Light-emitting apparatus and method for producing a light-emitting apparatus

Abstract

An light-emitting apparatus and a method for producing a light-emitting apparatus are disclosed. In an embodiment, the apparatus includes at least one organic device and an outcoupling layer, wherein the at least one organic device emits electromagnetic radiation during operation, wherein the outcoupling layer contains optical structures, and wherein the apparatus has a non-Lambertian radiation distribution curve during operation. The outcoupling layer influences the radiation passing through it in an optically varying manner by the optical structures along a lateral direction in order to produce the non-Lambertian radiation distribution curve.

Claims

1. An apparatus comprising: an organic device with an optical cavity; and an outcoupling layer; wherein the optical cavity is configured to cause the organic device, during operation, to emit electromagnetic radiation through a radiation exit surface of the organic device, the electromagnetic radiation being focused in a forward direction perpendicular to a surface of the outcoupling layer facing away from the radiation exit surface; wherein the radiation exit surface is a main surface of the organic device; wherein the outcoupling layer contains optical structures; wherein the apparatus has a non-Lambertian radiation distribution curve during operation; wherein the outcoupling layer influences the radiation passing through it in an optically varying manner by the optical structures along a lateral direction in order to produce the non-Lambertian radiation distribution curve; wherein a radiation distribution of the focused electromagnetic radiation includes a central region with a higher radiation intensity than its surroundings, and wherein the radiation distribution of the focused electromagnetic radiation takes a shape of a cos.sup.n (φ) curve, φ being an observation angle in an interval between −90° and 90° and n being a number greater than 1.

2. The apparatus according to claim 1, wherein the optical structures scatter or deflect the radiation passing through the outcoupling layer.

3. The apparatus according to claim 1, wherein the outcoupling layer has a gradient, at least in regions, along the lateral direction with regard to a local scatter effect or a local directional effect of the outcoupling layer.

4. The apparatus according to claim 1, wherein a distribution of the optical structures varies with regard to their concentration or their mean size along the lateral direction.

5. The apparatus according to claim 1, wherein a material composition of the optical structures varies along the lateral direction.

6. The apparatus according to claim 1, wherein the outcoupling layer is formed as a scattering layer, at least in regions, and wherein the optical structures of the scattering layer are scatter particles.

7. The apparatus according to claim 1, wherein the outcoupling layer is formed, at least in regions, as a microlens layer, and wherein the optical structures of the microlens layer are microlenses.

8. The apparatus according to claim 7, wherein the microlenses have different shapes along the lateral direction to achieve a variation with regard to a directional effect of the outcoupling layer.

9. The apparatus according to claim 1, wherein the organic device is formed pliantly and has a curved radiation exit surface.

10. The apparatus according to claim 1, wherein the organic device is arranged obliquely to one or more additional organic devices, wherein the one or more additional organic devices each comprise an optical cavity, wherein the outcoupling layer has a plurality of sub-regions spaced apart, and wherein the sub-regions are associated respectively with the organic device and the one or more additional organic devices.

11. The apparatus according to claim 1, wherein the organic device has a roughened radiation exit surface, the roughness of which varies along the lateral direction.

12. The apparatus according to claim 1, wherein refraction indices of adjacent layers of the organic device influence the non-Lambertian radiation distribution curve.

13. The apparatus according to claim 1, wherein the outcoupling layer is formed as a scattering layer at least in regions and the optical structures of the scattering layer are scatter particles, wherein, along the lateral direction, the outcoupling layer has a continuous gradient progression at least in regions with regard to a local scatter effect, and wherein, for achieving locally varying scatter effects, a material composition or a concentration or a geometrical size of the scatter particles varies along the lateral direction within the scattering layer.

14. The apparatus according to claim 1, wherein the radiation exit surface extends, in a lateral direction, from at least an outermost edge of the outcoupling layer to an opposing outermost edge of the outcoupling layer.

