CN110574498A - Display device and electronic apparatus - Google Patents

Display device and electronic apparatus Download PDF

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Publication number
CN110574498A
CN110574498A CN201880028873.XA CN201880028873A CN110574498A CN 110574498 A CN110574498 A CN 110574498A CN 201880028873 A CN201880028873 A CN 201880028873A CN 110574498 A CN110574498 A CN 110574498A
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Prior art keywords
electrode
organic electroluminescent
display device
electroluminescent layer
potential
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辻川真平
笠原直也
系长总一郎
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Sony Corp
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Sony Corp
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/30—Devices specially adapted for multicolour light emission
    • H10K59/35—Devices specially adapted for multicolour light emission comprising red-green-blue [RGB] subpixels
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/805—Electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays
    • H10K59/17—Passive-matrix OLED displays
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/805—Electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K99/00—Subject matter not provided for in other groups of this subclass

Abstract

to provide a display device and an electronic apparatus in which leakage current between pixels is suppressed. [ solution ] the display device includes: an organic electroluminescent layer; a first electrode provided on one main surface side of the organic electroluminescent layer and shared by a plurality of pixels; a plurality of second electrodes provided on the other major surface side of the organic electroluminescent layer and each provided to each pixel; and a plurality of third electrodes provided on the other major surface side of the organic electroluminescent layer and between each of the plurality of second electrodes.

Description

Display device and electronic apparatus
Technical Field
The present disclosure relates to a display device and an electronic apparatus.
Background
In recent years, demands for higher definition and lower power consumption of display devices for mobile use have been increasing.
For example, a display device using an organic electroluminescent element (organic electroluminescent diode: OLED) disclosed in patent document 1 below is expected to be applied to mobile use because the display device is self-luminous and consumes low electric power.
However, in such an organic electroluminescent element, an organic electroluminescent layer is provided in common to all the light emitting elements, and thus leakage of a driving current is more likely to occur between the adjacent light emitting elements.
For this reason, patent document 1 discloses a technique of providing a relief pattern for a blocking electrode and a charge transport layer between light emitting elements. Further, patent document 2 discloses a technique in which a portion of each pixel of the hole transport layer other than the light emitting region is subjected to surface treatment with ultraviolet rays to increase the resistance value of the portion irradiated with ultraviolet rays, thereby suppressing a leakage current between pixels. Further, patent document 3 discloses a technique of suppressing a leakage current by periodically applying a drive voltage to a light emitting element.
Reference list
Patent document
Patent document 1: japanese unexamined patent application publication (Japanese translation of published PCT application) No. JP2003-530660
Patent document 2: japanese unexamined patent application publication No.2004-158436
Patent document 3: japanese unexamined patent application publication No.2014-52617
Disclosure of Invention
Problems to be solved by the invention
Incidentally, in an organic electroluminescence (organic EL) display, display is generally performed by driving an organic electroluminescence element using a thin film transistor formed on a glass substrate. For example, amorphous silicon or polycrystalline silicon is used as a channel material of a transistor applied in a display of a television and a smart phone, and the like.
Meanwhile, for a high-definition small-sized display device having a pixel pitch of 10 μm or less and a resolution exceeding 2500ppi, there may be a case where an organic electroluminescent element is driven by a MOS (metal oxide semiconductor) transistor formed on Si.
The techniques disclosed in patent documents 1 and 2 are difficult to apply to such a display device having a high-definition pixel pitch. Further, the technique disclosed in patent document 3 is extremely complicated in controlling the drive voltage.
Accordingly, the present disclosure proposes a new and improved display device and electronic apparatus, and makes it possible to suppress leakage current between pixels.
means for solving the problems
According to the present disclosure, there is provided a display device including: an organic electroluminescent layer; a first electrode provided on one main surface side of the organic electroluminescent layer and common to the plurality of pixels; a plurality of second electrodes provided for each pixel on the other major surface side of the organic electroluminescent layer, respectively; and a plurality of third electrodes each disposed between the second electrodes on the other main surface side of the organic electroluminescent layer.
further, according to the present disclosure, there is provided an electronic apparatus including a display portion including: an organic electroluminescent layer; a first electrode provided on one main surface side of the organic electroluminescent layer and common to the plurality of pixels; a plurality of second electrodes provided on the other main surface side of the organic electroluminescent layer, respectively corresponding to each pixel; and a plurality of third electrodes each disposed between the second electrodes on the other major surface side of the organic electroluminescent layer.
According to the present disclosure, a display device and an electronic apparatus, in each of which a leak current between pixels is suppressed, can be provided. Accordingly, unintentional light emission of the pixels due to the leakage current and a reduction in the color gamut of the display image associated with the unintentional light emission of the pixels can be prevented.
Effects of the invention
As described above, according to the present disclosure, a display device and an electronic apparatus, in each of which leakage current between pixels is suppressed, can be provided.
Note that the above effects are not necessarily restrictive. Any effect described in the present specification or other effects that can be grasped from the present specification can be achieved in addition to or instead of the above-described effects.
Drawings
Fig. 1 is an illustrative schematic cross-sectional view of a display device according to an embodiment of the present disclosure.
Fig. 2 is an explanatory schematic plan view of the arrangement of the discrete electrodes and the third electrode of the display device shown in fig. 1.
Fig. 3 is an explanatory schematic cross-sectional view of the configuration of the discrete electrodes of the display device shown in fig. 1.
Fig. 4 is a schematic circuit diagram of an organic electroluminescent element included in the display device shown in fig. 1.
Fig. 5 is a graph showing a relationship between a leakage current and a light emission current in the display device.
Fig. 6 is a graph showing a relationship between luminance and a leakage current and a light emitting current in a display device.
Fig. 7 is a plan view of the discrete electrode and the third electrode in terms of shape and arrangement in a modification of the present disclosure.
Fig. 8 is a plan view of the discrete electrode and the third electrode in terms of shape and arrangement in a modification of the present disclosure.
Fig. 9 is a plan view of the discrete electrode and the third electrode in terms of shape and arrangement in a modification of the present disclosure.
Fig. 10 is an illustrative schematic cross-sectional view of a discrete electrode and a third electrode according to a variation of the present disclosure.
Fig. 11 is an illustrative schematic cross-sectional view of a discrete electrode and a third electrode according to a variation of the present disclosure.
Fig. 12 is an illustrative schematic cross-sectional view of a discrete electrode and a third electrode according to a variation of the present disclosure.
Fig. 13 is a schematic sectional view of a display device according to a modification of the present disclosure.
Fig. 14 is an explanatory schematic cross-sectional view of the configuration of discrete electrodes according to a modification of the present disclosure.
