Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.
1 is a cross-sectional view of an upper light emitting organic light emitting display according to an embodiment. 2A is an enlarged cross-sectional view of the X region of FIG. 2B is a partial plan view of the overcoat layer of the X region of FIG.
1 and 2A, an upper emission organic light emitting display 100 according to an exemplary embodiment includes a substrate 110, a thin film transistor 120, an overcoat layer 160, an organic light emitting diode 140, a color filter 150).
The top emission organic light emitting display device 100 shown in FIGS. 1 and 2A is an organic light emitting display device of a top emission type or a top emission type in which the color filter 150 is located on the opposite side of the substrate 110 Or a bottom emission type or bottom emission type organic light emitting display in which the color filter 150 is disposed on the substrate 110 side. The upper emission organic light emitting display 100 has an advantage that it is advantageous in terms of lifetime and brightness by increasing the aperture ratio as compared with the bottom emission organic light emitting display.
A thin film transistor 120 including a gate electrode 121, an active layer 122, a source electrode 123 and a drain electrode 124 is disposed on a substrate 110. [
A gate electrode 121 is disposed on the substrate 110 and a gate insulating layer 131 for insulating the gate electrode 121 and the active layer 122 on the gate electrode 121 and the substrate 110 And an active layer 122 is disposed on the gate insulating layer 131. An etch stopper 132 is disposed on the active layer 122. An active layer 122 and an etch stop layer A source electrode 123 and a drain electrode 124 are disposed on the phosphor 132. The source electrode 123 and the drain electrode 124 are electrically connected to the active layer 122 in such a manner as to be in contact with the active layer 122 and are disposed on a partial area of the etch stopper 132. The etch stopper 132 may not be disposed.
For convenience of description, only the thin film transistors among the various thin film transistors that can be included in the top emission organic light emitting display device 100 are shown in this specification. The thin film transistor 120 is also referred to herein as an inverted staggered transistor in which the gate electrode 121 is located on the opposite side of the source electrode 123 and the drain electrode 124 with respect to the active layer 122. [ Structure or a bottom gate structure, but the gate electrode 121 is located on the same side as the source electrode 123 and the drain electrode 124 with respect to the active layer 122, Thin film transistors of the structure can also be used.
Although the passivation layer 133 is shown as planarizing the upper surface of the thin film transistor 120 in FIG. 1, the passivation layer 133 does not planarize the upper surface of the thin film transistor 120, but is disposed along the surface shape of the underlying elements It is possible.
An overcoat layer 160 is disposed on the passivation layer 133. Although the passivation layer 133 is shown in FIG. 1 as being included in the top emission organic light emitting diode display 100, the passivation layer 133 is not used and the overcoat layer 160 is immediately disposed on the thin film transistor 120 .
The overcoat layer 160 includes a plurality of convex portions 162 and a first connecting portion 161 connecting the convex portions 162 adjacent to each other. The first connection portion 161 is a portion located between adjacent convex portions 162. The overcoat layer 160 functions as a planarization layer in a portion where the plurality of convex portions 162 are not disposed.
As shown in FIG. 2B, each of the plurality of convex portions 162 and the first connecting portions 161 may be generally circular in plan view, but is not limited thereto. In general, the convex portion 162 and the first connection portion 161 may have a hemispherical shape, a semi-ellipsoid shape, Lt; / RTI > The plurality of convex portions 162 can be arranged in a circular shape in a plane. In other words, one convex portion 162 in a circular shape and another convex portion 162 adjacent to the convex portion 162 can be arranged in a circular structure integrally formed by sharing one side.
An organic light emitting diode 140 and a bank 136 including a first electrode 141, an organic light emitting layer 142 and a second electrode 143 are disposed on the overcoat layer 160. At this time, although not shown, it is possible to prevent the outgassing from the overcoat layer 160 from diffusing to the organic light emitting diode 140 while keeping the morphology of the protrusion 162 of the overcoat layer 160 as it is, An insulating second passivation layer (not shown) may be added between the overcoat layer 160 and the first electrode 141 so as to have a refractive index similar to that of the first electrode 141.
