JP2016126838A - Light emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission device that can effectively suppress malfunction of TFT because of intrusion of a part of light emitted in an organic light emission layer into a channel portion of TFT.SOLUTION: A light emission device has a light emission unit containing TFT 12 formed on a substrate 1, an organic light emission body portion 21 laminated on TFT 12 through a first insulation layer 7, and a contact hole 22 for electrically conductively connecting the organic light emission body portion 21 and the drain electrode 6b of TFT 12. The organic light emission body portion 21 has a laminate of a first electrode layer 8 electrically-connected to the contact hole 22 from TFT 12 side, an organic light emission layer 10 and a second electrode layer 11. A light emission area 20 is not overlapped with TFT 12 in a plan view, and a second insulation layer 9 is formed on the first insulation layer 7 and the first electrode layer 8 so as to surround the organic light emission layer 10, and the second insulation layer 9 has a light absorption characteristic of absorbing light emitted in the organic light emission layer 10.SELECTED DRAWING: Figure 1

Description

  The present invention provides a light emitting device including a light emitting portion including an organic light emitting layer having a self-luminous organic electroluminescence property called an organic electroluminescence (EL) or an organic LED (Organic Light Emitting diode: OLED). The present invention relates to a light emitting device applied to an organic EL display device, an organic LED printer (OLEDP) head, and the like.

  An example of a light-emitting device provided with a light-emitting portion having a conventional organic light-emitting layer is shown in FIGS. FIG. 5 is a cross-sectional view of the light-emitting portion of the light-emitting device, and is a cross-sectional view taken along line C1-C2 of FIG. 6 is a plan view of three light emitting units of the light emitting device of FIG. As shown in FIG. 5, the light emitting device includes a thin film transistor (TFT) 42 formed on a translucent substrate 31 such as a glass substrate, and a first made of acrylic resin or the like on the TFT 42. The organic light-emitting unit 51 includes a light-emitting unit including an organic light-emitting unit 51 stacked with an insulating layer 37 interposed therebetween, and a contact hole 52 that conductively connects the organic light-emitting unit 51 and the drain electrode 36b of the TFT 12. The body 51 includes a first electrode layer 38, an organic light emitting layer 40, and a second electrode layer 41, which are electrically connected to the contact hole 52 from the TFT 42 side. A second insulating layer 39 made of an acrylic resin or the like is formed on the first electrode layer 38 so as to surround the organic light emitting layer 40.

  5 and 6, reference numeral 50 denotes a light emitting region that emits light when an electric field is directly applied to the organic light emitting layer 40 by the first electrode layer 38 and the second electrode layer 41. The first electrode layer 38 is an anode and is made of a transparent electrode such as indium tin oxide (ITO), and the second electrode layer 41 is a cathode and is made of an Al—Li alloy, Mg—Ag. In the case where the work function such as an alloy is low and the light emitting and light reflecting metal or alloy is used, the light emitted from the organic light emitting layer 40 is emitted from the substrate 31 side. That is, a light emission device of the bottom emission type in which the light emission direction (the direction indicated by the white arrow in FIG. 5) is downward (bottom direction). On the other hand, when the first electrode layer 38 is a cathode and is made of the above light-shielding and light-reflecting metals or their alloys, and the second electrode layer 41 is an anode and is made of a transparent electrode, the light emitting direction Is a top emission type light emitting device in which is upward (top direction).

The TFT 42 includes, from the substrate 31 side, a semiconductor film including a gate electrode 32, a gate insulating film 33, a polysilicon film 34 as a channel portion, and a high-concentration impurity region 34a in which polysilicon contains impurities at a higher concentration than the channel portion. The insulating film 35 made of silicon nitride (SiN _x ), silicon oxide (SiO ₂ ), etc., the source electrode 36a, and the drain electrode 36b are sequentially stacked. In FIG. 6, 36aL is a source signal line for transmitting a source signal to the source electrode 36a, and 32L is a gate signal line for transmitting a gate signal to the gate electrode 32. The light emission intensity of each organic light emitting layer 40 can be controlled by controlling the voltage of the gate signal input to each gate signal line 32L. The source signal line 36aL functions as a power supply line.

