LIGHT-EMITTING ELEMENT, DISPLAY DEVICE, AND LIGHT-EMITTING ELEMENT MANUFACTURING METHOD

A light-emitting element according to the disclosure includes a bank including a base portion and a first protruding portion protruding from an upper face of the base portion, and a red light-emitting layer, in which at least a part of an end portion of the red light-emitting layer is located above the upper face of the base portion or adjacently to a side face of the first protruding portion.

TECHNICAL FIELD

The disclosure relates to a light-emitting element, a display device, and a light-emitting element manufacturing method.

BACKGROUND ART

Known methods for forming a pattern include a method using a printing technique such as an ink-jet method and a method using a photolithography technique such as a lift-off method.

PTL 1 discloses a method for forming a pattern of a conductive film using the lift-off method.

PTLs 2 to 4 disclose a method for forming a pattern of a function layer in a light-emitting element using the ink-jet method, and a bank including an upper face provided with a groove.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

There is a problem in the method for forming a pattern using the lift-off method in that burrs are generated at an end portion of a patterned function layer such that the burrs are peeled off, or the function layer is peeled off from an end face as a starting point.

Solution to Problem

To resolve such a problem, a light-emitting element according to an aspect of the disclosure includes a bank including a base portion and a first protruding portion protruding from an upper face of the base portion, and a first function layer, and is configured such that at least a part of an end portion of the first function layer is located above the upper face of the base portion or adjacently to a side face of the first protruding portion.

The light-emitting element according to an aspect of the disclosure may be configured such that at least a part of the first function layer is formed extending over the first protruding portion.

The light-emitting element according to an aspect of the disclosure may be configured such that an inclination angle of the side face of the first protruding portion is less than 90 degrees.

The light-emitting element according to an aspect of the disclosure may be configured such that a step between the upper face of the base portion and an upper face of the first protruding portion is less than 10 μm.

The light-emitting element according to an aspect of the disclosure may be configured such that the at least a part of the end portion of the first function layer is located above the upper face of the base portion.

The light-emitting element according to an aspect of the disclosure may be configured such that the first function layer has a thick end portion as compared to a portion formed in an opening of the bank.

The light-emitting element according to an aspect of the disclosure may be configured such that the first function layer includes at least any one layer of a light-emitting layer, a charge transport layer, and a charge injection layer.

The light-emitting element according to an aspect of the disclosure may be configured such that the bank further includes a second protruding portion protruding from the upper face of the base portion, and the at least a part of the end portion of the first function layer is located between the first protruding portion and the second protruding portion.

The light-emitting element according to an aspect of the disclosure may be configured such that a step between the upper face of the base portion and the upper face of the first protruding portion is larger than a thickness of the at least a part of the end portion of the first function layer, and a step between the upper face of the base portion and the upper face of the second protruding portion is larger than the thickness of the at least a part of the end portion of the first function layer.

The light-emitting element according to an aspect of the disclosure may be configured such that the first protruding portion surrounds an opening of the bank, and an entire part of the end portion of the first function layer is located above the upper face of the base portion or adjacently to the side face of the first protruding portion.

The light-emitting element according to an aspect of the disclosure may be configured such that the first protruding portion does not surround an opening of the bank.

The light-emitting element according to an aspect of the disclosure may be configured such that at least one side face of the first protruding portion includes a meandering shape or a zigzag shape.

The light-emitting element according to an aspect of the disclosure may be configured such that the first function layer includes a plurality of layers.

The light-emitting element according to an aspect of the disclosure further includes an insulating layer and an island-shaped electrode located on the insulating layer, and may be configured such that the bank covers an end portion of the island-shaped electrode, a distance from an upper face of the insulating layer to the upper face of the base portion is equivalent to a distance from a surface of the end portion of the island-shaped electrode to the upper face of the first protruding portion, the island-shaped electrode has a uniform thickness, and the first protruding portion is located above the end portion of the island-shaped electrode.

The light-emitting element according to an aspect of the disclosure further includes an insulating layer and an island-shaped electrode located on the insulating layer, and may be configured such that the bank covers an end portion of the island-shaped electrode, a distance from an upper face of the insulating layer to the upper face of the base portion is equivalent to a distance from an upper face of the island-shaped electrode to the upper face of the first protruding portion, at least a part of the end portion of the island-shaped electrode is thicker than a central portion of the island-shaped electrode corresponding to an opening of the bank, and the first protruding portion is located above the at least a part of the end portion of the island-shaped electrode.

The light-emitting element according to an aspect of the disclosure further includes an insulating layer including a flat portion and a depressed portion depressed from the flat portion, and may be configured such that the bank covers the depressed portion, and the first protruding portion is located above the flat portion.

A display device according to an aspect of the disclosure is configured to include the above-described light-emitting element.

The display device according to an aspect of the disclosure includes a second function layer including an end portion formed above the bank and located on a side opposite to the first function layer with respect to the bank, and may be configured such that at least a part of the second function layer is located above the upper face of the base portion or adjacently to the side face of the first protruding portion.

The display device according to an aspect of the disclosure includes a second function layer including an end portion formed above the bank and located on a side opposite to the first function layer with respect to the bank, and may be configured such that the bank further includes a second protruding portion protruding from the upper face of the base portion, and at least a part of an end portion of the second function layer is located between the first protruding portion and the second protruding portion.

The display device according to an aspect of the disclosure may be configured such that the bank further includes a third protruding portion protruding from the upper face of the base portion and being located between the first protruding portion and the second protruding portion, at least a part of the first function layer is formed extending over the first protruding portion, at least a part of the second function layer is formed extending over the second protruding portion, the at least a part of the end portion of the first function layer is located between the first protruding portion and the third protruding portion, and the at least a part of the end portion of the second function layer is located between the second protruding portion and the third protruding portion.

The display device according to an aspect of the disclosure may be configured such that the bank further includes a third protruding portion protruding from the upper face of the base portion and located between the first protruding portion and the second protruding portion, at least a part of the first function layer is formed extending over the first protruding portion and the third protruding portion, at least a part of the second function layer is formed extending over the second protruding portion and the third protruding portion, the at least a part of the end portion of the first function layer is located between the second protruding portion and the third protruding portion, and the at least a part of the end portion of the second function layer is located between the first protruding portion and the third protruding portion.

To resolve the above problems, there is provided a method of manufacturing a light-emitting element according to an aspect of the disclosure, including forming a bank so that the bank includes a base portion and a first protruding portion protruding from an upper face of the base portion, forming a sacrificing layer so that the sacrificing layer covers the bank, patterning the sacrificing layer so that an end portion of the sacrificing layer is located above the bank and at least a part of the end portion of the sacrificing layer is located above the upper face of the base portion or adjacently to a side face of the first protruding portion, forming a function material layer so that the function material layer covers the sacrificing layer and the bank, and patterning the function material layer by dissolving at least a part of the sacrificing layer.

The method of manufacturing a light-emitting element according to an aspect of the disclosure is a method of manufacturing a light-emitting element described above. The forming a bank includes forming a photoresist layer, and exposing the photoresist layer using a photomask including a light-transmitting portion with a high light transmittance, a light blocking portion with a low light transmittance, and a semi-transparent portion with an intermediate light transmittance between a light transmittance of the light-transmitting portion and a light transmittance of the light blocking portion. An opening of the bank is formed at a position corresponding to one of the light-transmitting portion and the light blocking portion, and the first protruding portion is formed at a position corresponding to the other of the light-transmitting portion and the light blocking portion.

