KR20190042895A - Light emitting diode and Electroluminescent display device including the same - Google Patents

Abstract

According to the present invention, provided are a light emitting diode and an electroluminescent display device comprising: a first electrode located at a first and a second pixel; a first light emitting layer located in the first pixel, and including a first light emitting material and a first electroactive material; a second light emitting layer located in the second pixel, and including a second light emitting material; and a second electrode covering the first and the second light emitting layer.

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting diode and an electroluminescent display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a light emitting diode capable of realizing a micro cavity effect with a simple structure and an electroluminescent display device including the same.

(PDP), plasma display (PDP), and plasma display devices (PDPs) have been rapidly developed in the field of display for processing and displaying a large amount of information. Panel devices (PDPs), and electroluminescent display devices have been developed and popularized.

The electroluminescent display includes a light emitting diode, and in the light emitting diode, includes an electron injection electrode (cathode), a hole injection electrode (anode), and a light emitting layer disposed therebetween. When electrons and holes are injected into the light emitting layer from the cathode and the anode, the electrons and holes are paired and then disappear and light is emitted from the light emitting diode.

The electroluminescent display device includes a red pixel, a green pixel, and a blue pixel, and red, green, and blue light are emitted from the light emitting diode of each pixel to realize a color image.

On the other hand, since the wavelengths of light emitted from red, green and blue pixels are different, a microcavity structure has been proposed in which the luminous efficiency is increased by varying the distance between the anode and the cathode in each pixel.

1 is a schematic cross-sectional view of a conventional micro cavity structure light emitting diode.

1, in the light emitting diode D in which the red pixel RP, the green pixel GP and the blue pixel BP are defined, the first electrode 10 is connected to the red pixel RP, The green pixel GP and the blue pixel BP, respectively.

The first electrode 10 may be made of a conductive material having a relatively large work function value and may be a positive electrode. For example, the first electrode 10 may include an electrode layer of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) A reflective electrode layer or a reflective layer.

A hole injection layer 30 is formed on the first electrode 10 and a hole transporting layer 40 is formed on the hole injection layer 30.

Further, a light emitting material layer 50 is formed on the hole transporting layer 40. The light emitting material layer 50 includes a red light emitting material pattern 52 corresponding to the red pixel RP, a green light emitting material pattern 54 corresponding to the green pixel GP, And may include a luminescent material pattern 56.

An electron transporting layer 60 and an electron injection layer 70 are sequentially stacked on the light emitting material layer 50 and a second electrode 4 is formed on the electron injection layer 70 . The second electrode 20 may be made of a conductive material having a relatively small work function value and may be a cathode. For example, the second electrode 20 may be formed of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg), and may be a semi-transparent electrode as a thin film.

That is, the light emitting diode D includes first and second electrodes 10 and 20 facing each other, a hole injecting layer 30, a hole transporting layer 40, a light emitting material layer 50, an electron transporting layer 60, And an emission layer including the electron injection layer 70 and located between the first and second electrodes 10 and 20.

The hole transport layer 40 has a first thickness t1 in the red pixel RP and a second thickness t2 in the green pixel GP that is smaller than the first thickness t1, Has a third thickness t3 that is less than the second thickness t2. Therefore, the first and second electrodes 10 and 20 have a first distance d1 in the red pixel RP and a second distance d2 in the green pixel GP that is smaller than the first distance d1 And has a third distance d3 smaller than the second distance d2 in the blue pixel BP.

In the light emitting diode D having such a structure, a part of the light of the first wavelength emitted from the red pixel RP is reflected by the first and second electrodes 10 and 20 spaced apart by the first distance d1, The luminous efficiency is improved. Part of the light of the second wavelength emitted from the green pixel GP is reflected between the first and second electrodes 10 and 20 spaced apart by the second distance d2 to improve the luminous efficiency, A part of the light of the third wavelength emitted from the first and second electrodes BP is reflected between the first and second electrodes 10 and 20 spaced apart by the third distance d3,

However, since at least one of the light emitting layers, for example, the hole transporting layer 40, must be formed so as to have different thicknesses in the pixels RP, GP, and BP in the conventional micro cavity light emitting diode D, There arises a problem that the manufacturing process and structure become complicated.

In addition, when the light emitting layer is formed by a solution process, its thickness control is limited.

An object of the present invention is to solve the problem of complicating the fabrication process and structure of a microcavity structure light emitting diode.

In order to solve the above problems, the present invention provides a liquid crystal display comprising: a first electrode located in first and second pixels; A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material; A second light emitting layer located in the second pixel and including a second light emitting material; And a second electrode covering the first and second light emitting layers.

In another aspect, the present invention provides a liquid crystal display comprising: a first electrode located in first and second pixels; A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material; A second light emitting layer located in the second pixel and including a second light emitting material and a second electroactive material; And a second electrode covering the first and second light emitting layers.

In another aspect, the present invention provides a liquid crystal display comprising: first and second electrodes facing each other in a first pixel; And a first light emitting layer disposed between the first and second electrodes, wherein the first light emitting layer has a first thickness in a first voltage state and a second thickness in a second voltage state, which is greater than the first voltage, A light emitting diode having a large second thickness is provided.

In another aspect, the present invention provides a semiconductor device comprising: a substrate; The above-described light emitting diode located above the substrate; And a thin film transistor located between the substrate and the light emitting diode and connected to the first electrode.

The present invention can prevent a complicated structure problem in a conventional electroluminescent display device implementing a microcavity by including the electroactive material in the red and green pixels.

