JP7554549B2 - Display device - Google Patents

Description

The present invention relates to a display device.

Display devices that use organic light-emitting diodes (OLEDs) as light-emitting elements are known (Patent Documents 1 to 3). One such display device that has been developed uses a blue OLED as the light-emitting element and a quantum dot layer as a light conversion layer that converts the wavelength of light emitted from the OLED (Patent Document 3).

Patent No. 5124051 JP 2006-308768 A Korean Patent Publication No. 10-2017-0096583

When a quantum dot layer is used as the light conversion layer, the conversion rate of the quantum dot layer is not 100%, so in the subpixels of each color, light from the quantum dot layer is extracted through a color filter. In the configuration described in Patent Document 3, in the red subpixel, a quantum dot layer that converts blue light to red light and a red color filter are sequentially arranged on the blue OLED. In the green subpixel, a quantum dot layer that converts blue light to green light and a green color filter are sequentially arranged on the blue OLED. In the blue subpixel, a blue color filter is arranged on the blue OLED without going through a quantum dot layer.

However, in a configuration in which a color filter is arranged, the light emission efficiency of the subpixel decreases due to the absorption of light by the color filter, making it difficult to achieve high brightness.

In view of the above-mentioned problems, the object of the present invention is to provide a display device that can achieve a high brightness display.

According to one aspect of the present invention, there is provided a display device having a pixel having a first subpixel of a first color, a second subpixel of a second color, a third subpixel of a third color, and a fourth subpixel of a fourth color, each of the first subpixel, the second subpixel, the third subpixel, and the fourth subpixel having a light-emitting element that emits light of the third color, each of the first subpixel, the second subpixel, and the fourth subpixel having a quantum dot layer that converts the wavelength of the light of the third color emitted from the light-emitting element, the first subpixel having a first color filter of the first color, the second subpixel having a second color filter of the second color, and the fourth subpixel emitting light of the fourth color without passing through a color filter.

The present invention makes it possible to achieve a highly bright display.

FIG. 1 is a block diagram showing a schematic configuration of a display device according to a first embodiment of the present invention. FIG. 2 is a diagram showing an example of an arrangement of pixels and sub-pixels on a panel of the display device according to the first embodiment of the present invention. FIG. 3 is a circuit diagram showing a schematic configuration of a sub-pixel of the display device according to the first embodiment of the present invention. FIG. 4 is a schematic diagram showing the schematic configuration of a pixel of the display device according to the first embodiment of the present invention and its light emission. FIG. 5 is an xy chromaticity diagram showing color coordinates of a cyan subpixel of the display device according to the first embodiment of the present invention. FIG. 6 is a schematic diagram showing the schematic configuration of a pixel of a display device according to a second embodiment of the present invention and its light emission. FIG. 7 is an xy chromaticity diagram showing color coordinates of a magenta subpixel of the display device according to the second embodiment of the present invention. FIG. 8 is a schematic diagram showing the schematic configuration of a pixel of a display device according to a third embodiment of the present invention and its light emission. FIG. 9 is an xy chromaticity diagram showing color coordinates of a yellow or white subpixel of the display device according to the third embodiment of the present invention. FIG. 10 is a schematic diagram showing the schematic configuration of a pixel of a display device according to a fourth embodiment of the present invention and its light emission. FIG. 11 is an xy chromaticity diagram showing color coordinates of a cyan subpixel of the display device according to the fourth embodiment of the present invention. FIG. 12 is a schematic diagram showing the schematic configuration of a pixel of a display device according to a fifth embodiment of the present invention and its light emission. FIG. 13 is an xy chromaticity diagram showing color coordinates of a yellow or white subpixel of the display device according to the fifth embodiment of the present invention. FIG. 14 is a schematic diagram showing a schematic configuration of a pixel of a display device according to a sixth embodiment of the present invention. FIG. 15 is a schematic diagram showing a schematic configuration of a pixel of a display device according to a seventh embodiment of the present invention.

[First embodiment]
A display device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

First, a schematic configuration of a display device according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG.
Fig. 1 is a block diagram showing a schematic configuration of a display device according to the present embodiment. Fig. 2 is a diagram showing an example of an arrangement of pixels and sub-pixels in a panel of the display device according to the present embodiment. Fig. 3 is a circuit diagram showing a schematic configuration of a sub-pixel of the display device according to the present embodiment.

The display device according to this embodiment uses OLEDs as light-emitting elements in pixels, and displays images based on input RGB data. Applications of the display device according to this embodiment may be, for example, computer image output devices, television receivers, smartphones, game consoles, etc., but are not limited thereto.

As shown in FIG. 1, the display device includes a timing controller (TCON) 1, a panel 2, a number of source drive ICs (SDIC) 3, and a number of gate drive ICs (GDIC) 4. The panel 2 includes a number of pixels arranged in a matrix, and functions as a display unit that displays an image.

The timing controller 1 is communicatively connected to a plurality of source drive ICs 3 and a plurality of gate drive ICs 4. The timing controller 1 controls the operation timing of the plurality of source drive ICs 3 and the plurality of gate drive ICs 4 based on timing signals (vertical synchronization signal, horizontal synchronization signal, data enable signal, etc.) input from an external system.

As described below, the pixels in panel 2 have subpixels of red (R), green (G), and blue (B), as well as a cyan (C) subpixel as a fourth subpixel. Based on RGB data, which is an input signal input from an external system, timing controller 1 generates RGBC data indicating the luminance of each subpixel of panel 2, and outputs the RGBC data as an output signal to multiple source drive ICs 3. Note that the number of source drive ICs 3 and gate drive ICs 4 is not limited to that shown in the figure.

Each of the multiple source drive ICs 3 supplies a voltage (video signal) for driving multiple pixels in the panel 2 via multiple data lines in response to the control of the timing controller 1. Each of the multiple gate drive ICs 4 supplies a scan signal to multiple pixels in the panel 2 via multiple gate lines in response to the control of the timing controller 1. In this way, the timing controller 1 functions as a display control device that controls the operation of the entire display device.

2(a) and 2(b) are diagrams illustrating the arrangement of pixel 20 and subpixels 21R, 21G, 21B, and 21C in panel 2. Panel 2 includes a plurality of pixels 20 arranged in a plurality of rows and a plurality of columns. Each of the plurality of pixels 20 includes subpixel 21R that emits red light, subpixel 21G that emits green light, subpixel 21B that emits blue light, and subpixel 21C that emits cyan light. In the following description, subpixels 21R, 21G, 21B, and 21C will be simply referred to as "subpixel 21" when there is no need to distinguish between the colors.