JP 2014-123540 A

  However, in the conventional light emitting device shown in FIGS. 5 and 6, a part of the light emitted from the organic light emitting layer 40 in the light emitting region 50 leaks to the second insulating layer 39 side and is the channel portion of the TFT 42. There was a possibility that the TFT 42 would malfunction due to light leakage current entering the polysilicon film 4. In order to cope with such problems, an organic EL element in which an organic light emitting layer is formed on a pixel forming layer made of an acrylic resin or the like and a light shielding material is contained in the pixel forming layer has been proposed. (For example, see Patent Document 1). However, in the organic EL element having the configuration disclosed in Patent Document 1, since the pixel forming layer is located in a portion overlapping the organic light emitting layer in plan view, light emitted from the organic light emitting layer is blocked by the pixel forming layer. As a result, there is a problem that the light emission efficiency may be lowered, and further, there is a problem that light is likely to leak to the side of the TFT so as not to overlap with the organic light emitting layer in plan view.

  Therefore, the present invention has been completed in view of the above problems, and is to effectively suppress a malfunction of the TFT due to a part of the light emitted from the organic light emitting layer entering the channel portion of the TFT. .

  The light-emitting device of the present invention conducts electrical conduction between a thin-film transistor formed on a substrate, an organic light-emitting part laminated on the thin-film transistor with a first insulating layer interposed therebetween, and the organic light-emitting part and the electrode of the thin-film transistor. A light emitting portion including a contact hole to be connected, wherein the organic light emitter portion includes a first electrode layer, an organic light emitting layer, and a second electrode electrically connected to the contact hole from the thin film transistor side. And the light emitting region does not overlap the thin film transistor in plan view, and the second light emitting layer surrounds the organic light emitting layer on the first insulating layer and the first electrode layer. In the light emitting device in which an insulating layer is formed, the second insulating layer has a light absorptivity for absorbing light emitted from the organic light emitting layer.

  In the light emitting device of the present invention, preferably, the second insulating layer has a light absorbing portion that absorbs light emitted from the organic light emitting layer in a portion other than the light emitting region.

  In the light emitting device of the present invention, it is preferable that the light absorbing portion is in a portion overlapping the channel portion of the thin film transistor in plan view.

  In the light emitting device of the present invention, it is preferable that the light absorbing portion is in a portion of the contact hole.

  The light-emitting device of the present invention includes a thin film transistor formed on a substrate, an organic light-emitting portion laminated on the thin film transistor with a first insulating layer interposed therebetween, and an organic light-emitting portion and an electrode of the thin-film transistor electrically connected A light emitting portion including a first electrode layer, an organic light emitting layer, and a second electrode layer electrically connected to the contact hole from the thin film transistor side. Light emission in which the second insulating layer is formed so as to surround the organic light emitting layer on the first insulating layer and the first electrode layer without being overlapped with the thin film transistor in plan view. In the device, the second insulating layer has a light absorptivity that absorbs light emitted from the organic light emitting layer, so that the light emitted from the organic light emitting layer is substantially on the side of the organic light emitting layer. Thin film transistor A thin film transistor can be prevented that effectively the malfunction enters the Yaneru unit.

  In the light-emitting device of the present invention, preferably, the second insulating layer has a light absorbing portion that absorbs light emitted from the organic light-emitting layer in a portion other than the light-emitting region, and thus the light emitted from the organic light-emitting layer is efficiently used. Can be absorbed.

  In the light emitting device of the present invention, preferably, since the light absorbing portion is in a portion overlapping the channel portion of the thin film transistor in a plan view, the light emitted from the organic light emitting layer is in a side of the organic light emitting layer. The entry into the channel portion can be more effectively suppressed.

  In the light emitting device of the present invention, preferably, since the light absorbing portion is located at the contact hole portion, light is multiple-reflected by a tapered contact hole such as an inverted conical shape and taken into the thin film transistor side. Can be suppressed.

FIG. 1 shows an example of an embodiment of a light-emitting device according to the present invention, which is a cross-sectional view of a light-emitting portion of the light-emitting device and is a cross-sectional view taken along line A1-A2 of FIG. FIG. 2 is a plan view of three light emitting units of the light emitting device of FIG. FIG. 3 shows another example of the embodiment of the light-emitting device of the present invention, which is a cross-sectional view of a light-emitting portion of the light-emitting device and is a cross-sectional view taken along line B1-B2 of FIG. FIG. 4 is a plan view of three light emitting units of the light emitting device of FIG. FIG. 5 shows an example of a conventional light-emitting device, which is a cross-sectional view of a light-emitting portion of the light-emitting device and is a cross-sectional view taken along line C1-C2 of FIG. 6 is a plan view of three light emitting units of the light emitting device of FIG.