Fig. 15 is a schematic cross-sectional view showing an example of the device without the third electrode.
Fig. 16 is a plan view of a pixel arrangement constituting the display device shown in fig. 15.
Fig. 17 is a schematic explanatory diagram of a leakage current between discrete electrodes.
Fig. 18 is a schematic explanatory diagram of a leakage current between discrete electrodes.
Fig. 19 is a graph schematically showing the relationship between the voltage and the current of the organic electroluminescent layer.
Fig. 20 is a schematic arrangement diagram of discrete electrodes included in the display device shown in fig. 15.
Detailed Description
Preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, a repetitive description of components having substantially the same functional configuration by being assigned the same reference numerals is omitted. Further, the size of each member in the drawings is appropriately emphasized for convenience of explanation, and they do not represent actual sizes or ratios between members.
Note that the description is given in the following order.
1. Background and summary of the disclosure
1.1. Leakage current problem in display devices
1.2. Overview of suppression of leakage current according to the present disclosure
2. Arrangement of display device
3. Verification of the effects of leakage current
4. Modification examples
5. Conclusion
<1. background and summary of the disclosure >
[1.1. problem of leakage Current in display device ]
First, before describing the present disclosure in detail, a problem of leakage current in a display device using an organic electroluminescent element is described. Fig. 15 is a schematic cross-sectional view of an example of a display device without a third electrode described later. Fig. 16 is a plan view of a pixel arrangement constituting the display device shown in fig. 15. Fig. 17 and 18 are schematic explanatory views of leakage current between discrete electrodes, respectively. Fig. 19 is a graph schematically showing the relationship between the voltage and the current of the organic electroluminescent layer. Fig. 20 is a schematic arrangement diagram of discrete electrodes included in the display device shown in fig. 15.
The display device 200 shown in fig. 15 is a display device using an active matrix organic electroluminescent element. In the display device 200, the organic electroluminescent layer 210 is disposed on the interlayer insulating film 280. A discrete electrode 220 as an anode is disposed on the organic electroluminescent layer 210 on one side of the interlayer insulating film 280, and a transparent common electrode 230 as a cathode is disposed on the opposite side. Further, a protective insulating film 240, a color filter layer 250, a sealing resin 260, and a protective glass 270 are sequentially stacked on the transparent common electrode 230. Meanwhile, a contact 281 and a wiring 283 which couple the discrete electrode 220 to a pixel driving circuit, not shown, are provided in the interlayer insulating film 280.
For example, when a voltage is applied between the transparent common electrode 230 and the discrete electrode 220, the organic electroluminescent layer 210 can emit white light. The white light emitted from the organic electroluminescent layer 210 passes through the transparent common electrode 230 and the protective insulating film 240 and enters the color filter layer 250. The color filter layer 250 includes a red color filter 250R, a green color filter 250G, and a blue color filter 250B, which are divided accordingly for each of the discrete electrodes 220. The red, green, and blue color filters 250R, 250G, and 250B convert incident light into red, green, and blue, respectively, and output the converted light toward the sealing resin side. The output light further passes through the sealing resin 260 and the protective glass 270, and is discharged to the outside.
An example of the pixel arrangement in the active matrix display device 200 is shown in a plan view in fig. 16. As shown in fig. 16, a red pixel SP as a sub-pixelRGreen pixel SPGAnd blue pixel SPBFormed by discrete electrodes 220 and corresponding red, green, and blue color filters 250R, 250G, and 250B. Such a large number of red pixels SPRGreen pixel SPGAnd blue pixel SPBLight of three primary colors of red, green and blue can be emitted to constitute one pixel. Arranging such pixels in a matrix allows a display panel to be formed, performing color display of an image corresponding to an input signal.
Here, the leakage current between pixels is checked. Fig. 17 and 18 are schematic explanatory views of leakage current between the discrete electrodes 220, respectively. Fig. 19 is a graph schematically showing the relationship between the voltage and the current of the discrete electrode (anode) 220 when a voltage is applied to the organic electroluminescent layer 210. As a result of trial production and inspection of various display elements by the present inventors, a case was observed in which the potential of the non-light-emitting discrete electrode 220 was significantly increased by the leakage current flowing between the discrete electrodes 220. The main path of the leakage current was found to be the underlying portion of the organic electroluminescent layer 210 shown in fig. 16. The detailed description is as follows.
In the above-described display device 200, the organic electroluminescent layer 210 is not non-separated for each color, and the discrete electrodes 220 corresponding to the sub-pixels are coupled at the bottom layer of the organic electroluminescent layer 210. The organic electroluminescent layer 210 is not a good insulator, and thus it is difficult to completely suppress leakage current between adjacent discrete electrodes 220. That is, an organic material layer into which charges (for example, holes) are easily injected is disposed on the organic electroluminescent layer 210 on the side of the discrete electrode 220, thereby enabling current to leak through such an organic material layer as a leakage path. In general, the organic electroluminescent layer 210 is considered to have a thickness equal to or less than about 1012sheet resistance of omega/□.
In consideration of such a leakage path of the organic electroluminescent layer 210, the resistance R of a portion where a leakage current flows between adjacent discrete electrodes 220IE-IEApproximately represented by (sheet resistance Ω/□ of the organic electroluminescent layer 210) multiplied by (distance between the discrete electrodes 220)/(length of one side of the discrete electrodes 220). In addition, in the applicationThe amount of leakage current is determined by the resistance R in the thickness direction of the organic electroluminescent layer 210 at the time of voltageSPAnd discrete electrode 220IE-IEThe influence of the relationship between them.
Meanwhile, in view of the light emission current characteristics shown in fig. 19, the light emission current of the organic electroluminescent layer 210 is very small in the case where the voltage applied by the discrete electrode 220 is relatively small. That is, the current-voltage characteristic is not ohmic, but rises sharply from around 3.5V; the resistance R of the organic electroluminescent layer 210 in the thickness direction in the case where the applied voltage is lowSPIs large. Therefore, in the case where display is intended to be performed using low-luminance light emission, the resistance RSPWith respect to the resistance RIE-IEBecomes large, resulting in a large influence of the leakage current.
Therefore, in the display device 200 shown in fig. 15, it is difficult to suppress a leakage current that undesirably flows between the discrete electrodes 220 that supply power to the organic electroluminescent layer 210. Further, it is considered that when a low voltage is applied to the organic electroluminescent layer 210 to perform low luminance display, the leakage current shows a more significant influence.