Specifically, a first electrode 141 for supplying one of electrons or holes to the organic light emitting layer 142 is disposed on the overcoat layer 160 in part. The first electrode 141 may be an anode, a pixel electrode, or an anode in a normal organic light emitting diode (OLED), or may be a cathode, a pixel electrode, or a cathode in an inverted OLED.
For example, the first electrode 141 may include a reflective plate 141a made of a conductive material. The reflection plate 141a may reflect light emitted from the organic light emitting layer 142 to improve the top emission efficiency. If the first electrode 141 itself functions as a reflector, the reflector 141a may not be separately provided under the first electrode 141.
The reflector 141a may be patterned in the same manner as the first electrode 141 when the reflector 141a is disposed below the first electrode 141. [ Accordingly, the first electrode 141 and the reflection plate 141a may function as multiple electrodes. Also, the first electrode 141 may be a multiple electrode including multiple layers, for example, a double electrode, and may include a reflection plate 141a in the first electrode 141 of the multiple layers. Hereinafter, it is assumed that the first electrode 141 includes a reflection plate 141a and the first electrode 141 and the reflection plate 141a function as multiple electrodes.
The reflection plate 141a and the first electrode 141 may be connected to the source electrode 123 of the thin film transistor 120 through a contact hole formed in the overcoat layer 160. [ The first electrode 141 is connected to the source electrode 123 on the assumption that the thin film transistor 120 is an N-type thin film transistor. However, when the thin film transistor 120 is a P-type thin film transistor The reflection plate 141a and the first electrode 141 may be connected to the drain electrode 124. In this case, The first electrode 141 may directly contact the organic light emitting layer 142 or may be electrically connected to the organic light emitting layer 142 via a conductive material.
The reflection plate 141a and the first electrode 141 are disposed in a shape following the morphology of the surface of the overcoat layer 160. [ Accordingly, the reflection plate 141a and the first electrode 141 have a convex morphology at the convex portion 162 of the overcoat layer 160. [
A bank layer 136 is disposed on the overcoat layer 160 and the reflection plate 141a and the first electrode 141 and includes an opening 136a for exposing the first electrode 141. [ The bank layer 136 serves to separate adjacent pixel (or sub pixel) regions, and may be disposed between adjacent pixel (sub pixel) regions.
The convex portion 162 and the first connection portion 161 of the overcoat layer 160 are disposed so as to overlap the opening portion 136a of the bank layer 136. [ The convex portion 162 and the first connection portion 161 of the overcoat layer 160 are overlapped with the color filter 150 to be described later, Overlaps the opening 136a of the bank layer 136 and the color filter 150 in the upper part.
An organic light emitting layer 142 is disposed on the first electrode 141 and a second electrode 143 is disposed on the organic light emitting layer 142 to supply one of electrons or holes to the organic light emitting layer 142. The organic light emitting layer 142 is arranged in a tandem white structure in which a plurality of organic light emitting layers are stacked to emit white light. The organic light emitting layer 142 includes a first organic light emitting layer that emits blue light and a second organic light emitting layer that is disposed on the first organic light emitting layer and emits light of a color that is mixed with blue and becomes white. The second organic luminescent layer may be, for example, an organic luminescent layer emitting yellowgreen light. The organic light emitting layer 142 may include only an organic light emitting layer that emits one of blue light, red light, and green light. At this time, the color filter 150 may not be included. The second electrode 143 may be a cathode, a common electrode, or a cathode in a normal organic light emitting device (OLED), or may be an anode, a common electrode, or an anode in an inverted OLED.
When the color filter 150 is included, the color filter 150 is disposed on the second electrode 143. An adhesive layer 170 may be included between the second electrode 143 and the color filter 150.
The color filter 150 may be one of a red color filter, a green color filter, and a blue color filter for converting the color of light emitted from the organic light emitting layer 142.
The color filter 150 is disposed on the second electrode 143 at a position corresponding to the light emitting region. Here, the light emitting region means a region where the organic light emitting layer 142 emits light by the first electrode 141 and the second electrode 143, and the color filter 150 is disposed at a position corresponding to the light emitting region, Means that the color filter 150 is disposed to prevent the light emitted from the light emitting regions from intermingling with each other to prevent blurring and ghosting.
