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 OLED display according to an exemplary embodiment of the present invention. 2 is an enlarged cross-sectional view of the X region of FIG. FIG. 2B is a partial plan view of the overcoat layer, the first electrode, and the pattern layer in the X region of FIG.
1 and 2, an OLED display 100 according to an exemplary embodiment includes a substrate 110, a thin film transistor 120, a color filter 150, an overcoat layer 160, a pattern layer 337, And an organic light emitting diode 140.
The organic light emitting diode display 100 shown in FIGS. 1 and 2A is a bottom emission organic light emitting diode display. However, the OLED display 100 according to an exemplary embodiment may be a top emission type OLED display in which the color filter 150 is located on the opposite side of the substrate 110.
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 OLED display 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.
A passivation layer 133 is disposed on the thin film transistor 120 and a color filter 150 is disposed on the passivation layer 133.
2A, the passivation layer 133 is shown to planarize the upper surface of the thin film transistor 120, but the passivation layer 133 does not planarize the upper surface of the thin film transistor 120, .
The color filter 150 may be one of a red color filter, a green color filter, and a blue color filter for converting light emitted from the organic light emitting layer 142 into color.
The color filter 150 is disposed on the passivation layer 133 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 may be disposed to overlap the light emitting region, and may have a size smaller than the light emitting region. The position and size of the color filter 150 may be determined not only by the size and position of the light emitting region but also by the distance between the color filter 150 and the first electrode 141 and the distance between the color filter 150 and the overcoat layer 160 The distance between the convex portions 161, the distance between the light emitting region and the light emitting region, and the like.
An overcoat layer 160 is disposed on the color filter 150 and the passivation layer 133. Although the passivation layer 133 is shown in FIG. 2A as being included in the 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 . Although the color filter 150 is shown in FIG. 2A as being disposed on the passivation layer 133, the color filter 150 may be disposed at any position between the overcoat layer 160 and the substrate 110 .
The overcoat layer 160 includes a plurality of convex portions 161 arranged to overlap with the color filter 150 and a first connecting portion 162 connecting the convex portions 161 adjacent to each other. FIG. 2A is a cross-sectional view of a plurality of hexagonal convex portions 161. FIG. The first connecting portion 162 is a high portion between the convex portions 161 adjacent to each other. The overcoat layer 160 functions as a planarization layer in a portion where the plurality of convex portions 161 are not disposed.
As shown in FIG. 2B, each of the convex portions 161 and the first connecting portions 162 may have a hexagonal shape as a whole, but it is not limited thereto, and may be a hemispherical shape, a semi-ellipsoid shape, . The plurality of convex portions 161 may be arranged in a hexagonal honeycomb structure on a plane. In other words, one convex portion 161 having a hexagonal shape and another convex portion 161 adjacent to the other convex portion 161 can be disposed in an integrally formed hexagonal honeycomb structure by sharing one side.
The organic light emitting device 140 including the first electrode 141, the organic light emitting layer 142 and the second electrode 143 and the bank 136 and the pattern layer 337 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 into the organic light emitting diode 140 while keeping the morphology of the protrusion 161 of the overcoat layer 160 as it is, An insulating second passivation layer (not shown) having a refractive index similar to that of the first electrode 141 may be added between the overcoat layer 160 and 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.
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 first electrode 141 may be connected to the drain electrode 124. 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 first electrode 141 is disposed in a shape following the morphology of the surface of the overcoat layer 160. Accordingly, the first electrode 141 has a convex morphology at the convex portion 161 of the overcoat layer 160. [
A bank layer 136 is disposed on the overcoat layer 160 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 161 of the overcoat layer 160 and the first connection portion 162 are disposed so as to overlap with the opening portion 136a of the bank layer 136. [ The convex portion 161 of the overcoat layer 160 and the first connection portion 162 are disposed to overlap the color filter 150 so that the convex portion 161 of the overcoat layer 160 and the first connection portion 162 overlap with the color filter 150 at the bottom and overlap with the opening 136a of the bank layer 136 at the top.
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.
2A, the thickness of the organic light emitting layer 142 between the convex portion 161 of the overcoat layer 160 and the first connection portion 162 is greater than the thickness of the convex portion 161 of the overcoat layer 160, May be thinner than the thickness of the organic light emitting layer 142 at the top of the organic light emitting layer 162. 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 161 of the overcoat layer 160 and the first connecting portion 162.
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, .
The organic light emitting layer 142 is formed between the convex portion 161 of the overcoat layer 160 and the first connection portion 162 in terms of the amount of light emitted from the organic light emitting layer 142 depending on the thickness d1, d2, d3, 142 may be larger than the emission amount per unit area of the organic light emitting layer 142 at the bottom of the convex portion 161 or the top of the first connection portion 162. 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 161 of the overcoat layer 160 and the first connection portion 162.
