KR102645607B1 - Light emitting diode and electroluminescent display device including the same - Google Patents

Abstract

The present invention relates to a light-emitting diode and an electroluminescent display device having a plurality of light-emitting stacks between a transparent electrode and a reflective electrode, wherein the light-emitting material layer is disposed in the maximum luminance region of each wavelength in the luminance contour, thereby displaying the light-emitting diode and the electroluminescent display. The luminous efficiency of the device is improved.

Description

Light emitting diode and electroluminescent display device {LIGHT EMITTING DIODE AND ELECTROLUMINESCENT DISPLAY DEVICE INCLUDING THE SAME}

The present invention relates to light emitting diodes, and more specifically to light emitting diodes and electroluminescent displays with high luminous efficiency.

Recently, as display devices have become larger, the demand for flat display devices that occupy less space has increased. One of these flat display devices includes light emitting diodes and is also called an organic light emitting display (OLED) device. The technology of electroluminescent (EL) display devices is developing at a rapid pace.

A light-emitting diode is a device that emits light when charge is injected into the light-emitting layer formed between the electron injection electrode (cathode) and the hole injection electrode (anode), the electrons and holes pair and then disappear. Not only can devices be formed on flexible transparent substrates such as plastic, but they also have the advantage of being able to be driven at low voltages (10V or less), relatively low power consumption, and excellent color purity.

The light-emitting layer may have a single-layer structure of a light-emitting material layer, or may have a multi-layer structure to improve light-emitting efficiency. For example, the light-emitting layer includes a hole injection layer (HIL), a hole transporting layer (HTL), an emitting material layer (EML), an electron transporting layer (ETL), and an electron transporting layer (ETL). It may have a multi-layer structure consisting of an electron injection layer (EIL).

In an electroluminescent display device, a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are formed for each red, green, and blue pixel area to emit red, green, and blue light, thereby realizing a color image.

However, because there are limitations in manufacturing a large-area organic light-emitting diode display device with a structure in which a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are formed for each pixel area, a light-emitting diode that emits white light is formed for the entire pixel area, and the color An electroluminescent display device using a filter has been proposed.

For example, a light-emitting stack containing a yellow-green light-emitting layer and a light-emitting stack containing a blue light-emitting layer are formed between the anode and the cathode, so that white light is emitted from the light-emitting diode and the white light passes through the color filter to produce color. The video is realized.

However, light emitting diodes and electroluminescent displays with such a multi-stack structure have a problem of low luminous efficiency, especially the low luminous efficiency of the blue light emitting layer.

The present invention seeks to solve the problem of low luminous efficiency in conventional multi-stack structure light emitting diodes and electroluminescence displays.

The present invention includes a transparent electrode; a reflective electrode facing the transparent electrode; a first charge generation layer positioned between the transparent electrode and the reflective electrode; a first light-emitting stack comprising a first light-emitting material layer having a first light-emitting wavelength range and positioned between the transparent electrode and the first charge generating layer; Comprising a second light-emitting material layer having a first emission wavelength range and a third light-emitting material layer having a second emission wavelength range greater than the first emission wavelength range, and positioned between the first charge generating layer and the reflective electrode A light emitting diode including a second light emitting stack is provided.

The light emitting diode of the present invention includes a second charge generation layer located between the second light emitting stack and the reflective electrode; It includes a fourth light-emitting material layer having the first light-emitting wavelength range and further includes a third light-emitting stack positioned between the second charge generating layer and the reflection.

In the light emitting diode of the present invention, the distance between the blue light emitting material layer and the transparent electrode is greater than the distance between the fourth light emitting material layer and the reflective electrode.

In the light emitting diode of the present invention, the second light emitting stack is located between the first charge generation layer and the third light emitting material layer and includes a fifth light emitting material having a third light emitting wavelength range that is larger than the second light emitting wavelength range. Includes more layers.

In the light emitting diode of the present invention, the distance between the first light emitting material layer and the fifth light emitting material layer is smaller than the distance between the second light emitting material layer and the fourth blue light emitting material layer.

In the light emitting diode of the present invention, the second light emitting material layer is located between the third light emitting material layer and the reflective electrode.

The light emitting diode of the present invention includes a second charge generation layer located between the second light emitting stack and the first charge generation layer; It includes a fourth light-emitting material layer having the first emission wavelength range and further includes a third light-emitting stack positioned between the first charge generation layer and the second charge generation layer.

In the light emitting diode of the present invention, the distance between the first light emitting material layer and the transparent electrode is greater than the distance between the second light emitting material layer and the reflective electrode.

In the light emitting diode of the present invention, the second light emitting stack is located between the second charge generation layer and the third light emitting material layer and includes a fifth light emitting material having a third light emitting wavelength range that is larger than the second light emitting wavelength range. Includes more layers.

In the light emitting diode of the present invention, the distance between the fifth light emitting material layer and the fourth light emitting material layer is smaller than the distance between the first light emitting material layer and the fourth light emitting material layer.

From another perspective, the present invention includes a transparent electrode; a reflective electrode facing the transparent electrode; a first charge generation layer positioned between the transparent electrode and the reflective electrode; Comprising a first light-emitting material layer having a first light-emitting wavelength range and a second light-emitting material layer having a second light-emitting wavelength range greater than the first light-emitting wavelength range, and located between the transparent electrode and the first charge generating layer a first light emitting stack; A light emitting diode is provided, including a third blue light emitting material layer having the first light emitting wavelength range and a second light emitting stack positioned between the first charge generation layer and the reflective electrode.

In the light emitting diode of the present invention, the first light emitting material layer is located between the second light emitting material layer and the reflective electrode.

In the light emitting diode of the present invention, the distance between the second light emitting material layer and the transparent electrode is smaller than the distance between the third light emitting material layer and the reflective electrode.

In the light emitting diode of the present invention, the first light emitting material layer is located between the second light emitting material layer and the transparent electrode.

In the light emitting diode of the present invention, the distance between the first light emitting material layer and the transparent electrode is greater than the distance between the third light emitting material layer and the reflective electrode.

The light emitting diode of the present invention includes a second charge generation layer located between the second light emitting stack and the first charge generation layer; It includes a fourth light-emitting material layer having the first emission wavelength range and further includes a third light-emitting stack positioned between the first charge generation layer and the second charge generation layer.

In the light emitting diode of the present invention, the third light emitting material layer includes a host and a dopant, and the electron mobility of the host is greater than the hole mobility of the host.

In the light emitting diode of the present invention, the first emission wavelength range is 440 to 480 nm, and the second emission wavelength range is 520 to 590 nm.

In the light emitting diode of the present invention, the first emission wavelength range is 440 to 480 nm, the second emission wavelength range is 520 to 590 nm, and the third emission wavelength range is 620 to 700 nm.

In another aspect, the present invention includes a substrate; The above-described light emitting diode located on the upper part of the substrate; An electroluminescent display device is provided including a thin film transistor located between the substrate and the light emitting diode and connected to the light emitting diode.

In the electroluminescent display device of the present invention, the light emitting diode corresponds to red, green, and blue pixel areas, and further includes red, green, and blue color filter patterns located in each of the red, green, and blue pixel areas.

In the light emitting diode of the present invention, the red, green, and blue color filter patterns are located between the substrate and the light emitting diode.

In the light emitting diode of the present invention, the red, green, and blue color filter patterns are located on the top of the light emitting diode.

The light emitting diode of the present invention improves the light emitting efficiency of the white light emitting diode by arranging the light emitting material layer at the point of maximum light emitting efficiency for each wavelength of light.

In addition, the low luminous efficiency and lifespan problems of the blue light emitting material can be compensated for by additionally disposing a blue light emitting material layer.

Therefore, light emitting diodes and electroluminescent displays with a multi-stack structure have high brightness with low power consumption.

