KR20210046623A - Quantum dot light-emitting device and display apparatus - Google Patents

Abstract

According to an embodiment of the present invention, disclosed is a quantum dot light emitting element which can have a narrow half width and high light efficiency. The quantum dot light emitting element comprises: a light emitting element emitting first light; a quantum dot layer including a plurality of quantum dots and absorbing the first light to emit second light and third light different from the first light; and a band pass filter disposed on the quantum dot layer and blocking a portion of the second light and a portion of the third light.

Description

Quantum dot light-emitting device and display apparatus TECHNICAL FIELD

Embodiments of the present invention relate to a quantum dot light emitting device and a display device.

Currently commercially available flat panel displays include a liquid crystal display, a plasma display panel, and an organic light emitting display device, among which liquid crystal displays are excellent. It is used in mobile devices, computer monitors, and televisions (TVs), etc., according to advantages such as visibility, easy thinning, low power consumption and low heat generation.

However, a liquid crystal display device is a light-receiving type display device that does not emit light by itself to form an image, but receives light from outside to form an image. Accordingly, a liquid crystal display device displays an image using light emitted from the backlight unit by disposing a backlight unit under the liquid crystal display panel.

As a light source of such a backlight unit, a light emitting diode (LED) having an excellent energy saving effect and a high response speed is widely used, and in order to improve the characteristics of a liquid crystal display device, the backlight unit and the light emitting diode are Research is actively underway.

Embodiments of the present invention provide a quantum dot light emitting device and a display device.

An embodiment of the present invention is a light emitting device that emits first light; A quantum dot layer including a plurality of quantum dots and absorbing the first light to emit second and third light different from the first light; And a band pass filter disposed on the quantum dot layer and blocking a part of the second light and a part of the third light.

In this embodiment, the quantum dots include a plurality of first quantum dots that absorb the first light and emit the second light, and a plurality of second quantum dots that absorb the first light and emit the third light. It may include.

In this embodiment, the first quantum dot and the second quantum dot are made of the same material and may have different sizes.

In this embodiment, the third light has a longer wavelength than the second light, and the band pass filter may block light in a region having a shorter wavelength among the second light and a region having a longer wavelength among the third light. have.

In this embodiment, the peak wavelength of the second light transmitted through the band pass filter is longer than the peak wavelength of the second light emitted from the quantum dot layer, and the peak of the third light transmitted through the band pass filter The wavelength may be shorter than the peak wavelength of the third light emitted from the quantum dot layer.

In this embodiment, the band pass filter may reflect at least a portion of the first light.

In this embodiment, the band pass filter may include a short wave pass filter and a long wave pass filter.

In this embodiment, a cutoff wavelength of the short-pass filter may be 655 nm or less, and a cutoff wavelength of the long-pass filter may be 500 nm or more.

In this embodiment, the first light may correspond to blue light or ultraviolet light, and the second light and the third light may correspond to green light and red light, respectively.

In this embodiment, the quantum dot may include a core including any one selected from ZnSe, ZnO, ZnTe, InP, GaP, InGaN, and InN.

In this embodiment, the quantum dot may further include a shell surrounding the core, and the cell may include any one selected from ZnS, ZnSe, GaP, and GaN.

Another embodiment of the present invention is a backlight unit; And a display panel that receives light from the backlight unit to display an image, and includes a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate, wherein the backlight unit, A light emitting device including a region emitting first light and a region emitting second light and third light, and the region emitting the second light and the third light may include: a light emitting device generating the first light; A quantum dot layer including a plurality of quantum dots and absorbing the first light to emit the second light and the third light different from the first light; And a band pass filter disposed on the quantum dot layer and blocking a portion of the second light and a portion of the third light.

In the present exemplary embodiment, an area emitting the first light and an area emitting the second light and the third light of the backlight unit may be disposed in an area corresponding to one edge of the display panel.

In this embodiment, a first light guide plate for transmitting the first light emitted from a region emitting the first light to the display panel; And a second light guide plate that transmits the second light and the third light transmitted through the band pass filter to the display panel.

In this embodiment, the display panel may further include a color filter for implementing colors.

In this embodiment, the quantum dots include a plurality of first quantum dots that absorb the first light and emit the second light, and a plurality of second quantum dots that absorb the first light and emit the third light. It may include.

In this embodiment, the third light has a longer wavelength than the second light, and the band pass filter may block light in a region having a shorter wavelength among the second light and a region having a longer wavelength among the third light. have.

In this embodiment, the band pass filter may reflect at least a portion of the first light.

In this embodiment, the first light may correspond to blue light, and the second light and the third light may correspond to green light and red light, respectively.