Advantageous Effects of Disclosure

According to an aspect of the disclosure, it is possible to reduce the above-described problem that the end portion of the function layer or the function layer itself is easily peeled off.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Display Device

FIG.1is a conceptional view illustrating a schematic configuration of a display device1according to an embodiment of the disclosure.

As illustrated inFIG.1, the display device1includes a display region DA and a frame region NA surrounding the display region DA.

The display region DA is provided with a red subpixel Pr corresponding to a light-emitting element ES (seeFIG.2) configured to emit red light, a green subpixel Pg corresponding to a light-emitting element ES configured to emit green light, and a blue subpixel Pb corresponding to a light-emitting element ES configured to emit blue light. Hereinafter, the red subpixel Pr, the green subpixel Pg, and the blue subpixel Pb are collectively referred to as “subpixels P”. AlthoughFIG.1illustrates an example in which the subpixels P are arranged in an oblique arrangement, the arrangement is not limited thereto, and the subpixels P may be arranged in any arrangement such as a stripe arrangement or a pentile arrangement. Each of the subpixels P includes a pixel circuit configured to control the corresponding light-emitting element ES, and has a one-to-one correspondence with the light-emitting element ES according to the disclosure.

The frame region NA is formed with a gate driver GD, a source driver SD, wiring lines (not illustrated) connecting the display region DA to the gate driver GD and the source driver SD, wiring lines and terminals (not illustrated) for supplying electric power and signals to the gate driver GD and the source driver SD, and the like.

FIG.2is a schematic cross-sectional view illustrating an example of a configuration of the display region DA of the display device1illustrated inFIG.1.

As illustrated inFIG.2, when the display device1according to the disclosure is a non-flexible display device, the display device1includes, for example, a glass substrate2, a thin film transistor layer3, a flattening film4, a light-emitting element layer5, a sealing layer6, an adhesive layer38, and a function film39.

As illustrated inFIG.2, the light-emitting element layer5includes a pixel electrode22, a bank23covering an end portion of the pixel electrode22, an active layer24covering the pixel electrode22, and a common electrode25covering the active layer24, and configures a light-emitting element ES.

The pixel electrode22is an island-shaped electrode provided for each of the subpixels P.

For example, the bank23is formed to cover an end portion (that is, an “edge”) of the pixel electrode22. Therefore, the bank23is also referred to as an “edge cover”. The light-emitting element ES in the disclosure includes the bank23surrounding the corresponding pixel electrode22.

The active layer24is an EL layer that performs electroluminescence (EL) or includes the EL layer. The active layer24is formed to cover the pixel electrode22exposed from an opening of the bank23.

The common electrode25is an electrode provided in common to all the subpixels P.

Hereinafter, in order to facilitate understanding of the disclosure, the light-emitting element layer5will be described in detail, and the other layers will not be described in detail.

Although the disclosure describes an example in which the display device1is a non-flexible display device, the disclosure is not limited thereto, and a flexible display device is also included within the scope of the disclosure.

Although the disclosure is described with respect to an example in which the pixel electrode22is an anode and the common electrode25is a cathode, the disclosure is not limited thereto, and an example in which the pixel electrode22is a cathode and the common electrode25is an anode is also included within the scope of the disclosure. The display device1may appropriately include an additional layer, and for example, may include a barrier layer in order to reduce entry of oxygen or moisture into the light-emitting element layer5. The barrier layer may be provided between the glass substrate2and the thin film transistor layer3.

Although the disclosure is described with respect to an example in which the bank23corresponding to the plurality of light-emitting elements ES is integrally formed and the adjacent light-emitting elements ES share the bank23, the disclosure is not limited thereto, and an example in which banks23corresponding to the respective light-emitting elements ES are separately formed and the light-emitting elements ES do not share the banks23is also included within the scope of the disclosure.

Configuration of Light-Emitting Element Layer

FIG.3is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.FIG.4is a schematic plan view illustrating an example of a positional relationship between the light-emitting layer40and the bank23in the light-emitting element layer5illustrated inFIG.3.FIG.3corresponds to a cross-sectional view taken along AA inFIG.4.

In an example illustrated inFIG.3, the pixel electrode22is an anode and the common electrode25is a cathode.

As illustrated inFIG.3, the active layer24includes a hole injection layer26and a light-emitting layer40. The active layer24may optionally include additional layers such as a hole transport layer, an electron transport layer, and an electron injection layer. If it is possible to directly inject a hole from the cathode to the light-emitting layer40, the active layer24may not include the hole injection layer26.

The hole injection layer26and the hole transport layer include a hole transport material and/or a photosensitive hole transport material. Examples of the hole transport material include NiO, CuI, Cu2O, CoO, Cr2O3, and CuAlS2. Examples of the photosensitive hole transport material includes OTPD, QUPD, and X-F6-TAPC.

Examples of the electron transport layer and the electron injection layer include ZnO, ZnS, ZrO, MgZnO, AlZnO, and TiO2.

The light-emitting layer40includes an inorganic light-emitting material or an organic light-emitting material such as quantum dots emitting light by recombination of electrons and holes. The quantum dot may be a core type, a core-shell type, or a core-multishell type. Examples of the core material and the shell material in the core-shell type quantum dots include CDSE/CdS, CdSe/ZnS, CdTe/CdS, InP/ZnS, GaP/ZnS, Si/ZnS, InN/GaN, InP/CdSSe, InP/ZNSeTe, GaInP/ZNSe, GaInP/ZnS, Si/AIP, InP/ZnSTe, GaInP/ZnSTe, and GaInP/ZnSSe.

The light-emitting layer40includes a red light-emitting layer40rformed in the light-emitting element ES corresponding to the red subpixel Pr, a green light-emitting layer40gformed in the light-emitting element ES corresponding to the green subpixel Pg, and a blue light-emitting layer40bformed in the light-emitting element ES corresponding to the blue subpixel Pb. The red light-emitting layer40rincludes a light-emitting material that emits red light by electroluminescence. The green light-emitting layer40gincludes a light-emitting material that emits green light by electroluminescence. The blue light-emitting layer40bincludes a light-emitting material that emits blue light by electroluminescence.

The bank23includes a base portion230, a first protruding portion231protruding from an upper face of the base portion230, and a second protruding portion232protruding from an upper face of the base portion230. Between the first protruding portion231and the second protruding portion232, a recessed portion50is formed.

As illustrated inFIG.4, an end portion42rof the red light-emitting layer40ris located above the bank23. An end portion42gof the green light-emitting layer40gis located above the bank23. An end portion42bof the blue light-emitting layer40bis located above the bank23. A positional relationship between the light-emitting layer40and the bank23will be described in detail later.

Manufacturing Method

A method of manufacturing the light-emitting element layer5illustrated inFIG.3will be described in detail below. The method of manufacturing the light-emitting element layer5is also referred to as a method of manufacturing the light-emitting element ES. The method of manufacturing the light-emitting element layer5is a part of the method of manufacturing the display device1.

In the following description, the “same layer” means a layer formed through the same process (film formation step), the “lower layer” means a layer formed through a process before that of the layer to be compared, and the “upper layer” means a layer formed through a process after that of the layer to be compared.

FIG.5is a schematic flowchart illustrating an example of the method of manufacturing the light-emitting element layer5illustrated inFIG.3.FIG.6is a schematic flowchart illustrating an example of a method of manufacturing the bank23illustrated inFIG.3.FIG.7is a schematic flowchart illustrating an example of a method of manufacturing the light-emitting layer40illustrated inFIG.3.FIG.8toFIG.14are schematic cross-sectional views each illustrating an example of a method of manufacturing the light-emitting element layer5illustrated inFIG.3.