For example, the color filter 150 is disposed to overlap the light emitting region, and may have a size smaller than the light emitting region. However, the position and size of the color filter 150 are not limited to the size and position of the light emitting region, the distance between the color filter 150 and the second electrode 143, the distance between the light emitting region and the light emitting region, Lt; / RTI >
2A, the thickness of the organic light emitting layer 142 between the convex portion 162 of the overcoat layer 160 and the first connection portion 161 is less than the thickness of the convex portion 162 of the overcoat layer 160, The thickness of the organic light emitting layer 142 may be thinner than the thickness of the organic light emitting layer 142 at the top. In particular, the thickness of the organic light emitting layer 142 may be the smallest at a position where the slope of the organic light emitting layer 142 is largest between the convex portion 162 of the overcoat layer 160 and the first connecting portion 161.
For example, when the organic light emitting layer 142 is formed by vapor deposition, the thickness of the organic light emitting layer 142 deposited in a direction perpendicular to the substrate 110 is the same, but when the organic light emitting layer 142 is formed of a morphology of the overcoat layer 160, Lt; / RTI > The thickness d1 of the organic light emitting layer 142 that is currently driven between the first electrode 141 and the second electrode 142 is the thinnest at a position where the slope of the organic light emitting layer 142 is the largest. The thickness d2 and the thickness d3 of the organic light emitting layer 142 which is current driven between the first electrode 141 and the second electrode 142 at the position where the slope of the organic light emitting layer 142 is the smallest, .
An organic light emitting layer 142 is formed between the convex portion 162 of the overcoat layer 160 and the first connection portion 161 in terms of the amount of emission of the organic light emitting layer 142 depending on the thickness d1, d2, d3, etc. of the organic light emitting layer 142. [ 142 may be greater than the amount of light emitted per unit area of the organic light emitting layer 142 at the bottom of the convex portion 162 or the top of the first connection portion 161. Particularly, the light emission amount of the organic light emitting layer 142 may be largest at a position where the slope of the organic light emitting layer 142 is largest between the convex portion 162 of the overcoat layer 160 and the first connection portion 161.
The organic light emitting layer 142 and the second electrode 143 are arranged in a shape following the morphology of the surface of the overcoat layer 160. As a result, the shape of the organic light emitting diode 140 having the microlens array structure using the convex portion 162 of the overcoat layer 160 can be realized.
When the organic light emitting device 140 has a microlens array structure for improving the external light extraction efficiency, the convex portions 162 of the overcoat layer 160 are formed on the surface of the organic light emitting device 140, ), The convex curvature appears. At this time, the effective light emitting region Y where the shortest thickness d1 of the organic light emitting layer 142 is thinned between the first electrode 141 and the second electrode 143 as the tilt is large, A region between the convex portion 162 of the first connection portion 160 and the first connection portion 161 occurs. When the organic light emitting diode 140 is driven, the electric field is locally concentrated in the efficient light emitting region and a main current path is formed to cause the main light emission. In the convex portion 162 of the overcoat layer 160, ) So that almost no light is extracted. In this inefficient light emitting region Z, although light is consumed, almost no light can be extracted, and the efficiency of extracting external light is lowered.
The top emission organic light emitting display 100 according to an exemplary embodiment may include a convex micro lens array pattern in the overcoat layer 160. The light emitted from the organic light emitting layer 142 is totally reflected within the organic light emitting layer 142 and the second electrode 143 and is trapped by the micro lens array structure at an angle smaller than the total reflection critical angle, The luminous efficiency can be increased.
At this time, the advancing angle of the light emitted from the organic light emitting layer 142 is changed by the inserted microlens array pattern, but the traveling angle of the light can be clearly different due to the minute difference of the microlens array shape.
The shape of the convex portion 162 of the overcoat layer 160 is formed through a process such as photolithography. When the heat treatment process performed at this time is controlled, the morphology of the convex portion 162 of the overcoat layer 160 Can be adjusted. The material of the overcoat layer 160 may be a general positive or negative photoresist. For example, the material of the overcoat layer 160 may be a negative photoresist where the exposure portion is cured. If the material of the overcoat layer 160 is a negative photoresist, it may be advantageous to make the overcoat layer 160 have a shape with a half height width larger than a radius. When the material of the overcoat layer 160 is a negative photoresist, the shape of the overcoat layer 160 in the reverse phase of the mask can be produced.