Another embodiment of the present invention is a substrate in which a first sub-pixel, a second sub-pixel, and a third sub-pixel respectively emitting blue light, green light, and red light are partitioned; A pixel electrode disposed on the substrate; A counter electrode disposed to face the pixel electrode; An intermediate layer disposed between the pixel electrode and the counter electrode, including a plurality of quantum dots, and emitting light; It is disposed in a region corresponding to the second sub-pixel and the third sub-pixel on any one of the pixel electrode and the opposite electrode disposed in a direction in which light is emitted, and blocks a part of the green light and a part of the red light. Disclosed is a display device including a band pass filter.

In another embodiment of the present invention, the pixel electrode includes a first pixel electrode, a second pixel electrode, and a third pixel electrode respectively corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel. Wherein the intermediate layer includes a first intermediate layer, a second intermediate layer, and a third intermediate layer respectively corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel, and the first sub-pixel A first light emitting device provided on the substrate and including the first pixel electrode sequentially disposed on the substrate, the first intermediate layer including a plurality of quantum dots emitting blue light, and the counter electrode;

A second light-emitting device provided in the second sub-pixel and including the second pixel electrode sequentially disposed on the substrate, the second intermediate layer including a plurality of quantum dots emitting green light, and the counter electrode; And the third pixel electrode provided in the third sub-pixel and sequentially disposed on the substrate, the third intermediate layer including a plurality of quantum dots emitting red light, and the counter electrode. May include;

In the present embodiment, the intermediate layer includes a plurality of quantum dots emitting blue light, a plurality of quantum dots emitting green light, and a plurality of quantum dots emitting red light, wherein light is emitted among the pixel electrode and the counter electrode. The color filter further includes a color filter disposed on any one disposed in the direction, wherein the color filter includes: a first area disposed in an area corresponding to the first sub-pixel and transmitting the blue light; A second region disposed in a region corresponding to the second sub-pixel and transmitting the green light; And a third area disposed in an area corresponding to the third sub-pixel and transmitting the red light, wherein the band pass filter is disposed in an area corresponding to the second area and the third area on the color filter. I can.

In the present embodiment, the quantum dots emitting blue light, the quantum dots emitting green light, and the plurality of quantum dots emitting red light include the same material and may have different sizes.

In another embodiment of the present invention, the band pass filter may block light in a region having a short wavelength among the green light and a region having a long wavelength among the red light.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

The quantum dot light emitting device and the display device according to the embodiments of the present invention are eco-friendly because they do not use cadmium (Cd), and may have a narrow half-width and high light efficiency.

1 is a schematic cross-sectional view of a quantum dot light emitting device according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a part A1 of a quantum dot layer included in the quantum dot light emitting device of FIG. 1.
3 is a graph showing a transmission spectrum of a band pass filter included in the quantum dot light emitting device of FIG. 1.
FIG. 4 is a graph showing spectra of light emitted from the quantum dot layer of the quantum dot light emitting device of FIG. 1 and passed through the band pass filter of FIG. 3 and after passing through the band pass filter of FIG. 3.
5 is a schematic cross-sectional view of a display device according to an exemplary embodiment of the present invention.
6 is a graph showing spectra of light emitted from a backlight unit included in the display device of FIG. 5 before passing through the color filter and after passing through the color filter.
7 is a graph comparing a spectrum after light emitted from the backlight unit included in the display device of FIG. 3 passes through a color filter and a spectrum after light emitted from the backlight unit including Cd passes through the color filter .
8 is a graph showing a color reproduction range of the quantum dot light emitting device of FIG. 1.
9 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.
10 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.
11 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.
12 is an enlarged cross-sectional view of a portion A2 of an intermediate layer included in the display device of FIG. 11.
13 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.

Since the present invention can apply various transformations and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. Effects and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, the same or corresponding constituent elements are assigned the same reference numerals, and redundant descriptions thereof will be omitted. .

In the following embodiments, terms such as first and second are used for the purpose of distinguishing one constituent element from other constituent elements rather than a limiting meaning.

In the following examples, expressions in the singular include plural expressions unless the context clearly indicates otherwise.

In the following embodiments, terms such as include or have means that the features or elements described in the specification are present, and do not preclude the possibility of adding one or more other features or components in advance.

In the following embodiments, when a part such as a film, a region, or a component is on or on another part, not only the case directly above the other part, but also another film, region, component, etc. are interposed therebetween. Includes cases where there is.

In the drawings, components may be exaggerated or reduced in size for convenience of description. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, and thus the present invention is not necessarily limited to what is shown.

1 is a schematic cross-sectional view of a quantum dot light-emitting device according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a part A1 of a quantum dot layer included in the quantum dot light-emitting device of FIG. 1.