Below, for simplification of description, a detailed description will be given while focusing on the red light-emitting layer40r(first function layer), the green light-emitting layer40g(second function layer), and the bank23above which the end portion42rof the red light-emitting layer40rand the end portion42gof the green light-emitting layer40gare located. In addition, out of the two protruding portions included in the bank23to be focused on, the protruding portion close to the red light-emitting layer40ris referred to as the first protruding portion231, and the protruding portion close to the green light-emitting layer40gis referred to as the second protruding portion232. The green light-emitting layer40gis located on the opposite side of the red light-emitting layer40rwith respect to the bank23to be focused on.

As illustrated inFIG.5, the thin film transistor layer3is formed on the glass substrate2(step S10), the flattening film4is formed on the thin film transistor layer3(step S12), an opening including a through hole4ais provided in the flattening film4(step S14), and the pixel electrode22is formed on the flattening film4(step S20). Next, the bank23is formed by using a photolithography technique (step S22).

As illustrated inFIG.6andFIG.8, in step S22, firstly, a photoresist layer70is formed as a bank material layer to cover the flattening film4and the pixel electrode22(step S30). The photoresist layer70includes a photoresist. Examples of the photoresist include acrylic-based, novolac-based, rubber-based, styrene-based, and epoxy-based photoresists. Such a photoresist may include a positive photoresist (hereinafter referred to as a “positive resist”) or a negative photoresist (hereinafter referred to as a “negative resist”). Therefore, the positive resist is insoluble in a developing solution before exposure, and is soluble in the developing solution after exposure. The negative resist is soluble in the developing solution before exposure and insoluble in the developing solution after exposure.

Next, the photoresist layer70is exposed to ultraviolet rays, electron beams, laser beams, and the like by using a photomask71(step S32). The photomask71is a half-tone mask or a gray-tone mask, and includes a light-transmitting portion72with a high light transmittance, a light blocking portion73with a low light transmittance, and a semi-transparent portion74with an intermediate light transmittance between that of the light-transmitting portion72and that of the light blocking portion73. When the photoresist layer70includes the negative resist as a result of such an exposure (seeFIG.8), a portion of the photoresist layer70corresponding to the light-transmitting portion72is insoluble in the developing solution. A portion of the photoresist layer70corresponding to the light blocking portion73remains soluble in the developing solution. A part of the portion of the photoresist layer70corresponding to the semi-transparent portion74is insoluble in the developing solution.

When the photoresist layer70includes the positive resist (not illustrated), a portion of the photoresist layer70corresponding to the light blocking portion73remains insoluble in the developing solution in step S32. A portion of the photoresist layer70corresponding to the light-transmitting portion72is soluble in the developing solution. A part of the portion of the photoresist layer70corresponding to the semi-transparent portion74is soluble in the developing solution.

Next, the photoresist layer70is developed using a developing solution (step S34). The developing solution may be an aqueous solution containing an inorganic alkali such as KOH or NaOH, an aqueous solution containing an organic alkali such as TMAH, or an organic solvent such as PGMEA, acetone, NMP, DMSO, and IPA.

By the process described above, when the photoresist layer70includes the negative resist (seeFIG.8), the base portion230of the bank23is formed from a portion corresponding to the light-transmitting portion72and the semi-transparent portion74of the photoresist layer70. From a portion corresponding to the light-transmitting portion72of the photoresist layer70, the first protruding portion231and the second protruding portion232of the bank23are formed. A portion corresponding to the light blocking portion73of the photoresist layer70is removed to form the opening23aof the bank23.

When the photoresist layer70includes the positive resist (not illustrated), the base portion230of the bank23is formed from a portion corresponding to the light blocking portion73and the semi-transparent portion74of the photoresist layer70. From a portion corresponding to the light blocking portion73of the photoresist layer70, the first protruding portion231and the second protruding portion232of the bank23are formed. A portion corresponding to the light-transmitting portion72of the photoresist layer70is removed to form the opening23aof the bank23.

That is, one of the light-transmitting portion72and the light blocking portion73of the photomask71corresponds to the first protruding portion231and the second protruding portion232of the bank23, and the other corresponds to the opening23aof the bank23.

The bank23may be formed by a process other than the process described above. For example, the bank23may be formed by a so-called etching method. In such a case, a bank material layer is formed, a photoresist layer is formed as a template layer on the bank material layer, the photoresist layer is exposed and developed to obtain a template, and the bank material layer is etched using such a template as a mask. Such etching is usually dry etching. For example, a sequence including forming, exposing, and developing the photoresist layer may be repeated two or more times without using a half-tone mask or a gray-tone mask.

A thickness Db of the base portion230is smaller than a thickness D1of the first protruding portion231and a thickness D2of the second protruding portion232(Db<D1and Db<D2). The thickness D1of the first protruding portion231and the thickness D2of the second protruding portion232may be different from or the same as each other. In order to simplify the manufacturing method, the thickness D1of the first protruding portion231and the thickness D2of the second protruding portion232are preferably the same.

In order to reduce film discontinuity of an upper layer overlying the bank23, it is preferable that a step (D1-Db) between the upper face of the base portion230and the upper face of the first protruding portion231not be too large. Similarly, it is preferable that a step (D2-Db) between the upper face of the base portion230and the upper face of the second protruding portion232not be too large. For example, these steps are preferably less than 10 μm.

In order to reduce film discontinuity of an upper layer overlying the bank23, an inclination angle T1of a side face of the first protruding portion231and an inclination angle T2of a side face of the second protruding portion are preferably smaller than 90 degrees. The inclination angle T1of the first protruding portion231and the inclination angle T2of the second protruding portion may be different from or the same as each other. In order to simplify the manufacturing method, the thickness D1of the first protruding portion231and the thickness D2of the second protruding portion232are preferably the same.

As illustrated inFIG.5, next, the hole injection layer26is formed (step S24). Subsequently, formation of the red light-emitting layer40r(step S26r), formation of the green light-emitting layer40g(step S26g), and formation of the blue light-emitting layer40b(step S26b) are performed in any order. Subsequently, the common electrode25is formed (step S28).

In an example, a case where step S26r, step S26g, and step S26bare performed in this order will be described below.

Formation of Red Light-Emitting Layer40r

The formation of the red light-emitting layer40r(step S26r) will be described below.

As illustrated inFIG.9, in step S26r, first, a photoresist layer60r(sacrificing layer) is formed on the hole injection layer26so that the photoresist layer60rcovers the pixel electrode22and the bank23(step S40). The photoresist layer60rincludes a photoresist. Examples of the photoresist include acrylic-based, novolac-based, rubber-based, styrene-based, and epoxy-based photoresists. The photoresist may include the positive resist or the negative resist.

Next, the photoresist layer60ris exposed to ultraviolet rays, electron beams, laser beams, and the like by using a photomask67r(step S42). The photomask67rincludes a light-transmitting portion68rwith a high light transmittance and a light blocking portion69rwith a low light transmittance. As a result of such exposure, when the photoresist layer60rincludes the positive resist (seeFIG.9), a portion corresponding to the light-transmitting portion68rof the photoresist layer60ris soluble in a developing solution. A portion corresponding to the light blocking portion69rof the photoresist layer60rremains insoluble in the developing solution. Here, a portion corresponding to the light blocking portion69rof the photoresist layer60ris referred to as a removed portion64r.

