Bending of an organic light-emitting diode device

Abstract

Organic light-emitting diode device with - a flexible substrate, - an organic light-emitting diode layer arrangement comprising an organic emitter layer formed on the flexible substrate and comprising a first luminescent region (5, 6), and - a control device for controlling the first lighting area (5) to illuminate, wherein - the substrate has a first bending area (1) in which the substrate is bent, characterized in that - the first luminous area has several emitter layers on top of each other, each emitting either the same color or different colors, - a bending radius changes within the first bending area along a bending line, whereby ◯ the first bending region (1) is wholly or partially coated with an anode layer and / or a cathode layer and / or a charge carrier layer, but without an organic emitter layer, or ◯ the first bending area (1) is coated with a light-emitting diode layer arrangement, but the control device does not control the bending area to light up.

Description

[0001] The present invention relates to an organic light-emitting diode device comprising a bendable substrate, an organic light-emitting diode layer arrangement comprising an organic emitter layer formed on the bendable substrate and comprising a first luminous region, and a control device for controlling the first luminous region to illuminate, wherein the substrate has a bending region in which the substrate is bent.

[0002] Organic light-emitting diodes are thin-film components made of organic, semiconducting materials. The advantage of such thin-film components is that they can be applied to a substrate and thus easily adopt the three-dimensional structure of that substrate. Furthermore, they can also be applied to flexible substrates and, due to their thin-film construction, can then be bent with the substrate within certain limits.

[0003] To date, organic light-emitting diodes (OLEDs) for automotive applications have primarily been manufactured two-dimensionally on a glass substrate. A corresponding OLED then possesses the two-dimensional structure of the glass substrate.

[0004] In contrast, significantly more spatial design options exist when the organic light-emitting diode is applied as an organic light-emitting diode layer array on a flexible substrate. For example, such a flexible substrate is a flexible plastic film. Such a plastic film can be wrapped around a cylinder or applied to a wavy surface. The film is therefore generally only bendable around one or more parallel bending axes. For example, enclosing a sphere with the flexible plastic film is not possible without appropriate incisions in the film.

[0005] Furthermore, the design possibilities with flexible OLEDs as 2.5D (curved 2D bodies) or 3D design bodies are currently severely limited by the large permissible bending radii of more than 10 mm. Another major technological challenge arises from the additional stress on the functional structures of the OLED caused by bending, which shortens the OLED's service life. Shaping by torsion represents the greatest mechanical stress on the component, which currently precludes its implementation in vehicle lighting.

[0006] The disadvantage of using solid glass substrates as supports is that such 2D glass substrates make spatial design of the light source impossible. The use of flexible OLEDs as 2.5D elements with bending radii of more than 10 mm also limits design freedom, as mentioned above. Furthermore, since torsion of the OLED is not possible, many individual OLED components are required to realize sophisticated 3D designs. The design complexity requires a high level of technical effort due to the use of many different individual OLEDs in the manufacturing and assembly process.

[0007] A rigid-flexible carrier plate for light-emitting diodes is known from DE 10 2009 009 288 A1. It has a rigid and a flexible carrier area. LEDs are arranged in the rigid carrier area.

[0008] The document DE 10 2012 004 759 A1 shows a rear light assembly for a motor vehicle. A control device individually controls the lighting elements of the rear light assembly.

[0009] US 2012 / 0206050 A1 discloses a detector-controlled lighting system. Several spotlights are connected via a connecting element that can be bent in two orthogonal directions.

[0010] Finally, EP 1 033 525 A2 discloses a flexible LED multi-module for a motor vehicle. Rigid circuit boards carrying LEDs are connected to flexible circuit boards.

[0011] Furthermore, JP 2008-107440 A discloses a display device comprising a display element with a display layer sandwiched between a transparent surface electrode layer and a back electrode layer. Furthermore, the device comprises a transparent surface protective film disposed on the upper surface of the display element and a back protective film disposed on the lower surface of the display element, with a large number of folding grooves arranged parallel to each other at equal intervals along the bending direction of the display element on the lower surface of the back protective film.

[0012] Furthermore, WO 2014 / 162 173 A1 discloses a device comprising: a plurality of layers configured to provide a user interface device; and a flexible layer overlying the plurality of layers; wherein the flexible layer is continuous across a bending region and at least one of the plurality of layers is discontinuous across the bending region.

[0013] The object of the present invention is therefore to provide an organic light-emitting diode device with which spatial luminous bodies can be more easily realized.