That is, since the light emitting layer in the red pixel and the green pixel includes the electroactive material and the distance between the first and second electrodes in the red pixel and the green pixel is changed by driving the electroluminescence display device, The first and second inter-electrode distances in at least one of the first and second inter-electrode distances may be substantially the same as the distances between the first and second inter-electrode distances in the blue pixel.

In addition, when the light emitting material layer includes quantum dots and an electroactive material, the charge balance can be improved and the lifetime and luminous efficiency of the light emitting diode and the electroluminescence display device can be improved.

1 is a schematic cross-sectional view of a conventional micro cavity structure light emitting diode.
2 is a schematic cross-sectional view of an electroluminescent display device according to the present invention.
3 is a schematic cross-sectional view of a light emitting diode according to a first embodiment of the present invention.
4A to 4D are graphs showing the thickness variation according to the amount of the electro-active material in the red pixel.
5 is a graph showing the relationship between the amount of the electro-active material and the thickness variation in the red pixel.
6A to 6D are graphs showing the thickness variation according to the amount of the electro-active material in the green pixel.
7 is a graph showing the relationship between the amount of the electro-active material and the thickness variation in the green pixel.
8 is a schematic cross-sectional view of a light emitting diode according to a second embodiment of the present invention.
9 is a schematic cross-sectional view of a light emitting diode according to a third embodiment of the present invention.

The present invention provides a liquid crystal display comprising: a first electrode located in first and second pixels; A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material; A second light emitting layer located in the second pixel and including a second light emitting material; And a second electrode covering the first and second light emitting layers.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the first and second pixels is the same.

The light emitting diode of the present invention further includes a third light emitting layer located in a third pixel and including a third light emitting material and the first electroactive material.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the three pixels is the same as the distance between the first and second electrodes in the first pixel.

In the light emitting diode of the present invention, the mass ratio of the first electroactive material to the first electroluminescent material in the first pixel is smaller than the mass ratio of the first electroactive material to the third electroluminescent material in the third pixel .

In the light emitting diode of the present invention, the amount of the first electroactive material in the first pixel is smaller than the first electroactive material in the third pixel.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the three pixels is larger than the distance between the first and second electrodes in the first pixel.

In the light emitting diode of the present invention, the mass ratio of the first electroactive material to the first light emitting material in the first pixel is the same as the mass ratio of the first electroactive material to the third light emitting material in the third pixel Do.

In the light emitting diode of the present invention, the amount of the first electroactive material in the first pixel is the same as the first electroactive material in the third pixel.

The light emitting diode of the present invention further includes a third light emitting layer located in the third pixel and including a third light emitting material and a second electroactive material having a larger dipole moment than the first electroactive material.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the three pixels is the same as the distance between the first and second electrodes in the first pixel.

In the light emitting diode of the present invention, each of the first and second light emitting layers includes a hole transport layer and a light emitting material layer, and the first light emitting material and the first electroactive material are included in the light emitting material layer of the first light emitting layer , And the second luminescent material is included in the luminescent material layer of the second luminescent layer.

In the light emitting diode of the present invention, the first luminescent material is a quantum dot.

In the light emitting diode of the present invention, each of the first and second light emitting layers includes a hole transport layer and a light emitting material layer, and each of the first and second light emitting materials is included in the light emitting material layer of the first and second light emitting layers , The first electroactive material is contained in the hole transport layer of the first light emitting layer.

In another aspect, the present invention provides a liquid crystal display comprising: a first electrode located in first and second pixels; A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material; A second light emitting layer located in the second pixel and including a second light emitting material and a second electroactive material; And a second electrode covering the first and second light emitting layers.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the first and second pixels is the same, and the amount of the first electroactive material is smaller than that of the second electroactive material.

In the light emitting diode of the present invention, the distance between the first and second electrodes in the first and second pixels is the same, and the dipole moment of the first electroactive material is smaller than that of the second electroactive material.

In another aspect, the present invention provides a liquid crystal display comprising: first and second electrodes facing each other in a first pixel; And a first light emitting layer disposed between the first and second electrodes, wherein the first light emitting layer has a first thickness in a first voltage state and a second thickness in a second voltage state, which is greater than the first voltage, A light emitting diode having a large second thickness is provided.

The light emitting diode of the present invention further includes a second light emitting layer located in the second pixel, and the second light emitting layer has a constant thickness in the first voltage state and the second voltage state.

In another aspect, the present invention provides a semiconductor device comprising: a substrate; The above-described light emitting diode located above the substrate; And a thin film transistor located between the substrate and the light emitting diode and connected to the first electrode.

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

2 is a schematic cross-sectional view of an electroluminescent display device according to the present invention.

2, the electroluminescent display 100 according to the present invention includes a substrate 110, a driving element Tr positioned on the substrate 110, a driving transistor Tr connected to the driving element Tr, And a light emitting diode (D).

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

A buffer layer 120 is formed on the substrate 110 and a thin film transistor Tr is formed on the buffer layer 120. The buffer layer 120 may be omitted.

A semiconductor layer 122 is formed on the buffer layer 120. The semiconductor layer 122 may be made of an oxide semiconductor material or polycrystalline silicon.

When the semiconductor layer 122 is made of an oxide semiconductor material, a light shielding pattern (not shown) may be formed under the semiconductor layer 122, and the light shielding pattern may prevent the light from being incident on the semiconductor layer 122. [ Thereby preventing the semiconductor layer 122 from being deteriorated by light. Alternatively, the semiconductor layer 122 may be made of polycrystalline silicon. In this case, impurities may be doped on both edges of the semiconductor layer 122.

