Flexible biodegradable substrate for organic electronic components, and method for producing same

Abstract

Different embodiments relate to a method for producing a flexible biodegradable substrate, having the steps of: providing (100) a leaf structure (10) made of a plant leaf, said leaf structure having a plurality of leaf veins; and treating (200) the leaf structure with a polymer solution (20) in order to change the mechanical properties of the leaf structure such that each leaf vein of the leaf structure is coated with a polymer layer made of the polymer solution in order to form a coated leaf structure (14, 18) as a support for organic electronic components, wherein one or more openings pass through the polymer layer, each of the openings being arranged between two of the leaf veins.

Description

[0001] Flexible, biodegradable substrate for organic electronic components and method for producing the same

[0002] Description

[0003] Various embodiments relate to a flexible, biodegradable substrate for organic electronic components and a method for producing a flexible, biodegradable substrate, for example for organic electronic components.

[0004] Generally, organic electronic components are formed on substrates or supports. Typically, such substrates are made of non-biodegradable materials, such as glass or plastic (e.g., PET, polyimide, etc.). However, the use of non-biodegradable materials can lead to environmental problems and incur significant energy costs for recycling at the end of their lifespan. Therefore, there is a need for biodegradable and environmentally friendly alternatives, for example, for substrates for organic electronic components.

[0005] As environmentally friendly alternatives, biodegradable substrates such as paper, functionalized cellulose, PVA (polyvinyl alcohol), and silk / fibroin have been investigated for organic electronic applications. As further alternatives, biodegradable polymers such as poly(glycolic acid) (PGA) or poly(lactic acid) (PLA) have been synthetically produced. However, these polymers require industrial processing for their production and have other disadvantageous properties such as low thermal and chemical stability.

[0006] Various embodiments relate to a method for producing a flexible, thermally and chemically robust, printable, biodegradable and environmentally friendly substrate, for example as an alternative to conventional substrates for organic electronic devices, the production of which is environmentally friendly.

[0007] Various embodiments relate to a flexible, biodegradable substrate, which may further exhibit novel properties that may be advantageous, for example, for organic electronic components. Examples of such novel properties include the substrate material being water-repellent and being easy to print. Furthermore, the substrate may be configured such that it can easily regain substantially its original shape (e.g., flat shape before bending) after severe bending, folding, and curving.

[0008] In various aspects, there can be provided a method for producing a flexible, biodegradable substrate, comprising: providing a leaf structure from a plant leaf, the leaf structure having a plurality of leaf veins; treating the leaf structure using a polymer solution to change the mechanical properties of the leaf structure such that each leaf vein of the leaf structure can be coated with a polymer layer from the polymer solution to form a coated leaf structure as a flexible, biodegradable substrate (or carrier) for organic electronic components.

[0009] By using a naturally occurring quasi-fractal sheet structure that is treated, modified, and / or coated with a transparent and biodegradable polymer solution (e.g., an ethylcellulose polymer solution), an environmentally friendly, cost-effective method for producing a flexible, biodegradable substrate can be provided. The method can make it possible to produce a flexible, robust, printable, biodegradable, and environmentally friendly, cost-effective substrate, for example, as an alternative to conventional substrates for organic electronic devices. According to various embodiments, treating the sheet structure can comprise immersing the sheet structure in the polymer solution.

[0010] According to various embodiments, the treatment of the leaf structure can be carried out in such a way that the leaf veins of the leaf structure are coated with the polymer layer in a conformal manner, e.g., completely surrounded.

[0011] Coating the leaf veins of the leaf structure 10 with the polymer layer can increase the elasticity of the leaf structure 10. Furthermore, the polymer layer or polymer coating can be configured such that it can soften or soften upon heating. As a result, the polymer chains of the polymer layer or polymer coating can rearrange and / or reorder, for example, upon application of a force and / or load.

[0012] According to various embodiments, the polymer solution may comprise cellulose, for example ethylcellulose.

[0013] According to a further aspect, a flexible, biodegradable substrate, for example for organic electronic components and / or devices, can be provided, wherein the substrate can have a plant leaf structure which can be coated with a biodegradable polymer layer.

[0014] Because the substrate comprises or consists of naturally occurring, widely available raw materials (plant leaf structure and polymer layer), the substrate can be produced cost-effectively and easily recycled and / or decomposed.

[0015] Furthermore, due to its flexible, networked structure (e.g., multiscale connections of leaf veins within the skeleton form a fractal-like (quasi-fractal) framework or skeleton), the plant leaf structure can provide increased mechanical and / or structural stability to the substrate.

[0016] Furthermore, the polymer layer can give the substrate novel properties that can be advantageous, for example, for organic electronic components. Examples of such novel properties can be that the surface of the substrate can be more durable. For example, the substrate can be water-repellent, easy to print (e.g. for the production of organic electronic components), and can withstand both highly concentrated alkalis and biologically relevant electrolytic environments (e.g. during the production process of the substrate and / or the organic electronic components formed thereon). In addition, the polymer layer can give the substrate properties that allow it to easily regain its shape after strong bends, folds, and curvatures, for example down to small bend radii.

[0017] According to various embodiments, the plant leaf structure may have a plurality of leaf veins, wherein the leaf veins may be conformally coated with the biodegradable polymer layer.

[0018] Thus, the coating of the leaf structure can be designed such that the polymer layer does not form a closed layer over or on the leaf structure. This allows high light transmission of the substrate to be achieved. According to various embodiments, the polymer layer can be designed such that holes, gaps, and / or openings can be formed between at least some of the leaf veins. Alternatively or additionally, the polymer layer can be designed such that the polymer layer can connect at least two adjacent leaf veins of the leaf structure to one another.

[0019] According to various embodiments, the polymer layer can be formed such that the substrate can have at least a first shape, and after bending, folding and / or curving the substrate can be brought into at least a second shape different from the first shape, and wherein the substrate can be brought from the at least second shape back into the at least first shape, preferably by means of heating or warming the substrate.

[0020] Embodiments are shown in the figures and are explained in more detail below.

[0021] It shows

[0022] Figure 1 is a schematic flow diagram of a method for producing a flexible, biodegradable substrate according to various embodiments;

[0023] Figure 2 Top views of a plant leaf during and after provision of the leaf structure, according to different embodiments;

[0024] Figure 3 schematic side views of the step of treating the sheet structure, according to various embodiments;

[0025] Figures 4A-B are schematic side and perspective views of a hot air dryer according to various embodiments;

[0026] Figure 5A shows schematic side views of a method for depositing a further polymer layer onto the sheet structure, according to various embodiments;

[0027] Figure 5B is a view of a sheet structure coated with ethylcellulose and chitosan, according to various embodiments;

[0028] Figure 6A Top views of leaf structures before and after treating the leaf structures according to different

[0029] Embodiments; Figure 6B is a graph illustrating the light transmittance of sheet structures according to various embodiments;

[0030] Figures 7A-C show top views of treated sheet structures before, during and after a bending test, according to different embodiments;

[0031] Figures 8A-B are top views of organic electrochemical transistors according to various embodiments;

[0032] Figure 8C is a graph showing the chronoamperometric response of the organic electrochemical transistors shown in Figures 8A-B, according to various embodiments;

[0033] Figure 9 shows an organic photodiode formed on the substrate according to various embodiments;

[0034] Figures 10A-C are graphs illustrating the optical and electrical properties of the organic photodiode shown in Figure 9, according to various embodiments;

[0035] Figure 11 shows several views of an organic light-emitting diode formed on the substrate according to various embodiments;

[0036] Figure 12A is a graph illustrating the optical and electrical properties of the light-emitting diode shown in Figure 11, according to various embodiments; and

[0037] Figure 12B shows an electrochemical cell according to various embodiments in a schematic side view or cross-sectional view.

