Method for creating optical structures in a planar adhesive layer

Abstract

The invention relates to a method for creating optical structures in a planar, radiation-curable adhesive layer (11), said method comprising the following steps: (a) providing a first protective layer (12); (b) applying an adhesive layer (11) onto the first protective layer (12); (c) pre-curing a selective sub-region (11.2) of the adhesive layer (11) by irradiating the selective sub-region (11.2) with radiation (14) from a first radiation source (24) over a first period of time with a first areal energy density, the selective sub-region (11.2) of the adhesive layer (11) not being fully cured; (d) curing the adhesive layer (11) by irradiating the entirety of the adhesive layer (11) with radiation (14) from the first radiation source (24) and / or a second radiation source (25) over a second period of time with a second areal energy density; and (e) obtaining a cured adhesive layer (11.3) having the optical structures (11.4), wherein the selective sub-region (11.2) having the optical structures (11.4) has a different refractive index compared to a region of the cured adhesive layer (11.3) outside of the selective sub-region.

Description

[0001] Method for producing optical structures in a flat adhesive layer

[0002] The invention relates to a method for producing optical structures in a planar, radiation-curable adhesive layer, as well as a use for such a method.

[0003] Adhesive layers that are curable by radiation are known from the prior art. US Pat. No. 7,046,904 B2 discloses UV-curable resin compositions for enclosing optical fibers or waveguides. Due to a refractive index different from that of the optical fiber after curing, the resin compositions allow the production of waveguides that transmit with virtually no loss. DE 10 2021 103 404 A1 discloses a carrier layer with a volume hologram, which is bonded to a substrate by means of a UV-curable adhesive layer.

[0004] Radiation-curable adhesive layers are also used in the field of optoelectronic components, where the optoelectronic components are enclosed by means of an encapsulation bonded to them. Such encapsulation is particularly common in organic optoelectronic components to protect organic layers, which are preferably vapor-deposited in a vacuum or processed from a solution, from direct contact with air, especially oxygen and / or moisture.

[0005] US 10,385,210 B2 discloses a UV-curable composition for encapsulating organic components. EP 1 611 484 B1 discloses a photoactive component consisting of organic layers of one or more stacked pi, ni, nip, and / or pin diodes, in which light traps are used to extend the optical path of the incident light in the photoactive layer.

[0006] Labels or light-guiding elements can be

[0007] Printing processes are applied to laminates or film composites. The processes required for this result in additional technical effort. Printed lettering or symbols can also suffer from limited durability, for example they can peel off or fade due to external influences. The same applies to additional, light-guiding elements. For example, optical elements can be applied to components using an additional film to change the light irradiation and / or light emission. Such films comprise an adhesive layer and a functional layer with the optical element, with the film being laminated to the component by means of the adhesive layer.

[0008] Furthermore, EP 54157 B1 discloses the application of light-guiding elements to improve the efficiency of solar cells. Grooves are introduced at regular intervals on the surface of a solar cell by laser ablation. These grooves are then filled with a highly scattering but non-absorbing material. This material scatters incident sunlight onto the photoactive layers of the solar cell.

[0009] It would be desirable to be able to incorporate such optical structures, in particular labels or light-guiding elements, into the laminates or film composites with reduced technical effort, in particular directly during their manufacture, whereby the durability of the optical structures should also be largely unaffected by external influences.

[0010] The invention is therefore based on the object of providing a method in which optical structures are introduced directly into a flat adhesive layer of a laminate or film composite as an integrated process step during the production of the laminate or film composite. The optical structures should in particular have a high degree of resilience to external influences. Furthermore, the invention is based on the object of providing a method in which optical structures are introduced into a protective layer or encapsulation of an optoelectronic component for light guidance and / or light scattering, in particular for improving efficiency.

[0011] The problem is solved by the subject matter of the independent claims. Advantageous embodiments emerge from the subclaims.

[0012] The object is achieved in particular by providing a method for producing optical structures in a planar adhesive layer, the adhesive layer being curable by means of radiation, comprising the following steps: a) providing a first protective layer; b) applying an adhesive layer to the first protective layer; c) pre-curing a selective partial area of ​​the adhesive layer by irradiating the selective partial area by means of radiation from a first radiation source over a first period of time with a first surface energy density, the selective partial area of ​​the adhesive layer not being completely cured; d) curing the adhesive layer by irradiating the entire area of ​​the adhesive layer by means of radiation from the first radiation source and / or a second radiation source over a second period of time with a second surface energy density;and e) obtaining a cured adhesive layer with the optical structures, wherein the selective partial region with the optical structures has a different refractive index than a region of the adhesive layer lying outside the selective partial region;

[0013] The use of the singular for the selective partial area of ​​the adhesive layer also includes a discontinuous selective partial area; the selective partial area can therefore also comprise a plurality of partial areas spatially separated from one another within the adhesive layer.