1 is a schematic circuit diagram of an electroluminescent display device according to the present invention.
Figure 2 is a schematic cross-sectional view of the electroluminescence display device of the present invention.
Figure 3 is a schematic cross-sectional view of a light emitting diode according to a first embodiment of the present invention.
Figure 4 is a photograph showing the luminance contour in a light emitting diode according to the first embodiment of the present invention.
Figure 5 is a schematic cross-sectional view of a light emitting diode according to a second embodiment of the present invention.
Figure 6 is a photograph showing a luminance contour in a light emitting diode according to a second embodiment of the present invention.
Figure 7 is a schematic cross-sectional view of a light emitting diode according to a third embodiment of the present invention.
Figure 8 is a photograph showing a luminance contour in a light emitting diode according to a third embodiment of the present invention.
Figure 9 is a schematic cross-sectional view of a light emitting diode according to a fourth embodiment of the present invention.
Figure 10 is a photograph showing a luminance contour in a light emitting diode according to a fourth embodiment of the present invention.
Figure 11 is a schematic cross-sectional view of a light emitting diode according to a fifth embodiment of the present invention.
Figure 12 is a photograph showing the luminance contour in a light emitting diode according to the fifth embodiment of the present invention.
Figure 13 is a schematic cross-sectional view of the electroluminescence display device of the present invention.
Figure 14 is a schematic cross-sectional view of a light emitting diode according to a sixth embodiment of the present invention.
Figure 15 is a photograph showing the luminance contour in a light emitting diode according to the sixth embodiment of the present invention.
Figure 16 is a graph showing the emission spectrum of a light emitting diode.

Hereinafter, preferred embodiments according to the present invention will be described with reference to the drawings.

1 is a schematic circuit diagram of an electroluminescent display device according to the present invention.

As shown in FIG. 1, in the electroluminescence display device, a gate wire (GL), a data wire (DL), and a power wire (PL) that cross each other to define the pixel area (P) are formed, and the pixel area (P) ), a switching thin film transistor (Ts), a driving thin film transistor (Td), a storage capacitor (Cst), and a light emitting diode (D) are formed.

The switching thin film transistor (Ts) is connected to the gate wire (GL) and the data wire (DL), and the driving thin film transistor (Td) and storage capacitor (Cst) are connected between the switching thin film transistor (Ts) and the power wire (PL). do. The light emitting diode (D) is connected to the driving thin film transistor (Td).

In this electroluminescent display device, when the switching thin film transistor (Ts) is turned on according to the gate signal applied to the gate wire (GL), the data signal applied to the data wire (DL) is turned on by the switching thin film transistor. It is applied to the gate electrode of the driving thin film transistor (Td) and one electrode of the storage capacitor (Cst) through (Ts).

The driving thin film transistor (Td) is turned on according to the data signal applied to the gate electrode, and as a result, a current proportional to the data signal flows from the power wiring (PL) to the light emitting diode (D) through the driving thin film transistor (Td). flows, and the light emitting diode (D) emits light with a luminance proportional to the current flowing through the driving thin film transistor (Td).

At this time, the storage capacitor Cst is charged with a voltage proportional to the data signal, so that the voltage of the gate electrode of the driving thin film transistor Td is maintained constant for one frame.

Therefore, the electroluminescence display device can display a desired image.

Figure 2 is a schematic cross-sectional view of the electroluminescence display device of the present invention.

As shown in FIG. 2, the electroluminescent display device 100 includes a substrate 110, a light emitting diode (D) located on top of the substrate 110, and a light emitting diode (D) located between the substrate 110 and the light emitting diode (D). It includes a driving thin film transistor (Td) connected to the light emitting diode (D), and a color filter 130 located between the substrate 110 and the light emitting diode (D).

The substrate 110 may be a glass substrate or a plastic substrate. For example, the substrate 110 may be made of polyimide.

The substrate 110 includes a red pixel area (RP), a green pixel area (GP), and a blue pixel area (BP), and the driving thin film transistor (Td) includes a red pixel area (RP), a green pixel area (GP), Located in each blue pixel area (BP). Meanwhile, the substrate 110 may further include a white pixel area (not shown), and a driving thin film transistor (Td) is also disposed in the white pixel area.

For example, the driving thin film transistor (Td) includes a semiconductor layer formed on the substrate 110, a gate electrode located on top of the semiconductor layer and overlapping it, a source electrode disposed on top of the gate electrode and connected to both ends of the semiconductor layer, and It may include a drain electrode.

A first insulating layer 120 is formed on the driving thin film transistor (Td), and a color filter 130 is formed on the first insulating layer 120. The color filter 130 includes a red color filter pattern 130a corresponding to the red pixel area (RP), a green color filter pattern 130b corresponding to the green pixel area (GP), and a blue pixel area (BP). It includes a blue color filter pattern 130c.

A second insulating layer 140 is formed on the color filter 130, and a contact hole 122 is formed in the first and second insulating layers 130 to expose one electrode, for example, the drain electrode, of the driving thin film transistor (Td). ) is formed.

That is, the color filter 130 is located between the first and second insulating layers 120 and 140. Meanwhile, when a white pixel area is included, a color filter is not formed in the white pixel area, and the first and second insulating layers 120 and 140 contact the entire surface in the white pixel area.

On the second insulating layer 140, the first electrode 150 connected to the driving thin film transistor (Td) through the contact hole 122 is formed separately for red, green, and blue pixel regions (RP, GP, BP). . The first electrode 150 may be an anode and may be made of a conductive material with a relatively high work function value. For example, the first electrode 150 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO).

Additionally, a bank 160 covering the edge of the first electrode 150 is formed on the second insulating layer 140. The bank 160 exposes the center of the first electrode 150 corresponding to the red, green, and blue pixel regions (RP, GP, BP).

A light emitting layer 152 is formed on the first electrode 150. The light emitting layer 152 emits white light and is formed integrally with the entire display area including the red, green, and blue pixel areas (RP, GP, and BP).

A second electrode 154 is formed on the substrate 110 on which the light emitting layer 152 is formed. The second electrode 154 is located in front of the display area including the red, green, and blue pixel areas (RP, GP, BP) and is made of a conductive material with a relatively small work function value and can be used as a cathode. . For example, the second electrode 154 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

The first electrode 150, the light emitting layer 152, and the second electrode 154 form a light emitting diode (D).

Although not shown, an encapsulation film may be formed on the second electrode 154 to prevent external moisture from penetrating into the light emitting diode (D). For example, the encapsulation film may have a stacked structure of a first inorganic insulating layer, an organic insulating layer, and a second inorganic insulating layer, but is not limited to this. Additionally, a polarizing plate may be attached to the outer surface of the first substrate 110 to reduce external light reflection. For example, the polarizer may be a circular polarizer.

Additionally, a cover window (not shown) may be attached to the outer surface of the substrate 110 or the outer surface of the polarizer. At this time, the substrate 110 and the cover window have flexible characteristics, making it possible to form a flexible display device.

The electroluminescent display device 100 of the present invention is a bottom emission type. That is, light from the light emitting layer 152 passes through the first electrode 152 and the color filter 130, and an image is displayed on the substrate 110 side.

That is, the first electrode 150 is a transparent electrode, the second electrode 154 is used as a reflective electrode, and the light from the light emitting layer 152 passes directly through the first electrode 150 or through the second electrode 154. After being reflected from, it passes through the first electrode 150.

In Figure 2, the color filter 130 is located between the first and second insulating layers 120 and 140. However, the color filter 130 has no restrictions on its position between the light emitting diode (D) and the substrate 110. For example, the color filter 130 may be located between the substrate 110 and the first insulating layer 120, and in this case, the second insulating layer 130 may be omitted.

Since white light from the light emitting diode (D) passes through the color filter 130, the electroluminescence display device 100 can display a color image.

FIG. 3 is a schematic cross-sectional view of a light emitting diode according to a first embodiment of the present invention, and FIG. 4 is a photograph showing a luminance contour in a light emitting diode according to a first embodiment of the present invention. (In Figure 4, the vertical axis is the distance from the first electrode.)

As shown in Figure 3, the light emitting diode (D) is located between the first electrode 150, which is a transparent electrode, the second electrode 154, which is a reflective electrode, and the first and second electrodes 150 and 154. It includes a light emitting layer 152. The thickness of the light emitting layer 152, that is, the distance between the first and second electrodes 150 and 154, may be about 250 to 350 nm.

The light-emitting layer 152 includes a charge generation layer 220 located between the first electrode 150 and the second electrode 154, and a first blue light-emitting material layer 216, and the first electrode 150 and the charge The first light-emitting stack 210 located between the generation layer 220, the yellow-green light-emitting material layer 234a, the second blue light-emitting material layer 234b on both sides of the yellow-green light-emitting material layer 234a, and the red light-emitting material layer ( 234c) and includes a second light emitting stack 230 located between the charge generation layer 220 and the second electrode 154. That is, the light emitting diode (D) has a double stack structure.