More specifically, it is as follows. In order to form the convex portion 162 of the overcoat layer 160, a photoresist is applied and patterned in a convex shape through a photolithography process, followed by heat treatment. At this time, the shape of the convex portion 162 of the overcoat layer 160 can be formed by performing the stepwise heat treatment in two steps, rather than performing the heat treatment at once. For example, the intermediate heat treatment at about 100 ° C or higher and 130 ° C or lower should be performed before the final heat treatment at about 200 ° C or higher and 250 ° C or lower.
At this time, the time for performing the intermediate heat treatment is related to the morphology of the convex portion 162 of the overcoat layer 160. As the time for performing the intermediate heat treatment is increased, the morphology of the convex portion 162 of the finally formed overcoat layer 160 is increased. Extremely, if only the final heat treatment is performed without time for performing the intermediate heat treatment, the morphology of the convex portion 162 of the overcoat layer 160 disappears and the overcoat layer 160 is planarized.
Using this tendency, various top emission organic light emitting display devices having different morphologies of convex portions 162 of the overcoat layer 160 were fabricated. When the convex portion 162 of the overcoat layer 160 has a certain morphology, that is, when the convex portion 162 of the overcoat layer 160 has a certain aspect ratio or the like, the organic light emitting element 140 has a maximum Emitting efficiency of the light emitting diode.
The upper emission organic light emitting display 100 according to an exemplary embodiment of the present invention may include an organic light emitting diode 140 through a light path that varies depending on the shape of the convex portion 162 of the overcoat layer 160 inserted to enhance external light extraction efficiency. So that the light that is trapped and totally trapped inside is extracted to the outside.
Since the optical path change depending on the shape of the convex portion 162 of the inserted overcoat layer 160 for improving the external light extraction efficiency is a major factor for improving the light extraction efficiency, the convex portion 162 of the overcoat layer 160, Height H (Height), Aspect Ratio (A / R), Half Height Width Half Height (F_A), Half Height Aspect Ratio (F_A Height aspect ratio Rm (Ratio of MLA = (F_A) / R (= H / F)), a slope (S / R) / (A / R))).
FIG. 3A is a conceptual illustration of the variables that determine the shape of the convex portion of the overcoat layer. FIG. 3B illustrates the parameters determining the shape of the convex portion of the overcoat layer in the top emission organic light emitting display according to an embodiment. 3C is a view for explaining the concept of the gap G at the bottom of the convex portion of the overcoat layer.
3A and 3B, the diameter D of the convex portion 162 of the overcoat layer 160 indicates the length between the centers of the two convex portions 161, and the height H indicates the distance between the centers of the convex portions 161 162 from the bottom to the top. The half height width F means the length of both sides of the convex portion 162 at a half (H / 2) position of the height as shown in FIG. 3A. The aspect ratio A / R of the convex portion 162 means a value obtained by dividing the height H of the convex portion 162 by the radius D / 2 of the convex portion 162.
The convex portion 162 may have a circular shape with a diameter D of 1 to 5 占 퐉 and a height H of 1 to 4 占 퐉.
The aspect ratio A / R of the convex portion 161A of the overcoat layer 160A has a value of about 0.35 or more and 0.8 or less when the aspect ratio A / R of the convex portion 161A of the overcoat layer 160 is It can be confirmed that the rate of current efficiency increase is higher than that in the case of having a value exceeding 0.8. Rather, if the aspect ratio A / R of the convex portion 162 of the overcoat layer 160 has a value of more than about 0.8, the current efficiency increasing rate tends to be lowered rather. In particular, when the aspect ratio of the convex portion 162 of the overcoat layer 160 has a value between about 0.4 and 0.7, it can be seen that the current efficiency increase rate is the maximum.