1 and 2, a quantum dot light-emitting device 10 according to an embodiment includes a light-emitting device 11 that emits first light and a plurality of quantum dots 12a and 12b, and absorbs the first light. Thus, a quantum dot layer 12 that emits second and third light, and a band pass filter 13 disposed on the quantum dot layer 12 and blocking part of the second light and the third light are included.

The first light is light that excites the quantum dots 12a and 12b included in the quantum dot layer 12, and may be blue light or ultraviolet light, and the light emitting device 11 emitting the first light passes a current through the semiconductor. It may include a plurality of light emitting diodes (LEDs) 11a that emit light.

The quantum dot layer 12 may include a plurality of first quantum dots 12a and second quantum dots 12b that absorb first light and emit second light and third light, respectively.

Quantum dots are spherical semiconductor nanomaterials having a size of several to hundreds of nm, and include a core composed of a material having a small band gap and a shell disposed to surround the core. I can. Quantum dots have a discontinuous band gap energy unlike a bulk material due to a quantum confinement effect. Accordingly, by introducing such quantum dots into a light emitting device, a light emitting device having high light efficiency and color purity can be implemented.

For example, a quantum dot containing cadmium (Cd), such as CdSe (Cadimium selenide), is suitable for implementing a light emitting device having a high photoluminescence quantum yield and a narrow full width at half maxium. However, since cadmium (Cd) is a highly toxic heavy metal element and is prohibited by the Restriction of Hazadous Substances (RoHS) regulations, research on light-emitting devices using eco-friendly quantum dots is required.

Therefore, the quantum dot light emitting device of this embodiment includes eco-friendly quantum dots 12a and 12b that do not contain heavy metal materials such as cadmium (Cd) or mercury (Hg), and the quantum dots 12a and 12b are ZnSe, ZnO, ZnTe , InP, GaP, InGaN, and may include a core including any one selected from InN.

The quantum dots 12a and 12b are disposed to surround the core and may further include a shell capable of increasing fluorescence and stability of the quantum dots by protecting the core, and the cells include ZnS, ZnSe, GaP, and GaN. It may include any one selected from among.

The quantum dots 12a and 12b included in the quantum dot layer 12 of the present embodiment absorb the first light and emit second light, for example, green light. For example, it may include a second quantum dot 12b that emits red light, and the first quantum dot 12a and the second quantum dot 12b are made of the same material and may have different sizes. However, the present invention is not limited thereto, and the first quantum dot 12a and the second quantum dot 12b may be formed of different materials.

That is, quantum dots have a characteristic that the spacing between energy bands varies depending on the size of the quantum dots, and therefore, even if the same quantum dots are used, light having different wavelengths can be emitted if the sizes are different. The smaller the size of the quantum dot, the larger the energy band gap, and thus the shorter the wavelength of emitted light.

The first quantum dot 12a emitting second light according to the present embodiment may be smaller in size than the second quantum dot 12b emitting third light. For example, the third light has a longer wavelength than the second light, the second light may be green light having a center wavelength of 530±5 nm and a half width of 40 to 60 nm, and the third light has a center wavelength of 625 It may be red light with ±5 nm and a half width of 40 to 60 nm.

A band pass filter 13 is disposed on the quantum dot layer 12 to transmit part of the second light and part of the third light and reflect or absorb the remaining light. The quantum dot light emitting device 10 of this embodiment has a band-pass filter 13, so that the quantum efficiency or half-width characteristics of the eco-friendly quantum dots 12a, 12b of this embodiment are not good compared to the quantum dots including cadmium (Cd). The characteristics can be improved. The specific configuration of the band pass filter 13 is as follows.

3 is a graph showing the transmission spectrum of the band pass filter included in the quantum dot light emitting device of FIG. 1, and FIG. 4 is a graph showing the light emitted from the quantum dot layer of the quantum dot light emitting device of FIG. 1 and before passing through the band pass filter of FIG. , Is a graph showing the spectrum of light after passing through the band pass filter of FIG. 3.

Referring to FIG. 3, a band pass filter 13 included in the quantum dot light emitting device 10 of the present embodiment includes a long wave pass filter (LWPF) 13a and a short wave pass filter (SWPF); It may include a short wave pass filter, 13b).

The long-pass filter 13a and the short-pass filter 13b may have a structure in which high and low refractive layers are alternately stacked, and the cutoff wavelength of the long-pass filter 13a is 500 nm or more. , The cutoff wavelength of the short-pass filter 13b may be 655 nm or less.

Referring back to FIG. 1, a region of green light having a short wavelength is blocked by a long-pass filter 13a, a region of red light having a long wavelength is blocked by a short-pass filter 13b, and blue light is a long-pass filter. It can be blocked, i.e. reflected or absorbed by (13a).