For example, the emission wavelength of each of the first and second blue light-emitting material layers 216 and 234b may be about 440 to 480 nm, and the emission wavelength of the yellow-green light-emitting material layer 234a may be about 520 to 590 nm, The emission wavelength of the red light emitting material layer 234c may be about 620 to 700 nm.

That is, the first light-emitting stack 210 includes a first light-emitting material layer (first blue light-emitting material layer, 216) having a first light-emitting wavelength range, and the second light-emitting stack 230 includes a first light-emitting material layer 216 having a first light-emitting wavelength range. A second light-emitting material layer (yellow-green light-emitting material layer, 234a) having a large second light-emitting wavelength range, a third light-emitting material layer (yellow-green light-emitting material layer, 234a) located on the upper surface side of the second light-emitting material layer (234a) and having a first light-emitting wavelength range ( a second blue light-emitting material layer, 234b), a fourth light-emitting material layer (red light-emitting material layer, 234c).

The third light-emitting material layer 234b is located between the second light-emitting material layer 234a and the second electrode 154, which is a reflective electrode, and the fourth light-emitting material layer 234c is transparent with the second light-emitting material layer 234a. It is located between the first electrode 150 or the charge generation layer 220.

In FIG. 3, the second light emitting stack 230 includes three light emitting material layers, including a red light emitting material layer 234c. The red light emitting material layer 234c is intended to increase color reproduction rate and may be omitted in the white light emitting diode. That is, the second light-emitting stack 230 may include only two light-emitting material layers, a yellow-green light-emitting material layer 234a and a second blue light-emitting material layer 234b.

Each of the first and second blue light-emitting material layers 216 and 234b, yellow-green light-emitting material layer 234a, and red light-emitting material layer 234c may include a phosphorescent or fluorescent organic light-emitting material or an inorganic light-emitting material such as quantum dots. there is.

For example, when the first and second blue light emitting material layers 216 and 234b include an organic light emitting material, each of the first and second blue light emitting material layers 216 and 234b is an anthracene derivative, pi. It may include a host selected from pyrene derivatives and perylene derivatives and a blue dopant.

When the yellow-green light-emitting material layer 234a includes an organic light-emitting material, the yellow-green light-emitting material layer 234a may include a host made of a carbazole-based compound or a metal complex and a yellow-green dopant.

When the red light-emitting material layer 234c includes an organic light-emitting material, the red light-emitting material layer 234c is CBP (4,4'-N, N'-dicarbazolebiphenyl) or Balq (bis (2-methyl-8-quinlinolato -N1,O8)-(1,1'-biphenyl-4-olato)aluminium) and Btp ₂ Ir(acac)(bis(2O-benzo[4,5-a]thienyl)pyridinato-N, It may contain a dopant selected from C3O)iridium(zcetylactonate) or Btp2Ir(acac)(iridium(III)bis(1-phenylisoquinolyl)-N,C2')acetyl.

The charge generation layer 220 includes an N-type charge generation layer 222 and a P-type charge generation layer 224. The N-type charge generation layer 222 is located between the first light-emitting stack 210 and the P-type charge generation layer 224.

The charge generation layer 220 generates charges or separates the charges into holes and electrons and supplies them to the first and second light emitting stacks 210 and 230. That is, the N-type charge generation layer 222 supplies electrons to the first blue light-emitting material layer 216 of the first light-emitting stack 210, and the P-type charge generation layer 224 supplies electrons to the second light-emitting stack 230. By supplying holes to the yellow-green light-emitting material layer 234a, the second blue light-emitting material layer 234b, and the red light-emitting material layer 234c, light emission having a plurality of light-emitting material layers 216, 234a, 234b, and 234c The luminous efficiency of the diode (D) can be increased and the driving voltage of the light emitting diode (D) can be lowered.

More specifically, the first light emitting stack 210 is sequentially stacked on the first electrode 150 and includes a hole injection layer 212 located between the first electrode 150 and the first blue light emitting material layer 216. And it may include a first hole transport layer 214 and a first electron transport layer 218 located between the first blue light emitting material layer 216 and the charge generation layer 220.

The second light-emitting stack 230 is sequentially stacked on the second hole transport layer 232 and the second blue light-emitting material layer 234b located between the charge generation layer 220 and the red light-emitting material layer 234c. 2 It may include a second electron transport layer 236 and an electron injection layer 238 located between the blue light emitting material layer 234b and the second electrode 154.

When the distance between the first and second electrodes 150 and 154 is about 300 nm, the center of the first blue light-emitting material layer 216 may be located at a distance of about 110 to 130 nm from the first electrode 150, The center of the second blue light-emitting material layer 234b may be located approximately 230 to 250 nm away from the first electrode 150. In addition, the center of the yellow-green light-emitting material layer 234a is located approximately 180 to 200 nm away from the first electrode 150, and the center of the red light-emitting material layer 234c is located approximately 140 to 160 nm away from the first electrode 150. It can be located spaced apart.

That is, the distance d1 between the first electrode 150 and the first blue light emitting material layer 216 is greater than the distance d2 between the second electrode 154 and the second blue light emitting material layer 234b.

In the light emitting diode (D) of the present invention, the second light emitting stack 230 includes a second blue light emitting material layer (234b) together with a yellow green light emitting material layer (234a), so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

That is, the blue light-emitting material layer has a problem of low light-emitting efficiency and lifespan, and the shortcomings of the blue light-emitting material layer are compensated by adding the second blue light-emitting material layer 234b to the second light-emitting stack 230.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (216, 234a, 234b, 234c) is located on the maximum luminance contour line, thereby improving or maximizing the luminous efficiency of the light emitting diode (D).

That is, referring to FIG. 4, the light emitted from the light emitting material layer is reflected by the second electrode 154, which is a reflective electrode, and then passes through the first electrode (150 in FIG. 3). 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 150.

The luminance contour line has a greater slope with respect to the second electrode 154 as the distance from the second electrode 154 increases.

As described above, the first blue light-emitting material layer 216 is located in the maximum luminance region of the blue wavelength at a distance of about 110 to 130 nm from the first electrode 150, and the second blue light-emitting material layer 234b is located in the first blue light-emitting material layer 234b. It is spaced approximately 230 to 250 nm away from the electrode 150 and is located in the maximum luminance region of the blue wavelength.

Additionally, the yellow-green light-emitting material layer 234a and the red light-emitting material layer 234c are disposed below the second blue light-emitting material layer 234b and are located in the maximum luminance region of the yellow-green wavelength and the maximum luminance region of the red wavelength, respectively.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Meanwhile, the second blue light-emitting material layer 234b may include a host whose electron mobility is greater than the electron mobility.

In the present invention, the second blue light-emitting material layer 234b is located on the side of the second electrode 154 in contact with the yellow-green light-emitting material layer 234a, and the yellow-green light-emitting material layer 234a with phosphorescent properties and the second blue light-emitting material layer 234a with fluorescent properties When the light emitting material layer 234b comes into contact with the light emitting material layer 234b, the light emitting efficiency decreases. However, if a host whose electron mobility is greater than the electron mobility is used in the second blue light-emitting material layer 234b, the electron injection characteristics from the second electrode 154 are improved, thereby preventing the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 210 and a second light emitting stack located between the first electrode 150, which is a transparent electrode, and the second electrode 154, which is a reflective electrode. 220), including a first blue light emitting material layer 216 of the first light emitting stack 210, a yellow green light emitting material layer 234a, a second blue light emitting material layer 234b of the second light emitting stack 230, As the red light-emitting material layer 234c is located in the maximum luminance region of each wavelength, the light-emitting efficiency of the light-emitting diode D is improved.

FIG. 5 is a schematic cross-sectional view of a light emitting diode according to a second embodiment of the present invention, and FIG. 6 is a photograph showing a luminance contour in the light emitting diode according to a second embodiment of the present invention. (In Figure 6, the vertical axis is the distance from the first electrode.)

As shown in Figure 5, the light emitting diode (D) is located between the first electrode 150, which is a transparent electrode, the second electrode 154, which is a reflective electrode, and the first and second electrodes 150 and 154. It includes a light emitting layer 152. The thickness of the light emitting layer 152, that is, the distance between the first and second electrodes 150 and 154, may be about 400 to 500 nm.

