JP4807677B2 - Display device - Google Patents

Description

  The present invention relates to a display device using an organic electroluminescence (EL) element.

  A display device using an organic EL element is self-luminous and does not require a backlight, can display an image with a wide viewing angle, and has attracted attention as a display with low power consumption.

  The organic EL element has a structure in which an organic EL layer is sandwiched between two electrodes. FIG. 8 shows a configuration example of a display device using a conventional organic EL element. A transparent electrode 102 constituting an anode, an organic EL layer 103, and a reflective electrode 104 constituting a cathode are sequentially formed on a glass substrate 101 with an insulating film 105a interposed therebetween. The transparent electrode 102, the organic EL layer 103, and the reflective electrode 104 constitute an organic EL element. The organic EL layer 103 is formed by stacking, for example, a hole transport layer, a light emitting layer, and an electron transport layer. The transparent electrode 102 is electrically connected to a drain 105 d of a TFT (Thin Film Transistor) 105 formed on the glass substrate 101. The TFT 105 is a TFT having a function of driving the organic EL element. Note that a shielding layer 106 is formed on the reflective electrode 104.

In order to drive the organic EL element, the transparent electrode 102 serving as the anode is organically driven based on the difference between the voltage applied to the transparent electrode 102 from the TFT 105 via the drain 105d and the voltage applied to the reflective electrode 104. Light is emitted by recombination of holes supplied through the hole transport layer of the EL layer 103 and electrons supplied from the reflective electrode 104 serving as the cathode through the electron transport layer of the organic EL layer 103. . In this case, light emission is extracted from the glass substrate 101 side through the transparent electrode 102. That is, the structure of the organic EL element is a so-called Bottom Emission structure. And the technique regarding the organic EL element which has such a Bottom Emission structure is also disclosed (for example, refer patent document 1).
JP 2002-108285 A (Page 15, FIG. 14)

  Since the organic EL element described above is different from a capacitor such as a liquid crystal of an active drive type liquid crystal display device, the number of TFTs per pixel is increased or the aperture ratio is lowered by providing a capacitor. As a result, there is a problem that the area of the organic EL layer of each pixel is reduced and the amount of light emitted from the glass substrate 101 side is reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a display device capable of improving the aperture ratio.

To achieve the above object, a display device according to a first aspect of the present invention, a plurality each having a first electrode, light emitting layer, and the second electrode is an organic electroluminescent device formed by sequentially laminating A first substrate formed by arranging the pixels in a matrix ,
A plurality of first transistors having a drain electrode or a source electrode electrically connected to the second electrode of the organic electroluminescence element of each pixel and controlling a current flowing to the organic electroluminescence element are formed. A second substrate,
An inter-pixel blocking wall that partitions the pixels, formed on the first substrate,
A second electrode of the organic electroluminescence element of each pixel is formed to extend on the inter-pixel shielding wall;
The second electrodes of the organic electroluminescence elements of the two pixels adjacent to each other through the inter-pixel shielding wall are divided into two on the inter-pixel shielding wall,
One of the two second electrodes of the organic electroluminescence element formed by being divided on the inter-pixel shielding wall and a drain electrode or a source electrode of the first transistor are arranged to face each other, and Electrically connected on the inter-pixel barrier,
Space is provided between the first substrate and the first transistor,
It is characterized by that.

  According to the present invention, the first substrate on which the organic electroluminescence element is formed and the second substrate on which the transistor is formed are constituted by different substrates, and are fixed to face each other. Therefore, the organic electroluminescence element If the light emission of the organic electroluminescence element is taken out from the first substrate side on which is formed, the transistor does not block the light emission.

A plurality of conductive spacers formed on the second substrate;
A drain electrode or a source electrode of the first transistor is formed on a second substrate including the plurality of conductive spacers;
The organic of the two pixels and the drain or source electrode, for said adjacent formed by cutting on the pixel between the shroud of the plurality of the formed uneven on the conductive spacer of the first transistor One of the two second electrodes of the electroluminescence element may be arranged to face each other and be electrically connected.

A second substrate formed on the second substrate and electrically connected to a gate electrode of the first transistor and a drain electrode or a source electrode, and outputs image data to the first transistor; A transistor may be provided.

  According to the present invention, the aperture ratio can be improved.

  A display device using an organic EL element according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a plan view showing an example of the configuration of a display device using an organic EL element applied to Embodiment 1 of the present invention, and FIG. 2 is broken along the one-dot chain line AA ′ in FIG. It is sectional drawing for one pixel shown.