In the above description, the half width represents the difference in wavelength between the two points corresponding to the position at which the maximum transmittance becomes 1/2 in the transmission spectrum of the band-pass filter, and the cutoff wavelength is the maximum transmittance in the transmission spectrum of the band-pass filter. It means the wavelength value corresponding to the position of 1/2.

4 is a spectrum of second and third light emitted from the quantum dot layer 12 of this embodiment and before passing through the band pass filter 13 of FIG. 3 and after passing through the band pass filter 13 of FIG. 3. The spectrum of the second light and the third light was compared.

The band pass filter 13 transmits light in a region having a long wavelength among the second light and a region having a short wavelength in the third light. That is, the band-pass filter 13 blocks the light of the short wavelength region of the second light and the long wavelength region of the third light, and as a result, the half width of the second light and the third light is narrowed.

4, the peak wavelength of the second light transmitted through the band pass filter 13 is longer than the peak wavelength of the second light emitted from the quantum dot layer 12, The peak wavelength of the third light is shorter than the peak wavelength of the third light emitted from the quantum dot layer 12.

That is, the half width of the second light and the third light emitted from the quantum dot layer 12 by the band pass filter 13 is narrowed, and the peak wavelength may be shifted.

In addition, since the cutoff wavelength of the long-pass filter 13a included in the band-pass filter 13 may be 500 nm or more, the first light having a wavelength shorter than that of green light, that is, at least a part of blue light or ultraviolet light, is the band-pass filter 13 ) Can be reflected.

Some of the first light reflected by the band pass filter 13 may be incident on the quantum dot layer 12 again, and the first light incident on the quantum dot layer 12 may excite the quantum dots 12a and 12b. , The quantum dot layer 12 may re-emit second light and third light using the re-incident first light.

That is, since the first light is not transmitted by the band pass filter 13 but is reflected and repeatedly incident on the quantum dot layer 12, the light efficiency of the quantum dot light emitting device 10 of the present embodiment may be improved.

5 is a schematic cross-sectional view of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the display device 100 according to an exemplary embodiment receives light from the backlight unit 110 and the backlight unit 110 to display an image, and the first substrate 122 and the second substrate 125 And a display panel 120 including a liquid crystal layer 123 interposed between the first substrate 122 and the second substrate 125.

The backlight unit 110 includes a region P _{1 emitting first light and a region P 23} emitting second light and third light, and emits second light and third light. The region P ₂₃ may include the quantum dot light emitting device 10 of FIG. 1, and the quantum dot light emitting device 10 includes a light emitting device 11 that emits first light, a plurality of quantum dots, and emits first light. A band pass filter disposed on the quantum dot layer 12 and the quantum dot layer 12 that absorbs and emits second light different from the first light and the third light, and blocks part of the second light and the third light ( 13) may be included.

The area P _{1 emitting the first light and the area P 23} emitting the second light and the third light may be disposed in an area corresponding to one edge of the display panel 120, and the backlight unit ( The 110 further includes a first light guide plate 30 for transferring the emitted first light to the display panel 120 and a second light guide plate 40 for transferring the second and third light to the display panel 120. I can.

The region P ₁ emitting the first light may include a light emitting diode package 20 including a plurality of light emitting diodes (LEDs) emitting first light, and The emitting region P ₂₃ may include the quantum dot light emitting device 10 of FIG. 1 described above.

The first light guide plate 30 and the second light guide plate 40 are disposed under the display panel 120, and ends of the first light guide plate 30 and the second light guide plate 40 each emit first light ( It is arranged to correspond to _{P 1 ) and the area P 23} emitting the second light and the third light.

The first light is transmitted to the display panel 120 through the first light guide plate 30, and the second light and the third light are transmitted to the display panel 120 through the second light guide plate 40. The first light, the second light, and the third light may correspond to blue light, green light, and red light, respectively, and the backlight unit 110 of the present embodiment implements white light by a combination of the first light, the second light, and the third light. I can.

The quantum dot layer 12 included in the quantum dot light emitting device 10 includes a plurality of first quantum dots (FIGS. 2 and 12A) that absorb first light and emit second light, and a third light by absorbing the first light. It may include a plurality of second quantum dots (Fig. 2, 12b) that emits light, and the band pass filter 13 blocks light in a region having a short wavelength among the second light and a region having a long wavelength among the third light , It is possible to reduce the half width of the second light and the third light.

In addition, the band-pass filter 13 reflects at least a portion of the first light, and the reflected first light is re-incident to the quantum dot layer 12, so it can be recycled, thereby improving the light efficiency of the quantum dot light emitting device 10. have. A detailed description has been described above and thus will be omitted.