The light emitting layer 152 includes a first charge generation layer 320 located between the first electrode 150 and the second electrode 154, and a first blue light emitting material layer 316, and the first electrode 150 and the first light-emitting stack 310 located between the first charge generation layer 320, the yellow-green light-emitting material layer 334a, the second blue light-emitting material layer 334b on both sides of the yellow-green light-emitting material layer 334a, and the red light-emitting material layer 334a. A second light-emitting stack 330 including a light-emitting material layer 334c and located between the first charge generation layer 320 and the second electrode 154, and the second light-emitting stack 330 and the second electrode 154 ) A third light emitting stack including a second charge generation layer 340 located between the second charge generation layer 340 and a third blue light emitting material layer 354 and located between the second charge generation layer 340 and the second electrode 154. Includes (350). That is, the light emitting diode (D) has a triple stack structure.

For example, the emission wavelength of each of the first to third blue light-emitting material layers 316, 334b, and 354 may be about 440-480 nm, and the emission wavelength of the yellow-green light-emitting material layer 334a may be about 520-590 nm. And, the emission wavelength of the red light emitting material layer 334c may be about 620 to 700 nm.

That is, the first light-emitting stack 310 includes a first light-emitting material layer (first blue light-emitting material layer, 316) having a first light-emitting wavelength range, and the second light-emitting stack 330 includes a first light-emitting material layer (first blue light-emitting material layer, 316) having a first light-emitting wavelength range. A second light-emitting material layer (yellow-green light-emitting material layer, 334a) having a large second light-emitting wavelength range, a third light-emitting material layer (yellow-green light-emitting material layer, 334a) located on the upper surface side of the second light-emitting material layer (334a) and having a first light-emitting wavelength range ( a second blue light-emitting material layer, 334b), a fourth light-emitting material layer (red light-emitting material layer, 334c), and the third light-emitting stack 350 includes a fifth light-emitting material layer (third blue light-emitting material layer, 354) having a first emission wavelength range.

The third light-emitting material layer 334b is located between the second light-emitting material layer 334a and the second electrode 154, which is a reflective electrode, or the second charge generation layer 340, and the fourth light-emitting material layer 334c is the second light-emitting material layer 334c. 2 It is located between the light emitting material layer 334a and the first electrode 150 or the first charge generation layer 320, which is a transparent electrode.

In Figure 5, the second light emitting stack 330 has three light emitting material layers including a red light emitting material layer 334c. Alternatively, the red light emitting material layer 334c may be omitted and the second light emitting stack 330 may include only two light emitting material layers, a yellow green light emitting material layer 334a and a second blue light emitting material layer 334b.

Each of the first to third blue light-emitting material layers 316, 334b, 354, yellow-green light-emitting material layer 334a, and red light-emitting material layer 334c includes a phosphorescent or fluorescent organic light-emitting material or an inorganic light-emitting material such as quantum dots. can do.

The first charge generation layer 320 includes a first N-type charge generation layer 322 and a first P-type charge generation layer 324. The first N-type charge generation layer 322 is located between the first light-emitting stack 310 and the first P-type charge generation layer 324. Additionally, the second charge generation layer 340 includes a second N-type charge generation layer 342 and a second P-type charge generation layer 344. The second N-type charge generation layer 342 is located between the second light-emitting stack 330 and the second P-type charge generation layer 344.

The first light emitting stack 310 is sequentially stacked on the first electrode 150 and includes a hole injection layer 312 and a first hole located between the first electrode 150 and the first blue light emitting material layer 316. It may include a transport layer 314 and a first electron transport layer 318 located between the first blue light-emitting material layer 316 and the first charge generation layer 320.

The second light-emitting stack 330 includes a second hole transport layer 332 located between the first charge generation layer 320 and the red light-emitting material layer 334c, a second blue light-emitting material layer 334b, and a second charge It includes a second electron transport layer 336 located between the generation layers.

The third light-emitting stack 350 is formed on a third hole transport layer 352 located between the second charge generation layer 340 and the third blue light-emitting material layer 354, and on the third blue light-emitting material layer 354. It may be sequentially stacked and include a third electron transport layer 356 and an electron injection layer 358 positioned between the third blue light emitting material layer 354 and the second electrode 154.

When the distance between the first and second electrodes 150 and 154 is about 412 nm, the center of the first blue light-emitting material layer 316 may be located about 100 to 120 nm away from the first electrode 150. Additionally, the center of the second blue light-emitting material layer 334b may be located approximately 240 to 260 nm away from the first electrode 150, and the center of the third blue light-emitting material layer 354 may be located approximately 240 to 260 nm apart from the first electrode 150. ) may be located approximately 350 to 370 nm apart.

In addition, the center of the yellow-green light-emitting material layer 334a is located approximately 200 to 220 nm away from the first electrode 150, and the center of the red light-emitting material layer 334c is located approximately 160 to 180 nm away from the first electrode 150. It can be located spaced apart.

That is, the distance d3 between the first electrode 150 and the first blue light emitting material layer 316 is greater than the distance d6 between the second electrode 154 and the third blue light emitting material layer 354. Additionally, the distance d4 between the first blue light emitting material layer 316 and the red light emitting material layer 334c is longer than the distance d5 between the second blue light emitting material layer 334b and the third blue light emitting material layer 354. small.

In the light emitting diode (D) of the present invention, the second light emitting stack 330 includes a second blue light emitting material layer 334b together with a yellow green light emitting material layer 334a, so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

In addition, the second blue light-emitting material layer 334b is disposed in a large space (large distance) between the yellow-green light-emitting material layer 334a and the third blue light-emitting material layer 354, so the second blue light-emitting material layer 334b It can have a thickness sufficient for light emission.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (316, 334a, 334b, 334c, 354) is located on the maximum luminance contour line, thereby improving or maximizing the luminous efficiency of the light emitting diode (D).

That is, referring to FIG. 6, the light emitted from the light emitting material layer is reflected by the second electrode 154, which is a reflective electrode, and then passes through the first electrode (150 in FIG. 5). 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 150.

As described above, the first blue light-emitting material layer 316 is located in the maximum luminance region of the blue wavelength at a distance of about 100 to 120 nm from the first electrode 150, and the second blue light-emitting material layer 334b is located in the first blue light-emitting material layer 334b. It is spaced about 240 to 260 nm from the electrode 150 and is located in the maximum luminance region of the blue wavelength, and the third blue light-emitting material layer 354 is spaced about 350 to 370 nm from the first electrode 150 and is located in the maximum luminance region of the blue wavelength. It is located in the luminance area.

Additionally, the yellow-green light-emitting material layer 334a and the red light-emitting material layer 334c are disposed below the second blue light-emitting material layer 334b and are located in the maximum luminance region of the yellow-green wavelength and the maximum luminance region of the red wavelength, respectively.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Moreover, the second blue light emitting material layer 334b may include a host whose electron mobility is greater than the hole mobility, and accordingly, the second blue light emitting material layer 334b is disposed in contact with the yellow green light emitting material layer 334a. This prevents the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 310 and a second light emitting stack located between the first electrode 150, which is a transparent electrode, and the second electrode 154, which is a reflective electrode. 330) and a third light emitting stack 350, including a first blue light emitting material layer 316 of the first light emitting stack 310, a yellow green light emitting material layer 334a of the second light emitting stack 330, and a second light emitting material layer 334a. The blue light emitting material layer 334b, the red light emitting material layer 334c, and the third blue light emitting material layer 354 of the third light emitting stack 350 are located in the maximum luminance region of each wavelength, so that the light emitting diode (D) Luminous efficiency is improved.

FIG. 7 is a schematic cross-sectional view of a light emitting diode according to a third embodiment of the present invention, and FIG. 8 is a photograph showing a luminance contour in the light emitting diode according to a third embodiment of the present invention. (In Figure 8, the vertical axis is the distance from the first electrode.)

As shown in FIG. 7, the light emitting diode (D) is located between the first electrode 150, which is a transparent electrode, the second electrode 154, which is a reflective electrode, and the first and second electrodes 150 and 154. It includes a light emitting layer 152. The thickness of the light emitting layer 152, that is, the distance between the first and second electrodes 150 and 154, may be about 400 to 500 nm.

The light-emitting layer 152 includes a first charge generation layer 420 located between the first electrode 150 and the second electrode 154, and a first blue light-emitting material layer 416, and the first electrode 150 and the first light-emitting stack 410 located between the first charge generation layer 420, a yellow-green light-emitting material layer 434a, a second blue light-emitting material layer 434b on both sides of the yellow-green light-emitting material layer 434a, and a red light-emitting material layer 434a. A second light emitting stack 430 including a light emitting material layer 434c and located between the first charge generation layer 420 and the second electrode 154, the second light emitting stack 430 and the first charge generation layer It includes a second charge generation layer 440 located between (420) and a third blue light-emitting material layer 454, and is located between the first charge generation layer 420 and the second charge generation layer 440. Includes a third light emitting stack 450. That is, the light emitting diode (D) has a triple stack structure.

