JP5242647B2 - Organic EL device - Google Patents

Description

  Embodiments described herein relate generally to an organic EL device.

  In a general organic EL device, a resin flat layer is formed on the entire surface of a TFT (Thin Film Transistor) element and its wiring, and an organic EL element having an anode, an organic material layer, and a cathode is formed thereon. In addition, lattice-like ribs made of a resin are formed between the organic EL elements to separate the organic EL elements from each other.

  When foreign matter such as dust or dirt is generated in the process of forming the organic layer or the cathode, pinholes are formed and moisture enters and causes dark spot defects. In particular, in the resin, the diffusion rate of moisture is about 10 times larger than the diffusion rate in the organic EL element. Therefore, when moisture enters from the ribs, the moisture diffuses in the lattice-like ribs and the resin flat layer, and pinholes are generated. There is a problem that the dark spot defect diffuses not only in the generated area but also in the surrounding area.

US Patent Application Publication No. 2005/249972 US Pat. No. 6,853,133 International Publication No. 97/43874 US Pat. No. 6,459,199 US Patent Application Publication No. 2005/280008

  An organic EL device capable of suppressing defects is provided.

According to one embodiment, the organic EL device includes a plurality of pixels arranged in a first direction and a second direction intersecting with the first direction. Each of the plurality of pixels includes an insulating film, a first electrode formed flat on at least a part of the insulating film, a light emitting layer formed flat on at least the first electrode, and the light emitting layer A second electrode formed thereon. The insulating film included in the pixel is formed across at least two pixels adjacent in the first direction and is separated from the insulating film included in the pixel adjacent in the second direction. The second electrode is formed above the insulating film and is not formed above the region where the insulating film is separated.

1 is a schematic configuration diagram of an organic EL display system including an organic EL device OD according to an embodiment. The top view of organic electroluminescent apparatus OD1 which is an example of organic electroluminescent apparatus OD. FIG. 3 is a cross-sectional view taken along the line AA ′ in FIG. 2. FIG. 3 is a BB ′ sectional view in a second direction of FIG. 2. Sectional drawing of organic substance layer ORGr, ORGg, ORGb. The manufacturing process figure of organic electroluminescent apparatus OD1. The top view of organic electroluminescent apparatus OD2 which is another example of organic electroluminescent apparatus OD. CC 'sectional drawing of the 1st direction of FIG. The graph which shows the relationship between the occurrence number of dark spot defect, and elapsed time.

  Hereinafter, embodiments of the organic EL device will be specifically described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an organic EL display system including an organic EL device OD according to an embodiment. The display system of FIG. 1 includes an organic EL device OD, a scanning signal line driver YDR, and a video signal line driver XDR. These are formed on the first substrate SUB. The organic EL device OD also includes scanning lines SL1 and SL2, a video signal line DL, and a pixel PX.

  The scanning lines SL1 and SL2 are formed in the first direction (for example, the horizontal direction). The scanning line signal driver YDR sequentially selects one of the scanning lines SL1 and one of the scanning lines SL2. The video signal line DL is formed in the second direction (for example, the vertical direction) so as to intersect the scanning lines SL1 and SL2. The video signal line driver XDR supplies a video signal to the video signal line DL. The pixel PX is formed at the intersection of the scanning lines SL1 and SL2 and the video signal line DL. The video signal from the video signal line driver XDR is supplied to the pixels PX connected to the scanning lines SL1 and SL2 selected by the scanning line signal driver YDR.

  The pixel PX includes one organic EL element OLED, TFT elements SWa to SWc, DR, and a pixel capacitor C. The organic EL element OLED emits light in red (R), green (G), or blue (B), and the pixel PX emits light in any one of the colors. In the present specification, a pixel including three organic EL elements OLED that emits red, green, and blue is not referred to as a “pixel”, and a pixel including any one of the organic EL elements OLED is referred to as a “pixel”. Call it.