When the photoresist layer60rincludes the negative resist (not illustrated), a portion corresponding to the light blocking portion69rof the photoresist layer60rremains soluble in the developing solution. A portion corresponding to the light-transmitting portion68rof the photoresist layer60ris insoluble in the developing solution. Therefore, a portion corresponding to the light-transmitting portion68rof the photoresist layer60ris referred to as the removed portion64r.

Next, a developing solution is used to develop the photoresist layer60r(step S44). The developing solution may be an aqueous solution containing an inorganic alkali such as KOH or NaOH, an aqueous solution containing an organic alkali such as TMAH, or an organic solvent such as PGMEA, acetone, NMP, DMSO, and IPA. The removed portion64ris removed by the development.

As illustrated inFIG.10, next, a red light-emitting material layer44ris formed above the hole injection layer26and on the photoresist layer60rso that the red light-emitting material layer44rcovers the photoresist layer60rand the bank23(step S46). The red light-emitting material layer44rcontains a light-emitting material that emits red light by recombining electrons and holes.

As illustrated inFIG.11, next, the photoresist layer60ris removed using a lift-off liquid (step S48). The lift-off liquid is a liquid that dissolves the photoresist layer60r, and may be the same as the developing solution. In step S48, the lift-off liquid is applied or sprayed on the red light-emitting material layer44r. The lift-off liquid passes through the red light-emitting material layer44r, reaches the photoresist layer60r, and dissolves the photoresist layer60r. Next, when the lift-off liquid is removed, the photoresist layer60rdissolved in the lift-off liquid is removed. Therefore, a portion formed on the photoresist layer60r, out of the red light-emitting material layer44r, is peeled off and removed. As a result, a portion formed directly on the hole injection layer26, out of the red light-emitting material layer44r, remains to serve as the red light-emitting layer40r. Therefore, the red light-emitting layer40rcorresponds to the removed portion64rof the photoresist layer60r. In addition, washing with a washing liquid may optionally be performed.

When the lift-off liquid is removed, a flow of the lift-off liquid applies an external force to the red light-emitting layer40r. In the end portion42rof the red light-emitting layer40r, a force applied to an end face of the end portion42rand the flow of the lift-off liquid attempting to enter between the end portion42rand the hole injection layer26easily act to peel off the red light-emitting layer40r. Therefore, in order to reduce the peeling of the red light-emitting layer40r, it is advantageous to protect at least a part of the end portion42rfrom the flow of the lift-off liquid. In order to reduce peeling of the red light-emitting layer40r, it is advantageous to protect at least a part of the end portion42rfrom the liquid flow also in subsequent processes such as washing with a washing liquid, forming a green light-emitting layer40g(step S26g), and forming a blue light-emitting layer40b(step S26b).

The first protruding portion231and the second protruding portion232of the bank23according to the disclosure alleviate the liquid flow. That is, the liquid flow in the recessed portion50and the opening23aof the bank23is weaker than an external liquid flow. Therefore, at least a part of the end portion42ris preferably located in the recessed portion50or the opening23ato be protected by the first protruding portion231and the second protruding portion232. In other words, it is preferable that at least a part of the end portion42rnot be located above the upper face of the first protruding portion231and not be located above the upper face of the second protruding portion232.

In order to reduce electric field concentration and short circuiting, the red light-emitting layer40ris larger than the corresponding opening23aof the bank23. Therefore, it is preferable that at least a part of the end portion42rof the red light-emitting layer40rbe located either adjacently to a side face and above the upper face of the base portion230, adjacently to a side face of the first protruding portion231, or adjacently to a side face of the second protruding portion232. Further, from the viewpoint of manufacturing accuracy, in consideration of a feature that widths of the side face of the base portion230, the first protruding portion231, and the second protruding portion232are small in a plan view seen from above, it is more preferable that at least a part of the end portion42rof the red light-emitting layer40rbe designed to be located above the upper face of the base portion230. At least a part of the end portion42rof the red light-emitting layer40ris preferably located between the first protruding portion231and the second protruding portion232.

This is because if at least a part of the end portion42ris designed to be located adjacently to the side face of the base portion230, compared to a case where such a part of the end portion42ris not located adjacently to the side face of the base portion230, such a part of the end portion42ris more likely to be located at the pixel electrode22due to manufacturing errors. Furthermore, if the end portion42ris designed to be located adjacently to the side face of the first protruding portion231or the second protruding portion232, compared to a case where the end portion42ris not located adjacently to the side face of the first protruding portion231or the second protruding portion232, such a part is more likely to be located above the upper face of the first protruding portion231or the second protruding portion232due to manufacturing errors.

Further, in order to reduce peeling of the red light-emitting layer40r, it is preferable to increase a joining strength between the red light-emitting layer40rand the hole injection layer26. In order to increase the joining strength between the red light-emitting layer40rand the hole injection layer26, it is preferable that an area where the red light-emitting layer40ris in contact with the hole injection layer26be large. In order to increase the contact area, it is more preferable that at least a part of the red light-emitting layer40rbe formed extending over the first protruding portion231from an electroluminescent region ELr. The electroluminescent region ELr of the red light-emitting layer40ris a portion formed in the opening23aof the bank23in the red light-emitting layer40r.

The photoresist layer60ris patterned in step S42and step S44to be suitable for the patterning of the red light-emitting layer40ras described above. That is, in step S42and step S44, the photoresist layer60ris preferably patterned such that the end portion62rof the photoresist layer60ris located above the bank23, and at least a part of the end portion62rof the photoresist layer60ris located either adjacently to the side face and above the upper face of the base portion230, adjacently to the side face of the first protruding portion231, or adjacently to the side face of the second protruding portion232.

Formation of Green Light-Emitting Layer

The formation of the green light-emitting layer40g(step S26g) will be described below.

As illustrated inFIGS.7and12, in step S26g, first, a photoresist layer60gis formed on the hole injection layer26and the red light-emitting layer40rso that the photoresist layer60gcovers the pixel electrode22and the bank23(step S40). The photoresist layer60gincludes a photoresist. Examples of the photoresist include acrylic-based, novolac-based, rubber-based, styrene-based, and epoxy-based photoresists. The photoresist may include the positive resist or the negative resist.

Next, the photoresist layer60gis exposed to ultraviolet rays, electron beams, laser beams, and the like by using a photomask67g(step S42). The photomask67gincludes a light-transmitting portion68gwith a high light transmittance and a light blocking portion69gwith a low light transmittance. As a result of such exposure, when the photoresist layer60gincludes the positive resist (seeFIG.12), a portion corresponding to the light-transmitting portion68gof the photoresist layer60gis soluble in a developing solution. A portion corresponding to the light blocking portion69gof the photoresist layer60gremains insoluble in the developing solution. Here, a portion corresponding to the light blocking portion69gof the photoresist layer60gis referred to as a removed portion64g.

When the photoresist layer60gincludes the negative resist (not illustrated), a portion corresponding to the light blocking portion69gof the photoresist layer60gremains insoluble in the developing solution. A portion corresponding to the light-transmitting portion68gof the photoresist layer60gis soluble in the developing solution. Therefore, a portion corresponding to the light-transmitting portion68gof the photoresist layer60gis referred to as the removed portion64g.

Next, a developing solution is used to develop the photoresist layer60g(step S44). The developing solution may be an aqueous solution containing an inorganic alkali such as KOH or NaOH, an aqueous solution containing an organic alkali such as TMAH, or an organic solvent such as PGMEA, acetone, NMP, DMSO, and IPA. As a result of the development, the removed portion64gis removed.