  The display device 10 is an active matrix display device including a thin film transistor (TFT) as an active element, and includes an organic EL element 11 for each pixel.

  The display device 10 includes a second substrate 14 on which a TFT 13 for controlling current and driving the organic EL element 11 is formed separately from the first substrate 12 on which the organic EL element 11 is formed. The first substrate 12 and the second substrate 14 face each other and are fixed to a support (not shown). The first substrate 12 and the second substrate 14 are made of, for example, borosilicate glass or quartz glass.

  On the first substrate 12, a transparent electrode 15 that is a first electrode constituting the organic EL element 11, a light emitting layer 16, and a reflective electrode 17 that is a second electrode are sequentially laminated. In addition, an inter-pixel blocking wall 18 is formed.

The transparent electrode 15 constitutes an anode or a cathode, and is formed of a material having a high light transmittance so that light emitted from the light emitting layer 16 is sufficiently transmitted. The transparent electrode 15 is mainly composed of, for example, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), or zinc oxide (ZnO). Material is used.

  The light emitting layer 16 is a layer that emits light by recombining electrons and holes to excite organic molecules, and is a layer made of an organic material. The light emitting layer 16 may have a multilayer structure including at least one of a hole transport layer and an electron transport layer in addition to the structure of one layer. For the light emitting layer 16, for example, polymer materials such as polycarbazole, polyparaphenylene, polyarylene vinylene, polythiophene, polyfluorene, polysilane, polyacetylene, polyaniline, polypyridine, polypyridine vinylene, and polypyrrole material are used.

  The reflective electrode 17 constitutes an anode or a cathode, and is formed of a highly reflective conductive film. The reflective electrode 17 is electrically connected to the drain electrode 136 of the driving TFT 13 formed on the opposing second substrate 14. For the reflective electrode 17, for example, gold, silver, copper, aluminum, indium, magnesium, calcium, barium, or an alloy thereof is used as a material.

The inter-pixel shielding wall 18 partitions each pixel so that the pixels do not interfere with each other. One pixel is constituted by a groove formed between the inter-pixel shielding walls 18. The inter-pixel shielding wall 18 is formed by dividing the reflective electrode 17 for each pixel when the reflective electrode 17 is formed on the light emitting layer 16 by being positioned between the pixels. The inter-pixel shielding wall 18 has a reverse taper type (inverted trapezoidal shape) in cross section, so that the reflective electrode 17 can be more easily divided. The inter-pixel shielding wall 18 is made of an electrically insulating material, for example, a material such as SiO ₂ or SiN.

  On the other hand, a driving TFT 13 and a conductive spacer 19 are formed on the second substrate 14.

  The driving TFT 13 is an element for controlling the amount of current flowing through the organic EL element 11. The driving TFT 13 has a bottom gate structure, and includes a gate electrode 131, a gate insulating layer 132 formed on the gate electrode 131, a semiconductor layer 133 for forming a single channel serving as a current path, and an ohmic contact. An na-Si layer (n + amorphous silicon layer) 134 as a contact layer, a source electrode 135, a drain electrode 136, and a protective layer 137 for insulating and protecting the source electrode 135 and the drain electrode 136, etc. Have.

For the gate electrode 131, for example, chromium, a chromium alloy, aluminum, an aluminum alloy, titanium, a titanium alloy, or a compound thereof is used as a material. For the gate insulating film 132, for example, a material such as SiO ₂ or SiN is used.

  The semiconductor layer 133 is formed on the gate electrode 131 with a gate insulating film 132 interposed therebetween. For the semiconductor layer 133, for example, an ia-Si layer (intrinsic amorphous silicon layer) is used as a material.

  The source electrode 135 and the drain electrode 136 are formed by, for example, forming a metal film on the second substrate 14, the na-Si layer 134 and the conductive spacer 19 by a sputtering method and etching the film. Is done. Thereby, the drain electrode 136 is also formed on the conductive spacer 19. For the source electrode 135 and the drain electrode 136, for example, a material such as chromium, a chromium alloy, aluminum, an aluminum alloy, titanium, a titanium alloy, or a compound thereof is used.