[0014] A protective layer is understood to mean, in particular, a layer for protecting an element arranged behind or beneath the protective layer, preferably a layer for increasing mechanical protection, in particular scratch resistance, a filter layer, preferably a layer with a UV filter, and / or a layer, in particular a barrier, against chemical compounds, contaminants, moisture and / or air, in particular oxygen. The protective layer is preferably a film, a film composite or a thin plate.

[0015] A radiation-curable adhesive layer is understood to mean in particular a material, preferably an adhesive, or a layer made of this material, by means of which a first element can be fixed, in particular glued, to a second element, in particular two layers can be glued to one another so that they are bonded to one another, the bonding between the first element and the second element being brought about by irradiation with radiation, in particular electromagnetic radiation or particle beams. In a preferred embodiment, the material of the radiation-curable adhesive layer is applied to the first and / or the second element in a liquid or pasty state and then pre-cured and / or cured by irradiation with radiation so that a bonding between the first element and the second element is produced.

[0016] A flat adhesive layer is understood to mean, in particular, an adhesive layer which extends essentially two-dimensionally over a predetermined surface area, in particular over a surface area of ​​the first protective layer.

[0017] A radiation source is understood to be a device which is set up to generate or emit radiation of a predetermined type, in particular electromagnetic radiation or particle beams. The radiation is preferably emitted in a directed manner, in particular the radiation is emitted as a beam of rays with a defined cross-section. The first and / or the second radiation source are preferably a lighting means, preferably a lamp, an LED or a laser, or a particle beam-emitting device, preferably an electron gun. In a preferred embodiment, in step b) the material of the radiation-curable adhesive layer is applied to the first protective layer in a liquid or pasty state; preferably the radiation-curable adhesive layer to be applied to the first protective layer is formed from a liquid or pasty material.

[0018] In a preferred embodiment, in step c) the optical structures are introduced by selectively pre-curing, in particular not completely curing, those partial regions of the adhesive layer which correspond to the optical structures to be produced by irradiation using radiation from the first radiation source over a first period of time with a first surface energy density.

[0019] The pre-curing in step c) creates a selective sub-region within the adhesive layer with a refractive index which is different from a region of the adhesive layer lying outside the selective sub-region and not yet irradiated in this process step. A change in the refractive index is possible in particular through the formation of microbubbles in the irradiated regions of the adhesive layer. The microbubbles display a diffusely scattering behavior of incident ambient light, as a result of which the optical structures created are visible. Due to uneven polymerization due to irradiation with radiation from the first radiation source, microbubbles are formed in the adhesive layer; in particular, disordered polymers are formed in liquid or pasty regions of the adhesive layer.

[0020] In a preferred embodiment, after step c) or in step d), the entire adhesive layer is cured over the entire surface, in particular completely. During this curing over the entire surface, in particular completely, differences in the refractive indices between the pre-cured selective partial region and the region of the adhesive layer lying outside the selective partial region, i.e. the remaining region of the adhesive layer, are maintained.

[0021] The method according to the invention for producing optical structures in a flat adhesive layer has advantages over the prior art. Advantageously, the optical structures are integrated directly into the adhesive layer as a component thereof. The production of the optical structures is an integral part of the process for producing the adhesive layer. Additional processing of separate elements containing these optical structures, as well as their application to the adhesive layer or the first or second protective layer, can therefore be omitted. Advantageously, the optical structures are protected from the effects of weather and mechanical damage. Advantageously, due to their integration directly into the adhesive layer, the optical structures have a service life corresponding to that of the adhesive layer.Phenomena such as flaking or fading are eliminated, the optical structures are particularly protected from the influence of UV radiation from sunlight and / or weathering processes due to weather influences.

[0022] According to a development of the invention, it is provided that the radiation from the first radiation source and / or the radiation from the second radiation source is electromagnetic radiation in the visible or in the UV (ultraviolet) range, or electron radiation. Preferably, the radiation from the first radiation source in step c) and / or the radiation from the first radiation source and / or the second radiation source in step d) is UV radiation in a wavelength range from 350 nm to 410 nm, and / or the first and / or the second surface energy density is in a range from 10 mJ / cm2 to 1000 mJ / cm2. Preferably, in step c) UV radiation in a wavelength range from 370 nm to 390 nm is used, while in step d) electromagnetic radiation in a wavelength range from 390 nm to 410 nm is preferably used.The wavelength range of the electromagnetic radiation can be adapted to the requirements of the material of the adhesive layer for curing.