The leakage current flowing between the discrete electrodes 220 described above may cause the color gamut of the display device 200 to decrease. For example, in making only the blue pixels SPBIn the case where light is emitted to display pure blue, a voltage can be applied between the discrete electrode 220B and the transparent common electrode 230 in the middle of fig. 20. However, as shown by the arrows in fig. 20, the leak current flows to the adjacent red and green pixels SPRAnd SPGCorresponding peripheral discrete electrodes 220R and 220G. As a result, the pixel SPBSurrounding pixels SPRAnd SPGBecomes red and green to emit light, thereby causing the pixel SPBThe color purity of the blue color shown in (a) is reduced. The same phenomenon occurs when other colors (e.g., red and green) are developed, resulting in a narrowing of the displayable color gamut.
In addition, in the case of having a fine pixel pitch PPThe color reproducibility due to the leakage current is remarkably reduced in the display device of (1), particularly at low luminance. Hereinafter, a specific description is given. At the inter-pixel pitch PPIs thinnerIn the case of small, it is generally reasonable to make the arrangement of the discrete electrodes 220 thinner to maintain a similar shape. In the case where the size of the discrete electrodes 220 is halved, for example, it is practical to roughly halve the distance between the discrete electrodes 220 adjacent to each other. This is to set the size of the discrete electrodes 220 and the distance between the discrete electrodes 220 based on the accuracy of photolithography at the time of manufacture.
Here, when the current-voltage characteristic of the organic electroluminescent layer 210 is similar to a simple resistance, the resistance of the organic electroluminescent layer 210 becomes inversely proportional to the area of the discrete electrode 220. For example, at a pixel pitch PPSet to 1/2, the resistance R of the portion of the organic electroluminescent layer 210 corresponding to the discrete electrode 220SPThe increase is four times.
Meanwhile, in consideration of the above expression, even when the pixel pitch P isPWhen changed, the resistance R between the discrete electrodes 220 is not changed because the ratio of the distance between the discrete electrodes 220 to the length of one side of the discrete electrodes 220 is not changedIE-IEnor are they considered changes. Thus, with the pixel pitch PPof the organic electroluminescent layer 210, the resistance R of the portion of the organic electroluminescent layer 210SPWith respect to the resistance R between the discrete electrodes 220IE-IECorresponding to the pixel pitch PPThe square of (a) increases inversely, resulting in an increased influence of leakage current between the discrete electrodes 220. As a result, the color reproducibility of the display device 200 is more likely to decrease at low luminance.
[1.2. overview of suppression of leakage Current according to the present disclosure ]
As described above, the present inventors have pointed out that the leakage current between the discrete electrodes 220 is generated by the organic electroluminescent layer 210. Further, the present inventors have found that the leakage current affects the color reproducibility of the display device 200, particularly at low luminance, and the influence of the leakage current with the pixel pitch PPIs increased.
In order to suppress such an influence of the leakage current, the present inventors have considered to provide an additional electrode (a third electrode described later) 90 between the discrete electrodes 20(20B, 20G, and 20R), as shown in fig. 1 and 2. Further, the present inventors have found that setting the potential of the third electrode 90 closer to the potential of the transparent common electrode 30 than the potential of the discrete electrode 20 enables the leakage current generated in the discrete electrode 20 to be absorbed by the third electrode 90. Hereinafter, the present disclosure will be described in more detail.
<2. configuration of display device >
Next, the display device according to the present embodiment is described in detail. Fig. 1 is a schematic sectional view of an example of a display device according to the present embodiment. Fig. 2 is an explanatory schematic plan view of the arrangement of the discrete electrodes and the third electrode of the display device shown in fig. 1. Fig. 3 is an explanatory schematic cross-sectional view of the configuration of the discrete electrodes of the display device shown in fig. 1. Fig. 4 is a schematic circuit diagram of an organic electroluminescent element included in the display device shown in fig. 1.
The display device 100 shown in fig. 1 to 4 is a top emission display device including an active matrix organic electroluminescent element. In the display device 100, the organic electroluminescent layer 10 is provided on the interlayer insulating film 80, the discrete electrode (second electrode) 20 as an anode is provided on the main surface of the organic electroluminescent layer 10 on the interlayer insulating film 80 side, and the transparent common electrode (first electrode) 30 as a cathode is provided on the main surface on the opposite side. Further, the third electrode 90 is provided between the discrete electrodes 20 on the main surface of the organic electroluminescent layer 10 on the interlayer insulating film 80 side. Further, a protective insulating film 40, a color filter layer 50, a sealing resin 60, and a protective glass 70 are sequentially stacked on the transparent common electrode 30. In the interlayer insulating film 80, a contact 81 and a wiring 83 for coupling the discrete electrode 20 to a pixel drive circuit are provided, and a contact 85 and a wiring 87 for coupling to the third electrode 90 are provided. Note that the circuit for driving the organic electroluminescence element OLED as shown in fig. 4 is appropriately provided in the interlayer insulating film 80 and the semiconductor substrate (not shown) in the bottom layer thereof.
In the present embodiment, similarly to the display device 200, in the display device 100, the red pixel SP as shown in fig. 16RGreen pixel SPGAnd blue pixel SPBAll form hexagonal sub-pixels; red pixel SPRGreen pixel SPGAnd blueColor pixel SPBAre combined to constitute one pixel. Arranging these pixels in a matrix enables an image to be displayed.
The organic electroluminescent layer 10 includes an organic light emitting material, and is provided on the discrete electrode 20 and the interlayer insulating film 80 as a continuous film common to all the organic electroluminescent elements OLED. In addition, the organic electroluminescent layer 10 emits light when an electric field is applied between the discrete electrodes 20 and the transparent common electrode 30.
Specifically, under application of an electric field, holes are injected from the discrete electrodes 20 into the organic electroluminescent layer 10, and electrons are injected from the transparent common electrode 30. The injected holes and electrons are recombined in the organic electroluminescent layer 10 to form excitons; the energy of the exciton excites the organic light emitting material to generate fluorescence or phosphorescence from the organic light emitting material.
Here, the organic electroluminescent layer 10 may be formed in a multi-layer structure in which a plurality of functional layers are stacked. For example, the organic electroluminescent layer 10 may be formed in a structure in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are stacked in this order from the discrete electrode 20 side. Further, the organic electroluminescent layer 10 may be formed to have a so-called tandem structure in which the light emitting layers are coupled via a charge generation layer or an intermediate electrode.
The organic electroluminescent layer 10 includes a hole transport material, an electron transport material, a charge transport material, an organic light emitting material, and the like according to its layer structure. These materials are not limited, and known materials may be used in combination as needed.
further, the wavelength of light emitted by the organic electroluminescent layer 10 may be appropriately set according to the application; in the display device 100 according to the present embodiment, the emission wavelength is set to allow the emission color to be white.