As illustrated inFIG.13, next, a green light-emitting material layer44gis formed above the hole injection layer26and on the photoresist layer60gso that the green light-emitting material layer44gcovers the photoresist layer60gand the bank23(step S46). The green light-emitting material layer44gcontains a light-emitting material that emits green light by recombining electrons and holes.

As illustrated inFIG.14, next, the photoresist layer60gis removed using a lift-off liquid (step S48). The lift-off liquid is a liquid that dissolves the photoresist layer60g, and may be the same as the developing solution. In step S48, the lift-off liquid is applied or sprayed on the green light-emitting material layer44g. The lift-off liquid passes through the green light-emitting material layer44g, reaches the photoresist layer60g, and dissolves the photoresist layer60g. Next, when the lift-off liquid is removed, the photoresist layer60gdissolved in the lift-off liquid is removed. Therefore, a portion formed on the photoresist layer60g, out of the green light-emitting material layer44g, is peeled off and removed. As a result, a portion formed directly on the hole injection layer26, out of the green light-emitting material layer44g, remains to serve as the green light-emitting layer40g. Therefore, the green light-emitting layer40gcorresponds to the removed portion64gof the photoresist layer60g. In addition, washing with a washing liquid may optionally be performed.

Due to the same reason as described above for the red light-emitting layer40r, in order to reduce peeling of the green light-emitting layer40g, it is preferable that at least a part of the end portion42gof the green light-emitting layer40gbe located either adjacently to a side face and above the upper face of the base portion230, adjacently to a side face of the first protruding portion231, or adjacently to a side face of the second protruding portion232. It is more preferable that at least a part of the end portion42gof the green light-emitting layer40gbe designed to be located above the upper face of the base portion230. At least a part of the end portion42gof the green light-emitting layer40gis preferably located between the first protruding portion231and the second protruding portion232. Further, it is more preferable that at least a part of the green light-emitting layer40gbe formed extending over the second protruding portion232from an electroluminescent region ELg. The electroluminescent region ELg of the green light-emitting layer40gis a portion formed in the opening23aof the bank23in the green light-emitting layer40g.

In step S42and step S44, the photoresist layer60gis preferably patterned such that the end portion62gof the photoresist layer60gis located above the bank23, and at least a part of the end portion62gof the photoresist layer60gis located either adjacently to the side face and above the upper face of the base portion230, adjacently to the side face of the first protruding portion231, or adjacently to the side face of the second protruding portion232.

Formation of Blue Light-Emitting Layer

Subsequently, formation of the blue light-emitting layer40b(step S26b) is executed similarly to the formation of the red light-emitting layer40r(step S26r) and the formation of the green light-emitting layer40g(step S26g).

Due to the same reason as described above for the red light-emitting layer40r, in order to reduce peeling of the blue light-emitting layer40b, it is preferable that at least a part of the end portion42bof the blue light-emitting layer40bbe located either adjacently to a side face and above the upper face of the base portion230, adjacently to a side face of the first protruding portion231, or adjacently to a side face of the second protruding portion232. It is more preferable that at least a part of the end portion42bof the blue light-emitting layer40bbe designed to be located above the upper face of the base portion230. At least a part of the end portion42bof the blue light-emitting layer40bis preferably located between the first protruding portion231and the second protruding portion232. Further, it is more preferable that at least a part of the blue light-emitting layer40bbe formed extending over the first protruding portion231or the second protruding portion232from an electroluminescent region ELb. The electroluminescent region ELb of the blue light-emitting layer40bis a portion formed in the opening23aof the bank23in the blue light-emitting layer40b, for example, as illustrated inFIG.3.

Next, the common electrode25is formed (step S28), and the formation of the light-emitting element layer5is completed.

End Portion of Light-Emitting Layer

FIG.15is a schematic cross-sectional view illustrating a configuration of the end portion42of the light-emitting layer40illustrated inFIG.3.

As illustrated inFIG.15, the end portion42of the light-emitting layer40includes a burr portion46, the end portion42of the light-emitting layer40includes a thick portion48, or a thickness of the end portion42of the light-emitting layer40is constant.

In step S46, the red light-emitting material layer44rcreeps up the side face of the photoresist layer60rand covers the hole injection layer26and the photoresist layer60r. Such a creep-up portion easily remains as a burr on the end portion42rof the red light-emitting layer40r. In the disclosure, the expression “the end portion42rof the red light-emitting layer40r(function layer) includes a burr portion46r” means that a portion that creeps up the side face of the first photoresist layer60rof the red light-emitting material layer44r(function material layer) remains as a burr at the end portion42rof the red light-emitting layer40r. Such creep-up may occur in any case where the side face of the first photoresist layer60ris tapered, inversely tapered, or vertical.

Alternatively, in step S46, the red light-emitting material layer44rmay thickly remain between the side face of the photoresist layer60rand the upper face of the hole injection layer26, and the thickly remaining portion is likely to be left at the end portion42rof the red light-emitting layer40r. In the disclosure, the expression “the end portion42rof the red light-emitting layer40r(function layer) includes a thick portion48r” means that the end portion42rof the red light-emitting layer40rdoes not include a burr, but a thickness of the end portion42rof the red light-emitting layer40ris larger than a thickness of the electroluminescent region ELr of the red light-emitting layer40r.

In the disclosure, the expression “the end portion42rof the red light-emitting layer40r(function layer) is thick” means either “the end portion42rof the red light-emitting layer40r(function layer) includes the burr portion46r” or “the end portion42rof the red light-emitting layer40r(function layer) includes the thick portion48r”, or both. On the other hand, the expression “a thickness of the end portion42rof the red light-emitting layer40r(function layer) is constant” excludes the expression that “the end portion42rof the red light-emitting layer40r(function layer) is thick”, that is, means that the end portion42rof the red light-emitting layer40rincludes neither the burr portion nor the thick portion, and the end portion42rof the red light-emitting layer40ris substantially equal in thickness to the electroluminescent region ELr (central portion) of the red light-emitting layer40r.

Cases where the end portion42gof the green light-emitting layer40gincludes and does not include the burr portion46gor the thick portion48gare expressed in a similar manner. Cases where the end portion42bof the blue light-emitting layer40bincludes and does not include the burr portion46bor the thick portion48bare expressed in a similar manner.

In either case, the end portion42of the light-emitting layer40includes an end face43.

COMPARATIVE EXAMPLE

FIG.16is a schematic cross-sectional view illustrating a configuration of a light-emitting element layer105according to a comparative example.

The light-emitting element layer105according to the comparative example is different from the light-emitting element layer5according to the disclosure illustrated inFIG.3in that the former includes a bank123not including a protruding portion and includes an active layer124including a light-emitting layer140including a red light-emitting layer140r, a green light-emitting layer140g, and a blue light-emitting layer140b. In other respects, the light-emitting element layer105according to the comparative example has a configuration equivalent to that of the light-emitting element layer5according to the disclosure illustrated inFIG.3, and is manufactured by an equivalent manufacturing method.