[0014] According to the invention, this object is achieved by an organic light-emitting diode device according to claim 1.

[0015] The organic light-emitting diode device therefore has a flexible carrier layer, which can be implemented, for example, as a plastic film. In particular, it can be a transparent plastic film.

[0016] Furthermore, the organic light-emitting diode device comprises an organic light-emitting diode layer arrangement having an organic emitter layer. The luminous phenomenon results from a recombination of the charge carriers in the emitter layer.

[0017] Furthermore, the LED layer arrangement is formed on the flexible carrier layer. For example, it can be formed by suitable deposition processes (evaporation or the like). A first and optionally a second planar luminous region is formed in which the carrier layer or the LED layer arrangement is not bent or is only slightly bent.

[0018] The carrier layer of the organic light-emitting diode device has a bending region in which the carrier layer is bent. The two flat or slightly curved light-emitting regions, which are connected by the bending region, may thereby form a defined angle to each other.

[0019] The organic emitter layer is not formed in at least part of the first bending region or, unlike the first luminous region, is not controlled to illuminate by the control device. Since the organic emitter layer is very sensitive to mechanical bending stresses, this prevents excessive bending of the bending region from damaging this organic layer or from using an area vulnerable to bending for a luminous function.

[0020] According to a further preferred embodiment, a bending axis is defined around which the entire first bending region is bent. This means that the first bending region takes the shape of a section of a cylinder shell. This allows the two luminous regions to be tilted relative to each other without twisting.

[0021] According to a further embodiment, the carrier layer can be bent in the first bending region by torsion. Since the emitter layer is absent in the bending region, there is no risk of damage to the organic layer stack due to torsion. Consequently, the torsion allows for significantly more spatial design options for the organic light-emitting diode device.

[0022] Furthermore, it can be provided that a second bending area is connected to the second flat luminous area, followed by a third luminous area. This would result in a single component with five separate areas, namely three luminous areas and two bending areas. The manufacture and assembly of such a component is correspondingly simpler than with several individual components.

[0023] Therefore, if two different bending areas with two different bending axes are planned, these bending axes do not have to run parallel to each other; in other words, they intersect at a single point. The non-parallel bending axes allow for the creation of bodies that deviate from the pure wave shape.

[0024] The organic light-emitting diode device is, of course, not limited to having only three luminous regions and two bending regions. Rather, it can also have additional bending and luminous regions. For example, bending and luminous regions can be arranged alternately in a chain of any length.

[0025] With multiple bending axes, these can form an angle to each other that differs from 0. A corresponding acute angle α can be in the range of 0° < α ≤ 90°. In certain configurations, the angle α is 90° or, for example, 45°.

[0026] A bending radius within the first bending area does not need to be constant along a bending line, but can vary. For example, a soft start and end can be provided, with a smaller bending radius in between.

[0027] A lighting area can be controlled homogeneously as a single lighting unit. Furthermore, a lighting area can also be divided into sub-lighting areas. Each of these sub-lighting areas can be controlled with a separate current or brightness. If necessary, the sub-lighting areas can also have different colors.

[0028] The two or more of the multiple luminous areas can be controlled independently of each other by a control device. Therefore, not all luminous areas of the organic light-emitting diode device need to be controlled uniformly, but rather they can be controlled individually or in groups. This expands the application range of the organic light-emitting diode device.

[0029] In principle, at least two of the illuminated areas can be controlled in series or in parallel by the control device. This means that these two illuminated areas will illuminate together and, if necessary, with equal brightness when controlled together. These interconnected illuminated areas do not have to be adjacent to each other; rather, another illuminated area can be arranged between the illuminated areas in addition to the bending area.

[0030] Furthermore, at least two of the illuminated areas can have different luminous colors. For example, a first illuminated area can be excited or controlled to glow red, and a second illuminated area to glow yellow. If necessary, the individual illuminated areas can also be excited to different brightness levels, so that, for example, a first area glows brighter than a second area.

[0031] The first luminous area has several emitter layers stacked on top of each other, each emitting either the same color or different colors. These layers can be controlled together or individually, for example, to display different colors in the same area.

[0032] In a preferred embodiment, both a first boundary line between the first luminous region and the first bending region and a second boundary line between the second luminous region and the first bending region run parallel to the bending axis. This has the advantage that the bending region is a section of a cylinder shell. According to an alternative embodiment, the respective boundary lines can also be at an angle to the corresponding bending axis, so that the adjacent luminous region is rotated accordingly relative to the bending axis.