For example, as shown in FIG. 2(a), subpixels 21R, 21G, 21B, and 21C are arranged in a fixed direction in pixel 20. In this case, as described below, subpixels 21R, 21G, 21C, and 21B are preferably arranged in the order of subpixel 21R, 21G, 21C, and 21B, or subpixel 21R, 21C, 21G, and 21B.

The sub-pixels 21R, 21G, 21B, and 21C may be arranged in a lattice pattern in the pixel 20, as shown in FIG. 2(b), for example. In this case, the sub-pixels 21R, 21G, 21B, and 21C can be arranged in a lattice pattern with any positional relationship.

The luminance of the sub-pixels 21R, 21G, 21B, and 21C is controlled according to the voltage output from the source drive IC 3. The sub-pixels 21R, 21G, 21B, and 21C emit light at a predetermined luminance ratio, allowing the pixel 20 to display various colors through additive color mixing.

In this way, the display device of this embodiment includes a cyan subpixel 21C as the fourth subpixel, and has a pixel configuration that supports four-color display of RGBC.

In this specification, red may be referred to as the first color, green as the second color, blue as the third color, and cyan, magenta, yellow, or white as the fourth color. In this specification, a red subpixel may be referred to as the first subpixel, a green subpixel as the second subpixel, a blue subpixel as the third subpixel, and a cyan, magenta, yellow, or white subpixel as the fourth subpixel. In this specification, a red color filter may be referred to as the first color filter, and a green color filter as the second color filter.

In addition, in this embodiment, quantum dot layers of each color are appropriately formed in the subpixel as light conversion layers. The quantum dot layers of each color function as wavelength conversion layers that convert the wavelength of light emitted from the OLED and incident thereon to emit light of each color. Specifically, for example, the red quantum dot layer converts blue light emitted from the blue OLED to emit red light. The green quantum dot layer converts blue light emitted from the blue OLED to emit green light. The cyan quantum dot layer converts blue light emitted from the blue OLED to emit cyan light. The yellow quantum dot layer converts blue light emitted from the blue OLED to emit yellow light. The quantum dot layer is composed of a layer of resin or the like in which quantum dots made of semiconductor materials or the like having particle sizes, materials, etc. corresponding to the output wavelength are dispersed.

Figure 3 shows a schematic configuration of a subpixel 21. Figure 3 shows a subpixel 21 included in one of the pixels 20, one source drive IC 3 connected to the subpixel 21, and one gate drive IC 4 connected to the subpixel 21.

The subpixel 21 includes a scan transistor M1, a drive transistor M2, and a diode D. The diode D is a light-emitting element of the display device, and is an OLED. The scan transistor M1 and the drive transistor M2 are, for example, thin-film transistors (TFTs). In this embodiment, the scan transistor M1 and the drive transistor M2 are n-channel types. However, the scan transistor M1 and the drive transistor M2 may be p-channel types. Note that if the drive transistor M2 is a p-channel type, the circuit configuration of the subpixel 21 may be different from that shown in FIG. 3.

The cathode of the diode D is connected to a potential line that supplies a potential VSS. The anode of the diode D is connected to the source of the drive transistor M2. The drain of the drive transistor M2 is connected to a potential line that supplies a potential VDD. The gate of the drive transistor M2 is connected to the source of the scan transistor M1.

A data line DL is connected to the drain of the scan transistor M1. The source drive IC3 supplies a video signal to the drain of the scan transistor M1 via the data line DL. A gate line GL is connected to the gate of the scan transistor M1. The gate drive IC4 supplies a control signal to the gate of the scan transistor M1 via the gate line GL. The scan transistor M1 is controlled to be on or off depending on the level of the control signal input to the gate.

The current flowing between the drain and source of the drive transistor M2 is controlled based on the voltage (video signal) input to the gate of the drive transistor M2 from the source drive IC3 via the data line DL and the scan transistor M1. The current flowing between the drain and source of the drive transistor M2 is supplied to the diode D, and the diode D emits light with a brightness according to that current. In this way, the diode D emits light with a brightness according to the video signal input to the subpixel 21.

Next, the pixel 20 of the display device according to this embodiment will be further described with reference to FIGS. 4 and 5. FIG. 4(a) is a cross-sectional view showing a schematic configuration of the pixel 20 of the display device according to this embodiment. FIG. 4(b) is a schematic diagram showing the emission of the pixel 20 of the display device according to this embodiment. FIG. 5 is an xy chromaticity diagram showing the color coordinates of the cyan sub-pixel 21C.

As shown in FIG. 4(a), each pixel 20 in the panel 2 has a red subpixel 21R, a green subpixel 21G, a blue subpixel 21B, and also a cyan subpixel 21C.

The panel 2 has an element substrate 100 and a color filter substrate 200. The color filter substrate 200 is disposed so as to face the element formation surface of the element substrate 100. The display device according to this embodiment is of a top emission type in which light is emitted from the element formation surface side of the glass substrate 30 in the element substrate 100. That is, in the display device according to this embodiment, the element formation surface side of the glass substrate 30 in the element substrate 100 is the display surface side.

The element substrate 100 has a glass substrate 30, which is a transparent substrate, and a blue OLED 32, which is a light-emitting element that emits blue light. In the following, an example will be described in which the glass substrate 30 and glass substrates 40, 50, and 60 described below are used as substrates for the panel 2, but various transparent substrates, such as flexible transparent resin substrates, can be used instead of these glass substrates.

In each pixel 20, four anode electrodes 34 made of metal electrodes are formed on the element formation surface of the glass substrate 30 so as to correspond to the sub-pixels 21R, 21G, 21B, and 21C. A blue organic light-emitting layer 36 made of an organic light-emitting material that emits blue light is formed on each anode electrode 34. A common cathode electrode 38 made of a transparent electrode is formed on each blue organic light-emitting layer 36.

In this way, in each pixel 20, an OLED 32 having an anode electrode 34, a blue organic light-emitting layer 36, and a cathode electrode 38 is formed for each of the sub-pixels 21R, 21G, 21B, and 21C. A sealing film (not shown) is formed on the entire surface of the glass substrate 30 on which the cathode electrode 38 is formed.

On the other hand, the color filter substrate 200 has a transparent glass substrate 40, color filters 42R and 42G, and quantum dot layers 44R, 44G, and 46G.