[0038] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top," "bottom," "front," "back," "fore," "rear," etc., will be used with reference to the orientation of the described figure(s). Since components of embodiments may be positioned in a number of different orientations, the directional terminology is for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.It is understood that the features of the various exemplary embodiments described herein may be combined with one another, unless specifically stated otherwise. The following description is therefore not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0039] In the context of this description, the term "leaf structure" (also called leaf skeleton or leaf framework) is understood, for example, to mean a plant leaf from which plant tissue (e.g., biomass) has been substantially completely removed such that only the skeleton or framework of the plant leaf remains, for example, made of cellulose, lignin, and / or hemicellulose, among others, forming a coherent and / or cross-linked leaf vein structure.

[0040] In the context of this description, the term "biodegradable" with regard to the substrate is understood to mean a substrate which consists of components and / or materials, for example renewable raw materials, the majority of which, for example more than 80%, for example more than 90%, can dissolve or decompose into its elementary components such as carbon, oxygen, hydrogen, carbon dioxide, humic acids, etc. and / or other minerals under the influence of external factors (enzymes, (micro)organisms, electromagnetic radiation (e.g. UV and light radiation), pressure, solvents (e.g. water), etc.) within a certain period of time (e.g. a period of time which is longer than the usual periods of the manufacturing process of the substrate and / or the organic electronic components, for example 10, 20, 50 times longer).

[0041] Cellulose and its derivatives, such as ethylcellulose, are biomolecules and polysaccharides consisting solely of organic compounds. Cellulose is the main component of plant cell walls. Therefore, it is understood that cellulose and its derivatives are, by definition, biodegradable. Furthermore, cellulose and its derivatives have the advantage of being non-toxic.

[0042] The term "flexible" with regard to the substrate is used in this description to mean that the substrate is bendable, flexible, elastic, movable and / or articulated in several folding directions without damage up to small bending radii.

[0043] Figure 1 illustrates a schematic flow diagram of a method for producing a flexible, biodegradable substrate according to various embodiments.

[0044] According to various embodiments, the method 1 for producing a flexible, biodegradable substrate may comprise providing 100 a leaf structure 10 from a plant leaf, and subsequently treating 200 the provided leaf structure 10 by means of a

[0045] Polymer solution 20 for changing the mechanical properties of the leaf structure 10 such that each leaf vein of the leaf structure 10 can be coated with a polymer layer from the polymer solution 20 in order to form a coated leaf structure 14, 18 as a flexible, biodegradable substrate for organic electronic components. By using a naturally occurring quasi-fractal leaf structure which is treated, modified and / or coated by means of a transparent and biodegradable polymer solution, an environmentally friendly, cost-effective method for producing a flexible, biodegradable substrate can be provided. The method can make it possible to produce a flexible, robust, printable, biodegradable and environmentally friendly, cost-effective substrate, for example as an alternative to conventional substrates for organic electronic devices.

[0046] According to various embodiments, the method 1 may further comprise, after the treatment 200, a step of drying 300 the treated sheet structure 14.

[0047] Method 1 is described in detail using Figures 2 to 4.

[0048] Figures 2A-C illustrate top views of a plant leaf during and after provision of the leaf structure, according to various embodiments.

[0049] According to various embodiments, providing 100 a leaf structure 10 may comprise providing 102 a plant leaf, the plant leaf having leaf veins and plant tissue (e.g., biomass) arranged between and / or around the leaf veins, treating 104 the plant leaf such that the plant tissue can be removed from the plant leaf, and drying 106 the treated plant leaf to form the leaf structure 10.

[0050] According to various embodiments, the leaf structure 10 can be a plant leaf skeleton or a plant leaf framework. For example, the leaf structure can be produced from a plant leaf that may have been degreened. In the leaf structure 10, for example, essentially only the leaf veins of the plant leaf may remain (e.g., without plant tissue). According to various embodiments, the leaf veins can, for example, essentially retain their three-dimensional, for example, network-like and / or quasi-fractal structure, which they had in the plant leaf before treatment.

[0051] According to various embodiments, the plant leaf can, for example, come from local plants. For example, the plant leaf can come from a magnolia tree, a rubber tree (e.g., Hevea brasiliensis), a Bodhi tree (e.g., Ficus religiosa), a rooibos (e.g., Fagus sylvatica), or from plants with large leaves (e.g., lotus, rhubarb, banana plants, etc.). The plant leaf can be washed before treatment, for example, using a solvent, such as an alcoholic solvent.

[0052] According to various embodiments, treating 104 the plant leaf may comprise immersing the plant leaf in an alkaline medium, for example together with heating the plant leaf immersed in the alkaline medium (for example at a temperature in a range of 60°C to 100°C) to form the leaf structure.

[0053] Example of providing 100 the leaf structure 10

[0054] Magnolia leaves were freshly sourced from local plants and washed under running water before being used for

[0055] were placed in an ultrasonic bath containing ethanol for 10 minutes to remove impurities. The leaves were then cut to a size of 2.5 x 2.5 cm, and the samples were placed in an aqueous solution of Na2CO3.10 H2O (sodium carbonate decahydrate / washing soda) in demineralized water and heated overnight at a constant temperature of 90 °C with stirring. The amount of Na2CO3.10 H2O to be used was determined by simply increasing the amount until the compound no longer dissolved. The samples were then removed and placed in a separate container containing fresh distilled water at room temperature, which was then placed in an ultrasonic bath for 20 minutes. This entire process was repeated until the water no longer changed color after the bath.The leaf veins were clearly visible at this time (see Figure 2A), and light brushing with gloved fingers was sufficient to remove excess biomass. The leaf skeletons were then bleached in a 10% bleach solution for 15 minutes before being dried and smoothed with weights.

[0056] Figure 2B shows the magnolia leaf after alkaline treatment. Figure 2C shows the treated magnolia leaf under magnification (scale bar - 500 pm).

[0057] Figures 3A-C illustrate schematic side views of the step of treating the sheet structure of the method for producing a flexible, biodegradable substrate, according to various embodiments.

[0058] According to various embodiments, the treatment 200 of the leaf structure 10 can be carried out in such a way that at least some leaf veins of the leaf structure 10, for example each leaf vein of the leaf structure 10, can be coated with the polymer layer in a conformal manner, for example completely surrounding it. Coating the leaf veins of the leaf structure 10 with the polymer layer can make it possible to increase the elasticity of the leaf structure 10. Furthermore, the polymer layer or polymer coating can be designed in such a way that it can soften or soften by means of heating or heating. As a result, the polymer chains of the polymer layer or polymer coating can rearrange and / or rearrange themselves, for example under the exertion of a force and / or load. For example, when the treated leaf structure 14, 18 (e.g.When the coated sheet structure 10 (i.e., the coated sheet structure) is warmed or heated, the sheet skeleton may experience thermal expansion, which may be exerted on the polymer chains of the polymer layer or polymer coating (and which may thus represent the force exerted on the polymer chains). According to various embodiments, treating 200 of sheet structure 10 may comprise obliquely inserting 202 of sheet structure 10 into polymer solution 20. For example, sheet structure 10 may be inserted into metal solution 30 at an angle α relative to the surface of metal solution 30 (e.g., from the horizontal plane) in a range of 10° to 60°. Obliquely inserting sheet structure 10 into polymer solution 20 may, for example, minimize or prevent bulging of sheet structure 10, and thus of the resulting substrate.