  The TFT elements DR and SWa and the organic EL element OLED are connected in cascade between the positive power supply terminal ND1 and the negative power supply terminal ND2. A scanning line SL1 is connected to the gate of the TFT element SWa. The pixel capacitor C and the TFT elements SWc and SWb are connected in cascade between the power supply terminal ND1 'and the video signal line DL. A connection node between the pixel capacitor C and the TFT element SWc is connected to the gate of the TFT element DR. The connection node of the TFT elements SWc and SWb is connected to the connection node of the TFT elements DR and SWa. The scanning line SL2 is connected to the gates of the TFT elements SWb and SWc.

  When the scanning line SL2 is selected and set to low, the TFT elements SWb and SWc are turned on, and charges corresponding to the video signal supplied to the video signal line DL are accumulated in the pixel capacitor C. When the scanning line SL1 is selected and set to low, the TFT element SWa is turned on, and the TFT element DR supplies a drive current corresponding to the electric charge accumulated in the pixel capacitor C to the organic EL element OLED. The organic EL element OLED emits light with a luminance corresponding to the magnitude of the drive current.

  FIG. 2 is a plan view of the organic EL device OD1 which is an example of the organic EL device OD. In the figure, three pixels PX each emitting red, green, and blue are drawn.

  The organic EL element OLED in the pixel PX includes a resin flat layer (insulating film) FL formed on the first direction wiring XW and the second direction wiring YW, a reflective layer (not shown), an anode AND, and an organic layer. (Not shown) and a cathode CTD.

  The resin flat layer FL is not formed on the entire surface, but is formed in stripes in the first direction. That is, the resin flat layer FL is formed in common across a plurality of pixels PX arranged in the first direction, and a gap GP is formed between the two pixels PX adjacent in the second direction so that the resin flat layer FL is not formed. And separated in the second direction.

  The anode AND is, for example, an ITO (Indium Tin Oxide) electrode. The anode AND is connected to the second direction wiring YW via the contact hole CH. Note that the first direction wiring XW and the second direction wiring YW in the figure correspond to the gate and drain of the TFT element SWa in FIG. 1, respectively. For the sake of simplification, the other wirings in FIG. 1 and the TFT elements SWa to SWc, DR are omitted in FIG.

  The cathode CTD is a translucent electrode such as an alloy of magnesium and silver. The cathode CTD is formed in a stripe shape in the first direction, like the resin flat layer FL. Although not shown in the figure, for example, on the outside of the rightmost pixel PX, a wiring connecting the striped cathodes CTD is formed in the second direction.

  Further, the cathode CTD is formed above the resin flat layer FL so as not to protrude in the second direction. In other words, the cathode CTD is not formed above the gap GP, and the resin flat layer FL is always formed between the second direction wiring YW and the cathode CTD. For this reason, even if a defect occurs in the organic layer ORG, the second direction wiring YW and the cathode CTD are not short-circuited.

  Note that the resin flat layer FL does not necessarily have to be formed in common across all the pixels PX arranged in the first direction, and may be formed over at least two pixels PX. For example, the resin flat layer FL may be formed across three pixels PX that respectively emit red, green, and blue. Further, it may be a stripe formed across two or more columns of pixels PX adjacent in the second direction. That is, the resin flat layer FL is not formed on the entire surface, and it is only necessary that the gap GP is provided and separated between at least one pixel PX and the pixel PX adjacent in the second direction.

  3 is a cross-sectional view taken along the line AA 'in the first direction of FIG. An insulating layer IL is formed on the first direction wiring XW, and a second direction wiring YW is formed thereon. A resin flat layer FL is formed on the insulating layer IL where the second direction wiring YW is not formed and on the second direction wiring YW. A reflective layer RL is formed on a part of the resin flat layer FL. The reflective layer RL is provided to reflect light emitted downward by a light emitting layer (not shown) in the organic layer ORG upward to improve luminous efficiency. That is, the organic EL element OLED in FIGS. 2 and 3 is a top emission type in which light is extracted from the top surface.