For example, the emission wavelength of each of the first to third blue light-emitting material layers 416, 434b, and 454 may be about 440-480 nm, and the emission wavelength of the yellow-green light-emitting material layer 434a may be about 520-590 nm. And, the emission wavelength of the red light-emitting material layer 434c may be about 620 to 700 nm.

That is, the first light-emitting stack 410 includes a first light-emitting material layer (first blue light-emitting material layer, 416) having a first light-emitting wavelength range, and the second light-emitting stack 430 includes a first light-emitting material layer 416 having a first light-emitting wavelength range. A second light-emitting material layer (yellow-green light-emitting material layer, 434a) having a large second light-emitting wavelength range, a third light-emitting material layer (yellow-green light-emitting material layer, 434a) located on the upper surface side of the second light-emitting material layer (434a) and having a first light-emitting wavelength range ( a second blue light-emitting material layer, 434b), a fourth light-emitting material layer (red light-emitting material layer, 434c), and the third light-emitting stack 450 includes a fifth light-emitting material layer (third blue light-emitting material layer, 454) having a first emission wavelength range.

The third light-emitting material layer 434b is located between the second light-emitting material layer 434a and the second electrode 154, which is a reflective electrode, and the fourth light-emitting material layer 434c is transparent with the second light-emitting material layer 434a. It is located between the first electrode 150 or the second charge generation layer 440, which is an electrode.

In FIG. 7, the second light emitting stack 430 includes three light emitting material layers, including a red light emitting material layer 434c. Alternatively, the red light emitting material layer 434c may be omitted and the second light emitting stack 430 may include only two light emitting material layers, a yellow green light emitting material layer 434a and a second blue light emitting material layer 434b.

Each of the first to third blue light-emitting material layers 416, 434b, 454, yellow-green light-emitting material layer 434a, and red light-emitting material layer 434c includes a phosphorescent or fluorescent organic light-emitting material or an inorganic light-emitting material such as quantum dots. can do.

The first charge generation layer 420 includes a first N-type charge generation layer 422 and a first P-type charge generation layer 424. The first N-type charge generation layer 422 is located between the first light-emitting stack 410 and the first P-type charge generation layer 424. Additionally, the second charge generation layer 440 includes a second N-type charge generation layer 442 and a second P-type charge generation layer 444. The second N-type charge generation layer 442 is located between the third light-emitting stack 450 and the second P-type charge generation layer 444.

The first light emitting stack 410 is sequentially stacked on the first electrode 150 and includes a hole injection layer 412 and a first hole positioned between the first electrode 150 and the first blue light emitting material layer 416. It may include a transport layer 414 and a first electron transport layer 418 located between the first blue light-emitting material layer 416 and the first charge generation layer 420.

The third light-emitting stack 450 includes a second hole transport layer 452 located between the first charge generation layer 420 and the third blue light-emitting material layer 454, the third blue light-emitting material layer 454, and the third blue light-emitting material layer 454. It may include a second electron transport layer 456 located between the two charge generation layers 440.

The second light-emitting stack 430 is sequentially stacked on the third hole transport layer 432 located between the second charge generation layer 440 and the red light-emitting material layer 434c, and the second blue light-emitting material layer 434b. It may include a third electron transport layer 436 and an electron injection layer 438 located between the second blue light emitting material layer 434b and the second electrode 154.

When the distance between the first and second electrodes 150 and 154 is about 412 nm, the center of the first blue light-emitting material layer 416 may be located about 100 to 120 nm away from the first electrode 150. Additionally, the center of the second blue light-emitting material layer 434b may be located approximately 350 to 370 nm away from the first electrode 150, and the center of the third blue light-emitting material layer 454 may be located approximately 350 to 370 nm away from the first electrode 150. ) may be located approximately 240 to 260 nm apart.

In addition, the center of the yellow-green light-emitting material layer 434a is located approximately 330 to 350 nm away from the first electrode 150, and the center of the red light-emitting material layer 434c is located approximately 300 to 320 nm away from the first electrode 150. It can be located spaced apart.

That is, the distance d7 between the first electrode 150 and the first blue light emitting material layer 416 is greater than the distance d10 between the second electrode 154 and the second blue light emitting material layer 434b. Additionally, the distance d8 between the first blue light emitting material layer 416 and the third blue light emitting material layer 454 is the distance d9 between the red light emitting material layer 434c and the third blue light emitting material layer 454. bigger than

In the light emitting diode (D) of the present invention, the second light emitting stack 430 includes a second blue light emitting material layer 434b together with a yellow green light emitting material layer 434a, so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (416, 434a, 434b, 434c, 454) is located on the maximum luminance contour line, thereby improving or maximizing the luminous efficiency of the light emitting diode (D).

That is, referring to FIG. 8, the light emitted from the light emitting material layer is reflected by the second electrode 154, which is a reflective electrode, and then passes through the first electrode (150 in FIG. 7). 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 150.

As described above, the first blue light-emitting material layer 416 is located in the maximum luminance region of the blue wavelength at a distance of about 100 to 120 nm from the first electrode 150, and the second blue light-emitting material layer 434b is located in the first blue light-emitting material layer 434b. It is spaced apart from the electrode 150 by about 350 to 370 nm and is located in the maximum luminance region of the blue wavelength, and the third blue light-emitting material layer 454 is spaced from the first electrode 150 by 240 to 260 nm and is located in the maximum luminance region of the blue wavelength. located in the area.

Additionally, the yellow-green light-emitting material layer 434a and the red light-emitting material layer 434c are disposed below the second blue light-emitting material layer 434b and are located in the maximum luminance region of the yellow-green wavelength and the maximum luminance region of the red wavelength, respectively.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Moreover, the second blue light emitting material layer 434b may include a host whose electron mobility is greater than the hole mobility, and accordingly, the second blue light emitting material layer 434b is disposed in contact with the yellow green light emitting material layer 434a. This prevents the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 410 and a second light emitting stack located between the first electrode 150, which is a transparent electrode, and the second electrode 154, which is a reflective electrode. 420) and a third light emitting stack 450, including a first blue light emitting material layer 416 of the first light emitting stack 410, a yellow green light emitting material layer 434a of the second light emitting stack 430, and a second light emitting material layer 434a. The blue light emitting material layer 434b, the red light emitting material layer 434c, and the third blue light emitting material layer 454 of the third light emitting stack 450 are located in the maximum luminance region of each wavelength, so that the light emitting diode (D) Luminous efficiency is improved.

FIG. 9 is a schematic cross-sectional view of a light emitting diode according to a fourth embodiment of the present invention, and FIG. 10 is a photograph showing a luminance contour in a light emitting diode according to a fourth embodiment of the present invention. (In Figure 10, the vertical axis is the distance from the first electrode.)

As shown in Figure 9, the light emitting diode (D) is located between the first electrode 150, which is a transparent electrode, the second electrode 154, which is a reflective electrode, and the first and second electrodes 150 and 154. It includes a light emitting layer 152. The thickness of the light emitting layer 152, that is, the distance between the first and second electrodes 150 and 154, may be about 250 to 350 nm.

The light-emitting layer 152 includes a charge generation layer 520 located between the first electrode 150 and the second electrode 154, a yellow-green light-emitting material layer 516a, and a first blue light-emitting material layer 516b. It includes a first light-emitting stack 510 located between the first electrode 150 and the charge generation layer 520, and a second blue light-emitting material layer 534, and includes the charge generation layer 520 and the second electrode 154. ) and a second light emitting stack 530 located between them. That is, the light emitting diode (D) has a double stack structure.

For example, the emission wavelength of each of the first and second blue light emitting material layers 516b and 534 may be about 440 to 480 nm, and the emission wavelength of the yellow green light emitting material layer 516a may be about 520 to 590 nm.

That is, the first light-emitting stack 510 is located on the lower surface side of the first light-emitting material layer (first blue light-emitting material layer, 516b) having a first emission wavelength range and the first light-emitting material layer 516b, and It includes a second light-emitting material layer (yellow-green light-emitting material layer, 516a) having a second light-emitting wavelength range that is larger than the light-emitting wavelength range, and the second light-emitting stack 530 includes a third light-emitting material layer (yellow-green light-emitting material layer, 516a) having a first light-emitting wavelength range ( It includes a second blue light-emitting material layer, 534).