[0059] According to various embodiments, the biodegradable polymer solution 20 may comprise a polysaccharide, for example, cellulose and / or derivatives thereof, for example, ethylcellulose. According to various embodiments, the polymer solution 20 may have a specific viscosity, which may be selected such that the leaf veins can be conformally coated with the polymer. For example, the viscosity may be in a range from 20 Pa-s to 50 Pa-s.

[0060] According to various embodiments, the treatment 200 of the sheet structure 10 may further comprise immersing 204 the sheet structure 10 in the polymer solution 20, for example, such that the sheet structure 10 may be completely immersed in the polymer solution 20. Immersing 204 may, for example, be for a specific period of time from 3 minutes to 24 hours, and / or, for example, at a temperature in a range from 20°C to 100°C, for example, 25°C to 90°C.

[0061] Furthermore, the method may, for example, comprise removing 206 (e.g., removing or pulling out) the sheet structure 10 from the polymer solution 20. The removing 206 of the sheet structure 10 from the polymer solution 20 may, for example, be carried out such that a conformal (e.g., uniform) coating of the sheet structure 10 with a polymer layer from the polymer solution close to the Landau-Levich regime can be achieved to produce the treated sheet structure 14.

[0062] For example, as shown in Fig. 2, the Landau-Levich regime may start from a static meniscus 22 near the surface of the polymer solution bath 20, with the dynamic meniscus 24 located directly above the static meniscus 22, in which the liquid may be sheared upwards, resulting in a uniformly thick polymer layer 12 on the sheet structure.

[0063] According to various embodiments, this layer thickness (h) at low tensile speeds ( ~ 1 mm / s ) can be approximately calculated as follows: where h is the layer thickness, r| is the liquid viscosity, V is the constant pulling speed and y is the surface tension.

[0064] However, since the Landau-Levich equation ( 1 ) is well applicable to Newtonian fluids and the ethylcellulose polymer solution may behave rather in the non-Newtonian shear-thinning regime, several approximations can be selected from the literature due to the complex and nonlinear rheological properties of non-Newtonian fluids.

[0065] An extension of the Landau-Levich analysis by Gutfinger and Tallmadge "Film of nonnewtonian fluids adhering to flat plates" , AIChE Journal , vol . 11 , no . 3 , p . 403-413 , 1965 takes into account the shear thinning of non-Newtonian fluids, where the film thickness can be given by equation ( 2 ): where h is the layer thickness, k is the viscosity of the non-Newtonian fluid, V is the constant pulling velocity, y is the surface tension, p is the fluid density, and g is the acceleration due to gravity. For a Newtonian fluid, the viscosity would not be a complex variant, so equation (2) reverts to the Landau-Levich regime for n = 1 and k = r|.

[0066] According to various embodiments, the polymer layer of the coated leaf structure 14 (for example, before drying the leaf structure) may have an average layer thickness (for example, around the leaf veins) which may be in a range of 0.1 pm to 500 pm.

[0067] According to various embodiments, the treatment 200 of the sheet structure 10 may further include a step of drying 208 the treated sheet structure 14, for example, to remove the excess polymer 12 from the sheet structure. The drying 208 may, for example, take place at room temperature.

[0068] According to various embodiments, the method may comprise further drying 300 of the treated sheet structure 14, for example by means of a vertically oriented hot air dryer 30.

[0069] Figures 4A-B illustrate schematic side and perspective views of the hot air dryer 30, respectively, according to various embodiments. According to various embodiments, the hot air dryer 30 can be configured such that the sheet structure 14 can be vertically oriented for drying 300 in the hot air dryer 30 to form the substrate 18.

[0070] According to various embodiments, the hot air dryer 30 may include a housing 31 (e.g., a chamber), a heat source 32 (e.g., a ceramic heater), and a fan 34. The heat source 32 and the fan 34 may, for example, be arranged such that the heated air 36 can flow in a direction along (e.g., parallel to) the surface of the treated sheet structure 14.

[0071] The leaf structure 14 can, for example, be suspended vertically and by means of a

[0072] Tilt adjustment element 38.

[0073] According to various embodiments, the polymer layer of the coated sheet structure 14 can have a layer thickness after drying 300 of the sheet structure, which can be in a range from 0.1 μm to 500 μm (wherein the total thickness of the coated sheet structure 10 can, for example, be in a range from 0.1 mm to 1 mm). The layer thickness after drying 300 of the sheet structure can be substantially the same as or different (smaller) than before drying 300 of the sheet structure. According to various embodiments, the sheet structure 14 coated with a polymer layer can be further coated after drying 300 of the sheet structure 14, for example with one or more polymer layers, which can, for example, comprise or consist of chitosan. The one or more further polymer layers can facilitate the adhesion of deposition materials (e.g.Metal or other relevant materials for the production of electronic components) with the coated substrate, for example.

[0074] Figure 5A illustrates a method for depositing a chitosan polymer layer according to various embodiments. As shown in Figure 5A, the coated sheet structure 14 (e.g. coated with ethylcellulose) can, for example, in a first step 1) be placed on a substrate 50 (e.g. on a flat and / or rigid substrate, for example made of glass), wherein the substrate 50 is coated with a chitosan polymer layer 52. This allows the coated sheet structure 14 to come into contact with the chitosan polymer layer 52 to form a stack on the substrate 50. In a second step 2), the stack formed in the first step 1) can be warmed or heated, for example at a temperature in a range of 90°C to 120°C. In a third step 3 ) the stack formed can be detached from the substrate 50, for example by means of ultrasonic treatment ( e . g .by peeling) to form a double-coated sheet structure 55. Such a method for depositing a further layer onto the sheet structure can have the advantage that, by using a substrate on which the further polymer layer is arranged, the coating of the polymer layer can be carried out in a simple manner. The resulting sheet structure 55 can, for example, have a more homogeneous, smoother chitosan polymer layer, as shown in Figure 5B.

[0075] Example of depositing another polymer layer onto the coated sheet structure

[0076] First, a thin layer of chitosan was spin-coated onto a borosilicate glass slide having the same dimensions as the leaf structure (Figure 5A, step 1). The freshly dip-coated ethylcellulose leaf structure was drained before being placed on the chitosan-coated glass (Figure 5A, step 2). The resulting stack was dried at 120°C for 3 hours (the results remained unchanged when the process was repeated at 90°C) before being placed in an ultrasonic bath containing deionized water. The inherently positively charged chitosan polymer layer bonds favorably to the negatively charged ethylcellulose layer during the drying process and can be easily detached from the glass surface upon ultrasonic treatment in water (Figure 5A, step 3).Since the chitosan layer originates from a smooth glass surface, this results in the substrate exhibiting a quasi-negative of the surface topology of the glass slide, along with artifacts related to adhesion strength and swelling. The hybrid substrate (Figure 5B) was subsequently heated in an oven at 60 °C overnight and incubated under 1 O for 24 hours prior to use. -6 mBar pressure to allow it to outgas.