15. The apparatus according to claim 1, wherein outermost edges of the outcoupling layer, in the lateral direction, are disposed directly over, or are between, outermost edges, in the lateral direction, of the radiation exit surface.

16. The apparatus according to claim 1, wherein an entire bottommost surface of the outcoupling layer contacts, exclusively, the radiation exit surface.

17. The apparatus according to claim 1, wherein n is a number between 1.2 and 4 inclusive.

18. The apparatus according to claim 1, wherein n is a number between 2 and 4 inclusive.

19. An apparatus, comprising: an organic device with an optical cavity; and an outcoupling layer; wherein the optical cavity is configured to cause the organic device, during operation, to emit electromagnetic radiation through a radiation exit surface of the organic device, the electromagnetic radiation being focused in a forward direction perpendicular to a surface of the outcoupling layer facing away from the radiation exit surface; wherein the outcoupling layer contains optical structures; wherein the outcoupling layer influences the radiation passing through it in an optically varying manner by the optical structures along a lateral direction; wherein a radiation distribution of the focused electromagnetic radiation includes a central region with a higher radiation intensity than its surroundings, and wherein the radiation distribution of the focused electromagnetic radiation takes a shape of a cos.sup.n (φ) curve, φ being an observation angle in an interval between −90° and 90° and n being a number greater than 1.

20. The apparatus according to claim 19, wherein n is a number between 1.2 and 4 inclusive.

21. The apparatus according to claim 19, wherein n is a number between 2 and 4 inclusive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages, preferred embodiments and developments of the device and of the method result from the embodiments explained below in connection with FIGS. 1 to 11B. These show:

(2) FIGS. 1 to 3 show schematic representations of various embodiments of an apparatus with an organic device,

(3) FIG. 4 shows a schematic representation of an apparatus with a plurality of organic devices,

(4) FIGS. 5 to 7 show schematic representations of other embodiments of an apparatus with an organic device,

(5) FIG. 8 shows a schematic representation of another embodiment of an apparatus with a plurality of organic devices,

(6) FIG. 9 shows a schematic representation of various radiation distribution curves and

(7) FIGS. 10A to 11B show schematic representations of embodiments of an apparatus with a plurality of organic devices and simulated radiation distributions for the various embodiments.

(8) Identical and similar elements or elements having the same effect are provided with the same reference signs in the figures. The figures are schematic representations in each case and therefore not necessarily true to scale. On the contrary, comparatively small elements and in particular layer thicknesses can be shown exaggeratedly large for clarification purposes.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(9) FIG. 1 shows an apparatus 100 with a device 10 and an outcoupling layer 3. The device 10 is an organic light-emitting diode in particular. The device 10 has a substrate 1 and a functional layer stack 2 arranged on the substrate.

(10) The functional layer stack has an organic active layer 23. The active layer 23 emits electromagnetic radiation during operation of the device, for example. The layer stack 2 also contains a first charge transport layer 21 and a second charge transport layer 22, wherein the organic active layer 23 is arranged between the first charge transport layer 21 and the second charge transport layer 22.

(11) The device 10 has a radiation exit surface 11. In FIG. 1, the radiation exit surface 11 is formed by a surface of the substrate 1 facing away from the layer stack 2. The outcoupling layer 3 is arranged on the side of the radiation exit surface 11 on the device 10. The outcoupling layer 3 has a plurality of optical structures 31. The outcoupling layer 3 has a central axis M running vertically. In particular, the central axis M runs through a geometrical center point or through a center of mass of the outcoupling layer 3.

(12) The outcoupling layer 3 is formed in particular as a scattering layer. The optical structures 31 are in particular scatter particles. In particular, the outcoupling layer 3 has approximately from the central axis M along a lateral direction, for instance up to a lateral edge-region of the outcoupling layer 3, a gradient with regard to a local scatter effect of the outcoupling layer 3. In particular, the gradient has a continuous progression.