The organic luminescent layer 142 and the second electrode 143 may include a first electrode 141 having a shape conforming to the morphology of the surface of the overcoat layer 160, And is arranged in a shape along the morphology of the upper surface of the first electrode 141. As a result, the shape of the organic light emitting diode 140 can be realized using the convex portion 161 of the overcoat layer 160.
When the organic light emitting diode 140 has a microlens array structure for improving the external light extraction efficiency, the convex portions 161 of the overcoat layer 160 are formed on the surface of the organic light emitting diode 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, An area between the convex portion 161 of the first connection portion 160 and the first connection portion 162 is generated. When the organic light emitting diode 140 is driven, the electric field is locally concentrated in the efficient light emitting region and the main current path is formed to generate the main light emission. In the convex portion 161 of the overcoat layer 160, the ineffective light emitting region Z ) 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 OLED display 100 according to an embodiment may include a convex micro lens array pattern on the color filter 150 in the overcoat layer 160. The light emitted from the organic light emitting layer 142 is totally reflected within the first electrode 141 and the organic light emitting layer 142 and is trapped by the microlens array structure inserted 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 161 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 161 of the overcoat layer 160 Can be adjusted.
More specifically, it is as follows. In order to form the convex portion 161 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 161 of the overcoat layer 160 can be formed by performing the heat treatment stepwise 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 161 of the overcoat layer 160. As the time for performing the intermediate heat treatment is increased, the morphology of the convex portion 161 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 161 of the overcoat layer 160 disappears and the overcoat layer 160 is planarized.
Using this tendency, various organic light emitting display devices having different morphologies of convex portions 161 of the overcoat layer 160 were fabricated. When the convex portion 161 of the overcoat layer 160 has some morphology, that is, when the convex portion 161 of the overcoat layer 160 has a certain aspect ratio, the organic light emitting element 140 has the maximum And whether or not it can operate with the luminous efficiency.
The organic light emitting diode display 100 according to an exemplary embodiment of the present invention includes a plurality of organic light emitting diodes 340 and a plurality of organic light emitting diodes 340, So that the totally trapped light is extracted to the outside.
Since the optical path change according to the shape of the convex portion 161 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 161 of the overcoat layer 160, Height H (Height), Aspect Ratio (A / R), F (Full Width Half Max), Half Height Width Aspect Ratio (F_A Height aspect ratio Rm (Ratio of MLA = (F_A) / R (= H / F)), slope (S (Slope) / R) / (A / R))).
3A is a conceptual illustration of the parameters that determine the shape of the convex portion 161 of the overcoat layer 160. FIG. FIG. 3B shows the parameters determining the shape of the convex portion of the overcoat layer in the organic light emitting display according to one 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 161 of the overcoat layer 160 means the length between the centers of the two convex portions 161, and the diameter D is the length of the convex portion 161 161) to the top of the first connection portion (162). The half-height width F means the length between the two convex portions 161 at half the height as shown in FIG. 3A. The aspect ratio A / R of the convex portion 161 means a value obtained by dividing the height H of the convex portion 161 by the radius D / 2 of the convex portion 161.
The convex portion 161 may have a hexagonal 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 0.2 to 0.8 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 161 of the overcoat layer 160 has a value of more than about 0.8, the tendency that the rate of current efficiency increase is rather lowered can be confirmed. In particular, when the aspect ratio of the convex portion 161 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.
The surface on which the organic light emitting diode 140 is disposed in the organic light emitting diode display 100 according to an exemplary embodiment is formed such that the aspect ratio A / R of the convex portion 161 of the overcoat layer 160A is about 0.2 or more And may be the top surface of the overcoat layer 160 having a value between about 0.8 and less. Or the surface on which the organic light emitting diode 140 is disposed in the organic light emitting diode display 100 according to an exemplary embodiment of the present invention may be formed such that the aspect ratio A / R of the convex portion 161 of the overcoat layer 160 is (Not shown) that follows the morphology of the overcoat layer 160 having a value between about 0.2 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 0.2 and about 0.8, The device 140 is formed on a gentle unflattened screen having an aspect ratio of between about 0.2 and about 0.8 and the anode 141, the organic light emitting layer 142, and the cathode 143 are formed of a gentle non-planar screen morphology As shown in FIG.