  Hereinafter, embodiments of a light-emitting device of the present invention will be described with reference to the drawings. However, each drawing referred to below shows main components of the light emitting device of the present invention. Therefore, the light-emitting device of the present invention may include well-known components such as a circuit board, a wiring conductor, a control IC, and an LSI that are not shown in the drawing.

  1 to 4 show various examples of embodiments of the light emitting device of the present invention. The light-emitting device of the present invention includes an organic light-emitting body laminated on a TFT 12 formed on a light-transmitting substrate 1 such as a glass substrate, and a first insulating layer 7 made of acrylic resin or the like on the TFT 12. A light emitting part including a contact hole 22 for conductively connecting the organic light emitting part 21 and the drain electrode 6b of the TFT 12 to the organic light emitting part 21 from the TFT 12 side. The first electrode layer 8, the organic light emitting layer 10, and the second electrode layer 11 that are electrically connected to each other are stacked, and the light emitting region 20 does not overlap with the TFT 12 in a plan view. A light-emitting device in which a second insulating layer 9 made of acrylic resin or the like is formed on the layer 7 and the first electrode layer 8 so as to surround the organic light-emitting layer 10, wherein the second insulating layer 9 is organic Light emitted from the light emitting layer 10 It is configured to have a light absorptive to absorb. With this configuration, it is possible to effectively suppress the malfunction of the TFT 12 due to the light emitted from the organic light emitting layer 10 entering the polysilicon film 4 that is the channel portion of the TFT 12 substantially on the side of the organic light emitting layer 10. 1 and 3, the second insulating layer 9 is formed on the side of the light emitting region 20 so as to surround the light emitting region 20 in plan view.

  1 and 2, reference numeral 20 denotes a light emitting region that emits light when an electric field is directly applied to the organic light emitting layer 10 by the first electrode layer 8 and the second electrode layer 11. That is, the light emitting region 20 corresponds to a portion where the organic light emitting layer 10 is directly laminated with the first electrode layer 8. The first electrode layer 8 is an anode and is made of a transparent electrode such as indium tin oxide (ITO), and the second electrode layer 11 is a cathode and is made of Al, Al-Li alloy, Mg. , Mg-Ag alloy (contains about 5 to 10% by weight of Ag), Mg-Cu alloy (contains about 5 to 10% by weight of Cu), etc. have a low work function (about 4.0 V or less), light shielding, light reflection In the case of a metal or alloy having a property, light emitted from the organic light emitting layer 10 is emitted from the substrate 1 side. That is, a bottom emission type light emitting device in which the light emitting direction (the direction indicated by the white arrow in FIG. 1) is downward (bottom direction) is obtained. On the other hand, when the first electrode layer 8 is a cathode and is made of the above light-shielding and light-reflecting metals or their alloys, and the second electrode layer 11 is an anode and is made of a transparent electrode, the light emitting direction Is a top emission type light emitting device in which is upward (top direction).

  Transparent electrodes used for the first electrode layer 8 or the second electrode layer 11 are indium tin oxide (ITO), indium zinc oxide (IZO), indium tin oxide added with silicon oxide (ITSO), oxidized It is made of a conductive material such as zinc (ZnO), phosphorus, or silicon (Si) containing boron and having a light transmitting property. The first insulating layer 7 and the second insulating layer 9 are made of acrylic resin, polyimide, polyamide, polyimide amide, benzocyclobutene, tetrafluoroethylene / perfluoroalkoxyethylene copolymer (PFA resin), polysiloxane, polysilazane. Etc. can be used. Polysiloxane has a skeletal structure formed by the bond of silicon (Si) and oxygen (O). The polysiloxane has an organic group containing at least hydrogen as an oxygen substituent, such as an alkyl group or an aromatic hydrocarbon group, and an organic group containing at least hydrogen and a fluoro group as an oxygen substituent. It may be. Polysilazane is a material formed using a polymer material having a bond of silicon (Si) and nitrogen (N) as a starting material. When an insulating layer made of the above organic material is used, the flatness of the surface can be improved and a flattening layer can be easily obtained.