As illustrated inFIG.16, an end portion142rof the red light-emitting layer140raccording to the comparative example is located above the upper face of the bank123, and the bank123does not include a protruding portion. Therefore, in the manufacturing process of the light-emitting element layer105, the end portion142rof the red light-emitting layer140ris not protected from the liquid flow. Therefore, the red light-emitting layer140ris easily peeled off. Furthermore, when the end portion142rof the red light-emitting layer140rincludes the burr portion, such a burr portion is easily peeled off. Furthermore, the green light-emitting layer140gand the blue light-emitting layer140baccording to the comparative example are also easily peeled off, and the burr portions included in the green light-emitting layer140gand the blue light-emitting layer140bare also easily peeled off.

In short, the light-emitting element layer105according to the comparative example has a problem that the light-emitting layer140and the burr portion included in the light-emitting layer140are easily peeled off. To resolve such an issue, the light-emitting element layer5according to the disclosure exhibits, as described above, an effect that the light-emitting layer40and the burr portion46included in the light-emitting layer40are less likely to be peeled off.

Film Discontinuity

FIG.17is an enlarged schematic partial cross-sectional view illustrating a portion of a configuration of the light-emitting element layer105according to the comparative example in an enlarged manner.FIG.18is an enlarged schematic partial cross-sectional view illustrating a portion of a configuration of the light-emitting element layer5according to the disclosure illustrated inFIG.3in an enlarged manner.

As illustrated inFIG.17, when the end portion142rof the red light-emitting layer140raccording to the comparative example includes a thick portion148r, the common electrode25is likely to be discontinuous. Furthermore, when the green light-emitting layer140gand the blue light-emitting layer140binclude thick portions, the common electrode25is likely to be discontinuous. Similarly, when an end portion142gof the green light-emitting layer140gaccording to the comparative example includes a burr portion146g, the common electrode25is likely to be discontinuous. Furthermore, when the red light-emitting layer140rand the blue light-emitting layer140binclude burr portions, the common electrode25is likely to be discontinuous. The common electrode25is located in a layer above the red light-emitting layer140r, the green light-emitting layer140, and the blue light-emitting layer140b.

In short, the light-emitting element layer105according to the comparative example has a problem that film discontinuity is likely to occur in an upper layer overlying the light-emitting layer140.

On the other hand, as illustrated inFIG.18, even in a case where the end portion42rof the red light-emitting layer40raccording to the disclosure includes the thick portion48rand the end portion42gof the green light-emitting layer40gaccording to the disclosure includes the burr portion46g, the common electrode25is unlikely to be discontinuous. This is because portions of the common electrode25formed in the recessed portion50and the opening23aof the bank23are likely to be formed thicker than the other portions.

Therefore, the light-emitting element layer5according to the disclosure exhibits an effect that the film discontinuity is less likely to occur in an upper layer overlying the light-emitting layer40.

In order to exhibit such an effect, a step between the upper face of the base portion230and the upper faces of the first protruding portion231and the second protruding portion232is preferably larger than the thicknesses of the end portions42r,42g, and42bof the red light-emitting layer40r, the green light-emitting layer40g, and the blue light-emitting layer40b. More specifically, it is more preferable that such a step be larger than assumed maximum thicknesses of the burr portions46r,46g, and46band the thick portions48r,48g, and48bpossibly included in the end portions42r,42g, and42b. The assumed maximum thickness is typically at least twice a design film thickness. To be more specific, the assumed maximum thickness of the end portion42rof the red light-emitting layer40ris twice or more the thickness in the electroluminescent region ELr of the red light-emitting layer40r. Similarly, the assumed maximum thicknesses of the end portions42gand42bof the green light-emitting layer40gand the blue light-emitting layer40bare twice or more the thicknesses in the electroluminescent regions ELg and ELb of the green light-emitting layer40gand the blue light-emitting layer40b. Note that when the end portions42r,42g, and42boverlap each other in the recessed portion50, such a step is preferably larger than a sum of the thicknesses of the overlapping end portions42r,42g, and42b. Therefore, it is preferable that the end portions48r,48g, and48bnot overlap each other in the recessed portion50.

Modified Example

FIGS.19and20are schematic plan views each illustrating a modified example of the positional relationship between the light-emitting layer40and the bank23in the light-emitting element layer5illustrated inFIG.3.

As illustrated inFIG.19, the bank23is preferably formed such that the first protruding portion231surrounds the opening23a(that is, the electroluminescent regions ELr, ELg, and ELb) of the bank23and an entire part of the end portion42rof the red light-emitting layer40ris located adjacently to the side face or the upper face of the base portion230or the side face of the first protruding portion231or the second protruding portion232. This is because the entire part of the end portion42ris protected, and thus, the peeling of the red light-emitting layer40ris further reduced. Similarly, the bank23is preferably formed such that an entire part of each of the end portions42gand42bof the green light-emitting layer40gand the blue light-emitting layer40bis located adjacently to the side face or above the upper face of the base portion230or adjacently to the side face of the first protruding portion231or the second protruding portion232. On the other hand, as illustrated inFIG.3, when the first protruding portion231does not surround the opening23aof the bank23, an alignment accuracy of the light-emitting layer40with respect to the bank23may be low, and there is an advantage that a manufacturing efficiency of the light-emitting element layer5is easily improved.

As illustrated inFIG.20, at least one side face of the first protruding portion231preferably includes a meandering shape or a zigzag shape. This is because a stress applied to or generated in the first protruding portion231is dispersed by the meandering shape or the zigzag shape. A strength of the first protruding portion231is improved by such stress dispersion. Similarly, at least one side face of the second protruding portion232also preferably includes a meandering shape or a zigzag shape.

Although not illustrated, the method and the configuration of the disclosure is applicable to a function layer other than the light-emitting layer40, and also applicable to a function layer including a plurality of layers. The method and the configuration of the disclosure are suitable for a function layer including nanoparticles. Examples of the function layer including nanoparticles include a light-emitting layer, a charge transport layer, and a charge injection layer.

Although a configuration in which the photoresist layers60rand60gused as a mold (template) for patterning the light-emitting layer40do not remain in the light-emitting element layer5is described above, the scope of the disclosure is not limited thereto. For example, a configuration in which a part of the photoresist layers60rand60gis included in the light-emitting element layer5as a charge transport layer, a charge injection layer, a charge shielding layer, or the like is also included within the scope of the disclosure.

Second Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.21is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.21, the light-emitting element layer5according to a second embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.3) according to the foregoing first embodiment except that the flattening film4(insulating layer) includes a flat portion80and a depressed portion82depressed from the flat portion80, and the bank23covers the depressed portion82to fill the depressed portion82.

Therefore, a method of manufacturing the light-emitting element layer5according to the second embodiment is equivalent to the method of manufacturing the light-emitting element layer5according to the foregoing first embodiment (seeFIGS.5to14) except that the depressed portion82is formed in addition to the through hole4ain step S14, and the photomask71includes the light-transmitting portion72and the light blocking portion73and does not include the semi-transparent portion in step S32.

FIG.22is a schematic cross-sectional view illustrating an example of the method of manufacturing the light-emitting element layer5illustrated inFIG.21.

As illustrated inFIG.22, steps S10and S12are executed, and then, an opening including the through hole4aand the depressed portion82is formed in the flattening film4(step S14). Next, steps S20and S22are executed.

In step S22, step S30is executed. In step S30, the photoresist layer70is formed to follow the flattening film4. Next, the photomask71not including the semi-transparent portion is used to expose the photoresist layer70(step S32). Next, step S34is executed.