(13) In FIG. 1, the outcoupling layer 3 has a gradient along the lateral direction from the central axis M to an edge region in particular with a continuous gradient progression with regard to a concentration of the optical structures 31. From the central axis M to the lateral edge-region the scatter effect increases in particular steadily. This means that the scatter effect in the immediate vicinity of the central axis M is at its smallest and the scatter effect of the outcoupling layer 3 is greatest at the edge-regions. Alternatively to variation of the concentration of the optical structures, in particular of the scatter particles, a different local scatter effect of the outcoupling layer 3 can be achieved by variations of the size of the scatter particles or by changes in the materiality of the scatter particles, or by various combinations of the variations of the concentration, the size and the materiality of the scatter particles.

(14) The organic device shown in FIG. 1 has an optical cavity, on account of which the device 10 radiates electromagnetic radiation in a directed forward direction. In FIG. 1 the substrate 1, through which the electromagnetic radiation produced by the active layer 23 passes during operation of the device, is formed to be radiation-permeable. This is a so-called bottom emitter. Diverging from FIG. 1, the device can be formed as a top emitter and/or as a flexible, for example, pliant device. In a top emitter the substrate is in particular impermeable to radiation. The substrate is a metal foil, for example. The outcoupling layer 3 can then be arranged on a side of the layer stack 2 facing away from the substrate. A transparent encapsulation layer can be arranged between the layer stack 2 and the outcoupling layer 3.

(15) The scatter effect of the outcoupling layer is at its lowest in the immediate vicinity of the central axis M and can go towards 0. The apparatus 100 has a local radiation characteristic in this region which is directed and non-Lambertian. The scatter effect increases in particular steadily from the central axis M to the lateral edge-regions of the outcoupling layer 3. The radiation characteristic of the apparatus thus changes from the central axis M along the radial direction up to the edge-regions of the outcoupling layer 3 from a non-Lambertian radiation distribution to a Lambert-like radiation distribution.

(16) The sum or the superimposition of the local radiation characteristics along the outcoupling layer leads to an overall radiation that is non-Lambertian. The apparatus 100 shown in FIG. 1 thus has a non-Lambert radiation distribution curve during operation, wherein to produce the non-Lambert radiation distribution curve the outcoupling layer 3 influences the radiation passing through it in a varying manner optically along the lateral direction by means of the distribution of optical structures. With such an outcoupling layer 3 the radiation characteristic of the apparatus 100 can be configured flexibly in the case of a predetermined device 10 by means of an appropriate design of the optical structures 31, due to which a factory flexibility in the setting of different light distribution curves is increased.

(17) Another embodiment of an apparatus is shown in FIG. 2. This embodiment substantially corresponds to the embodiment shown in FIG. 1. In contrast to this, the organic device 10 is formed flexibly. In particular, the device 10 is formed to be pliant, in particular elastically pliant. The device 10 has a curved radiation exit surface 11, which is formed, for example, by a surface of the substrate 1 facing away from the functional layer stack 2. The outcoupling layer 3 is arranged on the radiation exit surface 11 and in particular adjoins the radiation exit surface 11. The radiation exit surface 11 is curved in a concave manner in this case. In particular, the device 10 can take the shape of a half-cylinder. A particularly directed radiation characteristic of the apparatus 100 can be achieved with a flexible organic device.

(18) In FIG. 3 another embodiment of an apparatus is shown, which corresponds substantially to the embodiment shown in FIG. 1. In contrast to FIG. 1, in which the apparatus 100 has an external outcoupling layer 3, the outcoupling layer 3 shown in FIG. 3 is executed as an internal outcoupling layer 3. While the outcoupling layer 3 in FIG. 1 is arranged on the radiation exit surface 11 and thus outside of the organic device 10, the optical structures 31 according to FIG. 3 are embedded in the substrate 1 of the device 10. It is also possible to arrange the outcoupling layer 3 between the substrate 1 and the layer stack 2, for example, between the substrate and the first charge transport layer 21. Apart from this, it is also possible that the apparatus 100 has both an internal outcoupling layer 3 and an external outcoupling layer 3. In such cases the possibility exists in particular of combining internal and external outcoupling effect with one another.