The TFT 12 includes, from the substrate 1 side, a gate electrode 2, a gate insulating film 3, a polysilicon film 4 as a channel portion, and a semiconductor film comprising a high concentration impurity region 4 a in which impurities are contained in polysilicon at a higher concentration than the channel portion. The insulating film 5 made of silicon nitride (SiN _x ), silicon oxide (SiO ₂ ) or the like, the source electrode 6a, and the drain electrode 6b are sequentially stacked. The semiconductor constituting the TFT 12 may be made of an oxide semiconductor such as low-temperature polysilicon (LTPS), amorphous silicon, or indium gallium zinc oxide (IGZO). The TFT 12 shown in FIG. 1 is a bottom gate type TFT in which the gate electrode 2 is below the channel portion, but may be a top gate type TFT in which the gate electrode 2 is above the channel portion. It may be a double gate type TFT located both below and above the channel portion. The top gate type TFT and the double gate type TFT are preferable because the gate electrode 2 made of a light-shielding metal or the like is generally above the channel part, so that light can be further suppressed from entering the channel part. . In FIG. 2, 6aL is a source signal line for transmitting a source signal to the source electrode 6a, and 2L is a gate signal line for transmitting a gate signal to the gate electrode 2. By controlling the voltage of the gate signal input to each gate signal line 2L, the light emission intensity of each organic light emitting layer 10 can be controlled. The source signal line 6aL functions as a power supply line.

  The organic light emitting layer 10 has a self-emitting organic electroluminescent property that does not require a backlight. For example, the organic light emitting layer 10 is a laminated structure having a thickness of about several hundred nm, and is formed by laminating an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode from the cathode side. The thickness of each layer between the electrode layers is about several nm to several hundred nm. The thickness including the electrode layer is about 1 μm. As the light emitting material of the light emitting layer of the organic light emitting layer 10, a low molecular fluorescent dye material, a fluorescent polymer material, a metal complex material, or the like can be adopted.

In order to facilitate the injection of holes into the light emitting layer, the ionization energy of the light emitting layer is preferably 6.0 eV or less, and in order to facilitate the injection of electrons into the light emitting layer, the electron affinity of the light emitting layer is 2.5 eV. It is good that it is above. As the light emitting material of the light emitting layer, tris (8-quinolinolato) aluminum complex (Alq), bis (benzoquinolinolato) beryllium complex (BeBq), tri (dibenzoylmethyl) phenanthroline europium complex (Eu (DBM) ₃ (Phen) )), Ditoluyl vinyl biphenyl (DTVBi) and the like. Examples of the polymer material include π-conjugated polymers such as fluorescent poly (p-phenylene vinylene) and polyalkylthiophene, and these polymer materials can control carrier transport properties by introducing substituents. As the material for the electron transport layer, an anthraquinodimethane derivative, a diphenylquinone derivative, an oxadiazole derivative, a perylenetetracarboxylic acid derivative, and the like can be employed. As a material for the hole transport layer, 1,1-bis (4-di-p-aminophenyl) cyclohexane, a triphenylamine derivative, a carbazole derivative, or the like can be employed. Copper phthalocyanine, metal-free phthalocyanine, aromatic diamine, etc. can be adopted as the material for the hole injection layer that injects holes into the hole transport layer.

  The first electrode layer 8, the organic light emitting layer 10, and the second electrode layer 11 can be formed by a thin film forming method such as a vapor deposition method or a sputtering method. For example, the first electrode layer 8 can be formed by a sputtering method or the like, the organic light emitting layer 10 can be formed by a vacuum deposition method, an ink jet method, a spin coating method, a printing method, or the like, and the second electrode layer 11 can be formed by an electron beam (Electron). Beam: EB) Can be formed by vapor deposition, sputtering, or the like.

  In the light emitting device of the present invention, it is preferable that the light absorbing portion 9k is in a portion other than the light emitting region 20. In this case, the light emitted from the organic light emitting layer 10 can be efficiently absorbed by the light absorbing portion 9k. In addition, it is preferable that the light absorbing portion 9k is present in all portions other than the light emitting region 20 in the second insulating layer 9. In this case, the light emitted from the organic light emitting layer 10 can be more efficiently absorbed by the light absorbing portion 9k.

  In the light emitting device of the present invention, as shown in FIGS. 1 and 2, the second insulating layer 9 has a light absorbing portion 9 k that absorbs the light emitted from the organic light emitting layer 10 so that the organic light emitting layer 10 is surrounded by the light absorbing portion 9 It is formed in the peripheral part, and it is preferable that the edge and outline of the light absorption part 9k are larger than the edge and outline of the organic light emitting layer 10 in plan view. In this case, it is possible to more effectively suppress the light emitted from the organic light emitting layer 10 from leaking to the side of the TFT 12 substantially on the side of the organic light emitting layer 10 with the light absorbing portion 9k having the minimum size. .

  In the light emitting device of the present invention, it is preferable that the light absorbing portion 9k is in the contact hole 22 portion of the second insulating layer 9. In this case, light can be prevented from being reflected multiple times by the tapered contact hole 22 such as an inverted cone shape and taken into the TFT 12 side.