The first connecting portion 162 of the convex portion 161 of the overcoat layer 160 may be formed to have the same height as that of the convex portion 161 of the overcoat layer 160, It can be formed to have a gentle slope. When the overcoat layer 160 is formed such that the aspect ratio A / R of the convex portion 161 of the overcoat layer 160 is 0.2 or more and 0.8 or less according to this method, The organic light emitting diode 140 and the bank 136 may be formed on the organic light emitting layer 142,
When only the aspect ratio A / R is applied as a parameter defining the shape of the convex portion 161 of the overcoat layer 160, only the diameter D and the height H are defined by the same aspect ratio A / R The shape of the convex portion 161 of the overcoat layer 160 is significantly different when the values defined by the remaining variables such as the half height width F and the gap G between the convex portions are different.
4A to 4D are cross-sectional views in which shapes of convex portions 161 of the overcoat layer 160 are compared with each other at the same aspect ratio.
4A shows the positions of the first to third regions C, B, and A included in each of the equal portions when the convex portion 161 of the overcoat layer 160 is trisected on the basis of the height.
4B to 4D illustrate a case where the diameter D of the convex portion 161 of the overcoat layer 160 is the same as or similar to the height H so that the convex portions 161 of the overcoat layer 160 having the same or similar aspect ratio A / FIG. The aspect ratio A / R of the convex portion 161 of the overcoat layer 160 shown in FIGS. 4B to 4D is about 0.6. As described above, the convex portion 161 of the overcoat layer 160, Of not less than 0.2 and not more than 0.8.
4B shows the convex portion 161 of the overcoat layer 160 where the maximum slope Smax is located in the first region C when the height H of the convex portion 161 of the overcoat layer 160 is taken as the third ). At this time, the inclination S of the convex portion 161 means an angle between the tangential line of the lower surface of the convex portion 161 and the horizontal plane as shown in Figs. 3A and 3B. At this time, the maximum slope Smax means the slope of the maximum angle between the tangential line of the lower surface of the convex portion 161 and the horizontal plane.
4C shows the convex portion 161 of the overcoat layer 160 where the maximum slope Smax is located in the second region B when the height H of the convex portion 161 of the overcoat layer 160 is the third ).
4D shows the convex portion 161 of the overcoat layer 160 where the maximum slope Smax is located in the third region A when the height H of the convex portion 161 of the overcoat layer 160 is taken as the third ).
Although the aspect ratios A / R of the convex portions 161 of the overcoat layer 160 shown in FIGS. 4B to 4D are the same or similar to each other, depending on the shape of the convex portions 161 of the overcoat layer 160, There may be a shape of the convex portion 161 in which the path of the light emitted from the light source 142 is different and the light extraction efficiency is not improved at all.
Fig. 5 shows various shapes of convex portions of the overcoat layer with the same or similar aspect ratio (A / R).
3A and 5, if the shape of the convex portion 161 of the overcoat layer 160 is triangular as shown in FIG. 3A, then the half height width F of the convex portion 161 of the overcoat layer 160 ) Is half the diameter (D / 2). At this time, the slopes S of the lower surface of the convex portion 161 of the overcoat layer 160 are all the same.
5, the convex portion 161 of the overcoat layer 160 included in the OLED display 100 according to an exemplary embodiment may have a half height F of less than a radius D / 2 have. The half height width F of the convex portion 161 of the overcoat layer 160 is larger than the radius D / 2 because the side surface of the convex portion 161 has a fat shape, The light extraction efficiency can be lowered. In contrast, as described above, the half-height width F of the convex portion 161 of the overcoat layer 160 is smaller than the radius D / 2 because the side surface of the convex portion 161 has a slender shape, The external light extraction efficiency can be improved. At this time, the convex portion 161 of the overcoat layer 160 included in the organic light emitting display 100 according to an exemplary embodiment may have a ratio of the half height width F to the radius D / 2 of the convex portion 161 0.1 or less.
6 is a graph showing current efficiency enhancement (%) according to the half height width of each of the organic light emitting display devices in which the half height width F of the convex portion 161 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 OLED display 100 in which the convex portion 161 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 current efficiency increase rate was better than that in the case where the width (F) was less than 2.0 μm as compared with the case where the half height width (F) was 2.0 or more. Rather, if the half-height width F of the convex portion 161 of the overcoat layer 160 has a value of 2.0um or more, the tendency of the current efficiency increase rate to be lowered (the increase rate has a negative value) can be confirmed.