The conducting spacer 19 is for electrically connecting the drain electrode 136 formed thereon to the reflective electrode 17 on the first substrate 12. The conductive spacer 19 can be formed of the same material as the gate electrode 131 or can be formed independently of a material different from that of the gate electrode 131. Specifically, the conductive spacer 19 has the same material as that of the gate electrode 131, for example, chromium, chromium alloy, aluminum, aluminum alloy, titanium, titanium alloy, or a compound thereof. Materials such as SiO ₂ and SiN are used. When the conductive spacer 19 is formed of the same material as the gate electrode 131, for example, a metal film is formed on the second substrate 14 by a sputtering method or the like, and the gate electrode 131 and the conductive spacer 19 are etched by etching. Form.
Since the conducting spacer 19 has a tapered cross section, it is possible to prevent the drain electrode 136 formed thereon from being disconnected and the film thickness from becoming non-uniform. Further, the thickness of the conductive spacer 19 is sufficient if the drain electrode 136 and the reflective electrode 17 are in electrical contact with each other, and is preferably as thin as possible.

  The first substrate 12 and the second substrate 14 include a reflective electrode 17 of the organic EL element 11 corresponding to a predetermined pixel sandwiched between the inter-pixel shielding walls 18 on the first substrate 12, and a second substrate. 14 is positioned so as to face the drain electrode 136 of the driving TFT 13 corresponding to a predetermined pixel formed on the conductive spacer 19 on the upper surface 14 and is fixed to a support (not shown). The reflective electrode 17 and the drain electrode 136 are electrically connected.

  A scanning line 301 is electrically connected to the gate electrode 131 of the driving TFT 13, and a signal line 302 is electrically connected to the source electrode 135.

  In the display device 10, when the scanning line 301 is selected, a current corresponding to image data flows from the signal line 302 to the reflective electrode 17, the light emitting layer 16, and the transparent electrode 15 via the source electrode 135 and the drain electrode 136. . When a current flows through the light emitting layer 16, light is emitted by recombination of holes and electrons supplied in the light emitting layer 16. In the light emitting layer 16, the light emission amount is controlled according to the amount of current corresponding to the image data. In the display device 10, a large number of pixels are arranged in a matrix, and the amount of light emission is controlled in this way for each pixel, and an image is displayed. Light emitted from the light emitting layer 16 is taken out from the first substrate 12 side through the transparent electrode 15 (in the direction of the arrow in FIG. 2).

  In the display device of the present embodiment, light emitted from the light emitting layer 16 of the organic EL element 11 is extracted from the first substrate 12 side where the driving TFT 13 does not exist via the transparent electrode 15. Is not blocked by the driving TFT 13 and decreases, and the aperture ratio of the display device is improved. In addition, since the size of the driving TFT 13 is not limited due to a decrease in the aperture ratio, the organic EL element 11 can be driven with a large amount of current, and high luminance display is possible. Become. Further, since the organic EL element 11 is formed on the first substrate 12 different from the second substrate 14 on which the driving TFT 13 is formed, the interval between the pixels can be narrowed. High definition can be achieved.

(Embodiment 2)
FIG. 3 is a plan view showing an example of the configuration of a display device using an organic EL element applied to Embodiment 2 of the present invention, and FIG. 4 is broken along a dashed line BB ′ in FIG. It is sectional drawing for one pixel shown. The display device of the present embodiment is different from the first embodiment in that the conductive spacer is not used, and other configurations are the same as those in the first embodiment. Hereinafter, the same reference numerals are attached and the description of the first embodiment is used, and only the points different from the first embodiment will be described.

  In the display device 20, unlike the first embodiment, the connection portion of the drain electrode 236 of the driving TFT 13 that is electrically connected to the reflective electrode 17 of the first substrate 12 is electrically connected to the second substrate 14. It is formed without a spacer. The connecting portion of the drain electrode 236 is electrically connected to the reflective electrode 17 formed on the inter-pixel shielding wall 18 on the first substrate 12.

  The first substrate 12 and the second substrate 14 are formed on the reflective electrode 17 of the organic EL element 11 in a predetermined pixel formed on the inter-pixel shielding wall 18 on the first substrate 12, and on the second substrate 14. The pixel is positioned so that the drain electrode 236 of the driving TFT 13 in the predetermined pixel formed on the pixel is opposed to the pixel, and is fixed to a support (not shown). The reflective electrode 17 and the drain electrode 236 are electrically connected.

  In the display device of this embodiment mode, since it is not necessary to form a conductive spacer, manufacturing is facilitated and mass productivity is improved.