A red color filter 42R is formed on the surface of the glass substrate 40 facing the element substrate 100 so as to face the OLED 32 of the red subpixel 21R. A red quantum dot layer 44R is formed on the surface of the color filter 42R facing the element substrate 100. The red quantum dot layer 44R functions as a light conversion layer that converts the wavelength of light, and converts the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit red light. The light emitted from the quantum dot layer 44R contains unconverted blue light as well as red light.

In this way, a red subpixel 21R is formed, which has a blue OLED 32, a red quantum dot layer 44R, and a red color filter 42R.

A green color filter 42G is formed on the surface of the glass substrate 40 facing the element substrate 100 so as to face the OLED 32 of the green subpixel 21G. A green quantum dot layer 44G is formed on the surface of the color filter 42G facing the element substrate 100. The green quantum dot layer 44G functions as a light conversion layer that converts the wavelength of light, and converts the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit green light. The light emitted from the quantum dot layer 44G contains unconverted blue light as well as green light.

In this way, a green subpixel 21G is formed, which has a blue OLED 32, a green quantum dot layer 44G, and a green color filter 42G.

In addition, a green quantum dot layer 46G is formed on the surface of the glass substrate 40 facing the element substrate 100 so as to face the OLED 32 of the cyan subpixel 21C. The green quantum dot layer 46G functions as a light conversion layer that converts the wavelength of light, and converts the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit green light. The light emitted from the quantum dot layer 46G contains unconverted blue light as well as green light. The quantum dot layer 46G is formed with a thickness adjusted so as to have a conversion rate that emits cyan light, which is a mixture of green light and blue light. For this reason, for example, the quantum dot layer 46G is preferably formed thinner than the quantum dot layers 44R and 44G.

In this way, a cyan subpixel 21C is formed, which has a blue OLED 32 and a green quantum dot layer 46G. Note that subpixel 21C does not have a cyan color filter or other color filters. In other words, subpixel 21C emits cyan light without passing through a cyan color filter or other color filters. Note that when a subpixel does not have a color filter, this specification includes cases where the subpixel does not physically have a color filter, as well as cases where the subpixel has a transparent color filter.

On the other hand, on the surface of the glass substrate 40 facing the element substrate 100, no color filter or quantum dot layer is formed to face the OLED 32 of the blue subpixel 21B. Therefore, the blue subpixel 21B has a blue OLED 32, but does not have a blue color filter or other color filters or a quantum dot layer. In other words, the subpixel 21B emits blue light without passing through a blue color filter or other color filters.

In addition, a sealing film or the like (not shown) is formed on the entire surface of the glass substrate 40 on which the color filters 42R, 42G and the quantum dot layers 44R, 44G, 46G are formed.

In this way, pixel 20 is formed, having subpixels 21R, 21G, 21B, and 21C.

Figure 4(b) shows a schematic diagram of the light emission of each sub-pixel 21R, 21G, 21B, and 21C. In Figure 4(b), arrows Lr indicate red light, arrows Lg indicate green light, and arrows Lb indicate blue light, and the number of arrows indicates the amount of light. Also, for convenience, the arrangement of each component shown in Figure 4(b) does not match the arrangement of each component shown in Figure 4(a).

As shown in FIG. 4B, in the red subpixel 21R, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to red light Lr by the red quantum dot layer 44R and emitted from the quantum dot layer 44R. At this time, since the conversion rate of the quantum dot layer 44R is not 100%, unconverted blue light Lb is emitted from the quantum dot layer 44R together with the red light Lr. Also, a part of the blue light Lb is inactivated or absorbed in the quantum dot layer 44R. Next, the red light Lr emitted from the quantum dot layer 44R passes through the red color filter 42R and is emitted from the display surface of the panel 2. At this time, the blue light Lb emitted from the quantum dot layer 44R is absorbed by the color filter 42R.

As shown in FIG. 4B, in the green subpixel 21G, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to green light Lg by the green quantum dot layer 44G and emitted from the quantum dot layer 44G. At this time, since the conversion rate of the quantum dot layer 44G is not 100%, unconverted blue light Lb is emitted from the quantum dot layer 44G together with the green light Lg. Also, a part of the blue light Lb is inactivated or absorbed in the quantum dot layer 44G. Next, the green light Lg emitted from the quantum dot layer 44G passes through the green color filter 42G and is emitted from the display surface of the panel 2. At this time, the blue light Lb emitted from the quantum dot layer 44G is absorbed by the color filter 42G.

As shown in FIG. 4B, in the cyan subpixel 21C, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to green light Lg by the green quantum dot layer 46G and emitted from the quantum dot layer 46G. At this time, since the quantum dot layer 46G is formed with its thickness adjusted as described above, cyan light containing green light Lg and unconverted blue light Lb is emitted from the quantum dot layer 46G. FIG. 5 shows the color coordinates of the cyan subpixel 21C. In addition, since the quantum dot layer 46G is formed thinner than the quantum dot layers 44R and 44G, for example, the deactivation and absorption of blue light Lb is less than that of the quantum dot layer 44G. Next, the cyan light containing green light Lg and blue light Lb emitted from the quantum dot layer 46G is emitted from the display surface of the panel 2 without passing through a color filter.

As shown in FIG. 4(b), in the blue subpixel 21B, blue light Lb is first emitted from the OLED 32. Then, the blue light Lb is emitted directly from the display surface of the panel 2 without passing through the quantum dot layer or the color filter.

Thus, according to this embodiment, pixel 20 has subpixel 21C, which does not have a color filter, in addition to subpixels 21R, 21G, and 21B. Subpixel 21C has a higher light emission efficiency than subpixels 21R and 21G because it does not have a color filter. Thus, according to this embodiment, display can be performed using subpixel 21C, which has a high light emission efficiency, and therefore a highly bright display can be achieved.

For example, in this embodiment, white display can be achieved by emitting light from the red subpixel 21R and the cyan subpixel 21C, or by emitting light from the red subpixel 21R, the blue subpixel 21B, and the cyan subpixel 21C. In either case, white display is achieved using the subpixel 21C that does not have a color filter, so that a high brightness white display can be achieved.

Subpixel 21C as the fourth subpixel has high light emission efficiency and is a subpixel that can be frequently used to display white. For this reason, it is preferable that it is arranged closer to the center of pixel 20 than to the ends. For example, when subpixels 21R, 21G, 21B, and 21C are arranged in one direction in pixel 20, subpixel 21C is preferably arranged in the second or third position from one end of the arrangement of subpixels 21R, 21G, 21B, and 21C.

