S for green also has a curvature R that is convex toward the pixel definition wall 40 in a cross section orthogonal to the direction in which the edge of the green anode layer 14G extends.

As shown in FIG. 5, a part of the plasmon light generated on the red cathode surface 16RS which is an interface between the red EL layer 15R and the cathode layer 16 is indicated by an arrow ER in FIG. proceeds directly toward the sides 40S of the red, is reflected by the side surface 40S for red color. At this time, if the side surface 40S for red has a curvature R, the light reflected on the side surface 40S of the pixel definition wall 40 proceeds toward the red light output pixel 10R to which it belongs, and it belongs to The light is easily emitted within the pixel.

  Further, a part of the plasmon light generated on the green cathode surface 16GS which is an interface between the green EL layer 15G and the cathode layer 16 is also green, as indicated by an arrow EG in FIG. The light travels directly toward the side surface 40S and is reflected by the green side surface 40S. At this time, if the side surface 40S for red has a curvature R, the light reflected on the side surface 40S of the pixel definition wall 40 proceeds toward the green light emitting pixel 10G to which it belongs, and it belongs to The light is easily emitted within the pixel.

  The side surface 40S of the pixel definition wall 40 may be a smooth surface including a portion covered with the EL layer. That is, the pixel defining wall 40 is formed so as to fill in the concave portions in the concavo-convex structure of the anode layers 14R, 14G, and 14B, and the side surface 40S rising from the surface of the anode layers 14R, 14G, and 14B is formed on the anode layers 14R, 14G, and 14B. You may form as a smooth surface which does not reflect an uneven structure. If the side surface 40S is a smooth surface, the cathode surfaces 16RS, 16GS, and 16BS are easily formed as smooth surfaces even in the portion of the EL layer that covers the side surface 40S. Therefore, generation of plasmon light is suppressed on the side surface 40S of the pixel definition wall 40, and color mixing caused by this is also suppressed.

  The shape of the side surface 40S of the pixel definition wall 40 is, for example, in addition to the fine uneven surface shape, curved surface shape, and smooth surface shape in the cross section orthogonal to the direction in which the edges of the anode layers 14R, 14G, and 14B extend, for example The shape may be a staircase or may be a shape that warps into the pixel at the tip in the height direction.

  The shape of the side surface 40S of the pixel definition wall 40 may be different between, for example, the side surface 40S for red and the side surface 40S for green, or the side surface 40S for red and the side surface 40S for blue May be different from each other, or may be different from each other between the green side surface 40S and the blue side surface 40S.

[EL layer]
The height HE of each color EL layer 15R, 15G, 15B may be different for each color as long as it is smaller than the height HP of the corresponding color side surface 40S.
The ratio of the height HE of the EL layers 15R, 15G, and 15B for each color to the height HP of the side surface 40S is preferably 50% or less. If the ratio of the height HE to the height HP is 50% or less, the effects according to the above (1) to (4) are further enhanced.

[Plasmonic structure]
-At least one surface of anode layers 14R, 14G, and 14B for each color may not have a periodic uneven structure. At this time, in a pixel in which the surface of the anode layer does not have a periodic uneven structure, the uneven structure for forming the plasmonic structure may be separately formed on the surface of the EL layer.

  For example, if the surface of the red anode layer 14R does not have a periodic uneven structure, an uneven structure for forming a plasmonic structure is separately formed on the surface of the red EL layer 15R. Is done. Further, for example, if the surfaces of all the color anode layers 14R, 14G, and 14B do not have a periodic concavo-convex structure, the concavo-convex structure for forming the plasmonic structure is separately provided for all the colors. It is formed on the surface of the color EL layers 15R, 15G, 15B.

  In at least one of the anode layers 14R, 14G, and 14B for each color, the base layer may have a periodic uneven structure. At this time, the periodic uneven structure in the base layer is a structure for forming a plasmonic structure on the cathode surface through the anode layer and the EL layer.

For example, if the underlayer for the red anode layer 14R has a periodic uneven structure, the red cathode surface 16RS follows the uneven structure of the underlayer for the red anode layer 14R. A plasmonic structure is formed. Further, for example, if the underlying layers for all the color anode layers 14R, 14G, 14B have a periodic uneven structure, the underlying layer unevenness for each color anode layer 14R, 14G, 14B. Following the structure, plasmonic structures are formed on the cathode surfaces 16RS, 16GS, and 16BS for each color.
In each of the color output pixels 10R, 10G, and 10G, the lower electrode may be a cathode layer for each pixel, and the common electrode may be an anode layer.

  θ ... angle, R ... curvature, HE, HP ... height, 10R ... red light emitting pixel, 10G ... green light emitting pixel, 10B ... blue light emitting pixel, 14R ... red anode layer, 14G ... green anode layer, 14B ... Anode layer for blue, 15R ... EL layer for red, 15G ... EL layer for green, 15B ... EL layer for blue, 16 ... Cathode layer, 30R ... EL structure for red, 30G ... for green EL structure, 30B ... EL structure for blue, 40 ... pixel definition wall, 40S ... side surface.

Claims (3)

A pixel definition wall that divides the display surface into a plurality of pixel regions;
Pixels located in each of the plurality of pixel regions;
A common electrode common to each of the plurality of pixels,
The common electrode has a function of transmitting colored light,
Each of the plurality of pixels is
A lower electrode located in the pixel region;
An EL layer located in the pixel region and covering the lower electrode,
The common electrode covers the EL layer and the pixel definition wall,
Either one of the lower electrode and the common electrode is
A cathode having an interface in contact with the EL layer, the interface having a plasmonic structure in which a mode pitch is set so as to excite plasmon light included in a wavelength band of light emitted from the EL layer;
In the height direction with respect to the lower electrode,
The side surface is covered with the EL layer up to the middle of the side surface of the pixel definition wall,
Said height having the pixel defining walls much larger than the height included in the said EL layer,
The portion covered with the EL layer on the side surface of the pixel definition wall has a curved surface shape having a curvature that is convex toward the pixel definition wall,
The lower electrode includes a lower electrode surface that is in contact with the EL layer,
The angle formed between the side surface of the pixel definition wall and the lower electrode surface is 30 ° or more and 60 ° or less,
The side surface of the pixel definition wall is an EL display device that reflects the plasmon light toward the pixel region where the plasmon light is excited and emits the plasmon light from the pixel region through the common electrode . The side surface of the pixel definition wall is a smooth surface.
The EL display device according to claim 1 . The common electrode is a cathode;
The lower electrode is an anode having a periodic uneven structure,
The EL layer has an uneven shape following the uneven structure,
The plasmonic structure is a structure reflecting the uneven shape of the EL layer.
The EL display device according to claim 1 .

Images