As a result, the surface on which the organic light emitting diode 140 is disposed in the top emission organic light emitting display 100 according to the embodiment is formed such that the aspect ratio A / R of the convex portion 162 of the overcoat layer 160A is about And may be the upper surface of the overcoat layer 160 having a value between 0.35 and 0.8. Or the surface on which the organic light emitting diode 140 is disposed in the top emission organic light emitting display device 100 according to an embodiment of the present invention may be formed in such a manner that the aspect ratio A / R of the convex portion 162 of the overcoat layer 160 May be the top surface of a second passivation layer (not shown) that follows the morphology of the overcoat layer 160 having a value between about 0.35 and about 0.8. That is, the overcoat layer 160 or the second passivation layer (not shown) at this time is a gentle non-planar screen whose surface has an aspect ratio (A / R) of between about 0.35 and about 0.8, The device 140 is formed on a gentle unbalanced screen having an aspect ratio of between about 0.35 and about 0.8 and the first electrode 141, the organic light emitting layer 142, and the second electrode 143 are formed in a gentle non- And has a shape conforming to the morphology of the shot screen.
The convex portion 162 of the overcoat layer 160 may be formed to have a gentle slope by placing the intermediate heat treatment process in the convex portion 162 of the overcoat layer 160, can do. When the overcoat layer 160 is formed such that the aspect ratio A / R of the convex portion 162 of the overcoat layer 160 is 0.35 or more and 0.8 or less according to this method, The organic light emitting device 140 including the electrode 141, the organic light emitting layer 142, and the second electrode 143 and the bank layer 136 may be formed.
When only the aspect ratio A / R is applied as a parameter defining the shape of the convex portion 162 of the overcoat layer 160, only the diameter D and the height H are defined by the same aspect ratio A / R When the values defined by the remaining variables such as the half-height width F and the gap G between the convex portions as shown in FIG. 3C are changed, the shape of the convex portion 162 of the overcoat layer 160 It is obviously different.
4 is a cross-sectional view of the convex portion 162 of the overcoat layer 160 having a specific aspect ratio.
The aspect ratio A / R of the convex portion 162 of the overcoat layer 160 shown in FIG. 4 is about 0.45 and is 0.35 or more of the convex portion 162 of the overcoat layer 160, 0.8 or less.
2A, when the organic light emitting diode 140 has a microlens array structure for improving the external light extraction efficiency, the slope S of the convex portion 162 of the overcoat layer 160 is large The effective light emitting region Y in which the electric field is locally gathered as the shortest thickness d1 of the organic light emitting layer 142 between the first electrode 141 and the second electrode 143 becomes thinner, that is, the overcoat layer 160 A region between the convex portion 162 and the first connection portion 161 is generated.
In other words, the maximum slope Smax of the convex portion 162 is located at a position having the shortest thickness d1 of the organic light emitting layer 142. [
On the other hand, a part of the light emitted from the organic light emitting layer 142 propagates upward, while the other part propagates to the reflection plate 141a and is reflected by the reflection plate 141a to change the optical path in the upward direction.
Figures 5A and 5B show various shapes of convex portions of an overcoat layer having the same or similar aspect ratio (A / R).
5A, if the shape of the convex portion 162 of the overcoat layer 160 is triangular as shown in FIG. 3A, the half height width F of the convex portion 162 of the overcoat layer 160 may have a diameter (D / 2). The convex portion 162 of the overcoat layer 160 included in the upper emission organic light emitting display 100 according to an exemplary embodiment may have a half height F larger than a radius D / 2.
5B, the convex portion 162 and the half-height width F of the overcoat layer 160 having the half height width F larger than the radius D / 2 are smaller than the radius D / 2 And the protrusions 162a of the overcoat layer 160 are compared. 5B shows a light path in which light emitted from the same position of the organic light emitting layer 142 is reflected by the convex portion 162a having a shape different from that of the convex portion 162 of the overcoat layer 160. FIG.
The half height width F of the convex portion 162 of the overcoat layer 160 is greater than the radius D / 2 from the viewpoint of the top emission organic light emitting display device 100 according to the embodiment, The light path in the lateral direction of the reflection plate 141a is reduced and the external light extraction efficiency can be improved.
In contrast, as described above, the half-height width F of the convex portion 162a of the overcoat layer 160 is smaller than the radius D / 2 because the side surface of the convex portion 162a has a slender shape, The light path in the lateral direction of the light guide plate 141a increases and the external light extraction efficiency can be reduced.