A gate insulating layer 124 made of an insulating material is formed on the semiconductor layer 122. The gate insulating layer 124 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 130 made of a conductive material such as metal is formed on the gate insulating layer 124 to correspond to the center of the semiconductor layer 122.

Although the gate insulating layer 124 is formed on the entire surface of the substrate 110 in FIG. 2, the gate insulating layer 124 may be patterned to have the same shape as the gate electrode 130.

An interlayer insulating layer 132 made of an insulating material is formed on the gate electrode 130. The interlayer insulating film 132 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or may be formed of an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 132 has first and second contact holes 134 and 136 exposing both sides of the semiconductor layer 122. The first and second contact holes 134 and 136 are spaced apart from the gate electrode 130 on both sides of the gate electrode 130.

Here, the first and second contact holes 134 and 136 are also formed in the gate insulating film 124. Alternatively, when the gate insulating film 124 is patterned to have the same shape as the gate electrode 130, the first and second contact holes 134 and 136 may be formed only in the interlayer insulating film 132.

A source electrode 140 and a drain electrode 142 made of a conductive material such as a metal are formed on the interlayer insulating layer 132.

The source electrode 140 and the drain electrode 142 are spaced apart from each other around the gate electrode 130 and are electrically connected to the semiconductor layer 122 through the first and second contact holes 134 and 136, As shown in Fig.

The semiconductor layer 122 and the gate electrode 130, the source electrode 140 and the drain electrode 142 constitute the thin film transistor Tr. The thin film transistor Tr includes a driving element ).

The thin film transistor Tr has a coplanar structure in which the gate electrode 130, the source electrode 142, and the drain electrode 144 are positioned on the semiconductor layer 120.

Alternatively, the thin film transistor Tr may have an inverted staggered structure in which a gate electrode is positioned below the semiconductor layer and a source electrode and a drain electrode are located above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Although not shown, a gate line and a data line cross each other to define a pixel region, and a switching element connected to the gate line and the data line is further formed. The switching element is connected to the thin film transistor Tr which is a driving element.

In addition, a storage capacitor is formed for keeping the voltage of the gate electrode of the thin film transistor (Tr), which is a driving element, constant during one frame, the power wiring being formed in parallel with the data wiring or the data wiring Lt; / RTI >

A protective layer 150 having a drain contact hole 152 exposing the drain electrode 142 of the thin film transistor Tr is formed to cover the thin film transistor Tr.

A first electrode 160 connected to the drain electrode 142 of the thin film transistor Tr through the drain contact hole 152 is formed on the passivation layer 150 for each pixel region. The first electrode 160 may be an anode and may be formed of a conductive material having a relatively large work function value. For example, the first electrode 160 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) .

Meanwhile, when the electroluminescent display 100 of the present invention is a top emission type, a reflective electrode or a reflective layer may be further formed under the first electrode 160. For example, the reflective electrode or the reflective layer may be formed of an aluminum-palladium-copper (APC) alloy.

A bank layer 166 covering the edge of the first electrode 160 is formed on the passivation layer 150. The bank layer 166 exposes the center of the first electrode 160 corresponding to the pixel region.

A light emitting layer 170 is formed on the first electrode 160. The light emitting layer 170 includes a light emitting material and an electroactive material or an electroactive polymer.

Electroactive materials are substances whose morphology changes by application of an electric field (or voltage). For example, a shape having a long axis in the first direction by an electric field and a shape having a long axis in the second direction perpendicular thereto.

The electroactive material can be any one of polyvinylidene fluoride (PVDF), polyvinylidene cyanide (PVDCN), polyvinylidene chloride (PVDCL), amide polymer, urea polymer or carbonyl polymer.

For example, the PVDF may be any one of the following Formulas 1-1 to 1-3, PVDCN may be the following Formula 2, and PVDCL may be the following Formula 3. The amide polymer may be represented by the following formula 4-1 or 4-2, the urea polymer may be represented by the following formula 5-1 or 5-2, and the carbonyl polymer may be represented by the following formula 6-1 or 6-2 .

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

(2)

(3)

[Formula 4-1]

[Formula 4-2]

[Formula 5-1]

[Formula 5-2]

[Formula 6-1]

[Formula 6-2]

"N" in the formulas (1-1), (1-2) and (2-2) may be an integer of about 100-20000, "a" 0.3. (a + b = 1) Thus, the electroactive material can have a molecular weight of about 10,000 to 100,000.

The electroactive material has a dipole moment and the degree of morphological change of the electroactive material depends on the magnitude of the dipole moment.

The dipole moment values of the electroactive material are listed in Tables 1 and 2 below.

[Table 1]

[Table 2]

As shown in Table 1 and Table 2, electroactive materials have different molecular dipole moments. Therefore, even if the same amount of electroactive material is used, other shape changes occur.

The light emitting layer 170 may have a single layer structure of a light emitting material layer made of a light emitting material. The light emitting layer 170 may include a hole injection layer, a hole transporting layer, a light emitting material layer, and an electron transporting layer sequentially stacked on the first electrode 160 an electron transporting layer, and an electron injection layer.

At this time, the light emitting material layer may include an inorganic light emitting material such as a quantum dot or an organic light emitting material of phosphorescence or fluorescence.

A second electrode 180 is formed on the substrate 110 on which the light emitting layer 170 is formed. The second electrode 180 is disposed on the entire surface of the display region and is made of a conductive material having a relatively small work function value and can be used as a cathode. For example, the second electrode 180 may be formed of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

The first electrode 160, the light emitting layer 170, and the second electrode 180 form a light emitting diode D.