The display panel 120 includes a first substrate 122, a second substrate 125, and a liquid crystal layer 123 disposed between the first substrate 122 and the second substrate 125. The substrate 122 may include devices and wires such as a thin film transistor (TFT). A first electrode (not shown) may be disposed on the first substrate 122.

A color filter layer 124 for implementing a color may be disposed on a surface of the second substrate 125 on which the liquid crystal layer 123 is disposed, and the color filter layer 124 includes a color filter 124a and a color filter 124a. It may include a black matrix (124b) that partitions.

In addition, a second electrode (not shown) may be disposed on the surface of the color filter layer 124 on which the liquid crystal layer 123 is disposed.

The display device 100 of the present exemplary embodiment allows a current to flow between a first electrode (not shown) and a second electrode (not shown), thereby emitting according to the arrangement of liquid crystals according to on/off of the current. Controls the on/off of the light to be turned on.

The color filter layer 124 may include, for example, a region that transmits blue light, a region that transmits green light, and a region that transmits red light, and implements the color of the display device 100 using the transmitted light. .

Polarizing plates 121 and 126 may be disposed on outer surfaces of the first substrate 122 and the second substrate 125 of the display device, respectively, and various optical sheets may be disposed between the backlight unit 110 and the display panel 120. Fields (not shown) may be arranged.

6 is a graph showing the spectrum of light emitted from the backlight unit included in the display device of FIG. 5 before passing through the color filter and after passing through the color filter, and FIG. 7 is a backlight unit included in the display device of FIG. 3 This is a graph comparing the spectrum after the light emitted from passes through the color filter and the spectrum after the light emitted from the backlight unit including Cd passes through the color filter.

Referring to FIG. 6, a first light blue emitted from _{a region P 1} emitting first light of the backlight unit 110 of FIG. 5, and a region P emitting second light and third light The second light (Green) and the third light (Red) emitted from the quantum dot light emitting device 10 disposed at _{23) are incident on the color filter (C/F).}

The graph arranged in the center of FIG. 6 shows the transmission spectrum of the color filter C/F itself, and the color filter C/F has the transmittance of the color filter itself for blue light, green light, and red light.

After the incident first light, second light, and third light pass through the color filter, they have a spectrum such as a graph shown at the bottom of FIG. 6.

7 is a light emitted from a quantum dot light emitting device including cadmium (Cd) and light intensity according to wavelengths of blue light, green light, and red light after light emitted from the quantum dot light emitting device 10 of the present embodiment passes through the color filter. It is a graph comparing light intensities according to wavelengths of blue light, green light, and red light after passing through this color filter.

That is, the quantum dot light emitting device 10 of the present embodiment does not contain cadmium (Cd), includes eco-friendly quantum dots, and is configured to include a band pass filter 13 in order to improve the characteristics of eco-friendly quantum dots. With this configuration, it can be seen that the quantum dot light emitting device 10 of the present embodiment has similar characteristics to the conventional light emitting device including cadmium (Cd).

FIG. 8 is a graph showing the color reproduction range of the quantum dot light emitting device of FIG. 1, and Table 1 is a light emitting device containing cadmium (Cd) and a quantum dot light emitting device 10 not including cadmium (Cd) of FIG. It shows the color reproduction rate of and the matching rate of sRGB Gamut.

Referring to FIG. 8 and Table 1, the light emitted from the light emitting device including cadmium (Cd) and the quantum dot light emitting device 10 including the band pass filter 13 and not including the cadmium (Cd) of FIG. 1 Looking at the color reproducibility, the matching rate versus sRGB represents 100% in both cases, and the matching rate versus NTSC is 94.9% when it contains cadmium (Cd), and 93.5% when it does not contain cadmium (Cd). .

That is, it can be seen that the quantum dot light-emitting device 10 of FIG. 1 according to an embodiment of the present invention exhibits similar characteristics to the light-emitting device including cadmium (Cd) in color reproduction.

9 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.

Referring to FIG. 9, the display device 200 according to the present exemplary embodiment includes a first sub-pixel Pb and a second sub-pixel (Pb) emitting blue light (B), green light (G), and red light (B), respectively. Pg) and the third sub-pixel (Pr) includes a partitioned substrate 210, the first sub-pixel (Pb) is a first pixel electrode 220a sequentially stacked on the substrate 210, and emits blue light A first intermediate layer 240a including a plurality of quantum dots and a first light emitting device including an opposite electrode 250 are included, and the second sub-pixel Pg is sequentially stacked on the substrate 210. 2 A pixel electrode 220b, a second intermediate layer 240b including a plurality of quantum dots emitting green light, and a second light emitting device including a counter electrode 250 are included, and the third sub-pixel Pr is a substrate A third light emitting device including a third pixel electrode 220c sequentially stacked on 210, a third intermediate layer 240c including a plurality of quantum dots emitting red light, and a counter electrode 250 may be included. I can.