(Embodiment 3)
FIG. 5 is a plan view showing an example of the configuration of a display device using an organic EL element applied to Embodiment 3 of the present invention, and FIG. 6 is broken along a dashed-dotted line CC ′ in FIG. It is sectional drawing for one pixel shown. The display device of this embodiment is different from that of the first embodiment in the structure of the conductive spacer, and the other configurations are the same as those of the first embodiment. Hereinafter, the same reference numerals are attached and the description of the first embodiment is used, and only the points different from the first embodiment will be described.

The display device 30 has a plurality of conductive spacers 39 on the second substrate 14. The conductive spacer 39 is formed on the second substrate 14 in the extending direction of the signal line 302 (in the D direction in FIG. 5) along the inter-pixel blocking wall 18 on the opposing first substrate 12. Are formed at intervals of. The conducting spacer 39 can be formed of the same material as the gate electrode 131 or can be formed of a material different from that of the gate electrode 131 independently. Specifically, the conductive spacer 39 has the same material as the gate electrode 131, for example, chromium, chromium alloy, aluminum, aluminum alloy, titanium, titanium alloy, or a compound thereof, and different materials include, for example, Materials such as SiO ₂ and SiN are used. When the conductive spacer 39 is formed of the same material as that of the gate electrode 131, for example, a metal film is formed on the second substrate 14 by a sputtering method or the like, and the gate electrode 131 is separated from the gate electrode 131 by etching. Then, a plurality of conductive spacers 39 are formed.
Since the conducting spacer 39 has a tapered cross section, the drain electrode 136 formed thereon can be prevented from having a non-uniform film thickness.

  A portion of the drain electrode 136 formed on the conducting spacer 39 is formed in an uneven shape because a plurality of conducting spacers 39 are formed at a predetermined interval.

  The first substrate 12 and the second substrate 14 are formed on the reflective electrode 17 of the organic EL element 11 in a predetermined pixel formed on the inter-pixel shielding wall 18 on the first substrate 12, and on the second substrate 14. The drain electrode 136 of the driving TFT 13 in a predetermined pixel formed in a concavo-convex shape on the plurality of conductive spacers 39 is positioned so as to face and fixed to a support (not shown). . The reflective electrode 17 and the drain electrode 136 are electrically connected.

  In the display device of this embodiment, the drain electrode 136 formed in a concavo-convex shape on the conductive spacer 39 formed at a predetermined interval is electrically connected to the reflective electrode 17 formed on the inter-pixel shielding wall 18. Since it is made to connect to, electrical conductivity improves.

(Embodiment 4)
FIG. 7 is a cross-sectional view of one pixel showing an example of the configuration of a display device using an organic EL element applied to Embodiment 4 of the present invention. Note that the display device of the present embodiment is different from the third embodiment in the configuration having two TFTs, and the other configurations are the same as those in the third embodiment. Hereinafter, the description of the third embodiment will be referred to with the same reference numerals, and only the points different from the third embodiment will be described.

  The display device 40 includes a selection TFT 43 that outputs image data to the driving TFT 13 and a driving TFT 13 per pixel. The selection TFT 43 is also formed on the second substrate 14 in the same manner as the driving TFT 13.

  In this display device 40, the gate electrode 431 of the selection TFT 43 is electrically connected to the scanning line, one of the source electrode 435 and the drain electrode 436 of the selection TFT 43 is electrically connected to the signal line, and the other is driven. The TFT 13 is electrically connected to the gate electrode 131 of the TFT 13. A source electrode 135 of the driving TFT 13 is electrically connected to a positive constant voltage power line.

  In the display device 40, when a scanning line is selected, the selection TFT 43 is turned on, and a data voltage based on image data is applied from the signal line to the gate electrode 131 of the driving TFT 13 via the selection TFT 43. As a result, the driving TFT 13 is turned on, a current corresponding to the image data flows from the power supply line to the organic EL element 11 via the driving TFT 13, and the light emitting layer 16 emits light. When not selected, the selection TFT 43 is turned off, the voltage of the gate electrode 131 of the driving TFT 13 is held, current flows from the power supply line to the organic EL element 11 through the driving TFT 13, and the light emitting layer 16 emits light. .

  In the display device of this embodiment, light emitted from the light emitting layer 16 of the organic EL element 11 is extracted from the first substrate 12 side where the selection TFT 43 and the driving TFT 13 do not exist via the transparent electrode 15. The light quantity is not blocked by the selection TFT 43 and the driving TFT 13 and decreases, and the aperture ratio of the display device is improved. In addition, since the size of the selection TFT 43 and the driving TFT 13 is not limited because of a decrease in the aperture ratio, the organic EL element 11 can be driven with a large amount of current, and a high luminance display can be achieved. Is possible. Furthermore, since the organic EL element 11 is formed on the first substrate 12 different from the second substrate 14 on which the selection TFT 43 and the driving TFT 13 are formed, the distance between the pixels can be reduced. Therefore, high definition display is also possible.