As described above, the organic electroluminescent layer 10 is a continuous film common to the organic electroluminescent elements OLED, and is continuously formed across a plurality of pixels in a plan view. Here, in the case of an organic electroluminescent display having a pixel pitch of several tens of micrometers or more, organic electroluminescent layers emitting red, green, and blue light may be formed by dividing the organic electroluminescent layers for the respective colors by mask evaporation or the like. However, in the case of a high-definition small-sized display using Si-MOS having a pixel pitch of 10 μm or less, it is difficult to divide and form organic electroluminescent layers for respective colors. Therefore, in the case of manufacturing the display device 100 having a small pixel pitch, a method is suitable in which the organic electroluminescent layer 10 emitting white light is formed to cover the entire effective pixel area, and the color filter layer 50 disposed thereon disperses the light into red, green, and blue.
Meanwhile, it is considered that the organic electroluminescent layer 10 tends to cause a leakage current to easily flow between pixels because there is no break in the layer. However, in the display device 100 according to the present embodiment, a leakage current flows to the third electrode 90 described later, thereby suppressing movement of the leakage current between pixels.
The transparent common electrode 30 serves as a cathode of the organic electroluminescent element OLED. Therefore, in the case of applying a voltage to the organic electroluminescent layer 10, the potential of the transparent common electrode 30 becomes smaller than the potential of the discrete electrode 20 described later. Further, the transparent common electrode 30 is provided on the organic electroluminescent layer 10 as a continuous film common to all the light emitting elements. The transparent common electrode 30 may be formed as a light-transmitting electrode from a material having high light transmittance and a small work function. For example, the transparent common electrode 30 may be formed of a transparent conductive material, for example, indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, or gallium-doped zinc oxide, or may be formed of an alloy of a metal, for example, aluminum (Al), magnesium (Mg), silver (Ag), calcium (Ca), or sodium (Na), as a thin film (for example, 30nm or less) thin enough to have light transmittance. In addition, the transparent common electrode 30 may be formed by stacking a plurality of films including the above-described metal or alloy.
The discrete electrodes 20 are provided on the interlayer insulating film 80 for the respective pixels, and each electrode functions as an anode of the organic electroluminescence element OLED. As shown in fig. 2, a predetermined pixel pitch P corresponding to the arrangement (arrangement) and shape of the pixels is based onPThe discrete electrodes 20 are disposed at equal intervals. In particular, corresponding to redThe separate electrode 20R of the color pixel, the separate electrode 20G corresponding to the green pixel, and the separate electrode 20B corresponding to the blue pixel are repeatedly disposed with a boundary region of a predetermined interval therebetween. In addition, in the present embodiment, each of the discrete electrodes 20 has a hexagonal shape in a plan view.
The discrete electrode 20 may be formed as a light reflective electrode from a material having high light reflectance and high work function. For example, the discrete electrodes 20 may be formed of an alloy of a simple substance or a metal (e.g., Cr, Au, Pt, Ni, Cu, Mo, W, Ti, Ta, Al, Fe, or Ag), or may be formed by stacking a plurality of metal films. Among those described above, Al has a visible light reflectance of 90% or more, and can simultaneously have the functions of feeding and as a reflector. In the case where Al is used as the discrete electrode 20, a trace amount of Cu may be added.
As shown in fig. 3, in the discrete electrode 20, an electrode 201 and a light reflection layer 202 having conductivity may be stacked. In this case, a material suitable for injecting holes into the organic electroluminescent layer 10 may be used for the electrode 201. In addition, the electrode 201 may be formed of a transparent conductive material (e.g., indium zinc oxide or indium tin oxide) as a transparent electrode. The light reflective layer 202 may be made of a simple substance or an alloy of metals (e.g., Cr, Au, Pt, Ni, Cu, Mo, W, Ti, Ta, Al, Fe, or Ag).
Further, as shown in fig. 1, the third electrode 90 is provided in contact with the main surface of the organic electroluminescent layer 10 in the boundary region between the discrete electrodes 20. Further, as shown in fig. 2, in the present embodiment, the third electrode 90 is regularly disposed so as to be equidistant from the discrete electrodes 20R, 20G, and 20B adjacent to each other in a plan view. From another point of view, the third electrode 90 is disposed apart from and surrounds each of the discrete electrodes 20R, 20G, and 20B by a predetermined distance in a plan view.
The third electrodes 90 are each coupled to an internal circuit of the display device 100 via a contact 85 and a wiring 87, and are set to a common constant potential. Specifically, when a voltage is applied to the organic electroluminescent layer 10, the potential of the third electrode 90 is set to a value smaller than the potential of the transparent common electrode 30 plus the threshold voltage of the organic electroluminescent layer 10.
This enables a leakage current to preferentially flow to the third electrode 90 even in the case where a voltage is applied to the organic electroluminescent layer 10 through the transparent common electrode 30 and the discrete electrode 20 and a leakage current is generated from the applied discrete electrode 20 due to the applied voltage. Thus, a leakage current is prevented from flowing from the applied discrete electrode 20 to the adjacent discrete electrode 20. As a result, a voltage due to a leakage current is prevented from being generated between the discrete electrode 20 and the transparent common electrode 30, and the transparent common electrode 30 is not intended to cause the organic electroluminescent layer 10 to emit light.
Specifically, for example, as shown in fig. 2, when a voltage is applied to the organic electroluminescent layer 10 between the discrete electrode 20B and the transparent common electrode 30 in the middle in the figure, a leakage current generated in the discrete electrode 20B preferentially flows to the surrounding third electrode 90 (shown by an arrow in the figure). As a result, a leakage current is prevented from flowing to the peripheral discrete electrodes 20B and 20G, and the peripheral green and red pixels are prevented from emitting light. As a result, the color purity of the blue pixel corresponding to the discrete electrode 20B is prevented from being lowered, thereby enabling an image to be displayed in a wide color gamut in the display device 100.
The potential of the third electrode 90 as described above is preferably equal to or lower than the potential of the transparent common electrode 30. This enables the leakage current generated in the discrete electrode 20 to preferentially flow to the surrounding third electrode 90 more securely. In the present embodiment, the discrete electrode 20 is an anode and therefore can have a positive potential when a voltage is applied. Therefore, in this case, the potential of the third electrode 90 may be set to, for example, 0V or lower.