[0023] According to a further development of the invention, it is provided that the first time period for irradiating the selective partial area of ​​the adhesive layer in step c) is shorter than the second time period for irradiating the entire area of ​​the adhesive layer in step d). According to a further development of the invention, it is provided that the first surface energy density of the radiation for irradiating the selective partial area of ​​the adhesive layer in step c) is lower than the second surface energy density of the radiation for irradiating the entire area of ​​the adhesive layer in step d), preferably the first surface energy density of the radiation in step c) is 10 mJ / cm 2 up to 50 mJ / cm 2 and the second surface energy density of the radiation in step d) is 100 mJ / cm 2 up to 1000 mJ / cm 2Advantageously, the selective sub-region is cured homogeneously; in particular, there is no gradient of the refractive index within the selective sub-region. Advantageously, the density and / or diameter of the microbubbles formed in the selective sub-region during pre-curing are largely evenly distributed over the entire selective sub-region.

[0024] According to a further development of the invention, the first time period and / or the first surface energy density is varied during irradiation of individual regions within the selective sub-region of the adhesive layer in step c). Advantageously, shading can be generated within the selective sub-region by a specifically adapted spatial distribution of regions with different refractive indices.

[0025] According to a further development of the invention, it is provided that in a further step f) during or after step c), or during or after step d), preferably after step d), the adhesive layer is cured by means of thermal treatment.

[0026] According to a further development of the invention, it is provided that during the irradiation of the selective partial region of the adhesive layer by means of radiation in step c), regions of the adhesive layer lying outside the selective partial region are covered, preferably with a shadow mask, or the selective partial region of the adhesive layer is irradiated with radiation by means of a projection, in particular using a projector, or the selective partial region of the adhesive layer is irradiated with a focused or defocused beam from the first radiation source, preferably is scanned. The selective partial region of the adhesive layer is scanned in particular by the beam, e.g. a laser beam, being guided over the surface of the adhesive layer along a predetermined path by means of suitable beam deflection devices, a so-called scanner.

[0027] According to a further development of the invention, it is provided that the adhesive layer is formed from a material selected from the group consisting of acrylates, in particular cyanoacrylates, epoxy resins, silicones, and polyurethanes, in particular acrylate and / or urethane photopolymers; preferably, the adhesive layer has a photoinitiator for polymerizing the adhesive layer.

[0028] According to a development of the invention, it is provided that the radiation from the first radiation source in step c) is radiated into the adhesive layer from a first direction, preferably from a side of the adhesive layer facing away from the first protective layer, or preferably from a direction substantially perpendicular to the flat adhesive layer, and the radiation from the second radiation source in step d) is radiated into the adhesive layer from a second direction, preferably from a side of the adhesive layer facing the first protective layer. The second direction can essentially correspond to the first direction; preferably, the second direction is opposite to the first direction.Preferably, the first protective layer has a transmittance of at least 50%, preferably of at least 80%, or preferably at least 90%, at least for the radiation of the second radiation source, wherein the radiation is preferably radiated into the adhesive layer from a side of the adhesive layer facing the first protective layer, through which at least a portion of at least 50% of the radiation of the second radiation source passes.

[0029] According to a development of the invention, the optical structures are visual information, preferably a logo, an image, lettering, a number and / or a code, and / or an optically functional structure for guiding and / or scattering light, preferably an area with a different optical scattering effect compared to the area of ​​the adhesive layer lying outside the optical structures. Thus, by means of the method it is possible to integrate optically detectable, electronically readable or visually visible inscriptions, labels, trademarks or unique markings, in particular microcodes, into the adhesive layer as proof of manufacturer. Alternatively or additionally, decorative ornaments, figures or graphics can also be incorporated into the adhesive layer. Alternatively or additionally, the optical structures are optically functional structures for guiding and / or scattering light.In all the cases listed, the optical structures are preferably an area with a different optical scattering effect compared to the area of ​​the adhesive layer lying outside the optical structures.

[0030] According to a further development of the invention, it is provided that the adhesive layer is transparent in the visible range of light, preferably in a wavelength range from 400 nm to 800 nm.

[0031] According to a further development of the invention, it is provided that a second protective layer is arranged, preferably laminated, on the side of the adhesive layer opposite the first protective layer between step b) and step d), wherein the adhesive layer is arranged between the first protective layer and the second protective layer and connects them to one another in a materially bonded manner.

[0032] In connection with the present invention, an element, in particular a layer, which is applied, arranged or formed on another element, in particular another layer, is understood to mean a direct contact of the one element with the other element or an indirect contact, in particular by means of at least one further layer arranged therebetween.