The first light-emitting material layer 516b is located between the second light-emitting material layer 516a and the second electrode 154, which is a reflective electrode, or the charge generation layer 520.

Each of the first and second blue light emitting material layers 516b and 534 and the yellow green light emitting material layer 516a may include a phosphorescent or fluorescent organic light emitting material or an inorganic light emitting material such as quantum dots.

The charge generation layer 520 includes an N-type charge generation layer 522 and a P-type charge generation layer 524. The N-type charge generation layer 522 is located between the first light-emitting stack 510 and the P-type charge generation layer 524.

The first light emitting stack 510 is sequentially stacked on the first electrode 150 and includes a hole injection layer 512 and a first hole transport layer located between the first electrode 150 and the yellow-green light emitting material layer 516a ( 514) and a first electron transport layer 518 located between the first blue light emitting material layer 516b and the first charge generation layer 520.

The second light-emitting stack 530 is sequentially stacked on the second hole transport layer 532 and the second blue light-emitting material layer 534, which are located between the charge generation layer 520 and the second blue light-emitting material layer 534. It may include a second electron transport layer 236 and an electron injection layer 238 located between the second blue light emitting material layer 534 and the second electrode 154.

When the distance between the first and second electrodes 150 and 154 is about 300 nm, the center of the first blue light-emitting material layer 516b may be located at a distance of about 110 to 130 nm from the first electrode 150, The center of the second blue light-emitting material layer 534 may be located approximately 230 to 250 nm away from the first electrode 150. Additionally, the center of the yellow-green light emitting material layer 516a may be located approximately 30 to 50 nm away from the first electrode 150.

That is, the distance d11 between the first electrode 150 and the yellow-green light-emitting material layer 516a is smaller than the distance d12 between the second electrode 154 and the second blue light-emitting material layer 434.

In the light emitting diode (D) of the present invention, the first light emitting stack 510 includes a first blue light emitting material layer 516b together with a yellow green light emitting material layer 516a, so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (516a, 516b, 534) is located on the maximum luminance contour line, thereby improving or maximizing the light emitting efficiency of the light emitting diode (D).

That is, referring to FIG. 10, the light emitted from the light-emitting material layer is reflected by the second electrode 154, which is a reflective electrode, and then passes through the first electrode (150 in FIG. 9). 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 150.

As described above, the first blue light-emitting material layer 516a is located in the maximum luminance region of the blue wavelength at a distance of about 110 to 130 nm from the first electrode 150, and the second blue light-emitting material layer 534 is located in the first blue light-emitting material layer 534. It is spaced approximately 230 to 250 nm away from the electrode 150 and is located in the maximum luminance region of the blue wavelength.

Additionally, the yellow-green light-emitting material layer 516a is disposed below the first blue light-emitting material layer 516b and is located in the maximum luminance region of the yellow-green wavelength.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Moreover, the first blue light emitting material layer 516b may include a host whose electron mobility is greater than the hole mobility, and accordingly, the first blue light emitting material layer 516b is disposed in contact with the yellow green light emitting material layer 516a. This prevents the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 510 and a second light emitting stack located between the first electrode 150, which is a transparent electrode, and the second electrode 154, which is a reflective electrode. 530), and the yellow-green light-emitting material layer 516a of the first light-emitting stack 510, the first blue light-emitting material layer 516b, and the second blue light-emitting material layer 534 of the second light-emitting stack 530. By being located in the maximum luminance area of each wavelength, the luminous efficiency of the light emitting diode (D) is improved.

FIG. 11 is a schematic cross-sectional view of a light emitting diode according to a fourth embodiment of the present invention, and FIG. 12 is a photograph showing a luminance contour in a light emitting diode according to a fourth embodiment of the present invention. (In Figure 12, the vertical axis is the distance from the first electrode.)

As shown in FIG. 11, the light emitting diode (D) is located between the first electrode 150, which is a transparent electrode, the second electrode 154, which is a reflective electrode, and the first and second electrodes 150 and 154. It includes a light emitting layer 152. The thickness of the light emitting layer 152, that is, the distance between the first and second electrodes 150 and 154, may be about 400 to 500 nm.

The light-emitting layer 152 includes a first charge generation layer 620 located between the first electrode 150 and the second electrode 154, a yellow-green light-emitting material layer 616a, and a first blue light-emitting material layer 616b. A first light-emitting stack 610, which includes a first electrode 150 and a first charge generation layer 620, and a second blue light-emitting material layer 634, and a first charge generation layer 620. and a second light-emitting stack 630 located between the second electrode 154, a second charge generation layer 640 located between the second light-emitting stack 630 and the first charge generation layer 620, and It includes three blue light-emitting material layers 654 and a third light-emitting stack 650 located between the first charge generation layer 620 and the second charge generation layer 640. That is, the light emitting diode (D) has a triple stack structure.

For example, the emission wavelength of each of the first to third blue light-emitting material layers 616b, 634, and 654 may be about 440-480 nm, and the emission wavelength of the yellow-green light-emitting material layer 616b may be about 520-590 nm. And, the emission wavelength of the red light emitting material layer 334c may be about 620 to 700 nm.

That is, the first light-emitting stack 610 is located on the first light-emitting material layer (first blue light-emitting material layer, 616b) having a first light-emitting wavelength range and the lower surface of the first light-emitting material layer 616b, and emits first light. It includes a second light-emitting material layer (yellow-green light-emitting material layer, 616a) having a second light-emitting wavelength range that is larger than the wavelength range, and the second light-emitting stack 630 includes a third light-emitting material layer (yellow-green light-emitting material layer, 616a) having a first light-emitting wavelength range (yellow-green light-emitting material layer, 616a). It includes two blue light-emitting material layers (634), and the third light-emitting stack (650) includes a fourth light-emitting material layer (third blue light-emitting material layer (654)) having a first emission wavelength range.

The first light-emitting material layer 616b is located between the second light-emitting material layer 616a and the second electrode 154, which is a reflective electrode, or the first charge generation layer 620.

Each of the first to third blue light-emitting material layers 616b, 634, and 654 and the yellow-green light-emitting material layer 616a may include a phosphorescent or fluorescent organic light-emitting material or an inorganic light-emitting material such as quantum dots.

The first charge generation layer 620 includes a first N-type charge generation layer 622 and a first P-type charge generation layer 624. The first N-type charge generation layer 622 is located between the first light-emitting stack 610 and the first P-type charge generation layer 624. Additionally, the second charge generation layer 640 includes a second N-type charge generation layer 642 and a second P-type charge generation layer 644. The second N-type charge generation layer 642 is located between the third light-emitting stack 650 and the second P-type charge generation layer 644.

The first light-emitting stack 610 is sequentially stacked on the first electrode 150 and includes a hole injection layer 612 and a first hole transport layer ( 614) and a first electron transport layer 618 located between the first blue light emitting material layer 616b and the first charge generation layer 620.

The third light-emitting stack 650 includes a second hole transport layer 652 located between the first charge generation layer 620 and the third blue light-emitting material layer 654, the third blue light-emitting material layer 654, and the third blue light-emitting material layer 654. It may include a second electron transport layer 656 located between the two charge generation layers 640.

The second light-emitting stack 630 is formed on a third hole transport layer 632 located between the second charge generation layer 640 and the second blue light-emitting material layer 634, and on the second blue light-emitting material layer 634. It may be sequentially stacked and include a third electron transport layer 636 and an electron injection layer 638 positioned between the second blue light emitting material layer 634 and the second electrode 154.

When the distance between the first and second electrodes 150 and 154 is about 412 nm, the center of the first blue light-emitting material layer 616b may be located about 100 to 120 nm away from the first electrode 150. Additionally, the center of the second blue light-emitting material layer 634 may be located approximately 350 to 370 nm away from the first electrode 150, and the center of the third blue light-emitting material layer 654 may be located approximately 350 to 370 nm away from the first electrode 150. ) may be located approximately 240 to 260 nm apart.

Additionally, the center of the yellow-green light-emitting material layer 616a may be located approximately 20 to 40 nm away from the first electrode 150.

That is, the distance d13 between the first electrode 150 and the yellow-green light-emitting material layer 616a is smaller than the distance d14 between the second electrode 154 and the second blue light-emitting material layer 634.