With the above process, when the photoresist layer70includes the negative resist (seeFIG.22), the base portion230of the bank23is formed from a portion corresponding to the light-transmitting portion72of the photoresist layer70. From a portion corresponding to the flat portion80of the flattening film4, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the first protruding portion231and the second protruding portion232of the bank23are formed. Therefore, from a portion corresponding to the depressed portion82of the flattening film4, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the recessed portion50of the bank23is formed. In other words, the first protruding portion231and the second protruding portion232are located above the flat portion80, and the recessed portion50is located above the depressed portion82. A portion corresponding to the light blocking portion73of the photoresist layer70is removed to form the opening23aof the bank23.

According to the method of the second embodiment, a half-tone mask or a frame-tone mask is not used as the photomask71, and thus, it is possible to reduce a manufacturing cost of the light-emitting element layer5and improve a manufacturing efficiency thereof. The method and the configuration according to the second embodiment also exhibit similar effects to that of the foregoing first embodiment.

Modified Example

FIG.23is a schematic cross-sectional view illustrating a modified example of the light-emitting element layer5illustrated inFIG.21.

As illustrated inFIG.23, a depressed portion86depressed from a flat portion84may be formed in a flat glass substrate2(insulating layer). The thin film transistor layer3follows an upper face of the glass substrate2, and thus, the thin film transistor layer3is provided with the depressed portion82depressed from the flat portion80. An uppermost layer of the thin film transistor layer3is usually an insulating layer. The bank23covers the depressed portion82to fill the depressed portion82.

In such a case, the depressed portion86is formed in the glass substrate2before the thin film transistor layer3is formed, and thus, the formation of the depressed portion82does not damage the thin film transistor layer3. Therefore, it is possible to improve a function and a manufacturing efficiency of the light-emitting element layer5.

Third Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.24is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.24, the light-emitting element layer5according to a third embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.3) according to the foregoing first embodiment except that at least a part of an end portion of the pixel electrode22is thickened, and a distance from the upper face of the flattening film4to the upper face of the base portion230of the bank23is equivalent to a distance from the upper face of the pixel electrode22to the upper faces of the first protruding portion231and the second protruding portion232of the bank23. Hereinafter, a thickened portion of the end portion of the pixel electrode22is referred to as a protruding portion221. A thickness of the protruding portion221of the pixel electrode22is greater than a thickness of a central portion of the pixel electrode22corresponding to the opening23aof the bank23.

Therefore, a method of manufacturing the light-emitting element layer5according to the third embodiment is equivalent to the method of manufacturing the light-emitting element layer5according to the foregoing first embodiment (seeFIGS.5to14) except that the protruding portion221is formed in the pixel electrode22in step S20, and the photomask71includes the light-transmitting portion72and the light blocking portion73and does not include the semi-transparent portion in step S32.

FIG.25is a schematic cross-sectional view illustrating an example of the method of manufacturing the light-emitting element layer5illustrated inFIG.24.

In step S22, step S30is executed. In step S30, the photoresist layer70is formed to follow the pixel electrode22. Next, the photomask71not including the semi-transparent portion is used to expose the photoresist layer70(step S32). Next, step S34is executed.

By the process described above, when the photoresist layer70includes the negative resist (seeFIG.25), the bank23is formed from a portion corresponding to the light-transmitting portion72of the photoresist layer70. From a portion corresponding to the protruding portion221of the pixel electrode22, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the first protruding portion231and the second protruding portion232of the bank23are formed. Therefore, from a portion corresponding to a space between the pixel electrodes22, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the recessed portion50of the bank23is formed. In other words, the first protruding portion231and the second protruding portion232are located above the protruding portion221of the pixel electrode22, and the recessed portion50is not located above the pixel electrode22. A portion corresponding to the light blocking portion73of the photoresist layer70is removed to form the opening23aof the bank23.

According to the method of the third embodiment, a half-tone mask or a frame-tone mask is not used as the photomask71, and thus, it is possible to reduce a manufacturing cost of the light-emitting element layer5and improve a manufacturing efficiency thereof. The method and the configuration according to the third embodiment also exhibit similar effects to that of the foregoing first embodiment.

According to the configuration of the third embodiment, when the pixel electrode22is a reflective electrode, it is possible to reduce optical crosstalk because guided waves along the pixel electrode22and the bank23are prevented. When the pixel electrode22is a transmissive electrode, the efficiency of extracting light from the light-emitting element ES (so-called “external quantum efficiency”) does not decrease, as compared to a configuration in which the entire pixel electrode22is uniformly thick.

Fourth Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.26is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.26, the light-emitting element layer5according to a fourth embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.3) according to the foregoing first embodiment except that a whole of the pixel electrode22is thickened, and a distance from the upper face of the flattening film4to the upper face of the base portion230of the bank23is equivalent to a distance from the upper face of the pixel electrode22to the upper faces of the first protruding portion231and the second protruding portion232of the bank23.

Therefore, a method of manufacturing the light-emitting element layer5according to the fourth embodiment is equivalent to the method of manufacturing the light-emitting element layer5according to the foregoing first embodiment (seeFIGS.5to14) except that a whole of the pixel electrode22is formed thickened in step S20, and the photomask71includes the light-transmitting portion72and the light blocking portion73and does not include the semi-transparent portion in step S32.

FIG.27is a schematic cross-sectional view illustrating an example of the method of manufacturing the light-emitting element layer5illustrated inFIG.26.

In step S22, step S30is executed. In step S30, the photoresist layer70is formed to follow the pixel electrode22. Next, the photomask71not including the semi-transparent portion is used to expose the photoresist layer70(step S32). Next, step S34is executed.

By the process described above, when the photoresist layer70includes the negative resist (seeFIG.27), the bank23is formed from a portion corresponding to the light-transmitting portion72of the photoresist layer70. From a portion corresponding to the pixel electrode22, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the first protruding portion231and the second protruding portion232of the bank23are formed. Therefore, from a portion corresponding to a space between the pixel electrodes22, out of a portion corresponding to the light-transmitting portion72of the photoresist layer70, the recessed portion50of the bank23is formed. In other words, the first protruding portion231and the second protruding portion232are located above the pixel electrode22, and the recessed portion50is not located above the pixel electrode22. A portion corresponding to the light blocking portion73of the photoresist layer70is removed to form the opening23aof the bank23.

According to the method of the fourth embodiment, a half-tone mask or a frame-tone mask is not used as the photomask71, and thus, it is possible to reduce a manufacturing cost of the light-emitting element layer5and improve a manufacturing efficiency thereof. The method and the configuration according to the fourth embodiment also exhibit similar effects to that of the foregoing first embodiment.

According to the configuration of the fourth embodiment, when the pixel electrode22is a reflective electrode, it is possible to reduce optical crosstalk because guided waves along the pixel electrode22and the bank23are prevented. The thickness of the pixel electrode22is uniform, and thus, there is an advantage in that the pixel electrode22is easily formed as compared with a configuration according to the foregoing third embodiment.

Fifth Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.28is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.28, the light-emitting element layer5according to a fifth embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.3) according to the foregoing first embodiment except that the bank23includes only the base portion230and the first protruding portion231and does not include the second protruding portion. In such a case, the recessed portion50includes a first recessed portion51between the upper face of the base portion230and the side face on one side of the first protruding portion231and a second recessed portion52between the upper face of the base portion230and the side face on the other side of the first protruding portion231.

At least a part of the end portion42rof the red light-emitting layer40ris located either adjacently to the side face and above the upper face of the base portion230or adjacently to the side face of the first protruding portion231. Similarly, at least a part of the end portion42gof the green light-emitting layer40gand at least a part of the end portion42bof the blue light-emitting layer40bare located either adjacently to the side face and above the upper face of the base portion230or adjacently to the side face of the first protruding portion231. Therefore, the method and the configuration according to the fifth embodiment also exhibit similar effects to that of the foregoing first embodiment.