(19) An apparatus 100 with a plurality of organic devices 10 is shown in FIG. 4. The outcoupling layer 3 has a plurality of sub-regions 30 spaced apart at a distance. The sub-regions 30 are each associated with an organic device 10. The devices 10 are formed in particular as rigid devices. The scatter effect of the outcoupling layer 3 can take different values, for example, in sub-regions 30 discretely delimited from one another. In FIG. 4 the sub-region 30, which is associated with the centrally arranged organic device 10, has the smallest scatter effect, which can even go towards 0. The organic devices 10, in particular the organic devices 10 adjacent to one another, are arranged obliquely to one another. They thus form a three-dimensional arrangement of the devices 10. Together they form a geometrical shape, for example, which is similar to a half-cylinder.

(20) The sub-regions 30 have a growing scatter effect from the central axis M up to a lateral edge-region of the outcoupling layer 3. The devices 10 can have a forward direction in the radiation characteristic on account of their respective optical cavity. Due to the growing scatter effect, the local radiation characteristic of the apparatus changes from a non-Lambertian to a Lambert-like radiation characteristic at the edge-regions. The apparatus 100 described in FIG. 4 thus has an overall radiation characteristic that corresponds to an overall radiation characteristic of the apparatus described in FIG. 2.

(21) The embodiment shown in FIG. 5 substantially corresponds to the embodiment of an apparatus shown in FIG. 1. In contrast to this, the organic device 10 has a roughened radiation exit surface 11, the roughness of which varies locally. Unlike FIG. 1, in which the local variation of the scatter effect of the scattering layer 3 is achieved by the scatter particles, the local variation of the scatter effect can also be achieved by variation of the roughness of the radiation exit surface. A combination of the variation of the roughness and the variation of the design of the scatter particles is likewise possible.

(22) The embodiment of an apparatus shown in FIG. 6 substantially corresponds to the embodiment shown in FIG. 1. In contrast to this, the outcoupling layer 3 has a locally varying directional effect. For example, the outcoupling layer is a micro-optics layer, formed, for example, as a microlens layer, wherein the optical structures 31 can be microlenses. In a pure use of a micro-optics layer, in particular of microlenses, it is not necessary that the device 10 has an optical cavity, which radiates directed light from the outset. This means that the device 10 can be a Lambert radiator, for example. However, on account of the outcoupling layer 3 the apparatus has a non-Lambert radiation distribution curve.

(23) The different local directional effect of the micro-optics layer can be achieved, for example, by different configuration of the microlenses with regard to their shapes, focal lengths, geometrical sizes such as heights and widths or with regard to the area occupancy of the respective microlenses or combinations of these. The density and/or arrangement pattern, for instance hexagonal, square etc., are meant by the area occupancy, for example. The outcoupling layer 3 shown in FIG. 6 has a decreasing, in particular steadily decreasing, directional effect from the central axis M along the lateral direction up to an edge-region of the outcoupling layer 3. The outcoupling layer 3 thus has a gradient with regard to the directional effect along a radial direction.

(24) By analogy with FIG. 2, the apparatus shown in FIG. 7 has a flexibly formed device 10. The outcoupling layer 3 with the microlenses is formed curved. By analogy with FIG. 6, the outcoupling layer 3 in FIG. 7 has a continuous gradient progression with regard to the directional effect, at least in regions, along the lateral direction.