[0033] According to a development of the invention, it is provided that the adhesive layer is applied between steps b) and c) or during step c) with the side facing away from the first protective layer directly, or with a second protective layer and a further adhesive layer arranged in between, to an optoelectronic component, preferably a photovoltaic element, wherein the optoelectronic component is formed from an arrangement of cells connected in series, wherein when the selective partial area of ​​the adhesive layer is irradiated in step c), the radiation from the first radiation source is radiated from a side of the optoelectronic component facing away from the adhesive layer through the arrangement between the cells connected in series onto the adhesive layer, wherein regions of the adhesive layer lying outside the selective partial area of ​​the adhesive layer are covered by the arrangement of the cells connected in series, i.e.shaded, so that the selective partial area of ​​the adhesive layer which is accessible for the radiation through the arrangement between the cells is pre-cured. As a result, the selective partial area of ​​the adhesive layer which is pre-cured in step c) is determined by the arrangement of the cells connected in series and / or by those areas of the arrangement of the cells connected in series which do not absorb, or only absorb to an insignificant extent, the radiation from the first radiation source used in step c), in particular by the trenches obtained through the structuring. Irradiation of radiation through the arrangement between the cells connected in series is understood in particular to mean irradiation of radiation through the structuring, i.e. trenches, in particular the P3 trenches, of the cells connected in series.In a preferred embodiment, the trenches, in particular the P3 trenches, are transparent, i.e. at least partially or completely translucent for the wavelength range of the radiation.

[0034] The method for producing optical structures in an adhesive layer can advantageously be used in the production of flexible photovoltaic elements, whereby the optical structures for light guidance and / or light scattering are also introduced into the photovoltaic elements in a continuous roll-to-roll (R2R) production process.

[0035] According to a further development of the invention, it is provided that a reflector for reflecting the radiation of the first radiation source back into the adhesive layer is arranged on the side of the adhesive layer opposite the first radiation source, preferably for reflecting the radiation in a certain angular range, whereby the optical structures in the adhesive layer are additionally formed by means of the radiation reflected by the reflector.

[0036] In a preferred embodiment, the photovoltaic element comprises a plurality of photovoltaic cells arranged next to one another and connected in series. By irradiating the selective partial region of the adhesive layer in step c) from a side of the photovoltaic element facing away from the adhesive layer through the arrangement between the series-connected photovoltaic cells onto the adhesive layer, optical structures for deflecting light are created which, during normal operation of the photovoltaic element, deflect the sunlight incident on the front side towards the photoactive layers of the photovoltaic cells. The optical structures are formed in the adhesive layer in a region between the photovoltaic cells which are inactive for the photovoltaic conversion of light into electrical current.When irradiating the selective portion of the adhesive layer in step c), the photovoltaic cells act as a shadow mask.

[0037] By arranging a reflector opposite the front side of the photovoltaic element, i.e. the side of the photovoltaic element that is intended to face the sun, which is designed to specifically direct the radiation from the first radiation source, which is radiated on the back side of the photovoltaic element, i.e. the side of the photovoltaic element that is intended to face away from the sun, and which exits from the front of the photovoltaic element after passing through the arrangement between the series-connected photovoltaic cells, back into the selective partial regions of the adhesive layer, optical structures are obtained in the adhesive layer by means of reflected radiation. The optical structures for directing light are preferably formed in the regions of the photovoltaic element that are inactive for photovoltaic conversion.

[0038] The object of the present invention is also achieved by providing a use of the optical structures of an adhesive layer formed by a method according to the invention for light guidance and / or light scattering in an optoelectronic component, preferably a photovoltaic element, particularly preferably a solar cell, in particular according to one of the previously described embodiments. This results in particular in the advantages for the use which have already been described in connection with the method for producing optical structures in a planar adhesive layer.

[0039] In a preferred embodiment, the optoelectronic component is a flexible optoelectronic component, in particular a flexible photovoltaic element. A flexible optoelectronic component is understood to be an optoelectronic component that is bendable and / or stretchable within a specific region. The use of the photovoltaic cells of a flexible photovoltaic element as a shadow mask in the roll-to-roll process is particularly advantageous since, in the roll-to-roll process, aligning the laminate within a processing system is associated with a high level of technical outlay. Due to the method according to the invention, the optical structures to be formed are produced in a self-aligning manner in the adhesive layer, so that aligning the laminate before introducing the optical structures is not necessary.

[0040] The object of the present invention is also achieved by providing an optoelectronic component with optical structures for light guidance and / or light scattering produced in a planar adhesive layer according to the method according to the invention, in particular according to one of the previously described embodiments. In this case, the advantages which have already been described in connection with the method for producing optical structures in a planar adhesive layer and in the use of the optical structures of an adhesive layer formed according to a method according to the invention for light guidance and / or light scattering in an optoelectronic component arise in particular.