Further, the potential of the third electrode 90 is preferably the same as that of the transparent common electrode 30. As a result, the potential setting of the third electrode 90 described above can be achieved more easily, and the configuration of the display device 100 becomes simple. That is, the third electrode 90 and the transparent common electrode 30 may be coupled together by a wiring or the like, so that the potential may be managed by the same wiring. For example, in the case where the potential of the transparent common electrode 30 as a cathode is set to 0V, the potential of the third electrode 90 may be set to 0V. Further, for example, in the case where the potential of the transparent common electrode 30 is set to be negative and the potential difference between the transparent common electrode 30 and the anode is increased to improve the luminance of the organic electroluminescence element OLED, the potential of the third electrode 90 may also be set to be negative.
The lower limit value of the potential of the third electrode 90 is not particularly limited; it is sufficient that the current whose lower limit value is in the reverse direction does not substantially flow in the range of the organic electroluminescent layer 10. For example, the potential of the third electrode 90 may be about 10V less than the potential of the transparent common electrode 30. However, even when the potential of the third electrode 90 is set to a significantly lower potential, for example, a potential 5V lower than the potential of the transparent common electrode 30, the above-described effect of suppressing the leakage current is not significantly enhanced. When the potential of the third electrode 90 is set to be lower than the potential of the transparent common electrode 30 by 2V, the above-described effect of sufficiently suppressing the leakage current can be obtained.
In the present embodiment, the plurality of third electrodes 90 are island-like electrode groups having an area smaller than that of the discrete electrodes 20. Such a manner of disposing the plurality of third electrodes 90 in the form of dots enables a reduction in the area required for mounting the third electrodes 90, thereby making it possible to relatively increase the area of the discrete electrodes 20. This makes it possible to increase the area for the organic electroluminescent layer 10 to emit light, so that even in the case where the organic electroluminescent layer 10 is caused to emit light with the same luminance and the same current, the current density in the organic electroluminescent layer 10 can be relatively reduced. In this case, deterioration of the organic electroluminescent layer 10 can be suppressed, thereby allowing the display device 100 to have a longer life.
The area of each third electrode 90 is not particularly limited as long as the coupling with the contact 85 is ensured, and may be reduced according to the accuracy of the manufacturing process of the display device 100. For example, the area of each third electrode 90 may be 5% or less, preferably 3% or less, of the area of each discrete electrode 20.
Further, the distance between each third electrode 90 and the adjacent discrete electrode 20 is not particularly limited; the third electrode 90 and the discrete electrode 20 are disposed apart from each other so as not to cause a short circuit therebetween.
The third electrode 90 is disposed in the same layer as the discrete electrode 20. That is, the third electrode 90 is simultaneously formed in the same process at the time of manufacture. This makes it possible to easily and reliably dispose the third electrode 90 between the discrete electrodes 20 and to dispose the third electrode 90 in reliable contact with the organic electroluminescent layer 10.
the material and layer configuration of the third electrode 90 may be the same as the material and layer configuration of the discrete electrode 20.
The protective insulating film 40 is provided on the transparent common electrode 30, and protects the organic electroluminescent element OLED from the external environment, particularly, prevents water and oxygen from entering the organic electroluminescent layer 10. The protective insulating film 40 may be provided using, for example, a material having high light transmittance and low water permeability, for example, silicon oxide (SiO)x) Silicon nitride (SiN)x) Aluminum oxide (AlO)x) Or titanium oxide (TiO)x)。
The color filter layer 50 is provided on the protective insulating film 40, and performs color division of light generated in the organic electroluminescent element OLED for each pixel. Specifically, the color filter layer 50 includes a red color filter 50R, a green color filter 50G, and a blue color filter 50B divided for the respective discrete electrodes 20, respectively. The red color filter 50R, the green color filter 50G, and the blue color filter 50B convert incident light from the organic electroluminescent layer 10 side into red, green, and blue, respectively, and output the converted light to the sealing resin 60 side. In addition, the color filter layer 50 may be a resin layer that selectively transmits light of a visible light wavelength band corresponding to red, green, or blue light.
The sealing resin 60 is disposed on the color filter layer 50, and seals each member under the color filter layer 50. Further, a protective glass 70 is provided on the sealing resin 60 to protect the display portion of the display device 100.
The interlayer insulating film 80 is disposed under the organic electroluminescent layer 10 and supports the discrete electrode 20 and the third electrode 90. Meanwhile, the interlayer insulating film 80 accommodates a contact 81 and a wiring 83 which couple the discrete electrode 20 to a pixel drive circuit, not shown, and a contact 85 and a wiring 87 which couple the third electrode 90 to an external circuit. Note that the interlayer insulating film 80 may house other wirings, elements, and the like as necessary. The interlayer insulating film 80 is formed of, for example, insulating silicon oxynitride or the like. The wirings 83 and 87 are each composed of an electric conductor (e.g., copper (Cu) or aluminum (Al)), and couple the discrete electrode 20 and the third electrode 90 to an external circuit.
Note that as described above, the display device 100 includes a driving circuit for driving the organic electroluminescent element of the display device 100 in a semiconductor substrate or the like which is not shown. The driving circuit is generally formed by dividing into pixel units through a MOS process. Here, an example of a circuit constituting one pixel of the display device 100 is described. Fig. 4 is an explanatory circuit diagram of an example of a circuit constituting one pixel of the display device 100.
As shown in fig. 4, a circuit constituting one pixel of the display device 100 includes an organic electroluminescent element OLED, a driving transistor DTr, a capacitor element C, and a selection transistor STr.
As described above, the organic electroluminescent element OLED is a self-luminous type light-emitting element in which the discrete electrode 20, the organic electroluminescent layer 10, and the transparent common electrode 30 are stacked. The discrete electrode 20 of the organic electroluminescent element OLED is coupled to the power supply line PL via the driving transistor DTr, and the transparent common electrode 30 of the organic electroluminescent element OLED is coupled to the ground line at the ground potential. The organic electroluminescent element OLED is used as one pixel of the display device 100.
The driving transistor DTr is, for example, a field effect transistor. One of the source and the drain of the driving transistor DTr is coupled to the power supply line PL, and the other of the source and the drain of the driving transistor DTr is coupled to the discrete electrode 20 of the organic electroluminescent element OLED. Further, the gate of the driving transistor DTr is coupled to one of the source and the drain of the selection transistor STr. The driving transistor DTr is coupled in series to the organic electroluminescent element OLED and controls a current flowing to the organic electroluminescent element OLED according to the magnitude of the gate voltage applied from the selection transistor STr, thereby driving the organic electroluminescent element OLED.
The selection transistor STr is, for example, a field effect transistor. One of a source and a drain of the selection transistor STr is coupled to the gate of the driving transistor DTr, and the other of the source and the drain is coupled to the signal line DL. Further, the gate of the selection transistor STr is coupled to the scan line SL. The selection transistor STr samples a voltage of the signal line DL and then applies the sampled voltage to the gate of the driving transistor DTr, thereby controlling a signal voltage applied to the gate of the driving transistor DTr.