Accordingly, the upper light emitting organic light emitting display 100 according to an embodiment including the convex portion 162 of the overcoat layer 160 having the half height width F larger than the radius (D / 2) The light path in the lateral direction of the light guide plate 141a is reduced, and the external light extraction efficiency can be improved.
In this case, the convex portion 162 of the overcoat layer 160 included in the upper emission organic light emitting display 100 according to an exemplary embodiment may have a half height width F with respect to the radius D / 2 of the convex portion 162, May be 1.0 or more.
6 is a graph illustrating current efficiency enhancement according to the half height width of each of the top emission organic light emitting display devices in which the half height width F of the convex portion 162 of the overcoat layer 160 has various values %) Or enhancement of current efficiency (%)). At this time, the larger the current efficiency rising rate, the better the luminous efficiency.
For example, in the top emission organic light emitting diode display 100 in which the convex portion 162 of the overcoat layer 160 has a diameter D of 4.5 μm and a height H of 1.7 μm and an aspect ratio A / R of 0.76 It was confirmed that the half height width (F) of 2.0um or more is better than the half height width (F) less than 2.0. On the contrary, when the half-height width F of the convex portion 162 of the overcoat layer 160 has a value less than 2.0 탆, it is possible to confirm that the rate of current efficiency increase is rather lower (the rate of increase is negative).
If the half height width F is less than 2.0 탆 even if the aspect ratio A / R of the convex portion 162 of the overcoat layer 160 has an optimum value, The organic light emitting layer 142 is formed on the organic light emitting layer 142, As a result, the rate of current efficiency rise tends to be rather lowered, and the luminous efficiency is lowered.
On the other hand, the half height aspect ratio F_A / R of the convex portion 162 may be smaller than the aspect ratio A / R. At this time, the half height aspect ratio F_A / R of the convex portion 162 means the height H to the half height width F of the convex portion 162. That is, the half-height aspect ratio of the convex portion 162 to the aspect ratio may be smaller than 1.0. For example, when the aspect ratio A / R of the convex portion 162 is 0.35 or more and 0.8 or less as described above, the half height aspect ratio F_A / R of the convex portion 162 may be more than 0.30 but not more than 0.6.
As described above, the convex portion 162 of the overcoat layer 160 can have various shapes even if the half height F is larger than the radius D / 2 and the half height F is the same.
For example, when the half height width F of the convex portion 162 of the overcoat layer 160 is larger than the radius D / 2, the inclination of the convex portion 162 of the overcoat layer 160, (The shape of the convex portion 162 in Fig. 5A) that gradually increases from the bottom to the maximum inclination Smax and then decreases again.
The slope of the organic light-emitting layer 142 between the convex portion 162 of the overcoat layer 160 and the first connection portion 161 may be lowered due to the characteristics of the deposition process of the organic light-emitting layer 142, Is the largest, and the amount of light emitted by the organic light emitting layer 142 is the largest at the maximum slope Smax.
The convex portion 162 of the overcoat layer 160 has a shape in which the inclination at the bottom increases and then decreases at the maximum inclination (the convex portion 162 in FIG. 5A) The light emitted from the organic light emitting layer 142 proceeds at an angle smaller than the total reflection critical angle and the external light emission efficiency is increased through multiple reflection so that the maximum external light extraction efficiency can be obtained.
On the other hand, the overcoat layer 161 can increase the external light extraction efficiency when the first connection portion 161 connecting the convex portions has a gentle inclination. The separation distance G (Gap) at the bottom of the convex portion 162 is zero as shown in Fig. 3C. G is greater than 0, the effective light emitting area decreases because the gap between adjacent two convex portions 161 exists, and therefore, the light emitting efficiency can be reduced by the area of the separation distance G.
7 is a view showing a light path according to a maximum inclination of a convex portion of an overcoat layer.
Referring to FIG. 7, the convex portion 162 of the overcoat layer 160 has a shape that the slope at the bottom increases at the bottom and decreases at the maximum slope Smax (as shown in FIG. 5A) Shape).