  The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made. For example, in each of the above embodiments, the drain electrodes 136 and 236 of the driving TFT 13 are described as being electrically connected to the reflective electrode 17 of the organic EL element 11, but the source electrode 135 of the driving TFT 13 is replaced with the organic EL element. 11 may be electrically connected to the reflective electrode 17.

  Moreover, between the 1st board | substrate 12 and the 2nd board | substrate 14, you may make it seal with a photocurable resin etc., for example, and you may make it protect each element.

  In the third embodiment, a plurality of conductive spacers 39 are formed. However, only one conductive spacer 39 may be formed.

  In the third embodiment, the plurality of conductive spacers 39 are formed along the extending direction of the signal line 302, but the plurality of conductive spacers 39 are opposed to each other along the extending direction of the scanning line 301. You may make it form so that the shielding wall 18 between pixels on the 1st board | substrate 12 may be met.

  Further, in the first and second embodiments, the display device having only the driving TFT 13 has been described. However, the display device having the selection TFT 43 and the driving TFT 13 in the first and second embodiments can also be applied to the present invention.

  In each embodiment, the driving TFT 13 is described as having a bottom gate structure, but a driving gate having a top gate structure may be used.

  Further, in each of the embodiments, the drain electrodes 136 and 236 of the driving TFT 13 have been described as being directly electrically connected to the reflective electrode 17 of the organic EL element 11, but for example, electrical connection means such as a conductive spacer You may make it electrically connect via.

It is a top view of the display apparatus which concerns on Embodiment 1 of this invention. It is sectional drawing of the display apparatus which concerns on Embodiment 1 of this invention. It is a top view of the display apparatus which concerns on Embodiment 2 of this invention. It is sectional drawing of the display apparatus which concerns on Embodiment 2 of this invention. It is a top view of the display apparatus which concerns on Embodiment 3 of this invention. It is sectional drawing of the display apparatus which concerns on Embodiment 3 of this invention. It is sectional drawing of the display apparatus which concerns on Embodiment 4 of this invention. It is sectional drawing of the conventional display apparatus.

Explanation of symbols

  10, 20, 30, 40 ... display device, 11 ... organic EL element, 12 ... first substrate, 13 ... driving TFT, 43 ... selection TFT, 131 ... gate Electrode, 136, 236 ... Drain electrode, 135 ... Source electrode, 14 ... Second substrate, 15 ... Transparent electrode, 16 ... Light emitting layer, 17 ... Reflective electrode, 19, 39 ... Conduction spacer

Claims (3)

A first substrate, each first electrode, the light emitting layer, and a plurality of pixels having a second electrode sequentially laminated is formed by organic EL elements are formed by arranging in a matrix,
Wherein with a second electrode electrically connected to the drain electrode or the source electrode to be of the organic electroluminescence element in each pixel, a plurality of first controlling the current flowing the to the organic electroluminescence element in each pixel A second substrate on which a transistor is formed;
An inter-pixel blocking wall that partitions the pixels, formed on the first substrate,
A second electrode of the organic electroluminescence element of each pixel is formed to extend on the inter-pixel shielding wall;
The second electrodes of the organic electroluminescence elements of the two pixels adjacent to each other through the inter-pixel shielding wall are divided into two on the inter-pixel shielding wall,
One of the two second electrodes of the organic electroluminescence element of the two adjacent pixels formed on the barrier between the pixels, and a drain electrode or a source electrode of the first transistor Are arranged facing each other and electrically connected on the inter-pixel shielding wall,
Space is provided between the first substrate and the first transistor,
A display device characterized by that. A plurality of conductive spacers formed on the second substrate;
A drain electrode or a source electrode of the first transistor is formed on a second substrate including the plurality of conductive spacers;
The organic of the two pixels and the drain or source electrode, for said adjacent formed by cutting on the pixel between the shroud of the plurality of the formed uneven on the conductive spacer of the first transistor while a is arranged to face the two second electrodes of the electroluminescent elements are electrically connected,
The display device according to claim 1. A second substrate formed on the second substrate and electrically connected to a gate electrode of the first transistor and a drain electrode or a source electrode, and outputs image data to the first transistor; The display device according to claim 1, further comprising a transistor.

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