Each sub-pixel is partitioned by the pixel defining layer 230, and an encapsulation substrate 270 protecting the first, second, and third light emitting devices may be disposed on the counter electrode 250.

The first pixel electrode 220a, the second pixel electrode 220b, and the third pixel electrode 220c may be configured as a reflective electrode, and the counter electrode 250 may be configured as a transparent or translucent electrode. .

That is, the display device 200 according to the present exemplary embodiment may be a top emission type emitting light in the direction of the counter electrode 250.

The first intermediate layer 240a, the second intermediate layer 240b, and the third intermediate layer 240c may each include a plurality of quantum dots that emit blue light, green light, and red light, and in addition to the quantum dot layer, a hole injection layer (HIL) At least one of a hole injection layer), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL) may be further provided.

In the display device 200 of the present exemplary embodiment, an exciton generated by combining holes injected from the pixel electrodes 220a, 220b, and 220c and electrons injected from the counter electrode 250 in the quantum dot layer is excited. state) to a ground state and generate light.

As described above, since the quantum dot has a discontinuous energy band due to a quantum confinement effect, the display device 200 of the present embodiment can emit light having high light efficiency and color purity. .

Quantum dots included in the first intermediate layer 240a, the second intermediate layer 240b, and the third intermediate layer 240c of the present embodiment may be formed of the same material and may have different sizes. That is, the quantum dots included in the first intermediate layer 240a may be the smallest, and the quantum dots included in the third intermediate layer 240c may be the largest.

The quantum dot may be an eco-friendly quantum dot that does not contain heavy metal materials such as cadmium (Cd) or mercury (Hg), and a core including any one selected from ZnSe, ZnO, ZnTe, InP, GaP, InGaN, and InN, and ZnS , ZnSe, GaP, and may include a cell including any one selected from GaN.

The display device 200 of the present exemplary embodiment may include a band pass filter 260 that blocks a part of green light and a part of red light on the counter electrode 250, and the band pass filter 260 includes an encapsulation substrate 270. ) May be disposed in a region corresponding to the inner second sub-pixel Pg and the third sub-pixel Pr.

The band pass filter 260 of the present embodiment may be disposed to be common to the second sub-pixel Pg and the third sub-pixel Pr, and may include a long-pass filter 261 and a short-pass filter 262. have.

With the above configuration, the display device 200 of the present embodiment uses an eco-friendly quantum dot layer that does not contain cadmium (Cd) as a light emitting layer, and the half width of green light (G) and red light (R) by the band pass filter 260 The color purity can be increased by reducing.

10 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.

Referring to FIG. 10, the display device 300 according to the present exemplary embodiment includes a first sub-pixel Pb, a second sub-pixel Pg, and a third sub-pixel Pr that respectively emit blue light, green light, and red light. ) Includes a partitioned substrate 310, and the first sub-pixel Pb includes a first pixel electrode 320a sequentially stacked on the substrate 310, and a plurality of quantum dots emitting blue light. A first light emitting device including an intermediate layer 340a and a counter electrode 350 is included, and the second sub-pixel Pg includes a second pixel electrode 320b sequentially stacked on the substrate 310 and green light. A second intermediate layer 340b including a plurality of emitting quantum dots, and a second light emitting device including a counter electrode 350, and the third sub-pixel R is sequentially stacked on the substrate 310 A third light emitting device including a third pixel electrode 320c, a third intermediate layer 340c including a plurality of quantum dots emitting red light, and a counter electrode 350 may be included.

Each sub-pixel is partitioned by the pixel defining layer 330, and an encapsulation substrate 370 protecting the first, second, and third light emitting devices may be disposed on the counter electrode 350.

The first pixel electrode 320a, the second pixel electrode 320b, and the third pixel electrode 320c may be configured as a transparent or translucent electrode, and the counter electrode 350 may be configured as a reflective electrode. .

That is, the display device 300 according to the present exemplary embodiment may be a bottom emission type that emits light in the direction of the pixel electrodes 320a, 320b, and 320c.

The first intermediate layer 340a, the second intermediate layer 340b, and the third intermediate layer 340c may each include a plurality of quantum dots that emit blue light, green light, and red light, and the quantum dots are made of the same material. Can be, and can be of different sizes. That is, the quantum dots included in the first intermediate layer 340a may be the smallest, and the quantum dots included in the third intermediate layer 340c may be the largest.

The quantum dot may be an eco-friendly quantum dot that does not contain heavy metal materials such as cadmium (Cd) or mercury (Hg), and a core including any one selected from ZnSe, ZnO, ZnTe, InP, GaP, InGaN, and InN, and ZnS , ZnSe, GaP, and may include a cell including any one selected from GaN.