[0077] According to various embodiments, a flexible, biodegradable substrate 18, for example for organic electronic components, can thus be provided by means of the method described herein, wherein the substrate 18 can have a plant leaf structure which can be coated with at least one biodegradable polymer layer.

[0078] Because the substrate contains or consists of naturally occurring, widely available raw materials (plant leaf structure and polymer layer), the substrate can be produced cost-effectively and recycled and / or decomposed more easily.

[0079] Furthermore, the polymer layer can give the substrate novel properties that can be advantageous, for example, for organic electronic components. Examples of such novel properties can be that the surface of the substrate can be more durable. For example, the substrate can be heat-resistant, water-repellent, easy to print, and can withstand both highly concentrated alkalis and biologically relevant electrolytic environments. Furthermore, the substrate can be designed such that it can easily regain its flat shape after severe bending, folding, and curvature, for example down to small bending radii.

[0080] For example, Figure 6A shows the sheet structure before (left) and after (right) treatment 200, in this case, with an ethylcellulose solution, and subsequent drying 300 (e.g., curing) in a vertical hot air dryer 30. Figure 6A (left) illustrates a sheet structure (e.g., a leaf skeleton), which may, for example, be porous before treatment. After treatment (Figure 6A (right)), the cellulose-coated sheet structure, which may, for example, be non-porous, can be water and electrolyte resistant, heat resistant, and printable (e.g., for the production of organic electronic components).

[0081] For example, it has been observed that within biologically relevant temperature ranges, for example from 5 ° C to 40 ° C, for example from 15 ° C to 25 ° C, no changes in the consistency of the polymer layer occur, which can be caused during treatment ( e . g . during the manufacturing process ).

[0082] Regarding resistance to biologically relevant chemical environments, it was found that the substrate remained unchanged when constantly immersed in phosphate buffered saline (PBS) for 35 days, and the results were also unchanged when the liquid environment was changed to 10 M NaCl solution for 14 days. Thus, it was shown that the substrate can withstand 18 manufacturing conditions, for example for the manufacture of electronic components and / or devices. However, it is to be understood that the substrate described here may at least partially decompose after a longer period of time, for example 10, 100, 1000 times longer than the usual period for the manufacture of electronic components and / or devices, due to its biodegradability.

[0083] According to various embodiments, the polymer layer can coat the leaf structure in such a way that the polymer layer does not form a closed layer. For example, the molecules of the polymer, such as ethylcellulose, can fill the voids in the porous, quasi-fractal geometry of the leaf skeletons. This can lead to a substrate with novel properties due to the structural stability of the leaf framework, such as the lignocellulose framework, and the elasticity of the polymer chains, such as cellulose polymer chains.

[0084] According to various embodiments, the plant leaf structure may have a plurality of leaf veins, wherein the leaf veins are coated in a conformal manner, e.g., completely surrounded by the biodegradable polymer layer.

[0085] According to various embodiments, the polymer layer can, for example, be at least partially formed such that the polymer layer can connect at least two adjacent leaf veins of the leaf structure to one another. Alternatively or additionally, the polymer layer can, for example, be at least partially formed such that a gap between two adjacent leaf veins of the leaf structure cannot be filled with the polymer layer.

[0086] According to various embodiments, the polymer layer of the coated leaf structure 14 can have an average layer thickness that can range from 0.1 pm to 500 pm. The layer thickness can, for example, be different at the macro level, with the layer thickness around the leaf veins of the leaf structure and the layer thickness between adjacent leaf veins being approximately the same.

[0087] According to various embodiments, the design and / or formation of the polymer layer in the substrate can, for example, have the advantage that the substrate 18 can have good light transmission, for example in a range from 80% to 95%, for example from 85% to 90%.

[0088] According to various embodiments, the polymer layer of the coated sheet structure 14 can be formed such that the substrate 18 can have substantially similar light transmission as the untreated sheet structure 10.

[0089] Figure 6B illustrates a graph of the light transmission (in %) of a substrate 18 according to various embodiments (blue line) and of a borosilicate glass 80 (orange line) as a function of wavelength (in nm). The borosilicate glass 80 is considered the most transparent material, with the light transmission of the borosilicate glass 80 being measured at approximately 94%. The substrate 18 according to the invention, despite the polymer coating of the sheet structure, shows a very good, high light transmission in the visible and infrared range of 85%, which is very close to the most transparent material.According to various embodiments, the polymer layer can be formed such that the substrate has at least a first shape and, after bending, folding and / or curving the substrate, can be brought into at least one second shape different from the first shape, and wherein the substrate can be brought from the at least second shape back into the at least first shape, preferably by warming or heating the substrate. The first shape can, for example, be a substantially flat shape. The second shape can, for example, be a shape in which the substrate can have at least one bend, one fold and / or one curvature, for example with a small bending radius in a range of 5° to 10°. The heating can, for example, take place in a range of 60°C to 100°C, for example 80°C.Alternatively or additionally, heating can be carried out over a specific period of time, for example, from 10 seconds to 2 minutes, for example, 30 seconds. During this time, a load can be applied to the substrate, for example, using flat objects weighing more than 200 g.

[0090] In addition, due to its flexible, cross-linked structure, the plant leaf structure can provide the substrate with increased mechanical stability, for example with regard to bending, folding and even small bending radii.

[0091] For example, Figure 7 shows top views of treated sheet structures before (Figure 7A), during (Figure 7B), and after (Figure 7C) a bending test, according to various embodiments. As shown in Figure 7, the substrate described herein can be configured such that the substrate can easily regain its shape after severe bending, folding, and curving (e.g., recover from bending, folding, and curving). For example, in Figure 7, it was observed that the substrate can recover from bending, folding, and crushing (e.g., regain its flat shape). The substrate was subjected to a slight load at 80°C for 30 seconds to relieve the lateral stress (this ensures that the

[0092] substrate can retain its flatness).

[0093] According to various embodiments, the recovery of the substrate can be caused by the restructuring of the heated polymer chains of the polymer layer, which occupy the vacant sites when the surface softens under heat. The surface tension of the polymer, such as ethylcellulose, which can counteract the thermal expansion of the sheet structure lamellae, can allow the substrate to regain its shape even if it is crushed to such an extent that many of the structures inside audibly break.

[0094] The substrate 18 described herein may be suitable, for example, as a substrate for organic electronic components.

[0095] According to various embodiments, the substrate 18 can, for example, be designed such that it can be electrically insulating. Alternatively or additionally, the substrate 18 can, for example, be configured to be printable (e.g., with inorganic materials such as metals, and / or with organic materials such as semiconductors, polymers), preferably by means of inkjet printing, screen printing, electroplating, and / or vacuum deposition (e.g., physical vapor deposition).

[0096] Figures 8A-B illustrate top views of organic electrochemical transistors formed on the substrate described herein, according to various embodiments.

[0097] Organic electrochemical transistors (OECTs) were fabricated on ethyl cellulose-coated lignocellulose leaf skeleton substrates to demonstrate their practical suitability for organic electronics applications. The deposition of the polymer layer on the substrate was tested by both open-air screen printing and inkjet printing. A self-developed, manually operated open-air screen printing system was used for screen printing, while inkjet printing was performed using a Dimatix Materials Printer DMP-2850 from Fujifilm. Figure 8A shows the results of open-air fabrication using the inkjet printing method, and Figure 8B shows the results of open-air fabrication using screen printing.