  A contact hole CH is formed in the resin flat layer FL. The anode AND has a first region AND1 formed flat on the reflective layer RL on the resin flat layer FL, and a second region AND2 formed so as to fill the side wall and bottom of the contact hole CH. It is electrically connected to the two-way wiring YW.

  Further, an organic layer ORG is formed so as to cover the anode AND. A part of the organic layer ORG is also formed in the contact hole CH. In the structure of FIG. 3, since the rib for separating the pixels PX is not provided, the upper surface of the organic layer ORG is formed flat at least on the first region AND1 of the anode AND. Further, the organic layer ORG is in contact with the resin flat layer FL in a portion where the reflective layer RL and the anode AND are not formed. Since the rib made of resin is not provided, it is possible to suppress moisture from entering from the upper surface of the organic EL element OLED.

  Although not shown, the organic layer ORG includes, for example, a hole transport layer HTL, a light emitting layer EML, and an electron transport layer ETL. The holes injected from the anode AND into the light emitting layer EML through the hole transport layer HTL and the electrons injected from the cathode CTD through the electron transport layer ETL into the light emitting layer EML are recombined to form the light emitting layer EML. It emits light with a color corresponding to the impurities contained in. In the present specification, organic layers emitting red, green, and blue are represented as organic layers ORGr, ORGg, and ORGb, respectively, and any one of these is represented as an organic layer ORG.

  FIG. 4 is a BB ′ sectional view in the second direction of FIG. 2. In the resin flat layer FL formed on the second direction wiring YW, in addition to the contact hole CH, a gap GP is provided between two pixels PX adjacent in the second direction. An organic layer ORG is embedded in the gap GP. The diffusion rate of moisture in the organic layer ORG is about 1/10 of the diffusion rate in the resin flat layer FL. Therefore, by providing the gap GP and embedding the organic material layer ORG, it is possible to suppress diffusion of moisture that has entered from the surface of the organic EL element OLED in the second direction. As a result, it is possible to suppress the dark spot defect from diffusing in the first direction even if moisture enters.

  FIG. 5 is a cross-sectional view of the organic layers ORGr, ORGg, and ORGb. In this embodiment, no rib is provided.

  As shown in FIG. 4A, the organic layer ORGr includes a hole transport layer HTL, a red light emitting layer EMLr, a green light emitting layer EMLg, a blue light emitting layer EMLb, and an electron transport layer ETL. In the structure shown in the figure, the green light emitting layer EMLg and the blue light emitting layer EMLb do not emit light, and the red light emitting layer EMLr emits light, whereby the organic EL element OLED having the organic layer ORGr emits red light.

  As shown in FIG. 4B, the organic layer ORGr has a hole transport layer HTL, a modified red light emitting layer EMLr ′, a green light emitting layer EMLg, a blue light emitting layer EMLb, and an electron transport layer ETL. . The altered red light emitting layer EMLr 'is formed by irradiating the red light emitting layer EMLr with ultraviolet rays. In the structure shown in the figure, the modified red light emitting layer EMLr 'and blue light emitting layer EMLb do not emit light, and the green light emitting layer EMLg emits light, whereby the organic EL element OLED having the organic layer ORGg emits green light.

  As shown in FIG. 5C, the organic layer ORGb includes a hole transport layer HTL, a modified red light emitting layer EMLr ′, a modified green light emitting layer EMLg ′, a blue light emitting layer EMLb, and an electron transport layer ETL. And have. The altered red light emitting layer EMLr 'and green light emitting layer EMLg' are formed by irradiating the red light emitting layer EMLr and the green light emitting layer EMLg with ultraviolet rays, respectively. In the structure shown in the figure, the modified red light-emitting layer EMLr 'and green light-emitting layer EMLg' do not emit light, and the blue light-emitting layer EMLb emits light, whereby the organic EL element OLED having the organic layer ORGb emits blue light.