The capacitor element C is, for example, a capacitor. One end of the capacitor element C is coupled to the gate of the driving transistor DTr, and the other end of the capacitor element C is coupled to the power supply line PL. The capacitor element C maintains a voltage between the gate and the source of the driving transistor DTr at a predetermined voltage.
In the display device 100 according to the present embodiment described above, the third electrode 90 is provided between the discrete electrodes 20, and the potential of the third electrode 90 is smaller than the value of the potential of the transparent common electrode 30 plus the threshold voltage of the organic electroluminescent layer 10. This enables a leakage current to preferentially flow to the third electrode 90 even in the case where a voltage is applied to the organic electroluminescent layer 10 through the transparent common electrode 30 and the discrete electrode 20 and a leakage current is generated from the applied discrete electrode 20 due to the applied voltage. Thus, a leakage current is prevented from flowing from the applied discrete electrode 20 to the adjacent discrete electrode 20. As a result, a voltage due to a leakage current is prevented from being generated between the discrete electrode 20 and the transparent common electrode 30, and the transparent common electrode 30 is not intended to cause the organic electroluminescent layer 10 to emit light. Further, pixels corresponding to other surrounding colors are prevented from being accidentally illuminated, thereby enabling an image to be displayed in a wide color gamut in the display device 100.
As described above, as the pixel pitch becomes smaller, the influence of the leakage current becomes larger. Further, in the case of realizing a fine pixel pitch of 10 μm or less, it is appropriate to provide a continuous white organic electroluminescent layer and perform color conversion by a color filter layer, but on the other hand, the influence of leakage current in the continuous organic electroluminescent layer is also large. Even in the case of employing such a fine pixel pitch, the display device 100 according to the present embodiment described above can sufficiently suppress the influence of the leakage current between pixels.
<3. verifying the influence of leakage Current >
Next, the display device 100 and the display device 200 are compared with each other to verify the influence of the leakage current according to the presence or absence of the third electrode 90. Here, the power supply lines for light emission of the display devices 100 and 200 are each set to a positive voltage, for example, 8V, and the driving transistor DTr is turned on, thereby enabling the potential of the anode (the discrete electrodes 20 and 220) to be used to be about 6V at maximum. This is designed to allow a potential drop of about 2V at maximum to occur between the source and drain of the driving transistor DTr. Meanwhile, the potential of the cathode (transparent common electrodes 30 and 230) is set to the ground potential (0V).
First, fig. 5 shows the estimation results of the light emission current and the leakage current flowing to the adjacent discrete electrode 220 based on the current-voltage characteristics of the organic electroluminescent layer 210 shown in fig. 19 in the absence of the third electrode 90. Further, fig. 5 shows the measurement results of the light emission current and the leakage current flowing to the adjacent discrete electrode 20 in the display device 100. The numerical values in the graph of fig. 5 represent the voltage values of the discrete electrodes 20 and 220 in the case of light emission.
The light emission current (i.e., the current flowing through the organic electroluminescent layer 210) indicated on the horizontal axis is 10-12A or less, the leak current eventually reaches 1/10 or more of the light emitting current, and 10-13A or less is almost equal to the light emission current. Meanwhile, in the display device 100 in which the third electrode 90 is set to 0V, the leakage current is suppressed to about 1/10 of the leakage current of the display device 200, and the effect of suppressing the leakage current is particularly significant on the low voltage side equal to or lower than 3V. Further, in the display device 100 in which the third electrode 90 is set to-2V, the leak current can be suppressed to 1/100 or less of the display device 200.
Further, fig. 6 shows values obtained by subtracting the quotient of the leakage current flowing to the adjacent discrete electrodes 20 and 220 divided by the light emission current from 1 in the case where various voltages are applied to one of the discrete electrodes 20 and 220. The value on the vertical axis in the graph indicates the relationship between the light emission current and the leakage current, and is therefore a measure of the width of the color gamut of each of the display devices 100 and 200. The horizontal axis of fig. 6 indicates the luminance, specifically, the luminance in the case where the discrete electrodes 20 and 220 of all the sub-pixels of the organic electroluminescent element OLED (i.e., all the red, green, and blue sub-pixels belonging to all the pixels) are irradiated with a predetermined voltage.
As shown in fig. 6, in the display device 200 without the third electrode 90, the reduction of the color gamut due to the leakage current between the discrete electrodes 220 is not negligible at 1nit, which is a sufficiently visible luminance, and the reduction of the color gamut is also observed in the actual prototype panel, which needs improvement.
Meanwhile, in the display device 100 having the third electrode 90, even at the invisible low luminance of 0.001nit, the leakage current causing color mixing is 1/10 or less of the light emission current, and the reduction of the color gamut can be maintained at about 10%. However, as shown in fig. 6, the effect of setting the potential of the third electrode 90 to a voltage (-2V) still lower than the potential of the transparent common electrode 30 by 0V is not significant in consideration of the wide color gamut. Meanwhile, in the case where the potential of the third electrode 90 is set to be lower than the potential of the transparent common electrode 30, the power consumption of the display device 100 as a whole may increase in some cases. Therefore, in the case where it is necessary to suppress the leak current between the discrete electrodes 20 to the limit, it can be considered that the potential of the third electrode 90 is set to be still lower than the potential of the transparent common electrode 30.
Note that in the display device 100, the third electrodes 90 are each provided as a dot having a small area, but as described above, the leak current can be sufficiently suppressed. The area of the discrete electrode 20 in such a display device 100 is only about 12% smaller than the area of the discrete electrode 220 in the display device 200 shown in fig. 16, thereby making it possible to suppress the influence on the lifetime degradation of the organic electroluminescent layer 10 to the minimum.
<4. modification >
The embodiments of the present disclosure have been described above. Several variations of the above-described embodiments of the present disclosure are described below. Note that each of the modifications described below may be applied to the above-described embodiments of the present disclosure alone or may be applied to the above-described embodiments of the present disclosure in combination. Further, each modification may be applied instead of or in addition to the configuration described in the above-described embodiment of the present disclosure.
First, in the present embodiment described above, the transparent common electrode 30 is a cathode and the discrete electrode 20 is an anode, but the present disclosure is not limited thereto. The transparent common electrode 30 may be an anode and the discrete electrode 20 may be a cathode. In this case, when a voltage is applied to the organic electroluminescent layer 10, the potential of the transparent common electrode 30 is greater than that of the discrete electrode 20. Further, the potential of the third electrode 90 is greater than the potential of the transparent common electrode 30 minus the threshold voltage of the organic electroluminescent layer 10. This makes it possible to obtain an effect of suppressing the leakage current between the discrete electrodes 20.