In this way, according to this embodiment, a display device using an OLED and a quantum dot layer can achieve a highly bright display.

[Second embodiment]
A display device according to a second embodiment of the present invention will be described with reference to Figures 6 and 7. Note that components similar to those in the display device according to the first embodiment are given the same reference numerals and descriptions thereof will be omitted or simplified.

The basic configuration of the display device according to this embodiment is the same as that of the display device according to the first embodiment. The display device according to this embodiment differs from the display device according to the first embodiment in that the pixel 20 has a magenta subpixel 21M instead of a cyan subpixel 21C.

The pixel 20 in the display device according to this embodiment will be described below with reference to Figs. 6 and 7. Fig. 6(a) is a cross-sectional view showing a schematic configuration of the pixel 20 in the display device according to this embodiment. Fig. 6(b) is a schematic diagram showing the emission of the pixel 20 in the display device according to this embodiment. Fig. 7 is an xy chromaticity diagram showing the color coordinates of the magenta sub-pixel 21M.

As shown in FIG. 6(a), pixel 20 in panel 2 has a magenta subpixel 21M in addition to a red subpixel 21R, a green subpixel 21G, and a blue subpixel 21B.

A red quantum dot layer 46R is formed on the surface of the glass substrate 40 facing the element substrate 100 so as to face the OLED 32 of the magenta subpixel 21M. The red quantum dot layer 46R functions as a light conversion layer that converts the wavelength of light, converting the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit red light. The light emitted from the quantum dot layer 46R contains unconverted blue light as well as red light. The quantum dot layer 46R is formed with a thickness adjusted so as to have a conversion rate that emits magenta light, which is a mixture of red light and blue light. For this reason, for example, the quantum dot layer 46R is preferably formed thinner than the quantum dot layers 44R and 44G.

In this way, a magenta subpixel 21M is formed, which has a blue OLED 32 and a red quantum dot layer 46R. Note that the subpixel 21M does not have a magenta color filter or other color filters. In other words, the subpixel 21M emits magenta light without passing through a magenta color filter or other color filters.

Figure 6(b) shows a schematic diagram of the light emission of each sub-pixel 21R, 21G, 21B, and 21M. In Figure 6(b), arrows Lr indicate red light, arrows Lg indicate green light, and arrows Lb indicate blue light, and the number of arrows indicates the amount of light. Also, for convenience, the arrangement of each component shown in Figure 6(b) does not match the arrangement of each component shown in Figure 6(a).

As shown in FIG. 6B, in the magenta subpixel 21M, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to red light Lr by the red quantum dot layer 46R and emitted from the quantum dot layer 46R. At this time, since the quantum dot layer 46R is formed with its thickness adjusted as described above, magenta light containing red light Lr and unconverted blue light Lb is emitted from the quantum dot layer 46R. FIG. 7 shows the color coordinates of the magenta subpixel 21M. In addition, since the quantum dot layer 46R is formed thinner than the quantum dot layers 44R and 44G, for example, the deactivation and absorption of blue light Lb is less than that of the quantum dot layers 44R and 44G. Next, the magenta light containing red light Lr and blue light Lb emitted from the quantum dot layer 46R is emitted from the display surface of the panel 2 without passing through a color filter.

Thus, according to this embodiment, pixel 20 has sub-pixel 21M, which does not have a color filter, in addition to sub-pixels 21R, 21G, and 21B. Sub-pixel 21M has a higher light emission efficiency than sub-pixels 21R and 21G because it does not have a color filter. Thus, according to this embodiment, display can be performed using sub-pixel 21M, which has a high light emission efficiency, and therefore a highly bright display can be realized.

For example, in this embodiment, white display can be achieved by emitting light from the green subpixel 21G and the magenta subpixel 21M, or by emitting light from the green subpixel 21G, the blue subpixel 21B, and the magenta subpixel 21M. In either case, white display is achieved using the subpixel 21M that does not have a color filter, so that a high brightness white display can be achieved.

Subpixel 21M as the fourth subpixel has high light emission efficiency and is a subpixel that can be frequently used to display white. For this reason, it is preferable that it is arranged closer to the center of pixel 20 than to the end. For example, when subpixels 21R, 21G, 21B, and 21M are arranged in one direction in pixel 20, subpixel 21M is preferably arranged in the second or third position from one end of the arrangement of subpixels 21R, 21G, 21B, and 21M.

In this way, according to this embodiment, a display device using an OLED and a quantum dot layer can achieve a highly bright display.

[Third embodiment]
A display device according to a third embodiment of the present invention will be described with reference to Figures 8 and 9. Note that components similar to those of the display devices according to the first and second embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified.

The basic configuration of the display device according to this embodiment is the same as that of the display device according to the first embodiment. The display device according to this embodiment differs from the display device according to the first embodiment in that the pixel 20 has a yellow or white subpixel 21YW instead of a cyan subpixel 21C.

The pixel 20 in the display device according to this embodiment will be described below with reference to Figs. 8 and 9. Fig. 8(a) is a cross-sectional view showing a schematic configuration of the pixel 20 in the display device according to this embodiment. Fig. 8(b) is a schematic diagram showing the emission of the pixel 20 in the display device according to this embodiment. Fig. 9 is an xy chromaticity diagram showing the color coordinates of the yellow or white sub-pixel 21YW.

As shown in FIG. 8(a), pixel 20 in panel 2 has a yellow or white subpixel 21YW in addition to a red subpixel 21R, a green subpixel 21G, and a blue subpixel 21B.

On the surface of the glass substrate 40 facing the element substrate 100, a red quantum dot layer 46R and a green quantum dot layer 46G are formed so as to face the OLED 32 of the yellow or white subpixel 21YW. The red quantum dot layer 46R functions as a light conversion layer that converts the wavelength of light, converting the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit red light. The light emitted from the quantum dot layer 46R contains unconverted blue light together with the red light. The quantum dot layer 46R is formed with a thickness adjusted so that the transmission amount of blue light is a predetermined transmission amount. For this reason, for example, it is preferable that the quantum dot layer 46R is formed thinner than the quantum dot layers 44R and 44G. In addition, the green quantum dot layer 46G functions as a light conversion layer that converts the wavelength of light, converting the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit green light. The light emitted from quantum dot layer 46G contains unconverted blue light as well as green light. Quantum dot layer 46G is formed with its thickness adjusted so that the amount of blue light transmitted is a predetermined amount. For this reason, for example, quantum dot layer 46G is preferably formed thinner than quantum dot layers 44R and 44G.