  The structure of the organic EL device OD1 has been described above. Next, a manufacturing process of the organic EL device OD1 will be described.

  FIG. 6 is a manufacturing process diagram of the organic EL device OD1. First, TFT elements SWa to SWc, DR and wirings are formed on a first substrate SUB such as glass (step S1). Each TFT element is formed by, for example, a low temperature polysilicon technique. Here, the wiring refers to the first direction wiring XW and the second direction wiring YW that connect the TFT elements and the TFT elements and the organic EL element OLED in the pixel PX, in addition to the scanning lines SL1 and SL2 and the video signal line DL. Etc. Further, an insulating layer IL is formed between the first direction wiring XW and the second direction wiring YW.

  Next, a resin flat layer FL is formed on the wiring (the second direction wiring YW in the present embodiment) formed on the uppermost layer and on the insulating layer IL on which the second direction wiring YW is not formed. A reflective layer RL is formed on a part of (Step S2). As described above, the resin flat layer FL is formed in a stripe shape in the first direction. Subsequently, a contact hole CH that passes through the reflective layer RL and the resin flat layer FL and reaches the second direction wiring YW is formed (step S3). Further, an anode AND (step S4) is formed so as to fill the reflective layer RL and the side walls and bottom of the contact hole CH.

  Subsequently, without forming a rib, the organic layer ORG composed of the hole transport layer HTL, the light emitting layer, and the electron transport layer ETL is formed by the following steps S5 to S11.

  First, using a resistance heating type organic EL film forming apparatus, a hole transport layer HTL (step S5) and a red light emitting layer EMLr (step S6) are sequentially formed on the entire surface, and the first substrate SUB is formed into an organic EL film. Remove from device. Next, a photomask is arranged on the region where the organic layer ORGr is formed, and the red light emitting layer EMLr in the region where the organic layers ORGg and ORGb are formed is irradiated with ultraviolet light having a dominant wavelength of 365 nm (step S7). When irradiated with ultraviolet rays, the red light-emitting layer EMLr becomes a modified red light-emitting layer EMLr 'and does not emit red light.

  Subsequently, again using the organic EL film forming apparatus, a green light emitting layer EMLg is formed on the entire surface (step S8), and the first substrate SUB is taken out from the organic EL film forming apparatus. Next, a photomask is arranged on the region where the organic layers ORGr and ORGg are formed, and the green light emitting layer EMLg in the region where the organic layer ORGb is formed is irradiated with ultraviolet light having a dominant wavelength of 365 nm (step S9). When the ultraviolet ray is irradiated, the green light emitting layer EMLg becomes a modified green light emitting layer EMLg ′ and does not emit green light.

  Further, the blue light emitting layer EMLb (step S10) and the electron transport layer ETL (step S11) are sequentially formed on the entire surface using an organic EL film forming apparatus.

  As described above, the organic layer ORG is formed. In this way, the light emitting layers EMLr, EMLg, and EMLb of each color are not separately applied using a metal mask, but the light emitting layers EMLr and EMLg are irradiated with ultraviolet rays using a photomask to change the properties of the organic layer ORG. Controls the emission color. For this reason, the organic layer ORG can be formed with high accuracy without mixing the light emitting layer into the adjacent pixel PX without providing a rib.

  In the present embodiment, an example in which the red light emitting layer EMLr and the green light emitting layer EMLg are altered is shown. However, it is not always necessary to alter the quality of the red light emitting layer EMLr and the green light emitting layer EMLg.

  Thereafter, a cathode CTD is formed by vapor deposition (step S12). More specifically, first, a striped cathode CTD is formed in the first direction. At this time, as described above, the position is adjusted so that the cathode CTD is formed in a part above the resin flat layer FL and the cathode CTD is not formed on the gap GP of the resin flat layer FL. Further, a wiring in the second direction is formed outside the pixel PX so as to connect the striped cathodes CTD.