As shown in Fig. 7, even when the convex portion 162 of the overcoat layer 160 having the shape (the shape of the block portion 162 of Fig. 5A) decreases at the maximum slope Smax while the slope increases, It can have various shapes depending on the angle.
7, when the maximum slope Smax in the shape of the convex portion 162 of the overcoat layer 160 has a high angle of more than 60 degrees, for example, 70 degrees (Smax = 70 degrees) The advance angle of the light starting to proceed from the light emitting region is more than 42 degrees, which eventually gets trapped in the organic light emitting element 140, so that the luminous efficiency may not be increased.
Therefore, the shape of the convex portion 162 of the overcoat layer 160 is such that when the maximum slope Smax of the convex portion 162 is 40 to 60 degrees (for example, 50 degrees) Light emitted from the organic luminescent layer 142 is not trapped in the organic luminescent device 140, and thus the luminous efficiency can be increased.
8 is a graph showing current efficiency enhancement according to the maximum slope Smax of each of the top emission organic light emitting display devices in which the maximum slope Smax of the convex portion 162 of the overcoat layer 160 has various values. (%) Or enhancement of current efficiency (%)).
8, when the maximum slope Smax of the convex portion 162 of the overcoat layer 160 is less than 40 degrees, the light advancing angle in the effective luminescent region is larger than the flat organic light emitting element of the overcoat layer 160 It is confirmed that there is almost no improvement in efficiency. When the maximum slope Smax of the convex portion 162 of the overcoat layer 160 is more than 60 degrees, the light propagation angle is larger than the total reflection angle of the air layer outside the substrate 110 and the substrate 110, The amount of light trapped inside the device 140 is greatly increased and the efficiency is lower than that of the flat organic light emitting device of the overcoat layer 160.
As described above, the shape of the convex portion 162 of the overcoat layer 160 shown in FIG. 4 is such that when the maximum slope Smax of the convex portion 162 is 40 to 60 degrees, Light emitted from the organic luminescent layer 142 is not trapped in the organic luminescent element 140, so that luminous efficiency can be increased.
Fig. 9 shows a region having the maximum slope in accordance with the half-height aspect ratio Rm with respect to the aspect ratio of the convex portion.
The half height aspect ratio Rm of the convex portion 162 with respect to the aspect ratio is defined as a variable that determines the region having the sharpest maximum slope Smax as a ratio of the half height aspect ratio F_A / R to the aspect ratio A / R .
Referring to FIG. 9, when the half-height aspect ratio Rm of the convex portion 162 is greater than 1.0, the region having the maximum slope Smax is the first region C. When the half height ratio Rm of the aspect ratio of the convex portion 162 is 1.0, the region having the maximum slope Smax is the second region B. [ When the half-height aspect ratio Rm of the convex portion 162 with respect to the aspect ratio is less than 1.0, the region having the maximum slope Smax is the third region A. [
4, the maximum slope Smax of the convex portion 162 is set so as to satisfy the following relationship among the first to third regions from the bottom with respect to the height H: It can be seen that the front emission efficiency is the best when it is located in the third region A adjacent to the normal. As described above, when the organic light emitting diode 140 is driven, the electric field is locally concentrated in the efficient light emitting region Y and a main current path is formed to cause the main light emission, whereas the convex portion 162 of the overcoat layer 160 The light emission efficiency can be lowered as the maximum slope is located in the first region C and the second region B. In this case,
The light extraction efficiency or light emission efficiency according to the shape of the convex portion 162 when the overcoat layer 160 includes the convex portion 162 has been described. Hereinafter, even when the overcoat layer 160 includes recesses, the external light extraction efficiency or the light emission efficiency according to the shape of the recesses, like the protrusions 162, will be described with reference to FIG.
10 is a cross-sectional view illustrating an upper light emitting organic light emitting display including an overcoat layer including a plurality of recesses according to another embodiment.
Referring to FIG. 10, the top emission organic light emitting display 200 according to another embodiment has a structure in which the overcoat layer 260 is divided into a plurality of recesses (not shown) 264, and the other structures are substantially the same, and redundant description will be omitted. Elements of the OLED display 200 not shown in FIG. 10 may be the same as those of the OLED display 100 according to the previous embodiments.