An encapsulation film 190 is formed on the second electrode 180 to prevent external moisture from penetrating into the LED. The encapsulation film 190 may have a laminated structure of a first inorganic insulating layer 192, an organic insulating layer 194, and a second inorganic insulating layer 196, but is not limited thereto.

In addition, a polarizer (not shown) may be attached on the encapsulation film 190 to reduce external light reflection. For example, the polarizer may be a circular polarizer.

3 is a schematic cross-sectional view of a light emitting diode according to a first embodiment of the present invention.

A light emitting diode D is formed in each of the red pixel RP, the green pixel BP, and the blue pixel BP, as shown in FIG.

The light emitting diode D includes a first electrode 160 positioned in each of the red pixel RP, the green pixel BP and the blue pixel BP and a red pixel RP, A second electrode 180 covering all of the blue pixels BP and a light emitting layer 170 disposed between the first and second electrodes 160 and 180.

The first electrode 160 may be separated from the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the first electrode 160 is made of a conductive material having a relatively large work function value and can be used as an anode. For example, the first electrode 160 may include first and second layers of an aluminum-palladium-copper alloy, and a third layer of ITO and located between the first and second layers. have.

The second electrode 180 may be formed integrally with the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the second electrode 180 may be formed of a conductive material having a relatively low work function value and used as a cathode. For example, the second electrode 180 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg), and may be a thin transflective electrode.

The distance between the first and second electrodes 160 and 180 is substantially the same in the red pixel RP, the green pixel BP, and the blue pixel BP.

The light emitting layer 170 includes a light emitting material layer 230. The light emitting material layer 230 includes a first light emitting material layer 232 located in the green pixel GP and including a first light emitting material (not shown) A second light emitting material layer 234 including a material (not shown), and a third light emitting material layer 236 located at the red pixel RP and including a third light emitting material (not shown).

As described above, each of the first to third light emitting materials may be an inorganic light emitting material such as a quantum dot, or an organic light emitting material of fluorescence or phosphorescence.

Here, the first light emitting material layer 232 and the third light emitting material layer 236 may each include an electroactive material 260. Accordingly, when a voltage is applied to the first and second electrodes 160 and 180 for driving the light emitting diode D, the shape of the electroactive material 260 changes and the red and green pixels RP and GP The thickness of the first and third emissive material layers 232 and 236 increases. That is, the distance between the first and second electrodes 160 and 180 increases in the red and green pixels RP and GP. Since the second light emitting material layer 234 of the blue pixel BP includes only the second light emitting material without the electroactive material, the thickness of the second light emitting material layer 234 and the thicknesses of the first and second electrodes 234, (160, 180) does not change.

The electroactive material 260 may have a first weight ratio to the first light emitting material in the green pixel GP and a second weight ratio to the third light emitting material in the red pixel RP, And has a second weight ratio.

In other words, when the thicknesses and areas of the first and third emissive material layers 232 and 236 are the same, the amount of the electroactive material 260 may be larger in the red pixel RP than in the green pixel BP have.

Therefore, when the light emitting diode D is driven, the degree of increase in the distance between the first and second electrodes 160 and 180 in the red pixel RP is greater than the distance between the first and second electrodes 160 and 160 in the green pixel GP. , 180). That is, when the light emitting diode D is driven, the distance between the first and second electrodes 160 and 180 in the green pixel BP is larger than the distance between the first and second electrodes 160 and 180 ) And is larger than the first and second inter-electrode distances in the blue pixel (BP).

In other words, the distances between the first and second electrodes 160 and 180 in the light emitting diode D are the same in the red pixel RP, the green pixel BP, and the blue pixel BP, When the diode D is driven, the distance between the first and second electrodes 160 and 180 is changed by the electroactive material 260, thereby realizing a microcavity effect.

Accordingly, the distance between the first and second electrodes 160 and 180 can be made equal to each other, thereby simplifying the structure of the light emitting diode D, and improving the luminous efficiency by the microcavity effect.

When the first and third light emitting materials are quantum dots, the light emitting diode D and the electroluminescent display device (not shown) are formed by the electroactive material 260 in the first and third light emitting material layers 232 and 236, The lifetime and luminous efficiency of 100 of FIG. 2) can be improved.

The electroactive material 260 has a relatively large dipole moment, thereby increasing the dielectric constant of the first and third emissive material layers 232 and 236. If a strong electric field is applied to the quantum dots, damage of the quantum dots may occur. Since the permittivity of the first and third light emitting material layers 232 and 236 increases due to the electroactive material 260, Electrons are uniformly dispersed in the holes 232 and 236. That is, the concentration of the electric field with respect to the quantum dots is relaxed, and the damage of the quantum dots is prevented.

In the quantum dot light emitting diode using quantum dots, electrons are delivered to the light emitting material layer more quickly than holes, and the charged particles are broken. The electroactive material 260 having a large dipole moment attracts electrons to form first and third light emitting material layers The charge balance in the electrodes 232 and 236 is improved.

Therefore, when the first and third light emitting material layers 232 and 236 include the quantum dots and the electroactive material 260, the lifetime and luminous efficiency of the light emitting diode D and the electroluminescence display device 100 Can be improved.

3, the second light emitting material layer 234 of the blue pixel BP includes only the second light emitting material. However, the second light emitting material layer 234 may further include the electroactive material 260 have. In this case, the weight ratio of the electroactive material 260 to the second luminescent material in the blue pixel BP is smaller than the weight ratio of the electroactive material 260 to the first luminescent material in the green pixel GP.

The light emitting layer 170 may further include a hole transport layer 220 disposed between the first electrode 160 and the first, second, and third light emitting material layers 232, 234, and 236, respectively. 3, the electroactive material 260 is included in the first and third light emitting material layers 232 and 236, but the electroactive material 260 may be included in the hole transporting layer 220.