In this way, a yellow or white subpixel 21YW is formed, which has a blue OLED 32, a red quantum dot layer 46R, and a green quantum dot layer 46G. Note that the subpixel 21YW does not have a yellow color filter or other color filters. In other words, the subpixel 21YW emits yellow light or white light without passing through a yellow color filter or other color filters.

Subpixel 21YW can be configured as a yellow subpixel or a white subpixel by appropriately adjusting one or both of the amount of blue light transmission through red quantum dot layer 46R and the amount of blue light transmission through green quantum dot layer 46G. In the following, when subpixel 21YW is configured as a yellow subpixel, it is referred to as subpixel 21Y, and when subpixel 21YW is configured as a white subpixel, it is referred to as subpixel 21W.

Figure 8(b) shows a schematic diagram of the light emission of each sub-pixel 21R, 21G, 21B, and 21YW. In Figure 8(b), arrows Lr indicate red light, arrows Lg indicate green light, and arrows Lb indicate blue light, and the number of arrows indicates the amount of light. Also, for convenience, the arrangement of each component shown in Figure 8(b) does not match the arrangement of each component shown in Figure 8(a).

In the yellow or white subpixel 21YW, as shown in FIG. 8B, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to red light Lr by the red quantum dot layer 46R and emitted from the quantum dot layer 46R, and converted to green light Lg by the green quantum dot layer 46G and emitted from the quantum dot layer 46G. At this time, since the quantum dot layers 46R and 46G are formed with their thicknesses adjusted as described above, yellow light or white light containing red light Lr, green light Lg, and unconverted blue light Lb is emitted from the quantum dot layers 46R and 46G. FIG. 9 shows the color coordinates of the yellow or white subpixel 21YW. In addition, since the quantum dot layers 46R and 46G are formed thinner than the quantum dot layers 44R and 44G, for example, the deactivation and absorption of blue light Lb is less than that of the quantum dot layers 44R and 44G. Next, yellow light or white light containing red light Lr, green light Lg, and blue light Lb emitted from the quantum dot layers 46R and 46G is emitted from the display surface of the panel 2 without passing through a color filter.

Thus, according to this embodiment, pixel 20 has subpixel 21YW, which does not have a color filter, in addition to subpixels 21R, 21G, and 21B. Subpixel 21YW has a higher light emission efficiency than subpixels 21R and 21G because it does not have a color filter. Thus, according to this embodiment, display can be performed using subpixel 21YW, which has a high light emission efficiency, and therefore a highly bright display can be realized.

For example, in this embodiment, white display can be achieved by emitting light from the white subpixel 21W, emitting light from the blue subpixel 21B and the white subpixel 21W, or emitting light from the blue subpixel 21B and the yellow subpixel 21Y. In either case, white display is achieved using the subpixel 21Y or the subpixel 21W that does not have a color filter, so that a high brightness white display can be achieved.

Subpixel 21YW as the fourth subpixel has high light emission efficiency and is a subpixel that can be frequently used to display white. For this reason, it is preferable that it is arranged closer to the center of pixel 20 than to the end. For example, when subpixels 21R, 21G, 21B, and 21YW are arranged in one direction in pixel 20, subpixel 21YW is preferably arranged in the second or third position from one end of the arrangement of subpixels 21R, 21G, 21B, and 21YW.

In this way, according to this embodiment, a display device using an OLED and a quantum dot layer can achieve a highly bright display.

[Fourth embodiment]
A display device according to a fourth embodiment of the present invention will be described with reference to Figures 10 and 11. Note that components similar to those of the display devices according to the first to third embodiments are given the same reference numerals and descriptions thereof will be omitted or simplified.

The basic configuration of the display device according to this embodiment is the same as that of the display device according to the first embodiment. The display device according to this embodiment differs from the display device according to the first embodiment in that the pixel 20 has a cyan subpixel 21Cc that has a different configuration from the cyan subpixel 21C according to the first embodiment.

The pixel 20 in the display device according to this embodiment will be described below with reference to Figs. 10 and 11. Fig. 10(a) is a cross-sectional view showing a schematic configuration of the pixel 20 in the display device according to this embodiment. Fig. 10(b) is a schematic diagram showing the emission of the pixel 20 in the display device according to this embodiment. Fig. 11 is an xy chromaticity diagram showing the color coordinates of the cyan sub-pixel 21Cc.

As shown in FIG. 10(a), pixel 20 in panel 2 has a cyan subpixel 21Cc in addition to a red subpixel 21R, a green subpixel 21G, and a blue subpixel 21B.

A cyan quantum dot layer 46C is formed on the surface of the glass substrate 40 facing the element substrate 100 so as to face the OLED 32 of the cyan subpixel 21Cc. The cyan quantum dot layer 46C functions as a light conversion layer that converts the wavelength of light, converting the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit cyan light. The light emitted from the quantum dot layer 46C contains unconverted blue light as well as cyan light. The quantum dot layer 46C is formed with a thickness adjusted to have a conversion rate that emits cyan light. For this reason, for example, the quantum dot layer 46R is preferably formed thinner than the quantum dot layers 44R and 44G.

In this way, a cyan subpixel 21Cc is formed, which has a blue OLED 32 and a cyan quantum dot layer 46C. Note that the subpixel 21Cc does not have a cyan color filter or other color filters. In other words, the subpixel 21Cc emits cyan light without passing through a cyan color filter or other color filters.

Figure 10(b) shows a schematic of the light emission of each sub-pixel 21R, 21G, 21B, 21Cc. In Figure 10(b), arrows Lr indicate red light, arrows Lg indicate green light, arrows Lb indicate blue light, and arrows Lc indicate cyan light, and the number of arrows indicates the amount of light. Also, for convenience, the arrangement of each component shown in Figure 10(b) does not match the arrangement of each component shown in Figure 10(a).

In the cyan subpixel 21Cc, as shown in FIG. 10B, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to cyan light Lc by the cyan quantum dot layer 46C and emitted from the quantum dot layer 46C. At this time, since the quantum dot layer 46C is formed with its thickness adjusted as described above, cyan light containing cyan light Lc and unconverted blue light Lb is emitted from the quantum dot layer 46C. FIG. 11 shows the color coordinates of the cyan subpixel 21Cc. By using the cyan quantum dot layer 46C, it is possible to display a cyan color that is more outer in the xy chromaticity diagram than the cyan color resulting from the mixture of blue and green. In addition, since the quantum dot layer 46C is formed thinner than the quantum dot layers 44R and 44G, for example, the deactivation and absorption of the blue light Lb is less than that of the quantum dot layers 44R and 44G. Next, the cyan light containing the cyan light Lc and the blue light Lb emitted from the quantum dot layer 46C is emitted from the display surface of the panel 2 without passing through a color filter.