The overcoat layer 260 includes a plurality of recesses 264 and a second connection portion 263 connecting the recesses 264 adjacent to each other. In other words, the overcoat layer 260 includes a plurality of concave portions 264 arranged to overlap with the openings 136a of the bank layer 136 shown in FIG. 1 and a plurality of second connection portions 264 connecting the concave portions 264, (263).
A reflection plate 241a and a first electrode 241 are disposed on the overcoat layer 260. [ The organic light emitting layer 242 and the second electrode 243 are disposed on the overcoat layer 260 and the first electrode 241. The first electrode 241, the organic light emitting layer 242, and the second electrode 243 constitute the organic light emitting diode 240. A color filter (not shown) is disposed on the second electrode 243 so as to overlap the concave portion 264 and the second connection portion 263 connecting the concave portions 264 adjacent to each other.
The reflection plate 241a, the first electrode 241, the organic light emitting layer 242 and the second electrode 243 are arranged along the top surface of the overcoat layer 260 to form a shape along the morphology of the overcoat layer 260 Lt; / RTI >
As described with reference to FIGS. 3A and 3B, the half-height width F of the convex portion 162 of the overcoat layer 160 is greater than the radius D / 2, 264 may be greater than the radius (D / 2). The ratio of the half height width F to the radius D / 2 of the concave portion 264 may be 1.0 or more.
The recessed portion 264 of the overcoat layer 260 is formed in the same manner as the half height aspect ratio F_A / R of the convex portion of the overcoat layer 160 is smaller than the aspect ratio A / R as described with reference to FIGS. 3A to 3B. Height aspect ratio F_A / R may be less than the aspect ratio A / R. At this time, the half height aspect ratio F_A / R with respect to the aspect ratio A / R of the concave portion 264 may be smaller than 1.0.
At this time, the concave portion 264 may have a hexagonal shape with a diameter of 1 to 5 mu m and a height of 1 to 4 mu m. The recess 264 may have an aspect ratio of 0.35 to 0.8 and a half height aspect ratio of 0.30 to 0.60, but is not limited thereto.
4 to 5A, the convex portion 162 of the overcoat layer 160 has a concave portion 264 of the overcoat layer 260, like the inclined portion of the overcoat layer 160, Can have a shape increasing in slope at the bottom and gradually decreasing at the maximum slope.
The maximum slope of the concave portion 264 of the overcoat layer 260 is set to 40 占 퐉 as in the case where the maximum slope of the convex portion 162 of the overcoat layer 160 is 40 占 to 60 占 as described with reference to Figs. To 60 degrees.
When the overcoat layer 260 includes the concave portion 264, the convex portion 162 of the overcoat layer 160 of the upper light emitting display device 100 described with reference to FIG. The characteristics depending on the shapes of the concave portion 264 and the second connection portion 263 according to the omitted parameters are the same as those of the convex portion 162 and the first Is the same as that described above with reference to the connecting portion 262.
11 is a schematic system configuration diagram of an upper light emitting organic light emitting display according to the present embodiments.
11, a plurality of data lines DL and a plurality of gate lines GL are disposed in the upper light emitting organic light emitting display 300 according to the present embodiment, and a plurality of sub pixels SP An organic light emitting diode (OLED) display panel 310 arranged in a matrix type, a plurality of data lines by supplying data voltages to a plurality of data lines, a driving data driver 320, and a plurality of gate lines, A gate driver 330 for sequentially driving a plurality of gate lines, a controller 340 for controlling the data driver 320 and the gate driver 330, and the like.
Each of the plurality of pixels arranged in the organic light emitting display panel 310 according to the present embodiment includes the thin film transistor and the organic light emitting element described with reference to FIG.
According to the above-described embodiments, the top emission organic light emitting display can improve the extraction efficiency of external light by applying a microarray structure.
According to the above-described embodiments, the upper light emitting organic light emitting display device has the effect of improving the external light emitting efficiency and lowering the power consumption.
According to the above-described embodiments, the top emission organic light emitting display can increase the lifetime.
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 inventions. , Separation, substitution, and alteration of the invention will be apparent to those skilled in the art. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.