The light emitting layer 170 may include a hole injection layer 210 between the first electrode 160 and the hole transport layer 220 and a hole injection layer 210 between the light emitting material layer 230 and the second electrode 180. [ And an electron injection layer 250 positioned between the electron transport layer 240 and the second electrode 180. The electron injection layer 250 may be formed of an electron transport layer 240,

In other words, in the light emitting diode D of the present invention, the light emitting layer 230 of the first pixel P1 (green pixel) includes the first light emitting material and the electroactive material 260, And the light emitting layer 230 of the third pixel P3 includes a third light emitting material and an electroactive material 260. The light emitting layer 230 of the first pixel P3 includes a second light emitting material,

At this time, distances between the first and second electrodes 160 and 180 are the same in the first, second, and third pixels P1, P2, and P3, and the electro- (Density or amount) larger than that of the first pixel P2.

Therefore, the micro-cavity effect can be realized in the light-emitting diode D having the simple structure in which the distance between the first and second electrodes 160 and 180 is the same in the first to third pixels P1, P2, and P3, Accordingly, the light emitting efficiency of the light emitting diode D and the electroluminescent display device 100 (FIG. 2) can be improved.

[Change in thickness of light emitting layer]

The thickness variation (displacement) of the light emitting layer was measured while changing the mass ratio of the quantum dot (QD) to the electroactive material (EAM). Displacement was measured at 500mHz using a laser displacement sensor under sine wave driving conditions.

(1) Change in thickness of a light emitting layer in a red pixel

1) Experimental Example 1

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) having a size of about 10 nm and 1 g of a solution of an electroactive material (1 wt% in MEK (Methyl Ethyl Ketone) 10V) was applied to measure the thickness change (displacement) and is shown in Fig. 4A. (QD (10 mg): EAM (10 mg) = 1: 1) The displacement value in Experimental Example 1 is 2.53 탆.

2) Experimental Example 2

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.5 g of a solution of an electroactive material (1 wt% in MEK) of the above formula 1-3 was coated and a voltage change (displacement) The measurement is shown in Fig. 4B. (QD (10 mg): EAM (5 mg) = 2: 1) The displacement value in Experimental Example 2 is 1.53 탆.

3) Experimental Example 3

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.25 g of a solution of an electroactive material of Formula 1-3 (1 wt% in MEK) was coated and a voltage (10 V) The measurement is shown in Fig. 4C. (QD (10 mg): EAM (2.5 mg) = 4: 1) The displacement value in Experimental Example 3 is 0.62 탆.

4) Experimental Example 4

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.125 g of a solution of an electroactive material of the above formula 1-3 (1 wt% in MEK) was coated and a voltage (10 V) The measurement is shown in Fig. 4D. (QD (10 mg): EAM (1.25 mg) = 8: 1) The displacement value in Experimental Example 4 is 0.27 탆.

As shown in Figs. 4A to 4D, the thickness variation (displacement value) of the light emitting layer also increases as the amount of the electroactive material increases.

FIG. 5 shows the relationship between the quantum dots and the electroactive material in terms of the weight ratio in the red pixel, and FIG. 5 illustrates the weight ratio between the quantum dot and the electroactive material for obtaining the desired displacement value.

(1) Change in thickness of light emitting layer in green pixel

1) Experimental Example 5

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) having a size of about 8 nm and 1 g of a solution of an electroactive material (1 wt% in MEK) The change (displacement) is measured and shown in Fig. 6A. (QD (10 mg): EAM (10 mg) = 1: 1) The displacement value in Experimental Example 5 is 4.2 탆.

2) Experimental Example 6

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.5 g of a solution of an electroactive material (1 wt% in MEK) of the above formula 1-3 was coated and a voltage change (displacement) 6B. (QD (10 mg): EAM (5 mg) = 2: 1) The displacement value in Experimental Example 6 is 2.61 탆.

3) Experimental Example 7

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.25 g of a solution of an electroactive material of Formula 1-3 (1 wt% in MEK) was coated and a voltage (10 V) The measurement is shown in Fig. 6C. (QD (10 mg): EAM (2.5 mg) = 4: 1) The displacement value in Experimental Example 7 is 1.43 탆.

4) Experimental Example 8

A mixture of 1 mL of a quantum dot (InP / ZnSe) 10 mg / mL (in Toluene) and 0.125 g of a solution of an electroactive material of the above formula 1-3 (1 wt% in MEK) was coated and a voltage (10 V) The measurement is shown in Fig. 6D. (QD (10 mg): EAM (1.25 mg) = 8: 1) The displacement value in Experimental Example 8 is 0.64 탆.

As shown in Figs. 6A to 6D, the thickness variation (displacement value) of the light emitting layer also increases with the increase of the amount of the electroactive material.

7 illustrates the relationship between the quantum dots and the electroactive material in terms of the weight ratio in the green pixel, and FIG. 7 illustrates the weight ratio between the quantum dot and the electroactive material in order to obtain the desired displacement value.

Further, when the quantum dots of the same component are used, the quantum dots of the green pixel are smaller than the quantum dots of the red pixel, so that the displacement value in the green pixel is larger than the displacement value in the red pixel, even if the same amount of electroactive material is used.

8 is a schematic cross-sectional view of a light emitting diode according to a second embodiment of the present invention.

A light emitting diode D is formed in each of the red pixel RP, the green pixel BP and the blue pixel BP, as shown in FIG.