  In the light emitting device of the present invention, it is preferable that the light absorbing portion 9k is in a portion overlapping the channel portion of the TFT 12 in plan view. In this case, it is possible to suppress the light emitted from the organic light emitting layer 10 from entering the channel portion of the TFT 12 substantially on the side of the organic light emitting layer 10.

  In the light emitting device of the present invention, as shown in FIGS. 3 and 4, the light absorbing portion 9k corresponds to the entire second insulating layer 9, and the entire second insulating layer 9 has light absorptivity. May be. In this case, it is possible to more effectively suppress the light emitted from the organic light emitting layer 10 from entering the channel portion of the TFT 12 substantially on the side of the organic light emitting layer 10.

  The light absorbing portion 9k can be formed by previously mixing a pigment, a dye, metal particles, etc. into the resin paste when the second insulating layer 9 having a thickness of about 1 μm is formed by spin coating or the like. . The light absorbing portion 9k only needs to be capable of absorbing light emitted from the organic light emitting layer 10 and has a dark color tone or hue such as black, brown, dark blue, dark red, dark green, or, for example, A material that can absorb and cancel most of the emission spectrum such as red may be included. When the light absorbing portion 9k is partially formed in the second insulating layer 9 as shown in FIGS. 1 and 2, when the second insulating layer 9 is formed by spin coating, a plurality of coating steps are performed. By forming the resin resist layer so as to be divided every time, it is possible to separately form the light absorbing portion 9k and other parts having translucency in the second insulating layer 9.

  In addition, the light absorbing portion 9k may be configured such that the light absorption is higher on the TFT 12 side of the second insulating layer 9, that is, on the lower layer side in FIGS. Alternatively, the portion closer to the organic light emitting layer 10 may have higher light absorption. In these cases, light leaking to the TFT 12 side can be more effectively suppressed.

  Note that the light-emitting device of the present invention is not limited to the above embodiment, and may include appropriate design changes and improvements.

  The light-emitting device of the present invention can be configured as an organic LED printer (OLEDP) head, for example, by forming the light-emitting portions in a row in the x direction mainly in FIG. In addition, the organic EL display device can be configured by forming the light emitting portions so as to be two-dimensionally (planarly) aligned in the x direction and the y direction in FIG. Furthermore, the light emitting device and the organic EL display device using the light emitting device of the present invention can be applied to various electronic devices. The electronic devices include lighting devices, automobile route guidance systems (car navigation systems), ship route guidance systems, aircraft route guidance systems, indicators for vehicles such as automobiles, instrument panels, smartphone terminals, mobile phones, tablets. Terminals, personal digital assistants (PDAs), video cameras, digital still cameras, electronic notebooks, electronic books, electronic dictionaries, personal computers, copiers, game machine terminal devices, televisions, product display tags, price display tags, industrial use Programmable display device, car audio, digital audio player, facsimile, printer, automatic teller machine (ATM), vending machine, medical display device, digital display wristwatch, and the like.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Gate electrode 3 Gate insulating film 4 Polysilicon film 4a High concentration impurity region 5 Insulating film 6a Source electrode 6b Drain electrode 7 First electrode layer 8 First electrode layer 9 Second insulating layer 9k Light absorption part 10 Organic light emitting layer 11 Second electrode 20 Light emitting region 21 Organic light emitter 22 Contact hole

Claims (4)

  A thin film transistor formed on a substrate, an organic light emitting unit laminated on the thin film transistor with a first insulating layer interposed therebetween, and a contact hole for conductively connecting the organic light emitting unit and the electrode of the thin film transistor The organic light emitter is formed by laminating a first electrode layer, an organic light emitting layer, and a second electrode layer electrically connected to the contact hole from the thin film transistor side. And the second insulating layer is formed on the first insulating layer and the first electrode layer so as to surround the organic light emitting layer, and the light emitting region does not overlap the thin film transistor in plan view. The light emitting device, wherein the second insulating layer has a light absorption property to absorb light emitted from the organic light emitting layer.   2. The light emitting device according to claim 1, wherein the second insulating layer has a light absorbing portion that absorbs light emitted from the organic light emitting layer in a portion other than the light emitting region.   The light-emitting device according to claim 2, wherein the light absorption part is in a portion overlapping with a channel part of the thin film transistor in a plan view.   The light-emitting device according to claim 2, wherein the light absorbing portion is located at the contact hole.