The display device 300 according to the present exemplary embodiment may include a band pass filter 360 that blocks a part of green light and a part of red light, and the band pass filter 360 includes a second sub-pixel outside the substrate 310 ( It may be disposed only in regions corresponding to Pg) and the third sub-pixel Pr. However, the present invention is not limited thereto, and the band pass filter 360 may be disposed between the second pixel electrode 320b and the third pixel electrode 320c and the substrate 310.

The band-pass filter 360 of the present embodiment may be disposed to be common to the second sub-pixel Pg and the third sub-pixel Pr, and may include a long-pass filter 361 and a short-pass filter 362. have.

11 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention, and FIG. 12 is an enlarged cross-sectional view of a part A2 of an intermediate layer included in the display device of FIG. 11.

11 and 12, the display device 400 according to the present exemplary embodiment includes a first sub-pixel Pb and a second sub-pixel Pb emitting blue light B, green light G, and red light R, respectively. Including the substrate 410 in which the sub-pixel Pg and the third sub-pixel Pr are partitioned, the pixel electrode 420 sequentially stacked on the substrate 410, a plurality of quantum dots, and emitting light An intermediate layer 440 and a counter electrode 450 may be included.

The pixel electrode 420 may be configured as a reflective electrode, and the counter electrode 450 may be configured as a transparent or translucent electrode.

That is, the display device 400 according to the present exemplary embodiment may be a top emission type emitting light in the direction of the counter electrode 450.

The intermediate layer 440 may include a plurality of quantum dots (Qb) emitting blue light, a plurality of quantum dots (Qg) emitting green light, and a plurality of quantum dots (Qr) emitting red light, and hole injection in addition to the quantum dot layer At least one of a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL) may be further provided. The quantum dots Qb, Qg, and Qr may all be made of the same material, and may have different sizes depending on the wavelength of the emitted light. In addition, the quantum dots Qb, Qg, and Qr may not contain heavy metals such as cadmium (Cd).

In the display device 400 of the present exemplary embodiment, holes injected from the pixel electrode 420 and electrons injected from the counter electrode 450 are combined in a quantum dot layer including the quantum dots Qb, Qg, and Qr. The excitons generate light as they fall from the excited state to the ground state. That is, the intermediate layer 440 may emit white light.

A color filter 480 for implementing the color of the display device 400 may be disposed on the counter electrode 430, and the color filter is disposed in a region corresponding to the first sub-pixel Pb and transmits blue light. The first region 480a, the second region 480b disposed in the region corresponding to the second sub-pixel Pg and transmitting green light, and the third sub-pixel Pr disposed in the region corresponding to the red light. It may include a third area 480c.

A region corresponding to the second sub-pixel Pg and the third sub-pixel Pr on the color filter 480, that is, a region corresponding to the second region 480b and the third region 480c of the color filter 480 In the band pass filter 460 is disposed.

The band-pass filter 460 of the present embodiment may be disposed to be common to the second sub-pixel Pg and the third sub-pixel Pr, and may include a long-pass filter 461 and a short-pass filter 462. have. The band pass filter 460 may reflect or absorb a portion of green light and red light emitted from the intermediate layer 440 to reduce half widths of green light and red light emitted to the outside, thereby improving color purity of the display device 400.

An encapsulation substrate 470 may be disposed on the band pass filter 460.

This embodiment illustrates a configuration in which the band pass filter 460 is disposed between the encapsulation substrate 470 and the color filter 480, but the present invention is not limited thereto, and the band pass filter 460 is an encapsulation substrate 470 ) May be disposed on the outer side.

13 is a schematic cross-sectional view of a display device according to another exemplary embodiment of the present invention.

Referring to FIG. 13, the display device 500 according to the present exemplary embodiment includes a first sub-pixel Pb, a second sub-pixel Pg, and a third sub-pixel Pr that respectively emit blue light, green light, and red light. ) Includes a partitioned substrate 510, a pixel electrode 520 sequentially stacked on the substrate 510, an intermediate layer 540 including a plurality of quantum dots and emitting light, and a counter electrode 550 Can include.

The pixel electrode 520 may be configured as a transparent or translucent electrode, and the counter electrode 550 may be configured as a reflective electrode.

That is, the display device 500 according to the present exemplary embodiment may be a bottom emission type that emits light toward the pixel electrode 520.

The intermediate layer 540 includes a plurality of quantum dots (FIG. 12, Qb) emitting blue light, a plurality of quantum dots (FIG. 12, Qg) emitting green light, and a plurality of quantum dots (FIG. 12, Qr) emitting red light. In addition to the quantum dot layer, at least one of a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL). One more can be provided. The quantum dots Qb, Qg, and Qr may all be made of the same material, and may have different sizes depending on the wavelength of the emitted light. In addition, the quantum dots Qb, Qg, and Qr may not contain heavy metals such as cadmium (Cd).