The light emitting diode D includes a first electrode 160 positioned in each of the red pixel RP, the green pixel BP and the blue pixel BP and a red pixel RP, A second electrode 180 covering all of the blue pixels BP and a light emitting layer 170 disposed between the first and second electrodes 160 and 180.

The first electrode 160 may be separated from the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the first electrode 160 is made of a conductive material having a relatively large work function value and can be used as an anode. For example, the first electrode 160 may include first and second layers of an aluminum-palladium-copper alloy, and a third layer of ITO and located between the first and second layers. have.

The second electrode 180 may be formed integrally with the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the second electrode 180 may be formed of a conductive material having a relatively low work function value and used as a cathode. For example, the second electrode 180 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg), and may be a thin transflective electrode.

The distance between the first and second electrodes 160 and 180 is substantially the same in the red pixel RP, the green pixel BP, and the blue pixel BP.

The light emitting layer 170 includes a light emitting material layer 330. The light emitting material layer 330 includes a first light emitting material layer 332 located at the green pixel GP and including a first light emitting material (not shown) A second light emitting material layer 334 including a material (not shown), and a third light emitting material layer 336 located at the red pixel RP and including a third light emitting material (not shown).

As described above, each of the first to third light emitting materials may be an inorganic light emitting material such as a quantum dot, or an organic light emitting material of fluorescence or phosphorescence.

The first light emitting material layer 332 may further include a first electroactive material 362 and the third light emitting material layer 336 may further include a second electroactive material 364. [ Accordingly, when a voltage is applied to the first and second electrodes 160 and 180 for driving the light emitting diode D, the shapes of the first and second electroactive materials 362 and 364 are changed and the red and green The thicknesses of the first and third emissive material layers 332 and 336 of the pixels RP and GP increase. That is, the distance between the first and second electrodes 160 and 180 increases in the red and green pixels RP and GP. Since the second light emitting material layer 334 of the blue pixel BP includes only the second light emitting material without the electroactive material, the thickness of the second light emitting material layer 334 and the thicknesses of the first and second electrodes 334, (160, 180) does not change.

At this time, the weight ratio of the second electroactive material 364 to the third electroluminescent material is substantially the same as the weight ratio of the first electroactive material 362 to the first electroluminescent material, The dipole moment of the material 364 is greater than the dipole moment of the first electroactive material 362. [ Therefore, the thickness displacement value of the third light emitting material layer 336 by the second electroactive material 364 is smaller than the thickness displacement of the first light emitting material layer 332 by the first electroactive material 362 Value.

Therefore, when the light emitting diode D is driven, the degree of increase in the distance between the first and second electrodes 160 and 180 in the red pixel RP is greater than the distance between the first and second electrodes 160 and 160 in the green pixel GP. , 180). That is, when the light emitting diode D is driven, the distance between the first and second electrodes 160 and 180 in the green pixel BP is larger than the distance between the first and second electrodes 160 and 180 ) And is larger than the first and second inter-electrode distances in the blue pixel (BP).

In other words, the distances between the first and second electrodes 160 and 180 in the light emitting diode D are the same in the red pixel RP, the green pixel BP, and the blue pixel BP, The distance between the first and second electrodes 160 and 180 is changed by the first and second electroactive materials 362 and 364 when the diode D is driven, thereby realizing a microcavity effect.

Accordingly, the distance between the first and second electrodes 160 and 180 can be made equal to each other, thereby simplifying the structure of the light emitting diode D, and improving the luminous efficiency by the microcavity effect.

When the first and third light emitting materials are quantum dots, the first and second electroactive materials 362 and 364 in the first and third emissive material layers 332 and 336 form a light emitting diode D ) And the electroluminescent display device (100 of FIG. 2) can be improved.

The first and second electroactive materials 362 and 364 have a relatively large dipole moment, thereby increasing the dielectric constant of the first and third emissive material layers 332 and 336. When a strong electric field is applied to the quantum dots, damage of the quantum dots may occur. Since the dielectric constant of the first and third emissive material layers 332 and 336 increases due to the first and second electroactive materials 362 and 364, 1 and the third light emitting material layers 332 and 336 are uniformly dispersed. That is, the concentration of the electric field with respect to the quantum dots is relaxed, and the damage of the quantum dots is prevented.

Further, in the quantum dot light emitting diode using quantum dots, electrons are delivered to the light emitting material layer more quickly than holes, and the charged particles are broken. The first and second electroactive materials 362 and 364 having large dipole moments attract electrons 1 and the third light emitting material layers 332 and 336 are improved.

Therefore, when the first and third light emitting material layers 332 and 336 include the quantum dots and the first and second electroactive materials 362 and 364, the light emitting diode D and the electroluminescence display device 100) and the luminous efficiency can be improved.

The light emitting layer 170 may further include a hole transport layer 320 disposed between the first electrode 160 and the first to third light emitting material layers 332, 334, and 336, respectively. Although the first and second electroactive materials 362 and 364 are shown as being included in the first and third emissive material layers 332 and 336 in FIG. 8, the first and second electroactive materials 362, 364 may be included in the hole transport layer 320.

The light emitting layer 170 may include a hole injection layer 310 positioned between the first electrode 160 and the hole transport layer 320 and a hole injection layer 310 between the light emitting material layer 330 and the second electrode 180. [ And an electron injection layer 350 positioned between the electron transport layer 340 and the second electrode 180. The electron injection layer 350 may be formed of an electron transport layer 340,

In other words, in the light emitting diode D of the present invention, the light emitting layer 330 of the first pixel P1 (green pixel) includes the first light emitting material and the first electroactive material 362, and the second pixel P2 And the light emitting layer 330 of the third pixel P3 (red pixel) includes the third light emitting material and the second electroactive material 364. The light emitting layer 330 of the second pixel P3 includes a second light emitting material.