In the above case, the potential of the third electrode 90 is preferably equal to or higher than the potential of the transparent common electrode 30, and more preferably the same as the potential of the transparent common electrode 30. Further, the upper limit of the potential of the third electrode 90 is not particularly limited, and may be in a range in which a current in the reverse direction does not substantially flow to the organic electroluminescent layer 10. However, by setting the potential of the third electrode 90 to be higher than the potential of the transparent common electrode 30 by 2V, the above-described effect of suppressing the leakage current can be sufficiently obtained.
In the present embodiment described above, the shapes of the pixel and discrete electrode 20 are hexagonal, but the present disclosure is not limited thereto. The arrangement of the third electrode around the discrete electrodes may also be appropriately changed according to the shape of the discrete electrodes and the application thereof.
Fig. 7 to 9 show examples of changes in the shapes of the discrete electrodes and the arrangement of the third electrodes. In fig. 7, the discrete electrodes 21R, 21G, and 21B corresponding to red, green, and blue each have a rectangular shape according to the shape of the pixel, and are arranged in a stripe shape. Further, the third electrodes 90A are provided apart from each other on the extension lines of the respective corners of the discrete electrodes 21R, 21G, and 21B so as not to short-circuit the discrete electrodes 21R, 21G, and 21B.
In fig. 8, the discrete electrodes 22R, 22G, and 22B corresponding to red, green, and blue colors each have a square shape according to the shape of the pixel. Further, the third electrodes 90B are provided apart from each other on the extension lines of the respective corners of the discrete electrodes 22R, 22G, and 22B so as not to short-circuit the discrete electrodes 22R, 22G, and 22B. However, the third electrode 90B is not disposed on an extension line of a part of the corner of each of the discrete electrodes 22R, 22G, and 22B. As described above, the third electrodes 90B are regularly arranged, and a part thereof may not be arranged as needed. Further, the third electrode may be disposed around a discrete electrode susceptible to a leakage current, and the third electrode may not be disposed around other discrete electrodes.
Fig. 9 shows the arrangement of the discrete electrodes 23R, 23G, 23B, and 23W in the case where the color filter layer has a white pixel without using a color conversion member. The discrete electrodes 23R, 23G, 23B, and 23W corresponding to red, green, blue, and white each have a square shape according to the shape of the pixel. Further, the third electrode 90C is provided on the extension line of each corner of the discrete electrodes 23R, 23G, 23B, and 23W, and does not short-circuit with the discrete electrodes 23R, 23G, 23B, and 23W. In the case of using such a white pixel, it is advantageous to increase the maximum luminance.
Note that, in the present embodiment and the above-described modifications, the third electrode has been described as a point, but the present disclosure is not limited thereto. For example, the third electrode may take a variety of shapes, and may be, for example, a linear electrode extending between discrete electrodes. The third electrode may have a mesh shape extending between the discrete electrodes.
Further, the arrangement of the discrete electrode and the third electrode on the interlayer insulating film may also be changed as necessary according to the formation method of the discrete electrode and the third electrode. In fig. 10, the interlayer insulating film 80A has a convex portion 803, and the discrete electrode 24 and the third electrode 90D are provided on the convex portion 803. The interlayer insulating film 80A, the discrete electrodes 24, and the third electrode 90D as described above can be obtained by forming an anode and a new common electrode on an interlayer insulating film used in a typical LSI (large scale integrated circuit) wiring, and performing processing by using known photolithography and dry etching.
In fig. 11, an interlayer insulating film 80B is further embedded in the gap region between the discrete electrode 25 and the third electrode 90E. In this case, the plane formed by the discrete electrode 25, the third electrode 90E, and the interlayer insulating film 80B is relatively smooth, so that it is possible to prevent a thin portion from being locally formed in the case of forming an organic electroluminescent layer. As a result, light can be uniformly emitted regardless of the portion. This structure can also be realized by using a known typical LSI manufacturing process or a TFT (thin film transistor) manufacturing process.
Further, in fig. 12, the interlayer insulating film 80C has a convex portion 803A, and the discrete electrode 26 and the third electrode 90F are provided on the convex portion 803A. Further, an insulating film 805 is formed over the discrete electrode 26 and the third electrode 90F. In this case, the organic electroluminescent layer in the opening region of the insulating film 805 emits light, and the effective region of the discrete electrode 26 is an opening region surrounded by the insulating film 805. Compared with the structure in fig. 10, such a structure can be formed by further forming an insulating film on the electrode and then removing a part of the insulating film to form an opening.
Further, as a wiring for supplying power to the third electrode, for example, as shown in fig. 13, a light shielding layer 88 including a metal may be used instead. The light shielding layer 88 is provided in the interlayer insulating film 80 and blocks light emitted from the organic electroluminescent layer 10 to protect the pixel driving MOS transistor and the TFT in the lower layer. The light shielding layer 88 is continuously formed in the entire display portion of the display device 100, and may be formed of, for example, a metal layer having low reflectance and low transmittance, for example, titanium nitride or tungsten. By coupling the light shielding layer 88 and the third electrode 90 to each other using the contact 87A, and by coupling the light shielding layer 88 to an external circuit, the potential of the third electrode 90 can be set.
In the present embodiment described above, the discrete electrodes 20 have a function as a reflective plate, but the present disclosure is not limited thereto. For example, as shown in fig. 14, the discrete electrodes 27 are formed of a transparent conductive material (e.g., indium zinc oxide or indium tin oxide) as transparent electrodes. Meanwhile, a reflection plate 89 (e.g., a metal film) is provided below the discrete electrodes 26 in the interlayer insulating film 80D.
further, the display device according to the present disclosure may be a bottom emission type. In this case, the discrete electrodes are transparent electrodes, and the reflective plate in the interlayer insulating film is omitted.
Further, in the present embodiment described above, the organic electroluminescent layer is continuously formed on a plurality of pixels, but this is not limitative; the organic electroluminescent layer emitting each of red light, green light, and blue light may be formed by dividing the organic electroluminescent layer for each color by mask evaporation or the like. In the case where such a pixel pitch is relatively large (for example, several tens of micrometers or more), a method of dividing the organic electroluminescent layer of each color is suitable. Further, such a configuration is also possible in the case where the display device is driven by a thin film transistor including amorphous silicon, polycrystalline silicon, an oxide semiconductor, or the like. In the case where the organic electroluminescent layer is divided for each color as described above, the display device having the third electrode according to the present disclosure can appropriately suppress leakage current between pixels.