[0033] The flexible carrier layer can be applied to a variety of three-dimensional structures or holders, for example, in a motor vehicle. These structures or holders can then become suitable supports for lighting devices.

[0034] In a particularly preferred application, a motor vehicle is equipped with such an organic light-emitting diode device as described above. For example, a tail light, a brake light, and / or a turn signal can be realized with this organic light-emitting diode device. In this way, for example, the rear light of a motor vehicle, which has these lights, can be implemented with a single light-emitting diode device. The three-dimensional design not only allows compliance with legal requirements regarding brightness and angular distribution, but also opens up unique design possibilities.

[0035] The present invention will now be explained in more detail with reference to the accompanying drawings, in which: Fig. 1 is a plan view of an unbent organic light-emitting diode device having multiple light-emitting and bending regions; Fig. 2 an organic light-emitting diode device with a special geometric design and marked light-emitting function sections; and Fig. 3 a motor vehicle in which, for example, a rear light is equipped with an organic light-emitting diode device according to the invention.

[0036] The exemplary embodiments described in more detail below represent preferred embodiments of the present invention. It should be noted that the individual features can be implemented not only in the described feature combinations, but also on their own or in other combinations.

[0037] In the example of Fig. 1 shows a plan view of an organic light-emitting diode device with a linear contour. A flexible carrier layer, which may be, for example, a transparent plastic film, is used as the carrier. The flexible carrier layer is at least partially coated with an organic light-emitting diode layer arrangement. Such an organic light-emitting diode layer arrangement typically has several layers, one of which represents a cathode and another an anode. Between the anode layer and the cathode layer, for example, there is a hole-conducting layer and an emitter or recombination layer. Such a layer arrangement is, for example, a few tenths of a millimeter thick. It therefore only slightly impairs the flexibility of the carrier layer. In principle, however, the emitter layer is at risk in a bending area when bent with a bending radius that is too small.

[0038] In the picture of Fig. Figure 1 shows the organic light-emitting diode layer arrangement in plan view, which is why the individual layers are not visible. Depending on the design, the flexible carrier layer underlying the organic light-emitting diode layer arrangement may or may not be visible in some areas in the plan view.

[0039] The special form of Fig. 1 developed or not yet bent 2D LED device results from the 3D body that is to be obtained after bending. With the linear 2D structure, in the bent state, for example, a type of triangular cylinder or an open quadrilateral cylinder can be realized. In contrast, with the somewhat more complex 2D structure of Fig. 2 For example, after bending, a kind of quarter sphere can be obtained. A lighting device shaped in this way can, for example, emit light in four of six spatial directions.

[0040] In the simple example of Fig. 1, the organic light-emitting diode device has five different physical regions. In a sequence from left to right in the drawing, a first luminous region 5, a first bending region 1, a second luminous region 6, a second bending region 2, and a third luminous region 7 are arranged in series. The specific geometry of the individual regions is not important for the principle of the present invention. What is essential here is that a bending region, here the first bending region 1, does not have a complete OLED. In particular, there is no sensitive organic layer in the first bending region 1. Such a sensitive organic layer cannot be damaged by strong bending, kinking, or torsion. If appropriate, the bending region 1 is completely or partially coated with an anode layer and / or a cathode layer and / or a charge carrier conductor layer.However, these layers are generally less sensitive to mechanical stress.

[0041] In the example of Fig. 1, the second bending region 2, like the luminous regions 5, 6, and 7, is coated with a light-emitting diode layer arrangement, so that the second bending region 2 can also be excited to glow. Specifically, a luminous surface LF1 is provided within the luminous region 5. The luminous region 5 thus has an edge to the bending region 1, which either has an emission layer and is not activated to glow, or has no emission layer at all. However, this edge is purely optional. In the present example, such an edge is also provided on the right side toward the second luminous region 6.

[0042] The second luminous region 6, the second bending region 2 and the third luminous region 7 together form a second luminous surface LF2. The second bending region 2 is therefore located within the luminous surface LF2. Therefore, the possible bending radius in the second bending region 2 is greatly restricted due to the complex structure of the OLED. In contrast, the first bending region 1 is located according to the invention in a non-luminous region of the OLED, i.e. at least the emission layer of the OLED is not formed here. As a result, significantly smaller bending radii are possible in the first bending region 1 than in the second bending region 2 with the complete light-emitting diode layer arrangement of the OLED. If necessary, even torsions and kinks are possible in the first bending region 1.