If the half-height width F has a value of 2.0um or more even if the aspect ratio A / R of the convex portion 161 of the overcoat layer 160 has an optimum value, The angle of the proceeding light is equal to or greater than the total reflection critical angle (42 degrees), which must be trapped between the substrate 110 and 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 161 may be larger than the aspect ratio A / R. At this time, the half height aspect ratio F_A / R of the convex portion 161 means the height H with respect to the half height width F of the convex portion 161. Height aspect ratio of the convex portion 161 with respect to the aspect ratio may be larger than 1.0. As described above, for example, when the aspect ratio A / R of the convex portion 161 is 0.7 or more and 0.8 or less, for example, the half height aspect ratio F_A / R of the convex portion 161 may be more than 0.8 and less than 2.0.
As shown in FIG. 5, the convex portion 161 of the overcoat layer 160 may have various shapes even if the half-height width F is smaller than the radius: (D / 2) and the half height width F is the same .
For example, when the half height width F of the convex portion 161 of the overcoat layer 160 is smaller than the radius: D / 2, the convex portion 161 of the overcoat layer 160, (The shape of f1 in Fig. 5) in which the slope S of the slope gradually increases from the bottom to the top. In the same case, the slope S of the convex portion 161 of the overcoat layer 160 gradually decreases from the maximum slope Smax to the minimum slope Smin. The shape gradually increases from the minimum slope Smin F2 < / RTI > shape). Also, in the same case, the slope S of the convex portion 161 of the overcoat layer 160 gradually increases to reach the maximum slope Smax and then decreases again (f3 in Fig. 5).
The slope of the organic light-emitting layer 142 between the convex portion 161 of the overcoat layer 160 and the first connection portion 162 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. Therefore, when the convex portion 161 has the shape of f1 or the shape of f2, the position with the largest amount of light emission is located at the bottom or the top of the convex portion 161. [ In this case, the light emitted from the organic light emitting layer 142 is totally reflected within the first electrode 141 and the organic light emitting layer 142 and is trapped by the inserted micro-lens array structure at an angle smaller than the total reflection critical angle, The effect of increasing the external luminous efficiency is inevitably reduced.
In other words, in the organic light emitting diode display 100 according to the embodiment, when the convex portion 161 of the overcoat layer 160 has a shape that the inclination at the bottom increases and then decreases at the maximum slope (f3 in FIG. 5) The light emitted from the light source 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 connecting portion connecting the convex portions has a gentle inclination. The separation distance G (Gap) at the bottom of the convex portion 161 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.
7A and 7B are diagrams showing optical paths along the maximum inclination of convex portions of the overcoat layer.
7A and 7B, the convex portion 161 of the overcoat layer 160 has a shape (shape f3 in FIG. 5) in which the inclination at the bottom increases and the maximum slope Smax decreases as shown in FIG. 5, Lt; / RTI >
7A and 7B, even when the convex portion 161 of the overcoat layer 160 having the shape decreasing at the maximum slope Smax (shape f3 in FIG. 5) is increased, the angle of the maximum slope Therefore, it can have various shapes.
7A and 7B, when the maximum inclination Smax of the convex portion 161 of the overcoat layer 160 is higher than 60 degrees, for example, 70 degrees (FIG. 7A) or 65 degrees (FIG. 7B), the traveling angle of the light starting from the effective light emitting region is more than 42 degrees, which is once again trapped in the organic light emitting device 140, so that the luminous efficiency may not be increased.
Therefore, the shape of the convex portion 161 of the overcoat layer 160 shown in FIGS. 4B to 4D is such that when the maximum slope Smax of the convex portion 161 is 40 degrees to 60 degrees (for example, 50 degrees) The light emitted from the organic light emitting layer 142 is not trapped in the organic light emitting diode 140 when the traveling angle of the light starts to progress from the effective light emitting area.
8 is a graph showing current efficiency enhancement (%) according to the maximum slope Smax of each of the organic light emitting displays in which the maximum slope Smax of the convex portion 161 of the overcoat layer 160 has various values, ) Or enhancement of current efficiency (%)).
8, when the maximum slope Smax of the convex portion 161 of the overcoat layer 160 is less than 40 degrees, the light advancing angle in the effective light emitting 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 inclination Smax of the convex portion 161 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 161 of the overcoat layer 160 shown in FIGS. 4B to 4D is such that when the maximum slope Smax of the convex portion 161 is 40 to 60 degrees, The light emitted from the organic light emitting layer 142 is not trapped in the organic light emitting diode 140, so that the light emitting efficiency can be increased.
4B to 4D illustrate how the maximum slope Smax is applied to the first region C to the third region A when the height H of the convex portion 161 of the overcoat layer 160 is taken as the third reference, Of the overcoat layer 160 are located.