(25) The embodiment shown in FIG. 8 of an apparatus with a plurality of devices 10 spaced apart from one another corresponds substantially to the embodiment shown in FIG. 4. In contrast to this, the sub-regions 30 of the outcoupling layer 3 of the apparatus 100 each have a gradient with regard to a local directional effect of the sub-regions 30 and the outcoupling layer 3, at least in regions. It is also possible that sub-regions 30 with a locally varying scatter effect and sub-regions with a locally varying directional effect are combined with one another. This means that the outcoupling layer 3 can contain sub-regions 30 that have a gradient with regard to the scatter effect, for example, and contain other sub-regions 30 that have a gradient with regard to the directional effect, for example.

(26) Various radiation distribution curves K and K1 to K4 are shown in FIG. 9. The curves each describe the radiation intensity I per angle unit φ. The curve K1 corresponds to a Cos(φ) distribution and thus a Lambertian radiation distribution curve. The curves K2, K3 and K4 are cos.sup.2 (φ), cos.sup.3 (φ) and cos.sup.4 (φ) curves. The curve K represents a radiation distribution curve of a white organic light-emitting diode with an outcoupling layer 3 formed as a scattering layer. In all distributions K and K1 to K4 the overall intensity is of the same magnitude. In other words, the areas below the respective curves are of the same size. The higher the cosine power, the more directed the radiation characteristic.

(27) In FIG. 10A an apparatus 100 is shown with three organic devices 10. The centrally arranged organic device 10 has a Lambertian or Lambert-like radiation distribution curve. A first sub-region 30 of the outcoupling layer 3 is associated with this centrally arranged device 10, wherein the first sub-region 30 has no or a particularly small scatter effect or directional effect. The two outer organic devices 10 can have a Lambertian or Lambert-like radiation distribution curve respectively. However, another sub-region 30 is associated with the outer organic device 10, which region has a locally varying directional effect. The radiation passing through the outer sub-regions 30 is thus influenced locally in an optically different manner by the sub-regions 30 on account of the variation of the directional effect, so that the outer devices 10 with the associated sub-regions 30 each produce a non-Lambertian radiation distribution curve.

(28) The three organic devices 10 have respectively one radiation exit surface 11, wherein the radiation exit surface 11 of the centrally arranged device 10 forms with the radiation exit surfaces 11 of the outer organic devices 10 respectively a reflex angle, for example, an angle of 225°.

(29) In FIG. 10B a radiation distribution of the apparatus 100 described in FIG. 10A is shown. Dark grey shades correspond in FIG. 10B to a higher radiation intensity than light grey tones. The maximum of the radiation intensity lies on the central axis. Starting out from the central axis M, the radiation intensity falls in each direction perpendicular to the central axis M in particular continuously, but at a different rate. Along a lateral direction on which the devices 10 are arranged, the radiation distribution has an elongated extended region with a higher radiation intensity than its surroundings. Such an apparatus wo is especially suitable for an illumination of a rectangular object with a different length and width, for example. The object is a conference table, for example.

(30) The embodiment shown in FIG. 11A substantially corresponds to the embodiment shown in FIG. 10A. In contrast to this, all three sub-regions 30 have locally varying directional effects. The radiation exit surface 11 of the centrally arranged device 10 forms with the radiation exit surfaces 11 of the outer organic devices 10 respectively an obtuse angle, for instance an angle of 135°.

(31) In FIG. 11B a radiation distribution of the apparatus 100 described in FIG. 11A is shown. The maximum of the radiation intensity lies on the central axis M, wherein the radiation intensity declines, starting out from the central axis M, substantially equally fast in all directions perpendicular to the central axis M. Such an apparatus wo is especially suitable for focusing of a light bundle, for example, as a spotlight.

(32) Apart from the sub-regions 30 in FIGS. 10A and 11A, the outcoupling layer 3 can also have sub-regions 30 with a locally varying scatter effect or sub-regions 30 with different scatter effects.

(33) The invention is not limited by the description of the invention with reference to the embodiments to this description. On the contrary, the invention comprises every new feature and every combination of features, which includes in particular every combination of features in the claims, even if this feature or this combination is not itself explicitly specified in the claims or embodiments.