[0098] Figure 8C illustrates a graph of the chronoamperometric response of the organic electrochemical transistors shown in Figures 8A-B, according to various embodiments. Figure 8 shows the current behavior of the semiconducting channel of the organic electrochemical transistor (OECT) fabricated on the sheet substrate. When the gate voltage is applied with different amplitudes (orange), the current through the transistor channel changes accordingly (blue) over time. This demonstrates the basic operation of an OECT fabricated on this substrate.

[0099] The substrate described herein has been shown to be an insulating, flexible and biodegradable substrate for the fabrication of free-air OECTs, primarily because of its chemical inertness and partial hydrophobicity, which allows the incorporation of most electrolytes.

[0100] As illustrated in Figure 9 , fully functional organic photodiodes could be fabricated on this substrate .

[0101] Figures 10A-C show the optical and electrical properties of the organic photodiode shown in Figure 9. In detail, Figure 10A shows the measured external quantum efficiency of the organic photodiode 18 (in blue) (i.e., the photodiode fabricated on sheet substrates) as a function of wavelength, compared with the measured external quantum efficiency of the same photodiode 80 (in green) fabricated on the ordinary glass substrate. In Figures 10B (dark current) and I OC (bright current), the results of the current measurements for the organic photodiode 18 (in blue) (i.e., for the photodiode fabricated on sheet substrates) are shown as a function of the electrical voltage, compared with the results of the current measurements for the organic photodiode 80 fabricated on glass substrates (e.g., borosilicate glass).

[0102] Furthermore, the substrate (which has a polymer layer deposited by vacuum deposition) was tested as a support for organic light-emitting diodes. Figure 11 shows views of such a fully functioning organic light-emitting diode, which emits light as can be seen in the photographs of Figure 11.

[0103] Figure 12A illustrates a graph of the optical and electrical properties of the light-emitting diode shown in Figure 11, according to various embodiments. As shown in Figure 12A, the diode current (blue) increases as the forward voltage is increased (x-axis). The luminance of the diode (red) also increases with increasing forward voltage.

[0104] Figure 12B illustrates an electrical cell in the form of an accumulator as an exemplary electrochemical cell, which has a separator 106 formed by one or more than one sheet structure 10 (e.g. coated with the polymer layer).

[0105] It was clearly recognized that a sheet structure is suitable as a basis for forming a separator and in particular favors cost-effective production and a more compact design of the cell. The sheet structure can, for example, provide a carrier which is coated with the components of the cell. Such a sheet structure is very cheap to produce compared to conventional concepts, is available all over the world and, due to its properties, favors the production of a high-performance separator. An electrical cell (also referred to simply as a cell) is understood to be a device by means of which electrical energy can be absorbed, released or stored in the form of other (e.g. chemical or potential) energy. An electrical cell has two half-cells (also referred to as electrodes 1041, 104r), which (e.g.by means of an electrolyte and / or a separator 106). The electrical cell can be configured as a capacitive or electrochemical cell, as described in more detail below.

[0106] An electrochemical cell is an electrical cell by means of which chemical energy and electrical energy can be converted into one another and, for example, the chemical energy can be stored. If chemical energy is converted into electrical energy by means of the electrochemical cell, which can be taken from the electrochemical cell, it is of the galvanic cell type (also known as a battery). If the electrochemical cell absorbs electrical energy and converts this into chemical energy, it is of the electrolysis cell type. An electrochemical cell of the accumulator type can be operated either as an electrolysis cell or as a battery. The chemical energy generated when the electrolysis cell is in operation can be stored in the accumulator and converted back into electrical energy when the battery is in operation.

[0107] The electrodes 1041, 104r of the electrochemical cell (simply also referred to as electrochemical electrodes) are coupled to one another in such a way (e.g. by means of an electrolyte and / or a separator) that they can exchange electrical charge with one another (e.g. in the form of ions). During operation of the electrochemical cell, oxidation takes place at the electrode operated as the anode (simply also referred to as the electrochemical anode), and the corresponding reduction takes place at the electrode operated as the cathode (simply also referred to as the electrochemical cathode), which interact with one another by means of the exchange of electrical charge (also referred to as charge exchange). The separator of an electrochemical cell clearly provides an ion-conductive membrane by means of which the charge exchange (e.g. ion exchange) between reduction and oxidation takes place.

[0108] Examples of an electrochemical anode include or consist of one or more of the following materials: zinc (oxidation potential is approximately -0.76 V relative to a standard hydrogen electrode), carbon (e.g., in a carbon modification such as graphite). The oxidation potential of graphite can be approximately -0.86 V relative to a standard hydrogen electrode.

[0109] Examples of an electrochemical cathode comprise or consist of one or more than one of the following materials: lithium or at least one chemical compound (e.g., an oxide) comprising lithium, such as lithium cobalt oxide (e.g., LiCoO2), whose oxidation potential may be in a range from about +4.3 V to about -3.8 V versus LiO / Li+, lithium manganese oxide (e.g., LiMn2O4), whose oxidation potential may be in a range from about +4.3 V to about -3.8 V versus LiO / Li+; and / or an oxide, such as manganese dioxide (e.g., MnO2), whose oxidation potential may be about +0.250 V versus a standard hydrogen electrode.

[0110] The two electrochemical electrodes 1041, 104r differ from each other in their electrochemical potential, so that an electrical potential is developed between them. The respective electrochemical potential of an electrochemical electrode is a function of the electrode's chemical composition and can be compared, for example, with an electrode of a different electrochemical potential using the electrochemical series, which is a list of redox pairs according to their standard electrode potential (redox potential under standard conditions versus the standard hydrogen electrode).

[0111] By means of the (e.g. electrically insulating) separator 106, the two electrodes 1041, 104r of the electrochemical cell are separated from one another (e.g. spatially and / or electrically), wherein the separator is optionally permeable to ions. For example, the separator can have a lower conductivity for electrons than for ions. Alternatively or additionally, the separator 106 can be gas-permeable and / or have the electrolyte, which is accommodated, for example, in cavities (e.g. channels) of the separator 106. For example, the separator 106 can be porous and / or have filaments, e.g. a composite of filaments (e.g. in the form of a sheet structure, a woven fabric, a knitted fabric, a braid, net, fleece or the like) and / or a network of interconnected cavities (e.g. channels).

[0112] What has been described for the electrochemical cell can apply analogously to a capacitive cell. In the case of an electrochemical cell, the two electrodes 1041, 104r can differ from each other in their electrochemical potential. The first electrochemical electrode 1041 can, for example, have a first electrochemical potential (then also referred to as the first electrochemical potential electrode). The second electrochemical electrode 104r can, for example, have a second electrochemical potential (then also referred to as the second electrochemical potential electrode). For example, one of the two electrochemical electrodes 1041, 104r can provide an electrochemical anode and the other of the two electrodes 1041, 104r can provide an electrochemical cathode.