  Thereafter, the first substrate SUB on which the organic EL device OD1 is formed and the second substrate (not shown) on which the desiccant is attached are bonded (step S13). More specifically, an ultraviolet curable adhesive is disposed between the first and second substrates, and the two substrates are bonded by irradiating the adhesive with ultraviolet rays while applying pressure. The desiccant is provided to suppress the deterioration of the organic EL element OLED due to moisture. Note that a thermosetting adhesive may be used instead of the ultraviolet curable adhesive.

  Further, the organic EL device OD1 is obtained by cleaving the first substrate and the second substrate for each organic EL device OD1.

  Next, modified examples of FIGS. 2 to 4 will be described.

  FIG. 7 is a plan view of an organic EL device OD2 which is another example of the organic EL device OD. In FIG. 7, the same reference numerals are given to the components common to FIG. 2, and the differences will be mainly described below.

  The organic EL device OD2 of FIG. 7 is different from the organic EL device OD1 of FIG. 2 in the shape of the resin flat layer FL, and is formed in an island shape and separated for each pixel PX. In other words, a gap GP is provided between two pixels PX adjacent in the second direction, and a gap GP2 is provided between two pixels PX adjacent in the first direction, both in the second direction and the first direction. To be separated.

  The second direction wiring YW is formed below the flat resin layer FL so as not to protrude in the first direction. In other words, the second direction wiring YW is not formed below the gap GP2, and the resin flat layer FL or the anode AND2 is always interposed between the second direction wiring YW and the cathode CTD. For this reason, even if a defect occurs in the organic layer ORG, the second direction wiring YW and the cathode CTD are not short-circuited.

  FIG. 8 is a CC ′ cross-sectional view in the first direction of FIG. 7. In the resin flat layer FL, a gap GP2 is provided between two pixels PX adjacent in the first direction. An organic layer ORG is embedded in the gap GP2. Thereby, it can suppress that the water | moisture content which penetrate | invaded from the surface of organic EL apparatus OD2 diffuses in a 2nd direction and a 1st direction. As a result, even if moisture permeates, it is possible to suppress the dark spot defect from diffusing in the second direction and the first direction. However, as the gap GP2 is provided, the opening area is smaller than that of the organic EL device OD1 shown in FIGS.

  The sectional view in the second direction in FIG. 7 is the same as that in FIG.

  The inventor conducted an experiment to compare the number of occurrences of dark spot defects in the conventional organic EL device, the organic EL device OD1 in FIG. 2, and the organic EL device OD2 in FIG. FIG. 9 is a graph showing the relationship between the number of occurrences of dark spot defects and the elapsed time. The conventional organic EL device has a configuration in which ribs for separating organic EL elements are provided and a resin flat layer is formed on the entire surface. 24 units of these three organic EL devices are manufactured and left in a high-temperature and high-humidity layer (temperature 85 ° C, humidity 85%), the display is confirmed after a predetermined time, and the number of dark spot defects is visually confirmed. did. In order to confirm the effect of the present embodiment, no desiccant is provided on the second substrate SUB2.

  As shown in FIG. 9, in the conventional organic EL device, the dark spot defect starts to occur after 20 hours, and the dark spot defect occurs in all the organic EL devices after 30 hours.

  In contrast, in the organic EL device OD1, a dark spot defect starts to occur after 30 hours, and after 50 hours, a dark spot defect occurs in all the organic EL devices OD1. The organic EL device OD1 has a structure in which moisture does not easily enter compared to a conventional organic EL device because no resin rib is formed. In addition, since the resin flat layer FL is formed in a stripe shape, diffusion of moisture is suppressed. Therefore, dark spot defects are less likely to occur compared to conventional organic EL devices.