The half height aspect ratio Rm with respect to the aspect ratio of the convex portion 161 is the ratio of the half height aspect ratio F_A / R to the aspect ratio A / R and the region having the sharpest maximum slope Smax is the first region C ) To the third region (A). When the half-height aspect ratio Rm of the convex portion 161 with respect to the aspect ratio is less than 1.0, the region having the maximum slope Smax is the first region C. [ When the half-height aspect ratio Rm of the convex portion 161 with respect to the aspect ratio 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 161 with respect to the aspect ratio is more than 1.0, the region having the maximum slope Smax is the third region A.
The optical path of the light emitted from the organic light emitting layer 142 shown in FIGS. 4B to 4D is the same as the first to third It can be seen that the front emission efficiency is the best when the first region A is located in the third region A adjacent to the normal region. 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 161 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 the light emission efficiency according to the shape of the convex portion 161 when the overcoat layer 160 includes the convex portion 161 has been described. Hereinafter, even when the overcoat layer 160 includes recessed portions, the external light extraction efficiency or the light emitting efficiency depending on the shape of the recessed portion, like the protruded portions 161, will be described with reference to FIG.
9 is a cross-sectional view for explaining an organic light emitting display including an overcoat layer including a plurality of recesses and a step reducing layer according to another embodiment.
Referring to FIG. 9, the OLED display 200 according to another embodiment of the present invention includes a plurality of recesses 636 in the overcoat layer 660 as compared with the OLED display 100 of FIGS. 1 and 2B And the other constitutions are substantially the same, and redundant explanations are omitted. The elements of the organic light emitting display 200, which are not shown in FIG. 9, may be the same as the elements of the organic light emitting display 100 according to the embodiments described with reference to FIGS. 1 and 2B.
The overcoat layer 260 includes a plurality of recesses 263 formed to overlap the color filter 250 and a second connection portion 264 connecting the recesses 263 adjacent to each other. In other words, the overcoat layer 260 includes a plurality of concave portions 263 arranged so as to overlap with the openings 136a of the bank layer 136 shown in FIG. 1 and a plurality of second connection portions 263 connecting the concave portions 263, (264).
A first electrode (241) is disposed on the overcoat layer (260). A pattern layer 237 is disposed on the overcoat layer 260 and the first electrode 241 and the organic light emitting layer 242 and the second electrode 243 are disposed on the first electrode and the pattern layer 237. The first electrode 241, the organic light emitting layer 242, and the second electrode 243 constitute the organic light emitting diode 240.
The first electrode 241, the organic light emitting layer 242 and the second electrode 243 may be disposed along the top surface of the overcoat layer 260 to have a shape conforming to the morphology of the overcoat layer 260.
As described with reference to FIGS. 3A and 3B, the half-height width F of the convex portion 161 of the overcoat layer 160 is smaller than the radius D / 2, The half-height width F of the protrusion 263 may be smaller than the radius D / 2. The ratio of the half height width F to the radius D / 2 of the concave portion 263 may be 0.1 or less.
As described with reference to FIGS. 3A and 3B, the recessed portion 263 of the overcoat layer 260 is formed in the same manner as the half height aspect ratio F_A / R of the overcoat layer 160 is larger than the aspect ratio A / R, Height aspect ratio F_A / R can be greater 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 263 may be larger than 1.0.
At this time, the concave portion 263 may have a hexagonal shape with a diameter of 1 to 5 mu m and a height of 1 to 4 mu m.
The convex portion 161 of the overcoat layer 160 has a shape that gradually decreases in the maximum inclination while the inclination increases, as described with reference to FIGS. 4B to 5, Can have a shape increasing in slope at the bottom and gradually decreasing at the maximum slope.
The maximum slope of the concave portion 263 of the overcoat layer 260 is set to 40 占 퐉 as in the case where the maximum inclination of the convex portion 161 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 263, the concave portion 263 is formed in the same manner as the convex portion 161 of the overcoat layer 160 of the OLED display 100 described with reference to FIG. The characteristics depending on the shape of the concave portion 263 and the second connection portion 264 according to the omitted parameters are the same as those of the convex portion 161 and the first connection portion 262). ≪ / RTI >
10 is a schematic system configuration diagram of an organic light emitting display according to the present embodiments.
10, a plurality of data lines DL and a plurality of gate lines GL are arranged in the organic light emitting diode display 300 according to the present embodiment, and a plurality of subpixels SP are arranged in a matrix type An organic light emitting diode (OLED) display panel 310 disposed on the organic light emitting display panel 310, a plurality of data lines driven by a plurality of data lines, a driving data driver 320, and a plurality of gate lines sequentially supplying scan signals, A gate driver 330 for sequentially driving 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 embodiments described above, the organic light emitting display device has the effect of improving the external light emitting efficiency and reducing the power consumption.
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.