[0113] In the case of a capacitive cell, the two capacitor electrodes 1041, 104r can match in their electrochemical potential and / or their chemical composition. Optionally, one or more of the capacitor electrodes 1041, 104r can be passivated, e.g. by means of a dielectric layer, and / or galvanically separated from one another (e.g. by means of the separator 106). The lower A capacitive cell (also referred to as capacitor) is understood to be a device by means of which electrical energy and potential energy of an electric field can be converted into one another, wherein the associated electrical charge is statically stored and generates the electric field. If electrical energy is absorbed by the capacitive cell, it is converted into the potential energy of the electric field that is formed between the electrodes (also referred to as capacitor electrodes).One of the capacitor electrodes acts as the anode and the other of the two capacitor electrodes acts as the cathode (also called capacitor anode and capacitor cathode). The capacitor electrodes can be metallic (e.g., matching the metal they comprise or are made of) and / or matching their electrochemical potential. Examples of a capacitor electrode comprise or consist of one or more of the following materials: carbon black, graphite, aluminum, and / or aluminum oxide.

[0114] According to various embodiments, the separator 106 may comprise or consist of a base layer 102 comprising or consisting of the sheet structure 10. According to various embodiments, the base layer 102 may comprise one or more than one sheet structure 10. The sheet structure 10 (or a base layer 102 comprising or consisting of the same) may have two opposing edges (also referred to as first edge 1021 and second edge 102r). The sheet structure 10 (e.g., a base layer 102 comprising or consisting of the same) may, for example, be elongated from the first edge to the second edge along a reference direction and may have a thickness transverse to the reference direction (e.g., along a direction perpendicular thereto) and / or be penetrated by a plurality of channels. Forming the base layer 102 may, for example, comprise one or more than one sheet structure (e.g.,several stacked sheet structures), for example with cellulose, preferably with ethylcellulose, and / or with a halogen complexing agent. The formation of the base layer can, for example, comprise connecting (e.g. laminating) several sheet structures arranged one above the other (also referred to as stacked sheet structures) to one another, for example by means of cellulose, preferably with ethylcellulose. Advantageous exemplary properties of the base layer comprise: plate-shaped (or at least band-shaped), porous, comprising filaments, penetrated by cavities (e.g. channels), dielectric, organic (or comprising at least one polymer).

[0115] An electrolyte can refer to a substance or a mixture of substances which can conduct ions, i.e. is ionically conductive. The electrolyte can comprise or be formed from solid or liquid components. For example, the electrolyte can comprise or be formed from one or more of the following components: a liquid electrolyte (e.g. conducting salt with solvent and optional additives), a polymer electrolyte, an electrolyte based on an ionic liquid, and / or a solid electrolyte. Optionally, the electrolyte can comprise a mixture of different components, e.g. a mixture thereof. Alternatively or additionally, several electrolyte types and / or components can be used alongside one another within a cell.

[0116] The term "ionically conductive" refers to a conductivity for ions (e.g. in a solid, a liquid and / or a gas), e.g. by means of a movement of cations and / or anions. The resulting electrical conductivity can be greater than 10~ 10 S / cm (Siemens per centimeter), e.g. in a range of approximately 10~ 10 S / cm to approximately ICü 1 S / cm (e.g. 10~ 4 S / cm) and / or greater than 10~ 9 S / cm, e.g. greater than 10~ 7 S / cm, e.g. greater than 10~ 5S / cm. The term "permeable" refers to the permeability (also referred to as permeability) for a fluid, e.g., a gas (then also referred to as gas permeable) and / or a liquid (then also referred to as liquid permeable). For example, in permeation, a material (the so-called permeate) can penetrate a solid. The permeability is given as GTR (gas transmission rate), which corresponds to one mole per square meter, second, and Pascal (e.g., under standard conditions), and can optionally be normalized to the length along which the permeability is given. The permeability can, for example, be greater than 0.1 cm 3 / m 2 Day, e.g. as 10 cm 3 / m 2 day, e.g. as 1000 cm 3 / m 2 Day.

[0117] Preferably, the electrodes 1041, 104r can be spaced apart from one another along the reference direction. Optionally, the first edge can be arranged in the first electrode 1041 and the second edge can be arranged in the second electrode 104r (e.g., embedded therein). Alternatively or additionally, the electrodes 1041, 104r are arranged at least laterally (also referred to as lateral).

[0118] In a less complex implementation, the separator may consist of the base layer 102. In other implementations, the base layer 102 may be integrated (or at least embedded) into the separator, for example, by coating the base layer 102 with one or more components of the separator 106.

[0119] For example, the separator 106 (or at least the base layer 102) may have a greater conductivity for ions than for electrons and / or may comprise a dielectric material (e.g., a porous matrix thereof). For example, the conductivity for ions may be 10 k -times the conductivity for electrons, where k is equal to 3 or greater, e.g., 4 or greater, e.g., 5 or greater, e.g., 6 or greater. Alternatively or additionally, a porosity of the separator 106 (or at least of the base layer 102) can be in a range from approximately 10 nm to approximately 100 pm (relative to the radius of the pores). The radius of a pore can be understood, for example, as the radius of a sphere having the volume of the pore.

[0120] Examples of the (e.g., dielectric) material include: an organic material (e.g., polymer), e.g., cellulose (e.g., ethylcellulose); an oxide (e.g., glass); a ceramic. Reference is made herein, among other things, to ethylcellulose as a dielectric material, although it should be understood that what is described herein may also apply to any other dielectric material.

[0121] The thickness of the base layer 102 can, for example, be in a range from approximately 1 pm to approximately 100 pm. The porosity of the base layer 102 can, for example, be in a range from approximately 10 nm to approximately 100 pm. The thickness of filaments of the base layer 102 can, for example, be in a range from approximately 10 nm (nanometers) to approximately 100 pm (micrometers). The distance of the first edge from the second edge can be greater than 10 k-times the thickness of the base layer 102, where k is equal to 3 or greater, e.g. 4 or greater, e.g. 5 or greater, e.g. 6 or greater.

[0122] Several of the cells provided herein are particularly suitable for being connected in series or parallel to one another (e.g. by stacking), which is generally difficult with conventional thin-film components (e.g. batteries).

[0123] The electrochemical cell illustrated in Fig. 12B can be understood as an exemplary implementation whose first electrode 1041 comprises or consists of manganese oxide and the second electrode 104r comprises zinc and / or zinc oxide. The base layer 102 has a leaf skeleton which is or will be coated on both sides with the first electrode 1041, the second electrode 104r, and components of the separator 106. The separator 106 can, for example, comprise or consist of ethylcellulose, which promotes particularly cost-effective production and is biodegradable. As described herein, the leaf structure 10, which is coated with the polymer layer, can be penetrated by channels. For example, the base layer 102 and / or the separator 106 can be penetrated by channels. The channels make it easier to absorb an electrolyte and / or increase their gas permeability.

[0124] The formation of channels can be stimulated by crosslinking the polymer layer (e.g. the polymer thereof) and / or by reducing the amount of polymer solution with which the sheet structure is coated before the polymer solution is transferred into the polymer layer and / or (e.g. the polymer thereof) is crosslinked.

[0125] Reducing the amount of polymer solution may, for example, comprise removing a portion of the polymer solution from the sheet substrate. This may be done, for example, by means of a substrate (then also referred to as a sacrificial substrate) that absorbs the portions of the polymer solution. It should be understood that other processes may also be used to reduce the amount of polymer solution with which the sheet structure is coated. The sacrificial substrate may, for example, be another sheet substrate and / or blotting paper.