As a circuit configuration for driving light emission of the display device, various known circuits may be used instead of the circuit shown in fig. 4. Various pixel driving methods have been devised including a correction operation for improving the uniformity of the panel of image quality, but the technology of the present disclosure is widely applicable regardless of these detailed pixel driving methods. However, in some cases, control may be employed in which the voltage applied to the third electrode is not always maintained at a constant value, but a switch, for example, a transistor, provided between the constant potential line and the third electrode is turned off for a period of time in which the contribution to light emission is small (for example, a correction operation).
<5. conclusion >
As described above, according to the present disclosure, the influence of leakage current between discrete electrodes in a display device including an organic electroluminescent element can be suppressed. Therefore, pixels corresponding to other surrounding colors are prevented from being accidentally lighted, thereby making it possible to display an image of a wide color gamut in the display device.
Note that the display device described above may be used as a display portion of various electronic apparatuses that display an input image signal or an internally generated image signal as a still image or a moving image. Examples of such electronic devices include: a music player including a storage medium (e.g., a semiconductor memory), an imaging device (e.g., a digital camera and a video camera), a notebook personal computer, a game device, and a portable information terminal (e.g., a mobile phone and a smart phone).
Although the preferred embodiments of the present disclosure have been described in detail above with reference to the drawings, the technical scope of the present disclosure is not limited to these examples. Obviously, those skilled in the art of the present disclosure can find various changes or modifications within the scope of the technical idea described in the claims, and it should be understood that such changes and modifications naturally belong to the technical scope of the present disclosure.
Further, the effects described herein are merely illustrative or exemplary and not restrictive. That is, in addition to or instead of the above-described effects, other effects that are obvious to those skilled in the art from the description of the present specification may be achieved according to the technology of the present disclosure.
Note that the technical scope of the present disclosure also includes the following configurations.
(1) A display device, comprising:
An organic electroluminescent layer;
A first electrode provided on one main surface side of the organic electroluminescent layer and common to the plurality of pixels;
A plurality of second electrodes provided for each pixel on the other main surface side of the organic electroluminescent layer; and
And a plurality of third electrodes each disposed between the second electrodes on the other major surface side of the organic electroluminescent layer.
(2) The display device according to (1), wherein when a voltage is applied to the organic electroluminescent layer, the potential of the first electrode is lower than the potential of the second electrode, and the potential of the third electrode is lower than a value obtained by adding the potential of the first electrode to a threshold voltage of the organic electroluminescent layer.
(3) The display device according to (2), wherein a potential of the third electrode is equal to or less than a potential of the first electrode.
(4) The display device according to (1), wherein, when a voltage is applied to the organic electroluminescent layer, the potential of the first electrode is larger than the potential of the second electrode, and the potential of the third electrode is larger than a value obtained by subtracting a threshold voltage of the organic electroluminescent layer from the potential of the first electrode.
(5) The display device according to any one of (2) to (4), wherein a potential of the third electrode is equal to a potential of the first electrode.
(6) The display device according to any one of (1) to (5), wherein the third electrode is provided in an island shape in a plan view.
(7) The display device according to any one of (1) to (6), wherein the third electrodes are provided at equal intervals from the second electrodes adjacent to each other in a plan view.
(8) The display device according to any one of (1) to (7), wherein the second electrode and the third electrode are provided in the same layer.
(9) The display device according to any one of (1) to (8), wherein the organic electroluminescent layer is continuously formed over a plurality of pixels in a plan view.
(10) An electronic device includes a display portion,
The display part comprises
An organic electroluminescent layer;
A first electrode provided on one main surface side of the organic electroluminescent layer and common to the plurality of pixels;
A plurality of second electrodes provided corresponding to each pixel, respectively, on the other major surface side of the organic electroluminescent layer; and
And a plurality of third electrodes each disposed between the second electrodes on the other major surface side of the organic electroluminescent layer.
[ list of reference numerals ]
10. 210 organic electroluminescent layer
20. 20B, 20G, 20R, 21B, 21G, 21R, 22B, 22G, 22R, 23B, 23G, 23R, 23W, 24, 25, 26, 27, 220B, 220G, 220R discrete electrodes
201 electrode
202 light reflecting layer
30. 230 transparent common electrode
40. 240 protective insulating film
50. 250 color filter layer
50R, 250R red color filter
50G, 250G green color filter
50B, 250B blue color filter
60. 260 sealing resin
70. 270 protective glass
80. 80A, 80B, 80C, 80D, 280 interlayer insulating film
81. 85, 87A, 281 contact points
83. 87, 283 wiring
88 light-shielding layer
89 reflecting plate
90. 90A, 90B, 90C, 90D, 90E, 90F third electrode
100. 200 display device

Claims (10)

1. a display device, comprising:
An organic electroluminescent layer;
A first electrode provided on one main surface side of the organic electroluminescent layer and common to a plurality of pixels;
A plurality of second electrodes each provided for each of the pixels on the other major surface side of the organic electroluminescent layer; and
A plurality of third electrodes each on the other major surface side of the organic electroluminescent layer, disposed between the plurality of second electrodes.
2. The display device according to claim 1, wherein when a voltage is applied to the organic electroluminescent layer, the potential of the first electrode is smaller than the potential of the second electrode, and the potential of the third electrode is smaller than a value obtained by adding a threshold voltage of the organic electroluminescent layer to the potential of the first electrode.
3. The display device according to claim 2, wherein a potential of the third electrode is equal to or less than a potential of the first electrode.
4. The display device according to claim 2, wherein a potential of the third electrode is the same as a potential of the first electrode.
5. The display device according to claim 1, wherein the third electrodes are arranged in an island shape in a plan view.
6. The display device according to claim 1, wherein the third electrode is arranged at equal intervals from the plurality of second electrodes adjacent to each other in a plan view.
7. the display device according to claim 1, wherein the second electrode and the third electrode are provided in the same layer.
8. The display device according to claim 1, wherein the organic electroluminescent layer is continuously formed over the plurality of pixels in a plan view.
9. the display device according to claim 1, wherein when a voltage is applied to the organic electroluminescent layer, the potential of the first electrode is larger than the potential of the second electrode, and the potential of the third electrode is larger than a value obtained by subtracting a threshold voltage of the organic electroluminescent layer from the potential of the first electrode.
10. An electronic device includes a display portion,
The display part comprises
An organic electroluminescent layer;
A first electrode provided on one main surface side of the organic electroluminescent layer and common to a plurality of pixels;
A plurality of second electrodes each provided on the other major surface side of the organic electroluminescent layer, correspondingly for each of the pixels; and
A plurality of third electrodes each on the other major surface side of the organic electroluminescent layer, disposed between the plurality of second electrodes.
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