[0043] Fig. Figure 2 shows a multi-angled two-dimensional structure of an organic light-emitting diode device before bending. Although the geometry is slightly different than in the example of Fig. 1, was for Fig. 2 the numbering of the individual functional areas has been adopted as far as possible. Specifically, the organic light-emitting diode device of Fig. 2 a first bending area 1, a second bending area 2, a third bending area 3 and a fourth bending area 4. The first bending area 1 lies between a first luminous area 5 and a second luminous area 6. The second bending area 2 lies between the second luminous area 6 and a third luminous area 7. The third bending area 3 lies between the third luminous area 7 and a fourth luminous area 8. Finally, the fourth bending area 4 lies between the fourth luminous area 8 and a fifth luminous area 9. The number of luminous areas is at least two and there is no upper limit. The number of bending areas is at least one and there is also no upper limit.

[0044] In the present example, bending areas 1 to 4 are rectangular. A light-emitting area adjoins each of the opposite sides. Each bending area is characterized by being curved in its final state, while each light-emitting area is essentially flat or slightly curved. The transition between a bending area and a light-emitting area is formed by a respective boundary line. Alternatively, the bending areas can also be triangular or trapezoidal.

[0045] Each bending zone 1 to 4 has a respective bending axis 1a, 2a, 3a, and 4a. This respective bending axis is not located in the plane of the unwound LED device, but rather above or below it, depending on the direction of bending. The distance of the respective bending axis from the plane of the LED device is determined by the respective, possibly variable, bending radius. The width 1b of the first bending zone 1, for example, can be selected as required, like that of the other bending zones.

[0046] In the case of Fig. 2, the two-dimensional, angled light-emitting diode device has the shape of two joined "L"s. The first "L" is formed by the regions 5, 1, 6, 2, and 7, while the second "L" is formed by the regions 7, 3, 8, 4, and 9. This means that the illuminated regions 5, 6, 7, 8, and 9 are also rectangular, but they can also have a different shape. The bending axes of the bending regions run perpendicular to the respective legs of the two "L"s. Each bending region 1, 2, 3, 4 has two opposite sides that form the boundary to adjacent illuminated regions. The boundary lines of a bending region to the adjacent illuminated regions do not have to be parallel and can converge if the bending region is triangular or trapezoidal, for example. However, a bending region can also take the shape of a parallelogram, for example.

[0047] The boundary lines between bending areas and luminous areas run parallel to the respective axis of the bending area. This is also only optional. In this example, bending areas 1 to 4 do not touch each other. This way, for example, torsions of the bending and luminous areas can be avoided. For example, luminous area 8 remains completely flat, even if the third bending area 3 is bent around the bending axis 3a and the fourth bending area 4 is bent around the bending axis 4a. Overall, the shape of the OLED and the position of the bending areas result in a 3D body, although the OLED is only bent along one axis in each bending area.

[0048] Fig. 2 further shows a concrete assignment of the lighting functionality to the individual areas of the light-emitting diode device.

[0049] For example, the first lighting area 5 has the functionality SL1, namely that of a first tail light. Part of the second lighting area 6 has the functionality BLL1, namely that of a first indicator light. Another part of the second lighting area 6 has the functionality SL2, namely that of part of a second tail light. The second bending area and part of the third lighting area 7 also have the functionality SL2. This means not only that a bending area can, in principle, also assume the lighting functionality like a lighting area, but also that the lighting functionality does not have to be linked to the physical boundaries of the individual lighting and bending areas.

[0050] In addition to the SL2 functionality, the third lighting area 7 also performs the BRL1 functionality of a first brake light. The fourth lighting area 8 performs the BRL2 and BLL2 functions for a second brake light and a second indicator light. The fifth lighting area 9 has the BLL3 functionality of a third indicator light.

[0051] According to the invention, bending regions 1, 3, and 4 do not have an OLED function. For this purpose, the emission layer and, if applicable, at least parts of the other layers of the organic light-emitting diode layer arrangement were omitted in these regions. Alternatively, none of the layers are omitted, but the region of strong bending is not electrically controlled. Therefore, it is irrelevant if damage occurs here. This allows the Fig. 2, the structure of a 2D light-emitting diode device shown in FIG. 1 can bend or twist more strongly in the bending regions 1, 3 and 4 than in the bending region 2, which has the full OLED functionality, ie the lighting function. It should be noted that the bending regions do not necessarily have bending axes as in the example of Fig. 2 must have.