In the display device 500 of the present embodiment, holes injected from the pixel electrode 520 and electrons injected from the counter electrode 550 are combined in a quantum dot layer including the quantum dots Qb, Qg, and Qr. The excitons generate light as they fall from the excited state to the ground state. That is, the intermediate layer 540 may emit white light.

A color filter 580 for implementing a color may be disposed on a surface of the pixel electrode 520 from which light is emitted, and the color filter 580 is disposed in a region corresponding to the first sub-pixel Pb, and blue light It is disposed in a region corresponding to the first region 580a transmitting light, the second sub-pixel Pg, and disposed in the second region 580b transmitting green light, and the region corresponding to the third sub-pixel Pr. A third area 580c that transmits red light may be included.

Regions corresponding to the second sub-pixel Pg and the third sub-pixel Pr on the surface of the color filter 580 from which light is emitted, that is, the second region 580b and the third region of the color filter 580 ( In the region corresponding to 580c), a band pass filter 560 is disposed.

The band-pass filter 560 of the present embodiment may be disposed to be common to the second sub-pixel Pg and the third sub-pixel Pr, and may include a long-pass filter 561 and a short-pass filter 562. have. The band pass filter 560 may reflect or absorb a portion of green light and red light emitted from the intermediate layer 540 to reduce half widths of green light and red light emitted to the outside, thereby improving color purity of the display device 500.

This embodiment illustrates a configuration in which the color filter 580 and the band pass filter 560 are disposed between the substrate 510 and the pixel electrode 520, but the present invention is not limited thereto, and the color filter 580 and The band pass filter 560 may be disposed on the outer surface of the substrate 510.

As described above, the present invention has been described with reference to an embodiment shown in the drawings, but this is only exemplary, and it will be appreciated by those of ordinary skill in the art that various modifications and variations of the embodiment are possible therefrom. Therefore, the true technical scope of the present invention should be determined by the technical spirit of the appended claims.

10: quantum dot light emitting element 11: light emitting element emitting first light
12: quantum dot layer 13: band pass filter
13a: long-pass filter 13b: short-pass filter
20: light emitting diode package 30: first light guide plate
40: second light guide plate 100, 200, 300, 400, 500: display device
110: backlight unit 120: display panel
121, 126: polarizing plate 122: first substrate
123: liquid crystal layer 124: color filter layer
125: second substrate 210, 310, 410, 510: substrate
220, 320, 420, 520: pixel electrode 230, 330: pixel defining layer
240, 340, 440, 540: intermediate layer 250, 350, 450, 550: counter electrode
260, 360, 460, 560: band pass filter
270, 370, 470, 570: encapsulation substrate
480, 580: color filter

Claims (10)

A light emitting device that emits first light;
A quantum dot layer that includes a plurality of quantum dots and absorbs the first light to emit second light having a longer wavelength than the first light and third light having a longer wavelength than the second light; And
And a band pass filter disposed on the quantum dot layer and blocking a part of the second light and a part of the third light,
The plurality of quantum dots do not contain cadmium or mercury,
The band pass filter is a quantum dot light emitting device that blocks light in a region having a short wavelength among the second light and a region having a long wavelength in the third light. The method of claim 1,
The quantum dot is a quantum dot light emitting device including a plurality of first quantum dots that absorb the first light and emit the second light, and a plurality of second quantum dots that absorb the first light and emit the third light . The method of claim 2,
The first quantum dot and the second quantum dot are made of the same material, and have different sizes of quantum dot light emitting devices. The method of claim 1,
The peak wavelength of the second light transmitted through the band pass filter is longer than the peak wavelength of the second light emitted from the quantum dot layer, and the peak wavelength of the third light transmitted through the band pass filter is in the quantum dot layer. A quantum dot light emitting device shorter than the peak wavelength of the emitted third light. The method of claim 1,
The band pass filter reflects at least a portion of the first light. The method of claim 1,
The band pass filter includes a short wave pass filter and a long wave pass filter. The method of claim 6,
The cutoff wavelength of the short-pass filter is 655 nm or less, and the cutoff wavelength of the long-pass filter is 500 nm or more. The method of claim 1,
The first light corresponds to blue light or ultraviolet light, and the second light and the third light correspond to green light and red light, respectively. The method of claim 1,
The quantum dot is a quantum dot light emitting device comprising a core including any one selected from ZnSe, ZnO, ZnTe, InP, GaP, InGaN, and InN. The method of claim 9,
The quantum dot may further include a shell surrounding the core, wherein the cell includes any one selected from ZnS, ZnSe, GaP, and GaN.

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