Thus, according to this embodiment, pixel 20 has sub-pixel 21Cc, which does not have a color filter, in addition to sub-pixels 21R, 21G, and 21B. Sub-pixel 21Cc has a higher light emission efficiency than sub-pixels 21R and 21G because it does not have a color filter. Thus, according to this embodiment, display can be performed using sub-pixel 21Cc, which has a high light emission efficiency, and therefore a highly bright display can be achieved.

For example, in this embodiment, white display can be achieved by emitting light from the red subpixel 21R and the cyan subpixel 21Cc, or by emitting light from the red subpixel 21R, the blue subpixel 21B, and the cyan subpixel 21C. In either case, white display is achieved using the subpixel 21Cc that does not have a color filter, so that a high brightness white display can be achieved.

Subpixel 21Cc as the fourth subpixel has high light emission efficiency and is a subpixel that can be frequently used to display white. For this reason, it is preferable that it is arranged closer to the center of pixel 20 than to the end. For example, when subpixels 21R, 21G, 21B, and 21Cc are arranged in one direction in pixel 20, subpixel 21Cc is preferably arranged in the second or third position from one end of the arrangement of subpixels 21R, 21G, 21B, and 21Cc.

As described above, according to this embodiment, a display device using an OLED and a quantum dot layer can achieve a display with high brightness.
[Fifth embodiment]
A display device according to a fifth embodiment of the present invention will be described with reference to Fig. 12 and Fig. 13. Note that components similar to those of the display devices according to the first to fourth embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified.

The basic configuration of the display device according to this embodiment is the same as that of the display device according to the first embodiment. The display device according to this embodiment differs from the display device according to the first embodiment in that the pixel 20 has a yellow or white subpixel 21YWy having a different configuration from the yellow or white subpixel 21YW according to the third embodiment, instead of the cyan subpixel 21C according to the first embodiment.

The pixel 20 in the display device according to this embodiment will be described below with reference to Figs. 12 and 13. Fig. 12(a) is a cross-sectional view showing a schematic configuration of the pixel 20 in the display device according to this embodiment. Fig. 12(b) is a schematic diagram showing the light emission of the pixel 20 in the display device according to this embodiment. Fig. 13 is an xy chromaticity diagram showing the color coordinates of the yellow or white sub-pixel 21YWy.

As shown in FIG. 12(a), pixel 20 in panel 2 has a yellow or white subpixel 21YWy in addition to a red subpixel 21R, a green subpixel 21G, and a blue subpixel 21B.

On the surface of the glass substrate 40 facing the element substrate 100, a yellow quantum dot layer 46Y is formed so as to face the OLED 32 of the yellow or white subpixel 21YWy. The yellow quantum dot layer 46Y functions as a light conversion layer that converts the wavelength of light, and converts the wavelength of the blue light emitted from the OLED 32 and incident thereon to emit yellow light. The light emitted from the quantum dot layer 46Y contains unconverted blue light as well as yellow light. The quantum dot layer 46Y is formed with a thickness adjusted so that the amount of blue light transmitted is a predetermined amount. For this reason, for example, the quantum dot layer 46Y is preferably formed thinner than the quantum dot layers 44R and 44G.

In this way, a yellow or white subpixel 21YWy is formed, which has a blue OLED 32 and a yellow quantum dot layer 46Y. Note that the subpixel 21YWy does not have a yellow color filter or other color filters. In other words, the subpixel 21YWy emits yellow light or white light without passing through a yellow color filter or other color filters.

Subpixel 21YWy can be configured as a yellow subpixel or a white subpixel by appropriately adjusting the amount of blue light transmitted through yellow quantum dot layer 46Y. In the following, subpixel 21YWy will be referred to as subpixel 21Yy when configured as a yellow subpixel, and as subpixel 21Wy when configured as a white subpixel.

Figure 12(b) shows a schematic diagram of the light emission of each sub-pixel 21R, 21G, 21B, 21YWy. In Figure 12(b), arrows Lr indicate red light, arrows Lg indicate green light, arrows Lb indicate blue light, and arrows Ly indicate yellow light, with the number of arrows indicating the amount of light. Also, for the sake of convenience, the arrangement of each component shown in Figure 12(b) does not match the arrangement of each component shown in Figure 12(a).

As shown in FIG. 12(b), in the yellow or white subpixel 21YWy, first, blue light Lb is emitted from the OLED 32. Next, the blue light Lb is converted to yellow light Ly by the yellow quantum dot layer 46Y and emitted from the quantum dot layer 46Y. At this time, since the quantum dot layer 46Y is formed with its thickness adjusted as described above, yellow light or white light containing yellow light Ly and unconverted blue light Lb is emitted from the quantum dot layer 46Y. FIG. 13 shows the color coordinates of the yellow or white subpixel 21YWy. In addition, since the quantum dot layer 46Y is formed thinner than the quantum dot layers 44R and 44G, for example, the deactivation and absorption of blue light Lb is less than that of the quantum dot layers 44R and 44G. Next, the yellow light or white light containing yellow light Ly and blue light Lb emitted from the quantum dot layer 46Y is emitted from the display surface of the panel 2 without passing through a color filter.

Thus, according to this embodiment, pixel 20 has sub-pixel 21YWy, which does not have a color filter, in addition to sub-pixels 21R, 21G, and 21B. Sub-pixel 21YWy has a higher light emission efficiency than sub-pixels 21R and 21G because it does not have a color filter. Thus, according to this embodiment, display can be performed using sub-pixel 21YWy, which has a high light emission efficiency, and therefore a highly bright display can be achieved.

For example, in this embodiment, white display can be achieved by emitting light from the white subpixel 21Wy, emitting light from the blue subpixel 21B and the white subpixel 21Wy, or emitting light from the blue subpixel 21B and the yellow subpixel 21Yy. In either case, white display is achieved using the subpixel 21Yy or the subpixel 21Wy that does not have a color filter, so that a high brightness white display can be achieved.

Subpixel 21YWy as the fourth subpixel has high light emission efficiency and is a subpixel that can be frequently used to display white. For this reason, it is preferable that it is arranged closer to the center of pixel 20 than to the end. For example, when subpixels 21R, 21G, 21B, and 21YWy are arranged in one direction in pixel 20, subpixel 21YWy is preferably arranged in the second or third position from one end of the arrangement of subpixels 21R, 21G, 21B, and 21YWy.