[0041] The invention is explained in more detail below with reference to the drawings, in which:

[0042] Fig. 1 is a schematic representation of an embodiment of a method for producing optical structures in a planar, radiation-curable adhesive layer on a protective layer in cross section;

[0043] Fig. 2 is a schematic representation of an embodiment of a method for producing optical structures in a planar, radiation-curable adhesive layer between two protective layers in cross section; and

[0044] Fig. 3 is a schematic representation of an embodiment of a method for producing optical structures in an adhesive layer arranged between photovoltaic cells and a protective layer of an optoelectronic component, in cross section.

[0045] Examples of implementation

[0046] Fig. 1 shows a schematic representation of an embodiment of a method for producing optical structures 11. 4 in a planar, radiation-curable adhesive layer 11 on a protective layer 12.

[0047] The method for producing optical structures in a planar adhesive layer 11, wherein the adhesive layer 11 is curable by means of radiation 14, comprises the following steps: a) providing a first protective layer 12 (Fig. 1a); b) applying an adhesive layer 11 to the first protective layer 12 (Fig. 1b); c) pre-curing a selective partial area 11.2 of the adhesive layer 11 by irradiating the selective partial area 11.2 by means of radiation 14 from a first radiation source 24 over a first period of time with a first surface energy density, wherein the selective partial area 11.2 of the adhesive layer 11 is not completely cured (Fig. 1c); d) Curing the adhesive layer 11 by irradiating the entire area of ​​the adhesive layer 11 by means of radiation 14 from the first radiation source 24 and / or a second radiation source 25 over a second period of time with a second surface energy density (Fig.ld) ; and e) obtaining a cured adhesive layer 11.3 with the optical structures 11.4 (Fig. 1e), wherein the selective partial region 11.2 with the optical structures 11.4 has a different refractive index than a region 11.3 of the adhesive layer 11 lying outside the selective partial region 11.2.

[0048] In this exemplary embodiment, the pre-curing of the selective partial area 11.2 of the adhesive layer 11 in step c) takes place over a first period of time of 2 s with a first surface energy density by means of radiation 14 of a UV laser as the first radiation source 24 with a wavelength of 380 nm, wherein the focused laser beam is guided, i.e. scanned, over the surface of the selective partial area 11.2 of the adhesive layer 11 by means of a galvano scanner (Fig. 1c). The power of the UV laser and / or the scanning speed of the radiation 14 is regulated such that the first surface energy density is always in the range between 10 mJ / cm2 and 50 mJ / cm 2 The selective subregion 11.2 of the adhesive layer 11 is not fully cured due to the selection of the aforementioned parameters for irradiating the selective subregion 11.2 with the radiation 14 from the first radiation source. The material of the adhesive layer 11 is an acrylate in this example, but other acrylates, in particular cyanoacrylates, epoxy resins, silicones, or polyurethanes, can also be used. Furthermore, the adhesive layer 11 comprises a photoinitiator for polymerizing the adhesive layer 11 upon irradiation with UV light.

[0049] In a further embodiment, the first time period and / or the first surface energy density are varied during the irradiation of individual regions within the selective subregion 11.2 of the adhesive layer 11 during pre-curing. This results in regions with different densities of the pre-cured adhesive layer 11, particularly within the selective subregion 11.2. In the present exemplary embodiment, regions of different densities in the selective subregion 11.2 are particularly due to the microbubbles (not shown) formed by irradiation.

[0050] As shown in Fig. 1d, in this exemplary embodiment, after pre-curing the selective partial area 11.2, the entire adhesive layer 11 is cured by irradiating the entire surface by sweeping over it with the radiation 14 using the laser radiation set to a wavelength of 400 nm from the UV laser used as the first radiation source 24 over a second period of 10 s, wherein the first radiation source 24 is used for the pre-curing in step c) and for the subsequent curing in step d). The surface energy density introduced into the adhesive layer 11 is approximately a factor of 20 greater than during pre-curing in step c), in particular the surface energy density is in the range between 200 mJ / cm 2 and 1000 mJ / cm 2. This creates the optical structures 11.4 within the fully cured adhesive layer 11.3 (Fig. 1e), wherein the optical structures 11.4 have a different refractive index than the area 11.3 of the adhesive layer lying outside the optical structures 11.4.

[0051] Fig. 2 shows a schematic representation of another embodiment of a method for producing optical structures 11.4 in a planar, radiation-curable adhesive layer 11 between two protective layers 12, 13. Identical and functionally identical elements are provided with the same reference numerals, so reference is made to the preceding description.

[0052] In this embodiment, after applying an adhesive layer 11, preferably in a pasty state, to the first protective layer 12 (Fig. 2 I), a second protective layer 13 is applied to the adhesive layer 11 (Fig. 2 II). The adhesive layer 11 is arranged to form a material bond between the first protective layer 12 and the second protective layer 13.