At this time, distances between the first and second electrodes 160 and 180 in the first to third pixels P1, P2, and P3 are the same, and the second electroactive material 364 is the same as the first electroactive material Lt; RTI ID = 0.0 > 362 < / RTI >

Therefore, the micro-cavity effect can be realized in the light-emitting diode D having the simple structure in which the distance between the first and second electrodes 160 and 180 is the same in the first to third pixels P1, P2, and P3, Accordingly, the light emitting efficiency of the light emitting diode D and the electroluminescent display device 100 (FIG. 2) can be improved.

9 is a schematic cross-sectional view of a light emitting diode according to a third embodiment of the present invention.

9, the light emitting diodes D are formed in the red pixel RP, the green pixel BP, and the blue pixel BP, respectively.

The light emitting diode D includes a first electrode 160 positioned in each of the red pixel RP, the green pixel BP and the blue pixel BP and a red pixel RP, A second electrode 180 covering all of the blue pixels BP and a light emitting layer 170 disposed between the first and second electrodes 160 and 180.

The first electrode 160 may be separated from the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the first electrode 160 is made of a conductive material having a relatively large work function value and can be used as an anode. For example, the first electrode 160 may include first and second layers of an aluminum-palladium-copper alloy, and a third layer of ITO and located between the first and second layers. have.

The second electrode 180 may be formed integrally with the red pixel RP, the green pixel BP, and the blue pixel BP. As described above, the second electrode 180 may be formed of a conductive material having a relatively low work function value and used as a cathode. For example, the second electrode 180 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg), and may be a thin transflective electrode.

Wherein the first and second electrodes 160 and 180 have a fourth distance d4 from the green pixel BP to the red pixel RP and a fourth distance d4 from the red pixel RP, And a large fifth distance d5.

The light emitting layer 170 includes a light emitting material layer 430. The light emitting material layer 430 includes a first light emitting material layer 432 disposed on the green pixel GP and including a first light emitting material (not shown) A second light emitting material layer 434 including a material (not shown), and a third light emitting material layer 436 located at the red pixel RP and including a third light emitting material (not shown).

The first light emitting material layer 432 and the second light emitting material layer 434 have a fourth thickness t4 and the third light emitting material layer 436 is larger than the fourth thickness t4 And has a fifth thickness t5.

As described above, each of the first to third light emitting materials may be an inorganic light emitting material such as a quantum dot, or an organic light emitting material of fluorescence or phosphorescence.

Here, the first light emitting material layer 432 and the third light emitting material layer 436 each include an electroactive material 460. Accordingly, when a voltage is applied to the first and second electrodes 160 and 180 to drive the light emitting diode D, the shape of the electroactive material 460 changes and the red and green pixels RP and GP The thickness of the first and third emissive material layers 432 and 436 increases. That is, the distance between the first and second electrodes 160 and 180 increases in the red and green pixels RP and GP. Since the second light emitting material layer 434 of the blue pixel BP includes only the second light emitting material without the electroactive material, the thickness of the second light emitting material layer 434 and the thicknesses of the first and second electrodes 434, (160, 180) does not change.

The electroactive material 460 has a first weight ratio to the first light emitting material in the green pixel GP and a second weight ratio to the third light emitting material in the red pixel RP, Lt; RTI ID = 0.0 > weight ratio. ≪ / RTI >

Accordingly, when the light emitting diode D is driven, the distance between the first and second electrodes 160 and 180 in the red pixel RP and the distance between the first and second electrodes 160 and 180 Since the distance between the first and second electrodes 160 and 180 is larger in the red pixel BP than in the green pixel GP, The distance between the first and second electrodes 160 and 180 in the green pixel BP is smaller than the distance between the first and second electrodes 160 and 180 in the red pixel RP, ) Is greater than the distance between the first and second electrodes.

In other words, the distance between the first and second electrodes 160 and 180 in the light emitting diode D is the same in the green pixel BP and the blue pixel BP. However, when the light emitting diode D is driven The distance between the first and second electrodes 160 and 180 is changed by the electroactive material 460, thereby realizing a microcavity effect.

Accordingly, the distance between the first and second electrodes 160 and 180 can be made equal to each other, thereby simplifying the structure of the light emitting diode D, and improving the luminous efficiency by the microcavity effect.

When the first and third light emitting materials are quantum dots, the electroactive material 460 in the first and third light emitting material layers 432 and 436 causes the light emitting diode D and the electroluminescent display device The lifetime and luminous efficiency of 100 of FIG. 2) can be improved.

The electroactive material 460 has a relatively large dipole moment, thereby increasing the dielectric constant of the first and third emissive material layers 432 and 436. When a strong electric field is applied to the quantum dots, damage of the quantum dots may occur. Since the permittivity of the first and third light emitting material layers 432 and 436 increases due to the electroactive material 460, Electrons are uniformly dispersed in the holes 432 and 436. That is, the concentration of the electric field with respect to the quantum dots is relaxed, and the damage of the quantum dots is prevented.

In the quantum dot light emitting diode using quantum dots, electrons are delivered to the light emitting material layer more quickly than holes, and the charged particles are broken. An electroactive material 460 having a large dipole moment attracts electrons to form first and third light emitting material layers The charge balance in the charge accumulating regions 432 and 436 is improved.

Accordingly, when the first and third light emitting material layers 432 and 436 include the quantum dots and the electroactive material 460, the lifetime and luminous efficiency of the light emitting diode D and the electroluminescence display device 100 Can be improved.