[0052] The individual areas of the organic light-emitting diode device are Fig. 3 but not in Fig. 2 is controlled by the control device 12. In a preferred embodiment, the individual functional areas can be controlled or addressed independently of the physical areas 1 to 9.

[0053] The embodiment of Fig. Figure 2 further shows that an organic light-emitting diode device as a single component can certainly have different emitter layers, allowing different luminous colors to be realized in different functional areas. If necessary, it may also be possible to drive the different areas with different current intensities, allowing the brightness to be varied accordingly.

[0054] Fig.Figure 3 schematically depicts a motor vehicle 10 whose rear light 11 is equipped with an organic light-emitting diode device as shown above. Such a rear light 11 typically has a tail light, a brake light, and a turn signal. According to legal requirements, the individual lights must not only have a certain brightness but also a specific angular distribution. This can be easily achieved here using a single organic light-emitting diode device. To achieve a certain brightness, a suitable area of ​​the light-emitting diode device is controlled with a corresponding current. The angular distribution can be achieved by appropriately bending sections of the light-emitting diode device, with several light areas possibly pointing in different directions, for example, to achieve a common tail light functionality (SL1 and SL2). The corresponding control device 12 is integrated into the motor vehicle 10.

[0055] This makes it possible to create a 3D OLED module from a single OLED, which consists of multiple bending lines on the component as well as the individual component dimensions and shapes. Furthermore, the resulting individual sub-areas can be controlled independently of one another through targeted segmentation of the OLED, thus realizing different lighting functions. One example demonstrated that in rear lighting, one sub-area fulfills the tail light function, while another sub-area represents the brake light. Alternatively, the areas can have a dual function, serving as both a tail light and a brake light, etc. This allows for any number of possible combinations in the circuitry of the individual sub-areas and their interaction. This opens up completely new design and configuration possibilities in lighting construction.

[0056] According to the present invention, the OLED contains both luminous and non-luminous regions. One or more bends of the OLED are located in a non-luminous region. This region is less complex and allows for greater bending (smaller bending radius) than in the luminous regions. Depending on the design, it is also conceivable to subject these regions to torsional loading.

[0057] The smaller bending radii enable completely new designs and package optimizations. Furthermore, different luminous areas can be located on the same OLED, which leads to design and cost advantages. The elimination of the sensitive organic components in areas subject to increased mechanical stress, which also allows for a reduction in bending radii without damaging the emissive layers, also does not further limit the component's service life.

Claims

[1] Organic light-emitting diode device with - a flexible substrate, - an organic light-emitting diode layer arrangement comprising an organic emitter layer formed on the flexible substrate and having a first luminous region (5, 6), and - a control device for controlling the first luminous area (5) to illuminate, wherein - the substrate has a first bending region (1) in which the substrate is bent, characterized by , that - the first luminous area has several emitter layers on top of each other, each emitting either the same colour or different colours, - a bending radius changes within the first bending area along a bending line, whereby ◯ the first bending region (1) is completely or partially coated with an anode layer and / or a cathode layer and / or a charge carrier layer, but without an organic emitter layer, or ◯ the first bending region (1) is coated with a light-emitting diode layer arrangement, but the control device does not control the bending region to light up. [2] The organic light-emitting diode device according to claim 1, wherein a bending axis (1a) is defined around which the entire first bending region (1) is bent. [3] Organic light-emitting diode device according to one of the preceding claims, wherein the substrate is bent by torsion in the first bending region (1). [4] Organic light-emitting diode device according to one of the preceding claims, wherein the organic light-emitting diode layer arrangement has a second luminous region (6), and the first bending region (1) connects the first luminous region (5) to the second luminous region (6), and wherein optionally a second bending region (2) adjoins the second luminous region (6) and a third luminous region (7). [5] Organic light-emitting diode device according to one of the preceding claims, wherein the first and the second luminous region (5, 6) are controlled independently of one another by a control device (12). [6] Organic light-emitting diode device according to one of claims 1 to 5, wherein the first and the second luminous region (5, 6) are controlled in series or in parallel by a control device (12). [7] Organic light-emitting diode device according to one of the preceding claims including claim 3, wherein both a first boundary line between the first luminous region (5) and the first bending region (1) and a second boundary line between the second luminous region (6) and the first bending region (1) run parallel to the bending axis (1a). [8] Organic light-emitting diode device according to one of the preceding claims, wherein the two luminous areas (5, 6) have different luminous colours. [9] Motor vehicle (10) in which a tail light, a brake light and / or a flashing light is realized with an organic light-emitting diode device according to one of the preceding claims.

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