[0053] In this exemplary embodiment, in comparison to Fig. 1, the selective partial area 11.2 is not pre-cured by scanning using a laser, but by irradiation using a lamp as the first radiation source 24, wherein the areas of the adhesive layer 11 lying outside the selective partial area 11.2 are covered. By arranging a shadow mask 15 on the second protective layer 13, an opening 10 is defined for a selective partial area 11.2 of the adhesive layer 11 to be pre-cured. By means of the radiation 14 of the first radiation source 24, in this exemplary embodiment a wavelength of 380 nm from a light-emitting diode (LED) or alternatively UV radiation filtered by a UV filter, the adhesive layer 11 is cured in the area of ​​the selective partial area 11.2 for a first time period of 2 s with a first surface energy density of 20 mJ / cm 2pre-cured, wherein the selective partial region 11 . 2 of the adhesive layer 11 is not completely cured. By pre-curing the selective partial region 11 . 2, the refractive index in the selective partial region 11 . 2 is changed, while the remaining region 11 . 1 of the adhesive layer 11 remains untreated (Fig. 2 I TT).

[0054] After pre-curing, the shadow mask 15 is removed and the entire adhesive layer 11 is irradiated over the entire surface by means of radiation 14 from the first radiation source 24 with a wavelength of 380 nm from a light-emitting diode (LED) or alternatively with UV radiation filtered by a UV filter and a surface energy density of 500 mJ / cm 2 cured over a second period of 10 s. This creates the optical structures 11 . 4 within the fully cured adhesive layer 11 . 3 .

[0055] Alternatively, in a further step f), in addition to the curing in step d), during or after step c), or during or after step d), preferably after step d), the adhesive layer (11) is cured by means of thermal treatment.

[0056] In a further embodiment, the optical structures 11 . 4 represent visual information, preferably a logo, an image, lettering, a number, and / or a code and / or the optical structures 11 . 4 are optically functional structures for guiding light and / or scattering light, preferably an area with a different optical scattering effect compared to the area 11 . 3 of the adhesive layer 11 lying outside the optical structures 11 . 4.

[0057] Fig. 3 shows a schematic representation of an embodiment of a method for producing optical structures 11. 4 in an adhesive layer 11 arranged between photovoltaic cells 21 and a protective layer 12 of an optoelectronic component 20, in cross section. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. In this embodiment, the optoelectronic component 20 is a photovoltaic element 20 comprising photovoltaic cells 21 connected in series.

[0058] In this exemplary embodiment, the optical structures 11.4 are produced in comparison to the previous exemplary embodiments in the adhesive layer 11 of an optoelectronic component 20, in particular an adhesive layer 11 between a protective layer 12 and photovoltaic cells 21 of the optoelectronic component 20. The adhesive layer 11 is applied directly to the photovoltaic cells 21 between steps b) and c) or during step c) with the side facing away from the first protective layer 12.

[0059] As can be seen in Fig. 3A, the photovoltaic element 20 comprises the photovoltaic cells 21 arranged on a substrate 18, each of which has a base electrode 17, a cover electrode 16 and a photoactive layer 22 arranged between the base electrode 17 and the cover electrode 16. Adjacent photovoltaic cells 21 are connected in series via the base electrode 17 and the cover electrode 16, wherein the base electrodes 17 of adjacent photovoltaic cells 21 are electrically separated from one another by a structure, the so-called P1 trench. Adjacent photovoltaic cells 21 are electrically separated from one another by means of a structure, the so-called P3 trench 23, at their cover electrodes 16. This structure, i.e. the P3 trench 23, is largely transparent to the radiation 14 from the first radiation source 24.The photoactive layers are electrically separated from one another by means of a structuring, the so-called P2 trench, via which adjacent base electrodes 17 are connected to cover electrodes 16.

[0060] In the interconnection region on and adjacent to the P3 trench 23, the photovoltaic cells 21 are not active. Sunlight incident on the photovoltaic element 20 in this region is absorbed or reflected and is not accessible for light absorption and thus for power generation (in Fig. 3, the protective layer 12 defines the sun-facing side, from which the sun shines during normal operation of the photovoltaic element 20). In order to also utilize this sunlight for the photovoltaic cells 21, optical structures 11.4 are created on the front side, i.e., the side of the photovoltaic element 20 that is intended to face the sun.