In the light emitting diode (D) of the present invention, the first light emitting stack 510 includes a first blue light emitting material layer 616b together with a yellow green light emitting material layer 616a, so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (616a, 616b, 634, 654) is located on the maximum luminance contour line, thereby improving or maximizing the luminous efficiency of the light emitting diode (D).

That is, referring to FIG. 12, the light emitted from the light-emitting material layer is reflected by the second electrode 154, which is a reflective electrode, and then passes through the first electrode (150 in FIG. 11). 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 150.

As described above, the first blue light-emitting material layer 616a is located in the maximum luminance region of the blue wavelength at a distance of about 110 to 130 nm from the first electrode 150, and the second blue light-emitting material layer 634 is located in the first blue light-emitting material layer 634. It is spaced apart from the electrode 150 by about 230 to 250 nm and is located in the maximum luminance region of the blue wavelength, and the third blue light-emitting material layer 654 is spaced from the first electrode 150 by 240 to 260 nm and is located in the maximum luminance region of the blue wavelength. located in the area.

Additionally, the yellow-green light-emitting material layer 616a is disposed below the first blue light-emitting material layer 616b and is located in the maximum luminance region of the yellow-green wavelength.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Furthermore, the first blue light emitting material layer 616b may include a host whose electron mobility is greater than the hole mobility, and accordingly, the first blue light emitting material layer 616b is disposed in contact with the yellow green light emitting material layer 616a. This prevents the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 610 and a second light emitting stack located between the first electrode 150, which is a transparent electrode, and the second electrode 154, which is a reflective electrode. 630) and a third light-emitting stack 650, including a yellow-green light-emitting material layer 616a of the first light-emitting stack 610, a first blue light-emitting material layer 616b, and a second light-emitting material layer 616b of the second light-emitting stack 630. As the blue light emitting material layer 634 and the third blue light emitting material layer 654 of the third light emitting stack 650 are located in the maximum luminance region of each wavelength, the light emitting efficiency of the light emitting diode D is improved.

Figure 13 is a schematic cross-sectional view of the electroluminescence display device of the present invention.

As shown in FIG. 13 , the electroluminescent display device 700 includes a first substrate 710, a second substrate 770 facing the first substrate 710, and an upper portion of the first substrate 710. A light emitting diode (D), a driving thin film transistor (Td) located between the first substrate 710 and the light emitting diode (D) and connected to the light emitting diode (D), a second substrate 770 and a light emitting diode ( D) includes a color filter 730 located between them.

Each of the first substrate 710 and the second substrate 770 may be a glass substrate or a plastic substrate. For example, each of the first substrate 710 and the second substrate 770 may be made of polyimide.

The first substrate 710 includes a red pixel region (RP), a green pixel region (GP), and a blue pixel region (BP), and the driving thin film transistor (Td) includes a red pixel region (RP) and a green pixel region (GP). ), located in each blue pixel area (BP). Meanwhile, the first substrate 710 may further include a white pixel area (not shown), and a driving thin film transistor (Td) is also disposed in the white pixel area.

For example, the driving thin film transistor (Td) includes a semiconductor layer formed on the first substrate 710, a gate electrode located on top of the semiconductor layer and overlapping it, and a source disposed on top of the gate electrode and connected to both ends of the semiconductor layer. It may include an electrode and a drain electrode.

An insulating layer 720 is formed on the driving thin film transistor (Td), and a contact hole 722 is formed in the insulating layer 120 to expose one electrode, for example, a drain electrode, of the driving thin film transistor (Td).

On the insulating layer 720, a first electrode 750 connected to the driving thin film transistor (Td) through the contact hole 122 is formed separately for each red, green, and blue pixel region (RP, GP, BP). The first electrode 750 may be an anode and may be made of a conductive material with a relatively high work function value. The first electrode 750 includes a transparent electrode layer and a reflective electrode (or reflective layer). For example, the first electrode 750 may have a triple-layer structure including a lower layer and an upper layer of an ITO layer (or IZO) and a middle layer of aluminum-palladium-copper (APC) alloy.

Additionally, a bank 760 covering the edge of the first electrode 750 is formed on the insulating layer 720. The bank 760 exposes the center of the first electrode 750 corresponding to the red, green, and blue pixel regions (RP, GP, BP).

A light emitting layer 752 is formed on the first electrode 750. The light emitting layer 752 emits white light and is formed integrally with the entire display area including the red, green, and blue pixel areas (RP, GP, and BP).

A second electrode 754 is formed on the first substrate 710 on which the light emitting layer 752 is formed. The second electrode 754 is located in front of the display area including the red, green, and blue pixel areas (RP, GP, BP) and is made of a conductive material with a relatively small work function value and can be used as a cathode. . For example, the second electrode 754 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg), and has a thin thickness to allow light to pass through.

The first electrode 750, the light emitting layer 752, and the second electrode 754 form a light emitting diode (D).

A color filter 730 is formed on the light emitting diode (D). That is, the color filter 730 is located between the light emitting diode (D) and the second substrate 770. The color filter 730 includes a red color filter pattern 730a corresponding to the red pixel area (RP), a green color filter pattern 730b corresponding to the green pixel area (GP), and a blue pixel area (BP). It includes a blue color filter pattern 730c.

Although not shown, a polarizing plate may be attached to the outer surface of the second substrate 770 to reduce external light reflection. For example, the polarizer may be a circular polarizer.

The electroluminescent display device 700 of the present invention is a bottom emission type. That is, light from the light emitting layer 752 passes through the second electrode 752 and the color filter 730, and an image is displayed on the second substrate 770.

That is, the first electrode 750 is a reflective electrode, the second electrode 754 is used as a transparent electrode (transflective electrode), and the light from the light emitting layer 752 passes directly through the second electrode 754 or is transmitted through the second electrode 754. After being reflected from the first electrode 750, it passes through the second electrode 754.

Since white light from the light emitting diode (D) passes through the color filter 730, the electroluminescence display device 700 can display a color image.

FIG. 14 is a schematic cross-sectional view of a light emitting diode according to a sixth embodiment of the present invention, and FIG. 15 is a photograph showing a luminance contour in a light emitting diode according to a sixth embodiment of the present invention. (In Figure 15, the vertical axis is the distance from the first electrode.)

As shown in Figure 14, the light emitting diode (D) is located between the first electrode 750, which is a reflective electrode, the second electrode 754, which is a transparent electrode, and the first and second electrodes 750 and 754. It includes a light emitting layer 752. The thickness of the light emitting layer 752, that is, the distance between the first and second electrodes 750 and 754, may be about 300 to 400 nm.

The light-emitting layer 752 includes a charge generation layer 820 located between the first electrode 750 and the second electrode 754, and a first blue light-emitting material layer 816, and the first electrode 750 and the charge It includes a first light-emitting stack 810 located between the generation layers 820, a yellow-green light-emitting material layer 834a, and a second blue light-emitting material layer 834b on the yellow-green light-emitting material layer 834a, and a charge generation layer ( It includes a second light emitting stack 830 located between 820) and the second electrode 754. That is, the light emitting diode (D) has a double stack structure.

For example, the emission wavelength of each of the first and second blue light emitting material layers 816 and 834b may be about 440 to 480 nm, and the emission wavelength of the yellow green light emitting material layer 834a may be about 520 to 590 nm.

That is, the first light-emitting stack 810 includes a first light-emitting material layer (first blue light-emitting material layer, 816) having a first light-emitting wavelength range, and the second light-emitting stack 830 includes a first light-emitting wavelength range. a second light-emitting material layer (second blue light-emitting material layer, 834b) and a third light-emitting material layer located on the lower surface of the second light-emitting material layer (834b) and having a second light-emitting wavelength range that is larger than the first light-emitting wavelength range. (yellow green light emitting material layer, 834a).

The second light emitting material layer 834b is located between the third light emitting material layer 834a and the second electrode 154, which is a transparent electrode.

Each of the first and second blue light emitting material layers 816 and 834b and the yellow green light emitting material layer 834a may include a phosphorescent or fluorescent organic light emitting material or an inorganic light emitting material such as quantum dots.

The charge generation layer 820 includes an N-type charge generation layer 822 and a P-type charge generation layer 824. The N-type charge generation layer 822 is located between the first light-emitting stack 810 and the P-type charge generation layer 824.

The first light emitting stack 810 is sequentially stacked on the first electrode 750 and includes a hole injection layer 812 and a first hole positioned between the first electrode 750 and the first blue light emitting material layer 816. It may include a transport layer 814 and a first electron transport layer 818 located between the first blue light-emitting material layer 816 and the charge generation layer 820.