  Further, in the organic EL device OD2, dark spot defects start to occur after 40 hours, and only after 50 hours, dark spot defects occur in the seven organic EL devices OD2. In the organic EL device OD2, since the resin flat layer FL is formed in a stripe shape, the diffusion of moisture is further suppressed as compared with the organic EL device OD1, and the occurrence of dark spot defects can be suppressed.

  As described above, in the embodiment, since the rib for separating the pixels PX is not provided, it is difficult for moisture to enter the organic EL device OD. Further, since the resin flat layer is formed in a stripe shape or an island shape, even if moisture enters the organic EL device, diffusion of moisture can be suppressed, and the spread of dark spot defects can be suppressed. In addition, instead of separately coating the light emitting layer using a metal mask, the light emitting color is controlled by altering the light emitting layer using a photomask. Therefore, the organic layer ORG can be formed with high accuracy without providing a rib. Furthermore, since the cathode is formed in a part above the resin flat layer FL, it is possible to prevent the cathode and the second direction wiring YW from being short-circuited without forming the resin flat layer FL over the entire surface.

  In the above-described embodiment, the example in which the organic EL device OD is used for the display device has been described.

  Based on the above description, those skilled in the art may be able to conceive additional effects and various modifications of the embodiments, but the aspects of the embodiments are not limited to the individual embodiments described above. Absent. Various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the embodiments derived from the contents defined in the claims and equivalents thereof.

PX pixel FL resin flat layer AND anode EMLr, EMLg, EMLb Light emitting layer CTD cathode OD, OD1, OD2 Organic EL device

Claims (3)

A plurality of pixels arranged in a first direction and a second direction intersecting the first direction;
Each of the plurality of pixels is
An insulating film;
A first electrode formed flat on at least part of the insulating film;
A light emitting layer formed flat on at least the first electrode;
A second electrode formed on the light emitting layer,
The insulating film of the pixel is
Formed across at least two pixels adjacent in the first direction, and
Separated from the insulating film of the pixel adjacent in the second direction ;
The organic EL device , wherein the second electrode is formed above the insulating film and is not formed above a region where the insulating film is separated . A plurality of first pixels arranged in a first direction and a second direction intersecting the first direction and emitting a first emission color, and a second emission color having a shorter center wavelength than the center wavelength of the first emission color A plurality of second pixels that emit, and a plurality of third pixels that emit a third emission color having a shorter center wavelength than the center wavelength of the second emission color,
Each of the first to third pixels is
An insulating film;
A first electrode formed flat on at least part of the insulating film;
A light emitting layer formed flat on at least the first electrode;
A second electrode formed on the light emitting layer,
The light emitting layer of the first pixel is between the first and second electrodes.
A first light emitting layer having the ability to emit the first emission color;
A second light emitting layer formed on the first light emitting layer and capable of emitting the second light emitting color;
A third light emitting layer formed on the second light emitting layer and having the ability to emit the third light emitting color;
The light emitting layer of the second pixel is between the first and second electrodes.
The first light emitting layer extending from the first pixel and losing its light emitting capability;
The second light emitting layer formed on the first light emitting layer extending from the first pixel and losing the light emitting ability;
A third light emitting layer extending from the first pixel and formed on the second light emitting layer, wherein the light emitting layer of the third pixel is between the first and second electrodes,
The first light-emitting layer extending from the second pixel and losing its light-emitting ability;
The second light-emitting layer that has lost its light-emitting ability, is formed on the first light-emitting layer that extends from the second pixel and has lost its light-emitting ability;
The third light emitting layer formed on the second light emitting layer extending from the second pixel and losing the light emitting capability, and
The insulating film of at least two pixels adjacent in the first direction among the plurality of first to third pixels is:
Formed across the at least two pixels, and
Separated from the insulating film of the first, second, or third pixel adjacent in the second direction ;
The organic EL device , wherein the second electrode is formed above the insulating film and is not formed above a region where the insulating film is separated .   The organic EL device according to claim 1, wherein a part of the light emitting layer is in contact with the insulating film.

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