[0061] According to the method for producing optical structures 11.4 in a planar adhesive layer 11, in an adhesive layer 11 arranged between the protective layer 12 and the photovoltaic cells 21, a selective partial region 11.2 of the adhesive layer 11 is pre-cured by irradiation using the radiation 14 of a first radiation source (24), wherein the cover electrodes 16 of the photovoltaic cells 21 are used as a shadow mask for covering the region 11.1 of the adhesive layer lying outside the selective partial region 11.2. Regions 11.1 of the adhesive layer 11 lying outside the selective partial region 11.2 of the adhesive layer 11 are covered by the arrangement of the cells 21 connected in series, so that the selective partial region 11.2 2 of the adhesive layer 11 , which is accessible for the radiation 14 through the arrangement between the cells 21 , is precured .The radiation 14 is radiated from the direction of the side of the photovoltaic element 20 facing away from the sun during normal operation of the photovoltaic element 20. As a result, the radiation 14 only reaches the areas of the adhesive layer 11 (facing the sun during normal operation of the photovoltaic element 20) through the P3 trenches 23, which are arranged opposite the photovoltaic cells 21 in the region of the P3 trenches 23 with respect to the substrate 18.

[0062] By means of a reflector 19 on the side of the adhesive layer 11 opposite the first radiation source 24, the radiation 14 of the first radiation source 24 emerging from the photovoltaic element 20 via the first protective layer 12 is directed back through the first protective layer 12 into the adhesive layer 11. Due to the angular arrangement of the reflector 19 in this exemplary embodiment with respect to the photovoltaic element 20, the radiation 14 reflected back into the adhesive layer 11 is directed into a region of the adhesive layer 11 which is directly adjacent to the region of the adhesive layer 11 which is directly irradiated by the radiation 14 radiating through the P3 trench as well as the base electrode 17 and substrate 18 into the adhesive layer 11 (Fig. 3a "beneath" the connection of the cover electrode 16 to the base electrode 17 of the adjacent photovoltaic cell 21), whereby the selective partial region 11.2 of the adhesive layer 11 also comprises this region.

[0063] As can be seen in Fig. 3B, after pre-curing, the adhesive layer 11 is irradiated from both sides of the photovoltaic element 20 by irradiating the entire area of ​​the adhesive layer 11 using radiation 14 from the first radiation source 24 and the radiation 14 from the second radiation source 25 from opposite sides of the photovoltaic element 20 until it is completely cured. The cured adhesive layer 11 has a selective partial area (11.2) with the optical structures (11.4) with a different refractive index compared to a region (11.3) of the adhesive layer (11) lying outside the selective partial area (11.2).

[0064] By forming the optical structures 11.4 in the adhesive layer 11, during active operation of the photovoltaic element 20 the incident sunlight is scattered or deflected into the photoactive layers of the photovoltaic cells 21 and can thus be absorbed by the photoactive layer 22 and can be used to generate electricity. In order for these optical structures 11.4 to be effective, they must be precisely aligned with the photovoltaic cells 21 or the P3 trenches 23. The invention uses the already existing structure of the photovoltaic element 20, namely in this exemplary embodiment the P3 trenches 23 of the photovoltaic element 20, with the cover electrodes 16 mainly acting as a shadow mask. Thus, for the production of optical structures 11.44 for light scattering at specific points of a laminate or film composite, advantageously a technically complex alignment of the laminates or film composites in the roll-to-roll manufacturing process, in particular of photovoltaic elements 20, is omitted.

[0065] This embodiment relates in particular to an optoelectronic component 20 produced in a roll-to-roll process, in particular an organic photovoltaic element 20.

Claims

Patent claims 1. A method for producing optical structures in a planar adhesive layer (11), wherein the adhesive layer (11) is curable by means of radiation (14), comprising the following steps: a) providing a first protective layer (12); b) applying an adhesive layer (11) to the first protective layer (12); c) pre-curing a selective partial region (11.2) of the adhesive layer (11) by irradiating the selective partial region (11.2) by means of radiation (14) from a first radiation source (24) over a first period of time with a first surface energy density, wherein the selective partial region (11.2) of the adhesive layer (11) is not completely cured; d) curing the adhesive layer (11) by irradiating the entire area of the adhesive layer (11) by means of radiation (14) from the first radiation source (24) and / or a second radiation source (25) over a second period of time with a second surface energy density; and e) obtaining a cured adhesive layer (11).3) with the optical structures (11.4), wherein the selective partial region (11.2) with the optical structures (11.4) has a different refractive index than a region (11.3) of the adhesive layer (11) lying outside the selective partial region (11.2).

2. The method according to claim 1, wherein the radiation (14) of the first radiation source (24) and / or the radiation (14) of the second radiation source (25) is electromagnetic radiation in the visible or UV range, or electron radiation, preferably the radiation (14) of the first radiation source (24) in step c) and / or the radiation (14) of the first radiation source (24) and / or the second radiation source (25) in step d) is UV radiation (14) in a wavelength range from 350 nm to 410 nm, and / or the first and / or the second surface energy density is in a range from 10 mJ / cm2 to 1000 mJ / cm2.