The light emitting layer 170 may further include a hole transport layer 420 disposed between the first electrode 160 and the first to third light emitting material layers 432, 434, and 436. Although the electroactive material 460 is shown in FIG. 9 as being included in the first and third emissive material layers 432 and 436, the electroactive material 460 may be included in the hole transport layer 420. In this case, the hole transporting layer 420 may have a larger thickness at the green pixel RP and the green pixel RP at the red pixel RP.

The light emitting layer 170 may include a hole injection layer 410 between the first electrode 160 and the hole transport layer 420 and a hole injection layer between the first electrode 160 and the hole transport layer 420, And an electron injection layer 450 positioned between the electron transport layer 440 and the second electrode 180. The electron transport layer 440 may be formed of an electron injection layer,

In other words, in the light emitting diode D of the present invention, the light emitting layer 430 of the first pixel P1 (green pixel) includes the first light emitting material and the electroactive material 460, The light emitting layer 430 of the first pixel P3 includes a second light emitting material and the light emitting layer 430 of the third pixel P3 and the red pixel includes the third light emitting material and the electroactive material 460. [

The distance between the first and second electrodes 160 and 180 in the first and second pixels P1 and P2 is equal to the distance between the first and second electrodes 160 and 180 in the third pixel P3. ) Is greater than the distance between the first and second electrodes (160, 180) in the first and second pixels (P1, P2) and the electroactive material (260) , P3). ≪ / RTI >

Therefore, the micro-cavity effect can be realized in the light-emitting diode D having the simple structure in which the distance between the first and second electrodes 160 and 180 is the same in the first and second pixels P1 and P2, The luminous efficiency of the light emitting diode D and the electroluminescent display device 100 (FIG. 2) can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It can be understood that

100: electroluminescence display device 160: first electrode
170: light emitting layer 180: second electrode
220, 320, 420: Hole transport layer 230, 330, 430: Light emitting material layer
232, 332, 432: first luminescent material layer 234, 334, 434: second luminescent material layer
236, 336, 436: third light emitting material layer 260, 362, 364, 460: electroactive material
GP (P1): green pixel BP (P2): blue pixel
RP (P3): red pixel D: light emitting diode

Claims (20)

A first electrode located at the first and second pixels;
A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material;
A second light emitting layer located in the second pixel and including a second light emitting material;
And a second electrode covering the first and second light-
.
The method according to claim 1,
Wherein a distance between the first and second electrodes in the first and second pixels is the same.
The method according to claim 1,
And a third light emitting layer located in the third pixel and including a third light emitting material and the first electroactive material.
The method of claim 3,
Wherein a distance between the first and second electrodes in the three pixels is equal to a distance between the first and second electrodes in the first pixel.
5. The method of claim 4,
Wherein a mass ratio of the first electroactive material to the first light emitting material in the first pixel is smaller than a mass ratio of the first electroactive material to the third light emitting material in the third pixel.
5. The method of claim 4,
Wherein the amount of the first electroactive material in the first pixel is smaller than the first electroactive material in the third pixel.
The method of claim 3,
Wherein a distance between the first and second electrodes in the three pixels is greater than a distance between the first and second electrodes in the first pixel.
8. The method of claim 7,
Wherein a mass ratio of the first electroactive material to the first light emitting material in the first pixel is equal to a mass ratio of the first electroactive material to the third light emitting material in the third pixel.
8. The method of claim 7,
Wherein the amount of the first electroactive material in the first pixel is the same as the first electroactive material in the third pixel.
The method according to claim 1,
And a third light emitting layer disposed on the third pixel and including a third light emitting material and a second electroactive material having a larger dipole moment than the first electroactive material.
11. The method of claim 10,
Wherein a distance between the first and second electrodes in the three pixels is equal to a distance between the first and second electrodes in the first pixel.
The method according to claim 1,
Wherein each of the first and second light emitting layers includes a hole transporting layer and a light emitting material layer,
Wherein the first light emitting material and the first electroactive material are included in the light emitting material layer of the first light emitting layer and the second light emitting material is contained in the light emitting material layer of the second light emitting layer.
13. The method of claim 12,
Wherein the first luminescent material is a quantum dot.
The method according to claim 1,
Wherein each of the first and second light emitting layers includes a hole transporting layer and a light emitting material layer,
Wherein each of the first and second light emitting materials is included in the light emitting material layer of the first and second light emitting layers and the first electroactive material is contained in the hole transporting layer of the first light emitting layer.
A first electrode located at the first and second pixels;
A first light emitting layer located in the first pixel and including a first light emitting material and a first electroactive material;
A second light emitting layer located in the second pixel and including a second light emitting material and a second electroactive material;
And a second electrode covering the first and second light-
.
16. The method of claim 15,
Wherein the distance between the first and second electrodes in the first and second pixels is the same and the amount of the first electroactive material is less than the second electroactive material.
16. The method of claim 15,
The distance between the first and second electrodes in the first and second pixels is the same,
Wherein the dipole moment of the first electroactive material is smaller than the second electroactive material.

First and second electrodes facing each other in a first pixel;
And a first light emitting layer positioned between the first and second electrodes,
Wherein the first light emitting layer has a first thickness at a first voltage state and a second thickness at a second voltage state that is greater than the first voltage and greater than the first thickness.
19. The method of claim 18,
And a second light emitting layer located in the second pixel,
Wherein the second light emitting layer has a constant thickness in the first voltage state and the second voltage state.
Claims [1]
A light emitting diode of any one of claims 1 to 19 positioned above the substrate;
A thin film transistor located between the substrate and the light emitting diode and connected to the first electrode;
Emitting element.

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