In this way, according to this embodiment, a display device using an OLED and a quantum dot layer can achieve a highly bright display.

Sixth Embodiment
A display device according to a sixth embodiment of the present invention will be described with reference to Fig. 14. Fig. 14 is a schematic diagram showing a schematic configuration of a pixel of the display device according to this embodiment. Note that components similar to those of the display devices according to the first to fifth embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified.

In the above first to fifth embodiments, the OLED is formed on the element substrate 100, and the color filter and the quantum dot layer are formed on the color filter substrate 200. However, the present invention is not limited to this. The OLED, the quantum dot layer, and the color filter may be formed on a single glass substrate.

In this embodiment, a case will be described in which a pixel including four sub-pixels similar to those in the first embodiment is formed on a single glass substrate. Note that a pixel including four sub-pixels similar to those in the second to fifth embodiments can also be formed on a single glass substrate in the same manner as in this embodiment.

As shown in FIG. 14, pixel 20 in panel 2 has a red subpixel 21R, a green subpixel 21G, a blue subpixel 21B, and also a cyan subpixel 21C.

Panel 2 has a glass substrate 50, but does not have a color filter substrate facing the glass substrate 50. The display device according to this embodiment is a top emission type in which light is emitted from the element formation surface side of the glass substrate 50. In other words, in the display device according to this embodiment, the element formation surface side of the glass substrate 50 is the display surface side.

Four anode electrodes 34 are formed on the element formation surface of the transparent glass substrate 50 to correspond to the sub-pixels 21R, 21G, 21B, and 21C. A blue organic light-emitting layer 36 is formed on each anode electrode 34. A common cathode electrode 38 is formed on each blue organic light-emitting layer 36. Thus, in each pixel 20, an OLED 32 is formed for each of the sub-pixels 21R, 21G, 21B, and 21C, as in the first embodiment. A sealing film 52 that seals the OLED 32 is formed on the cathode electrode 38.

A red quantum dot layer 44R is formed on the sealing film 52 so as to face the OLED 32 of the red subpixel 21R. A red color filter 42R is formed on the quantum dot layer 44R. In this way, a red subpixel 21R is formed, which has a blue OLED 32, a red quantum dot layer 44R, and a red color filter 42R.

A green quantum dot layer 44G is formed on the sealing film 52 so as to face the OLED 32 of the green subpixel 21G. A green color filter 42G is formed on the quantum dot layer 44G. In this way, a green subpixel 21G is formed, which has a blue OLED 32, a green quantum dot layer 44G, and a green color filter 42G.

A green quantum dot layer 46G is formed on the sealing film 52 so as to face the OLED 32 of the cyan subpixel 21C. In this way, the cyan subpixel 21C is formed, which has a blue OLED 32 and a green quantum dot layer 46G. Note that the subpixel 21C does not have a cyan color filter or any other color filters.

On the other hand, no color filter or quantum dot layer is formed on the sealing film 52 so as to face the OLED 32 of the blue subpixel 21B. Therefore, the blue subpixel 21B has a blue OLED 32, but does not have a blue color filter or other color filters or a quantum dot layer.

A sealing film 54 is formed on the entire surface of the glass substrate 50 on which the sub-pixels 21R, 21G, 21B, and 21C are formed, sealing the quantum dot layers 44R, 44G, and 46G and the color filters 42R and 42G. A cover film 56 made of a transparent resin film or the like is formed on the sealing film 54.

As in this embodiment, a pixel including four subpixels may be formed on a single glass substrate.

[Seventh embodiment]
A display device according to a seventh embodiment of the present invention will be described with reference to Fig. 15. Fig. 15 is a schematic diagram showing a schematic configuration of a pixel of the display device according to this embodiment. Note that components similar to those of the display devices according to the first to sixth embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified.

In the first to sixth embodiments, a top emission type configuration has been described, but the present invention is not limited to this. The display device may be a bottom emission type.

In this embodiment, a case will be described in which a display device including four subpixels similar to those in the first embodiment is a bottom emission type. Note that display devices including four subpixels similar to those in the second to fifth embodiments can also be configured as bottom emission types in the same manner as in this embodiment.

As shown in FIG. 15, pixel 20 in panel 2 has a red subpixel 21R, a green subpixel 21G, a blue subpixel 21B, and also a cyan subpixel 21C.

Panel 2 has a glass substrate 60, but does not have a color filter substrate facing the glass substrate 60. The display device according to this embodiment is a bottom emission type in which light is emitted from the side opposite the element formation side of the glass substrate 60. In other words, in the display device according to this embodiment, the side opposite the element formation side of the glass substrate 60 is the display surface.

A red color filter 42R and a red quantum dot layer 44R are sequentially laminated on the element formation surface of the transparent glass substrate 60 so as to correspond to the red sub-pixel 21R.

In addition, a green color filter 42G and a green quantum dot layer 44G are sequentially laminated on the element formation surface of the glass substrate 60 so as to correspond to the green subpixel 21G.

A green quantum dot layer 46G is formed on the element formation surface of the glass substrate 60 so as to correspond to the cyan subpixel 21C. No color filter is formed so as to correspond to the cyan subpixel 21C.

On the other hand, no color filter or quantum dot layer is formed on the element formation surface of the glass substrate 60 so as to face the blue subpixel 21B.

A sealing film 62 that seals the color filters 42R, 42G and the quantum dot layers 44R, 44G, 46G is formed on the entire element formation surface of the glass substrate 60 on which the color filters 42R, 42G and the quantum dot layers 44R, 44G, 46G are formed.

Four anode electrodes 34 are formed on the sealing film 62 to correspond to the sub-pixels 21R, 21G, 21B, and 21C. A blue organic light-emitting layer 36 is formed on each anode electrode 34. A common cathode electrode 38 is formed on each blue organic light-emitting layer 36. Thus, in each pixel 20, an OLED 32 is formed for each of the sub-pixels 21R, 21G, 21B, and 21C, as in the first embodiment. Note that, since this embodiment is a bottom emission type, the anode electrodes 34 can be configured as transparent electrodes.

In this way, a red subpixel 21R is formed, which has a blue OLED 32, a red quantum dot layer 44R, and a red color filter 42R.

A green subpixel 21G is also configured, which has a blue OLED 32, a green quantum dot layer 44G, and a green color filter 42G.