3. The method according to claim 1 or 2, wherein the first time period for irradiating the selective partial area (11.2) of the adhesive layer (11) in step c) is shorter than the second time period for irradiating the entire area of the adhesive layer (11) in step d).

4. Method according to one of the preceding claims, wherein the first surface energy density of the radiation (14) for irradiating the selective partial area (11.2) of the adhesive layer (11) in step c) is lower than the second surface energy density of the radiation (14) for irradiating the entire area of the adhesive layer (11) in step d), preferably the first surface energy density of the radiation is (14) in step c) 10 mJ / cm2 to 50 mJ / cm2, and the second surface energy density of the radiation (14) in step d) 100 mJ / cm2 to 1000 mJ / cm2.

5. Method according to one of the preceding claims, wherein the first time period and / or the first surface energy density is varied when irradiating individual regions within the selective partial region (11.2) of the adhesive layer (11) in step c).

6. Method according to one of the preceding claims, wherein in a further step f) during or after step c), or during or after step d), preferably after step d), the adhesive layer (11) is cured by means of thermal treatment.

7. Method according to one of the preceding claims, wherein during the irradiation of the selective partial area (11.2) of the adhesive layer (11) by means of radiation (14) in step c), areas (11.1) of the adhesive layer (11) lying outside the selective partial area (11.2) are covered, preferably with a shadow mask (15) , or the selective partial area (11.2) of the adhesive layer (11) is irradiated with radiation (14) by means of a projection, or is irradiated with a focused or defocused beam of the first radiation source (24), preferably scanned.

8. Method according to one of the preceding claims, wherein the adhesive layer (11) is made of a material selected from the group consisting of acrylates, in particular cyanoacrylates, epoxy resins, silicones, and polyurethanes, preferably the adhesive layer (11) has a photoinitiator for polymerizing the adhesive layer (11).

9. Method according to one of the preceding claims, wherein the radiation (14) of the first radiation source (24) in step c) is radiated into the adhesive layer (11) from a first direction, preferably from a side of the adhesive layer (11) facing away from the first protective layer (12), and the radiation (14) of the second radiation source (25) in step d) is radiated into the adhesive layer (11) from a second direction, preferably from a side of the adhesive layer (11) facing the first protective layer (12).

10. Method according to one of the preceding claims, wherein the optical structures (11.4) are visual information, preferably a logo, an image, lettering, a number, and / or a code, and / or an optically functional structure for light guidance and / or light scattering, preferably an area with a different optical scattering effect compared to the outside area (11.3) of the adhesive layer (11).

11. Method according to one of the preceding claims, wherein the adhesive layer (11) is transparent in the visible range of light.

12. Method according to one of the preceding claims, wherein a second protective layer (13) is arranged, preferably laminated, on the side of the adhesive layer (11) opposite the first protective layer (12) between step b) and step d), wherein the adhesive layer (11) is arranged between the first protective layer (12) and the second protective layer (13) and connects them in a materially bonded manner.

13. Method according to one of the preceding claims, wherein the adhesive layer (11) is applied between steps b) and c) or during step c) with the side facing away from the first protective layer (12) directly, or with a second protective layer (13) arranged therebetween and a further adhesive layer, to an optoelectronic component (20), preferably a photovoltaic element, wherein the optoelectronic component (20) is formed from an arrangement of cells (21) connected in series, wherein, when the selective partial region (11.2) of the adhesive layer (11) is irradiated in step c), the radiation (14) of the first radiation source (24) is radiated from a side of the optoelectronic component (20) facing away from the adhesive layer (11) through the arrangement between the series-connected cells (21) onto the adhesive layer (11), wherein regions (11.1) of the adhesive layer (11) lying outside the selective partial region (11.2) of the adhesive layer (11) are covered by the arrangement of the series-connected cells (21), such that the selective partial region (11.2) of the adhesive layer (11) which is accessible to the radiation (14) through the arrangement of the cells (21) is pre-cured.

14. The method according to claim 13, wherein a reflector (19) for reflecting the radiation (14) of the first radiation source (24) back into the adhesive layer (11) is arranged on the side of the adhesive layer (11) opposite the first radiation source (24), preferably for reflecting the radiation (14) in a specific angular range, whereby the optical structures (11.4) in the adhesive layer (11) are additionally formed by means of the radiation (14) reflected by the reflector (19).

15. Use of the optical structures (11.4) of an adhesive layer (11) formed in a method according to one of claims 1 to 14 for light guidance and / or light scattering in an optoelectronic component, preferably a photovoltaic element (20).

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