[0126] An example of coating the sheet substrate (e.g. with the polymer layer and / or the polymer solution) comprises stimulating cross-linking of the polymer (also referred to as cross-linking), e.g. the polymer of the polymer layer and / or the polymer solution. Cross-linking can take place by linking a large number of individual macromolecules of the polymer layer and / or the polymer solution to form a three-dimensional network. Cross-linking can be stimulated by heating and / or irradiation. Heating can take place, for example, by supplying thermal energy to the polymer layer and / or the polymer solution, for example by means of a heating device. Irradiation can take place, for example, by irradiating the polymer layer and / or the polymer solution with electromagnetic radiation, for example with ultraviolet radiation and / or with infrared radiation. Alternatively or additionally, cross-linking can take place chemically, e.g.B . by using oxidative or enzymatic polymerization .

[0127] The further the crosslinking of the polymer layer and / or the polymer solution has progressed, the smaller the porosity of the sheet structure 10 coated therewith can be.

[0128] In one example of crosslinking that can be performed in one of the exemplary implementations, the crosslinking is controlled and / or regulated. This makes it easier to provide a resulting porosity according to a specification. The specification can, for example, comprise a desired state of the porosity and / or represent at least one parameter associated therewith, such as gas permeability. For example, the specification can comprise or at least represent a desired state for a gas permeability of the separator 106 or at least of the sheet structure 10 coated with the polymer layer.

[0129] For example, a parameter for stimulating cross-linking can be changed based on an actual state of cross-linking, e.g., its difference from the specified value.

[0130] According to various embodiments, a process (or at least the device by which the process is carried out) by which crosslinking is stimulated can be calibrated. Calibration can include changing a duration and / or an intensity of the process based on the specification, the porosity, and / or based on the gas permeability. Once the process is calibrated, this facilitates the production of a variety of separators of the same quality.

[0131] Some examples are described below which relate to what is described herein and shown in the figures. Example 1 is a method for producing a flexible, biodegradable substrate, comprising: providing a leaf structure from a plant leaf, the leaf structure having a plurality of leaf veins; treating the leaf structure using a polymer solution (e.g. to change the mechanical properties of the leaf structure) such that each leaf vein of the leaf structure is coated with a polymer layer from the polymer solution, preferably to form a coated leaf structure as a flexible, biodegradable substrate for organic electronic components.

[0132] In Example 2, the method according to Example 1 may further optionally be configured such that treating the sheet structure comprises immersing the sheet structure in the polymer solution.

[0133] In Example 3, the method according to Example 1 or 2 can further optionally be arranged such that the treatment of the leaf structure is carried out in such a way that the leaf veins are coated conformally with the polymer layer.

[0134] In Example 4, the method according to Examples 1 to 3 may further optionally be configured such that the method further comprises, after the treatment, a step of drying the treated sheet structure, preferably by means of a vertically oriented hot air dryer.

[0135] In Example 5, the process according to Examples 1 to 4 may further optionally be arranged such that the polymer solution comprises cellulose, preferably ethylcellulose.

[0136] In Example 6, the method according to Examples 1 to 5 can further optionally be set up such that the polymer solution has a viscosity which is in a range from 20 Pa - s to 50 Pa - s. In Example 7, the method according to Examples 1 to 6 can further optionally be set up such that the polymer layer of the coated sheet structure has a layer thickness which is in a range from 0.01 pm to 500 pm.

[0137] In Example 8, the method according to Examples 1 to 7 may further optionally be configured such that the leaf structure has a three-dimensional structure.

[0138] In Example 9, the method according to Examples 1 to 7 may further optionally be arranged such that the provided leaf structure is a plant leaf skeleton.

[0139] Example 10 is a flexible , biodegradable substrate for organic electronic devices , wherein the substrate comprises a plant leaf structure coated with a biodegradable polymer layer .

[0140] In Example 11, the substrate according to Example 10 may further optionally be configured such that the plant leaf structure has a plurality of leaf veins, wherein the leaf veins are conformally coated with the biodegradable polymer layer.

[0141] In Example 12, the substrate according to Example 10 or 11 may further optionally be configured such that the biodegradable polymer layer has a layer thickness which is from 0.01 pm to 500 pm.

[0142] In Example 13, the substrate according to Examples 10 to 12 can further optionally be configured such that the polymer layer is formed such that the substrate has at least a first shape and, after bending, folding and / or curving the substrate, can be brought into at least one second shape different from the first shape, and wherein the substrate can be brought from the at least second shape back into the at least first shape, preferably by means of heating the substrate. In Example 14, the substrate according to Examples 10 to

[0143] 13 may further optionally be configured such that it is electrically insulating and / or which is configured to be printable, preferably by means of inkjet printing and / or screen printing.

[0144] In Example 15, the substrate can be prepared according to Examples 10 to

[0145] 14 is designed such that the leaf structure has a three-dimensional structure, preferably wherein the three-dimensional structure has a fractal-based design.

[0146] Example 16 is configured according to any one of Examples 1 to

[0147] 15, wherein the polymer layer is penetrated by one or more than one opening (then also referred to as a through opening or a channel), each opening being arranged between a plurality of the leaf veins. The channels can, for example, form holes, gaps, and / or openings between at least some of the leaf veins. For example, the coated leaf structure, which has the polymer layer and the leaf veins coated therewith, can be made porous by means of the channels (wherein the channels then provide the pores).

[0148] Example 17 is configured according to any one of Examples 1 to

[0149] 16 , wherein the leaf structure, the leaf veins of which are coated with the polymer layer, is or will be further coated with a chitosan polymer layer.

[0150] Example 18 is configured according to Example 17, wherein coating with the chitosan polymer layer comprises: placing the leaf structure, whose leaf veins are coated with the polymer layer, on an additional substrate coated with a chitosan polymer layer; and detaching the chitosan polymer layer, which is in contact with the polymer layer, from the additional substrate, preferably to form a double-coated sheet structure. Example 19 is configured according to any one of Examples 1 to 18, wherein the polymer layer is water-repellent.

[0151] Example 20 is configured according to any one of Examples 1 to

[0152] 19, wherein treating the leaf structure by means of the polymer solution comprises coating the leaf structure (e.g. its leaf veins) by means of the polymer solution (e.g. by dipping into the polymer solution).

[0153] Example 21 is configured according to any one of Examples 1 to

[0154] 20, wherein treating the sheet structure by means of the polymer solution comprises at least partially (ie partially or completely) converting the polymer solution (eg at least a part thereof) with which the sheet structure is coated into the polymer layer.

[0155] Example 22 is configured according to any one of Examples 1 to

[0156] 21, wherein treating the sheet structure by means of the polymer solution comprises crosslinking a polymer of the polymer solution and / or the polymer layer, preferably by irradiating the polymer solution and / or the polymer layer and / or by heating the polymer solution and / or the polymer layer.

[0157] Example 23 is configured according to any one of Examples 1 to

[0158] 22, further comprising calibrating a process by which the polymer is crosslinked, preferably based on a parameter representing a gas permeability of the separator.