According to the configuration of the fifth embodiment, at least a part of the end portion42rof the red light-emitting layer40rand at least a part of the end portion42gof the green light-emitting layer40gare separated by the first protruding portion231. Therefore, the end portion42rand the end portion42gdo not overlap each other in the recessed portion50. On the other hand, in the configuration according to the foregoing first embodiment, the end portions42r,42g, and42bmay overlap each other in the recessed portion50. Therefore, according to the configuration of the fifth embodiment, it is possible to manufacture the recessed portion50more shallowly than that in the configuration of the foregoing first embodiment. When the recessed portion50is manufactured shallowly, it is possible to apply the light-emitting layer40into the recessed portion50, and thus, it is possible to easily form the light-emitting layer40and possible to improve the manufacturing efficiency of the display device1.

Sixth Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.29is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.29, the light-emitting element layer5according to a sixth embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.28) according to the foregoing fifth embodiment except that the light-emitting layers40of different colors overlap each other on the first protruding portion231.

At least a part of the end portion42rof the red light-emitting layer40ris located either adjacently to the side face and above the upper face of the base portion230or adjacently to the side face of the first protruding portion231. Similarly, at least a part of the end portion42gof the green light-emitting layer40gand at least a part of the end portion42bof the blue light-emitting layer40bare located either adjacently to the side face and above the upper face of the base portion230or adjacently to the side face of the first protruding portion231. Therefore, the method and the configuration according to the sixth embodiment also exhibit similar effects to that of the foregoing fifth embodiment.

The red light-emitting layer40raccording to the sixth embodiment is formed extending over the first protruding portion231from the electroluminescent region ELr. Therefore, the red light-emitting layer40raccording to the sixth embodiment has a larger area where the red light-emitting layer40ris in contact with the hole injection layer26than the red light-emitting layer40raccording to the foregoing fifth embodiment. Therefore, a joining strength between the red light-emitting layer40rand the hole injection layer26is high, and thus, the peeling of the red light-emitting layer40ris further reduced.

Similarly, the green light-emitting layer40gand the blue light-emitting layer40baccording to the sixth embodiment are formed extending over the first protruding portion231from the electroluminescent regions ELg and ELb, and thus, the peeling of the green light-emitting layer40gand the blue light-emitting layer40bis further reduced.

According to the configuration of the sixth embodiment, the areas of the red light-emitting layer40rand the green light-emitting layer40gare larger than those in the configuration of the foregoing fifth embodiment. Therefore, the openings formed in the photoresist layers60rand60gare widened by the development in step S44(seeFIG.7). Application to the inside of the opening is facilitated by widening the opening, and thus, it is possible to easily form the light-emitting layer40, and it is possible to improve a manufacturing efficiency of the display device1.

Seventh Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.30is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.30, the light-emitting element layer5according to the fifth embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.3) according to the foregoing first embodiment except that the bank23includes the base portion230, the first protruding portion231, and the second protruding portion232, and further includes a third protruding portion233.

At least a part of the red light-emitting layer40ris formed extending over the first protruding portion231. Further, at least a part of the end portion42rof the red light-emitting layer40ris located in a third recessed portion53between the first protruding portion231and the third protruding portion233. Similarly, at least a part of the green light-emitting layer40gis formed extending over the second protruding portion232. Further, at least a part of the end portion42gof the green light-emitting layer40gis located in a fourth recessed portion54between the second protruding portion232and the third protruding portion233.

Therefore, according to the configuration of the seventh embodiment, similarly to the configuration of the foregoing first embodiment, the red light-emitting layer40rand the green light-emitting layer40gare less likely to be peeled off, and an upper layer overlying the red light-emitting layer40rand the green light-emitting layer40gis less likely to be discontinuous.

Further, according to the configuration of the seventh embodiment, at least a part of the end portion42rof the red light-emitting layer40rand at least a part of the end portion42gof the green light-emitting layer40gare separated by the third protruding portion233. Therefore, the end portion42rand the end portion42gdo not overlap each other in the recessed portion50. On the other hand, in the configuration according to the foregoing first embodiment, the end portions42r,42g, and42bmay overlap each other in the recessed portion50. Therefore, according to the configuration of the seventh embodiment, it is possible to manufacture the recessed portion50more shallowly than that of the configuration of the foregoing first embodiment. When the recessed portion50is manufactured shallowly, it is possible to apply the light-emitting layer40into the recessed portion50, and thus, it is possible to easily form the light-emitting layer40and possible to improve the manufacturing efficiency of the display device1.

Eighth Embodiment

Another embodiment of the disclosure will be described below. Note that, for convenience of description, members having the same functions as those of the members described in the above-described embodiment will be denoted by the same reference numerals and signs, and the description thereof will not be repeated.

FIG.31is a schematic cross-sectional view illustrating an example of a configuration of the light-emitting element layer5according to the disclosure.

As illustrated inFIG.31, the light-emitting element layer5according to an eighth embodiment has a configuration equivalent to that of the light-emitting element layer5(seeFIG.30) according to the foregoing seventh embodiment except that the light-emitting layers40of different colors overlap each other on the third protruding portion233.

At least a part of the red light-emitting layer40ris formed extending over the first protruding portion231and the third protruding portion233. Further, at least a part of the end portion42rof the red light-emitting layer40ris located in the fourth recessed portion54between the second protruding portion232and the third protruding portion233. Similarly, at least a part of the green light-emitting layer40gis formed extending over the second protruding portion232and the third protruding portion233. Further, at least a part of the end portion42gof the green light-emitting layer40gis located in the third recessed portion534between the first protruding portion231and the third protruding portion233.

Therefore, according to the configuration of the eighth embodiment, similarly to the configuration of the foregoing first embodiment, the red light-emitting layer40rand the green light-emitting layer40gare less likely to be peeled off, and an upper layer overlying the red light-emitting layer40rand the green light-emitting layer40gis less likely to be discontinuous.

According to the configuration of the eighth embodiment, at least a part of the end portion42rof the red light-emitting layer40rand at least a part of the end portion42gof the green light-emitting layer40gare separated by the third protruding portion233. Therefore, the end portion42rand the end portion42gdo not overlap each other in the recessed portion50. Therefore, according to the configuration of the eighth embodiment, as compared with the configuration of the foregoing first embodiment, it is possible to manufacture the recessed portion50more shallowly and the application into the recessed portion50is facilitated, and thus, it is possible to easily form the light-emitting layer40. A joining strength is high, and thus, the peeling of the light-emitting layer40is further reduced.

According to the configuration of the eighth embodiment, the areas of the red light-emitting layer40rand the green light-emitting layer40gare larger than those in the configuration of the seventh embodiment. Therefore, the openings formed in the photoresist layers60rand60gare widened by the development in step S44(seeFIG.7). Application to the inside of the opening is facilitated by widening the opening, and thus, it is possible to easily form the light-emitting layer40, and it is possible to improve a manufacturing efficiency of the display device1. A joining strength is high, and thus, the peeling of the light-emitting layer40is further reduced.

The disclosure is not limited to the embodiments described above, and various modifications may be made within the scope of the claims. Embodiments obtained by appropriately combining technical approaches disclosed in the different embodiments also fall within the technical scope of the disclosure. Furthermore, novel technical features can be formed by combining the technical approaches disclosed in each of the embodiments.