A cyan subpixel 21C is also configured, which has a blue OLED 32 and a green quantum dot layer 46G. Note that subpixel 21C does not have a cyan color filter or any other color filters.

On the other hand, on the element formation surface of the glass substrate 60, no color filter or quantum dot layer is formed to face the OLED 32 of the blue subpixel 21B. Therefore, the blue subpixel 21B has a blue OLED 32, but does not have a blue color filter or other color filters or a quantum dot layer.

A sealing film 64 that seals the OLED 32 is formed on the entire surface of the glass substrate 60 on which the cathode electrode 38 is formed.

As in this embodiment, a pixel including four subpixels may be configured as a bottom emission type.

[Example]
Next, the evaluation results of the display device according to this embodiment will be described with reference to Table 1. In the evaluation, the luminous efficiency of each sub-pixel and white display was calculated by simulation for the display devices of Examples 1 to 5 and Comparative Example 1.

In Examples 1 to 5, the luminous efficiency was calculated for the display devices according to the first to fifth embodiments, respectively. On the other hand, in Comparative Example 1, the luminous efficiency was calculated for a display device having the same red, green, and blue subpixels as the first to fifth embodiments, but with a pixel configuration that does not have a fourth subpixel.

The results of measuring the luminous efficiency of each subpixel for the display devices of Examples 1 to 5 and Comparative Example 1 are shown in Table 1. The luminous efficiency of the red, green, and fourth subpixels includes the conversion efficiency of the quantum dots. The luminous efficiency of the red and green subpixels includes the absorption rate of the color filters. Note that, due to the configuration of each subpixel, the luminous efficiency of each of the red, green, and blue subpixels of Examples 1 to 5 was the same as that of Comparative Example 1, as indicated by the arrows in Table 1.

From the results shown in Table 1, it was confirmed that in all of Examples 1 to 5, the luminous efficiency of the fourth subpixel that does not have a color filter is high. Furthermore, it was confirmed that Examples 1 to 5 have a higher luminous efficiency in white display and realize a white display with high brightness compared to Comparative Example 1. As a result, in Examples 1 to 5, it is possible to reduce the power consumption in white display compared to Comparative Example 1.

[Modified embodiment]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, an example was described in which an OLED was used as the light-emitting element, but this is not limited to this. Various light-emitting elements can be used instead of an OLED.

In the above embodiment, the pixel 20 has four sub-pixels 21R, 21G, and 21B and a fourth sub-pixel, but this is not limited to the above. The pixel 20 may have four or more sub-pixels.

1... timing controller 2... panel 3... source drive IC
4...Gate drive IC
20...Pixel 21...Sub-pixel 21R, 21G, 21B, 21C, 21M, 21YW, 21Cc, 21YWy...Sub-pixel 30...Glass substrate 34...Anode electrode 36...Blue organic light-emitting layer 38...Cathode electrode 40...Glass substrate 42R, 42G...Color filter 44R, 44G...Quantum dot layer 46G, 46R, 46C, 46Y...Quantum dot layer 50...Glass substrate 60...Glass substrate 100...Element substrate 200...Color filter substrate D...Diode DL...Data line GL...Gate line

Claims (14)

a pixel having a first subpixel of a first color, a second subpixel of a second color, a third subpixel of a third color, and a fourth subpixel of a fourth color;
each of the first subpixel, the second subpixel, the third subpixel, and the fourth subpixel has a light-emitting element that emits light of the third color;
each of the first subpixel, the second subpixel, and the fourth subpixel has a quantum dot layer that converts a wavelength of the third color light emitted from the light-emitting element;
the first subpixel has a first color filter of the first color;
the second subpixel has a second color filter of the second color;
the fourth subpixel emits light of the fourth color without passing through a color filter;
the first subpixel has a first quantum dot layer as the quantum dot layer, the first quantum dot layer converting the third color light into the first color light;
the second subpixel has a second quantum dot layer as the quantum dot layer, the second quantum dot layer converting the third color into the second color light;
the fourth subpixel has a third quantum dot layer as the quantum dot layer,
the third quantum dot layer is formed thinner than each of the first color filter and the second color filter ;
the third quantum dot layer is disposed on the side of the second color filter such that the second color filter and the third quantum dot layer are in contact with a surface of a second substrate;
the first color is red, the second color is green, the third color is blue, and the fourth color is cyan or magenta; and
the quantum dot layer of the fourth subpixel converts the third color to green, and the fourth color is cyan;
the quantum dot layer of the fourth subpixel converts the third color to red and the fourth color is magenta; or
The quantum dot layer of the fourth subpixel converts the third color to cyan, and the fourth color is cyan.
A display device comprising: The display device according to claim 1 , wherein the third subpixel emits light of the third color without passing through a color filter. The display device according to claim 2 , wherein the third quantum dot layer converts the third color light into the first color or the second color light. the third quantum dot layer includes one layer that converts the third color light to the first color light and another layer that converts the third color light to the second color light;
The one layer and the other layer do not overlap in a plan view.
3. The display device according to claim 2. The display device according to claim 2 , wherein the third quantum dot layer converts the third color light into the fourth color light. 6. The display device according to claim 2, wherein the third quantum dot layer is formed to be thinner than the first quantum dot layer and the second quantum dot layer. 7. The display device according to claim 1, wherein the first subpixel, the second subpixel, the third subpixel, and the fourth subpixel are arranged to be aligned in one direction. 8. The display device according to claim 7, wherein the fourth subpixel is arranged at a second or third position in an arrangement of the first subpixel, the second subpixel, the third subpixel, and the fourth subpixel which are arranged to be aligned in the one direction. 7. The display device according to claim 1, wherein the first subpixel, the second subpixel, the third subpixel, and the fourth subpixel are arranged in a lattice pattern. The display device according to claim 1 , wherein the light-emitting element is an organic light-emitting diode. The display device according to claim 1 , wherein the third subpixel does not have a quantum dot layer. The light emitting device further includes a first substrate on which the light emitting element is formed,
The second substrate is disposed opposite to the first substrate, and the quantum dot layer, the first color filter, and the second color filter are formed on the second substrate.
12. The display device according to claim 1, wherein the first and second electrodes are arranged in a first direction. The light emitting element, the quantum dot layer, the first color filter, and the second color filter are formed on the surface of the second substrate.
12. The display device according to claim 1, wherein the first and second electrodes are arranged in a first direction. Light is emitted from a surface of the second substrate opposite the surface .
14. The display device according to claim 13 .

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