The second light-emitting stack 830 is sequentially stacked on the second hole transport layer 832 and the second blue light-emitting material layer 834b located between the charge generation layer 820 and the yellow-green light-emitting material layer 834a. 2 It may include a second electron transport layer 836 and an electron injection layer 838 located between the blue light emitting material layer 834b and the second electrode 754.

When the distance between the first and second electrodes 750 and 754 is about 360 nm, the center of the first blue light-emitting material layer 816 may be located about 20 to 40 nm away from the first electrode 750, The center of the second blue light-emitting material layer 834b may be located approximately 260 to 300 nm away from the first electrode 750. Additionally, the center of the yellow-green light emitting material layer 834a may be located approximately 180 to 220 nm away from the first electrode 750.

That is, the distance d15 between the first electrode 750 and the first blue light-emitting material layer 716 is smaller than the distance d16 between the second electrode 754 and the second blue light-emitting material layer 834b.

In the light emitting diode (D) of the present invention, the second light emitting stack 830 includes a second blue light emitting material layer (834b) together with a yellow green light emitting material layer (834a), so that blue light emission efficiency is improved and the light emitting diode (D) ) lifespan is increased.

That is, the blue light emitting material layer has a problem of low light emitting efficiency and lifespan, and the shortcomings of the blue light emitting material layer are compensated by adding the second blue light emitting material layer 834b to the second light emitting stack 830.

Additionally, in the light emitting diode (D) of the present invention, each light emitting material layer (816, 834a, 834b) is located on the maximum luminance contour line, thereby improving or maximizing the light emitting efficiency of the light emitting diode (D).

That is, referring to FIG. 15, the light emitted from the light emitting material layer is reflected from the first electrode 750, which is a reflective electrode, and then passes through the second electrode (750 in FIG. 14), which is the second electrode 754 or the second electrode 754. 1 The wavelength at which maximum luminance is realized is determined depending on the distance from the electrode 750.

As described above, the first blue light-emitting material layer 816 is located in the maximum luminance region of the blue wavelength at a distance of about 20 to 40 nm from the first electrode 750, and the second blue light-emitting material layer 834b is located in the first blue light-emitting material layer 834b. It is spaced approximately 260 to 300 nm away from the electrode 750 and is located in the maximum luminance region of the blue wavelength.

Additionally, the yellow-green light-emitting material layer 834a is disposed below the second blue light-emitting material layer 834b and is located in the maximum luminance region of the yellow-green wavelength.

Accordingly, the luminous efficiency of the light emitting diode (D) is greatly improved.

Moreover, the second blue light emitting material layer 834b may include a host whose electron mobility is greater than the hole mobility, and accordingly, the second blue light emitting material layer 834b is disposed in contact with the yellow green light emitting material layer 834a. This prevents the problem of reduced luminous efficiency.

As described above, the light emitting diode (D) of the present invention includes a first light emitting stack 810 and a second light emitting stack located between the first electrode 750, which is a reflective electrode, and the second electrode 754, which is a transparent electrode. 830), and the first blue light-emitting material layer 816 of the first light-emitting stack 810, the yellow-green light-emitting material layer 834a, and the second blue light-emitting material layer 834b of the second light-emitting stack 830. By being located in the maximum luminance area of each wavelength, the luminous efficiency of the light emitting diode (D) is improved.

FIG. 16 is a graph showing the light emission spectrum of the light emitting diode, which is the light emission spectrum of the light emitting diode Ex shown in FIG. 5 and the light emitting diode from which the second blue light emitting material layer 334b is omitted.

In the light emitting diode (Ex) of the present invention, the second blue light emitting material layer 334b is disposed in the maximum luminance area in the second light emitting stack 330, thereby increasing the blue wavelength intensity, as shown in FIG. 16.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the technical spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

100, 700: electroluminescence display device 150, 750: first electrode
152, 752: light emitting layer 154, 754: second electrode
212, 312, 412, 512, 612, 812: Hole injection layer
214, 232, 314, 332, 352, 414, 432, 452, 514, 534, 614, 632, 652, 814, 832: Hole transport layer
216, 234a, 234b, 234c, 316, 334a, 334b, 334c, 354, 416, 434a, 434b, 434c, 454, 516a, 516b, 534, 616a, 616b, 634, 654, 816, 834a, 834b: Luminescent material floor
218, 236, 318, 336, 356, 418, 436, 456, 518, 536, 618, 636, 656, 818, 836: Electron transport layer
238, 358, 458, 538, 658, 838: electron injection layer
220, 320, 340, 420, 440, 520, 620, 640, 820: Charge generation layer
D: light emitting diode

Claims (26)

a transparent electrode;
a reflective electrode facing the transparent electrode;
a first charge generation layer positioned between the transparent electrode and the reflective electrode;
a first light-emitting stack comprising a first light-emitting material layer having a first light-emitting wavelength range and positioned between the transparent electrode and the first charge generating layer;
a second light-emitting material layer having a first light-emitting wavelength range, and a third light-emitting layer having a second light-emitting wavelength range greater than the first light-emitting wavelength range and positioned between the second light-emitting material layer and the first charge generating layer. a material layer, and a fifth light-emitting material layer having a third light-emitting wavelength range that is greater than the second light-emitting wavelength range and positioned between the third light-emitting material layer and the first charge generating layer, wherein the first charge generating layer includes: A light emitting diode comprising a second light emitting stack positioned between the layer and the reflective electrode.
According to claim 1,
a second charge generation layer positioned between the second light emitting stack and the reflective electrode;
A light emitting diode comprising a fourth light emitting material layer having the first light emitting wavelength range and further comprising a third light emitting stack positioned between the second charge generation layer and the reflective electrode.
According to claim 2,
A light emitting diode wherein the distance between the first light emitting material layer and the transparent electrode is greater than the distance between the fourth light emitting material layer and the reflective electrode.
delete According to claim 2,
A light emitting diode wherein the distance between the first light emitting material layer and the fifth light emitting material layer is smaller than the distance between the second light emitting material layer and the fourth light emitting material layer.

delete According to claim 1,
a second charge generation layer positioned between the second light emitting stack and the first charge generation layer;
A light emitting diode comprising a fourth light emitting material layer having the first light emitting wavelength range and further comprising a third light emitting stack positioned between the first charge generation layer and the second charge generation layer.
According to claim 1 or 7,
A light emitting diode wherein the distance between the first light emitting material layer and the transparent electrode is greater than the distance between the second light emitting material layer and the reflective electrode.
delete According to claim 7,
A light emitting diode wherein the distance between the fifth light emitting material layer and the fourth light emitting material layer is smaller than the distance between the first light emitting material layer and the fourth light emitting material layer.

delete delete delete delete delete delete According to claim 1,
A light emitting diode wherein the third light emitting material layer includes a host and a dopant, and the electron mobility of the host is greater than the hole mobility of the host.
According to claim 1,
A light emitting diode wherein the first emission wavelength range is 440 to 480 nm, and the second emission wavelength range is 520 to 590 nm.
According to claim 1,
The first emission wavelength range is 440 to 480 nm, the second emission wavelength range is 520 to 590 nm, and the third emission wavelength range is 620 to 700 nm.
With a substrate;
a light emitting diode according to any one of claims 1 to 3, 5, 7, 10, and 17 to 19 located on the upper part of the substrate;
A thin film transistor located between the substrate and the light emitting diode and connected to the light emitting diode.
An electroluminescent display device comprising:
According to claim 20,
The light emitting diodes correspond to red, green and blue pixel areas,
An electroluminescent display device further comprising red, green, and blue color filter patterns located in each of the red, green, and blue pixel regions.
According to claim 21,
The red, green and blue color filter patterns are located between the substrate and the light emitting diode.
According to claim 21,
The red, green and blue color filter patterns are located on top of the light emitting diode. According to claim 3,
The distance between the reflective electrode and the transparent electrode is 412 nm,
The distance between the first light emitting material layer and the transparent electrode is 100 to 120 nm,
A light emitting diode wherein the distance between the fourth light emitting material layer and the transparent electrode is 350 to 370 nm.
According to claim 5,
The distance between the reflective electrode and the transparent electrode is 300 nm,
The distance between the second light emitting material layer and the transparent electrode is 30 to 50 nm,
A light emitting diode where the distance between the third light emitting material layer and the transparent electrode is 230 to 250 nm.
delete