[0159] Example 24 is configured according to any one of Examples 1 to

[0160] 23, wherein treating the leaf structure with the polymer solution comprises removing a portion of the polymer solution with which the leaf structure is coated from the leaf structure, for example after dipping and / or by means of a sacrificial substrate, wherein the sacrificial substrate is preferably porous and / or comprises (e.g., consists of) fibers, wherein the sacrificial substrate is again preferably absorbent and / or comprises (e.g., consists of) a blotting sheet. The removal of polymer solution promotes penetration of the polymer layer by through-openings between the leaf veins.

[0161] Example 25 is set up according to Example 24, wherein the part of the polymer solution is absorbed (e.g., sucked up) by means of the sacrificial substrate.

[0162] Example 26 is configured according to any one of Examples 1 to 25, wherein the coated sheet structure comprising the polymer layer and the sheet veins coated therewith is used to form an electrical device (e.g., providing a substrate on which the device is formed).

[0163] Example 27 is configured according to Example 26, wherein the electrical component is an organic component, a semiconductor component, and / or one of the following components: an optoelectronic component (e.g., a photodiode or a light-emitting diode), a transistor, an electrical cell.

[0164] Example 28 is configured according to Example 27, wherein the electrical cell is an electrochemical or capacitive cell; and / or wherein the electrical cell comprises one or more than one electrode with which the sheet structure is coated, preferably on both sides.

[0165] Example 29 is using a sheet structure according to any one of Examples 1 to 28, which is, for example, the coated sheet structure comprising the polymer layer and the sheet veins coated therewith, to form (e.g., as a component) a separator (e.g., by coating the sheet structure) of an electrical cell, and preferably to form the electrical cell comprising the separator.

[0166] Example 30 is using a sheet structure according to any one of Examples 1 to 29, which is, for example, the coated sheet structure comprising the polymer layer and the sheet veins coated therewith, to provide an electrical cell comprising a separator formed by means of the sheet structure (e.g., by means of coating the sheet structure).

[0167] Example 31 is an electrical (e.g. electrochemical or capacitive) cell (e.g. the electrical cell from any one of Examples 1 to 30), comprising: a first electrode (e.g. first electrical potential); a second electrode (e.g. second electrical potential); a separator which is arranged at least in sections between the first electrode and the second electrode (and, for example, spatially separates them from one another); a leaf structure according to any one of Examples 1 to 30, which is, for example, the coated leaf structure which has the polymer layer and the leaf veins coated therewith, wherein the separator is formed by means of the leaf structure.

[0168] Example 32 is a method (e.g., for forming the electrical cell according to Example 31), comprising: forming a first electrode (e.g., first electrical potential); forming a second electrode (e.g., second electrical potential); and forming a separator disposed at least partially between the first electrode and the second electrode, wherein the separator is formed by means of a sheet structure according to any one of Examples 1 to 31, which is, for example, the coated sheet structure comprising the polymer layer and the sheet veins coated therewith.

[0169] Example 33 is the use of a result of the process according to Example 32 as an electrical (e.g. electrochemical or capacitive) cell.

[0170] Example 34 is configured according to any one of Examples 1 to 33, further comprising: coating the first electrode and the second electrode at least in sections with a component (e.g., a polymer) of a separator, which is preferably arranged between the first electrode and the second electrode and / or in which the sheet structure according to any one of Examples 1 to 33 is embedded. This promotes a compact design.

[0171] Example 35 is configured according to any one of Examples 1 to 34, further comprising: embedding a first edge of the sheet structure (or a base layer formed therefrom) according to any one of Examples 1 to 34 into a first electrode (e.g., by coating the first edge with the first electrode) of an electrical cell; and / or embedding a second edge of the sheet structure (or a base layer formed therefrom) according to any one of Examples 1 to 34 into a second electrode (e.g., by coating the second edge with the second electrode) of an electrical cell. This promotes a compact design.

[0172] Example 36 is configured according to Example 35, further comprising: wherein the forming of one or more than one (e.g., the first and / or second) electrodes and / or the embedding thereof is performed by means of liquid-phase deposition, preferably by immersing the sheet structure (or a base layer formed therefrom) in a liquid phase. This simplifies manufacturing.

[0173] Example 37 is configured according to any one of Examples 1 to

[0174] 36, wherein an electrical cell formed by means of the sheet structure according to any one of examples 1 to 36 has one or more than one electrode with which the sheet structure is coated, preferably on both sides.

[0175] Example 38 is configured according to any one of Examples 1 to

[0176] 37, wherein an electrical cell formed by the sheet structure according to any one of examples 1 to 37 has one or more than one electrode into which the sheet structure extends; and / or which extends into a portion of the separator.

[0177] Example 39 is configured according to any one of Examples 1 to

[0178] 38, wherein the polymer layer has one or more of the following properties: smooth to facilitate subsequent printing processes; penetrated by channels (e.g., nanoporous) to accommodate electrolyte; a degree of nanoporosity in a range of about 10 nm to about 100 nm.

[0179] Example 40 is configured according to any one of Examples 1 to 39, wherein the polymer layer comprises one or more than one of the following materials: chitosan, cellulose, polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), graphene oxide, and allotropes of these materials, e.g., comprising chitosan sheets and / or fibers.

Claims

Patent claims 1. Method (1) for producing a flexible, biodegradable substrate, comprising - Providing (100) a leaf structure (10) from a plant leaf, wherein the leaf structure (10) has a plurality of leaf veins; - Treating (200) the sheet structure (10) by means of a polymer solution (20) to change the mechanical properties of the sheet structure (10) such that each sheet vein of the sheet structure (10) is coated with a polymer layer from the polymer solution (20) to form a coated sheet structure (14, 18) as a flexible, biodegradable substrate for organic electronic components, wherein the polymer layer is penetrated by one or more than one opening, each opening being arranged between two of the sheet veins.

2. The method (1) according to claim 1, wherein treating (200) the sheet structure (10) comprises immersing (204) the sheet structure (10) in the polymer solution (20).

3. Method (1) according to claim 1 or 2, wherein the treatment (200) of the leaf structure (10) is carried out such that the leaf veins are coated conformally with the polymer layer.

4. The method (1) according to any one of claims 1 to 3, wherein the method (1) further comprises, after the treating (200), a step of drying (300) the treated sheet structure (14), preferably by means of a vertically oriented hot air dryer (30).

5. Process (1) according to one of claims 1 to 4, wherein the polymer solution (20) comprises cellulose, preferably ethyl cellulose.

6. Method (1) according to one of claims 1 to 5, wherein the polymer solution (20) has a viscosity which is in a range from 20 Pa -s to 50 Pa -s.

7. Method (1) according to one of claims 1 to 6, wherein the polymer layer of the coated sheet structure (14) has a layer thickness which is in a range of 0.01 pm to 500 pm.

8. Method (1) according to one of claims 1 to 7, wherein the sheet structure (10) has a three-dimensional structure.

9. Method (1) according to one of claims 1 to 8, wherein the provided leaf structure (10) is a plant leaf skeleton.

10. A flexible, biodegradable substrate for organic electronic components, the substrate comprising a plant leaf structure coated with a biodegradable polymer layer, the polymer layer being penetrated by one or more than one opening, each opening being arranged between two leaf veins of the plant leaf structure.

11. The substrate of claim 10, wherein the plant leaf structure has a plurality of leaf veins, the leaf veins being conformally coated with the biodegradable polymer layer.

12. Substrate according to claim 10 or 11, wherein the biodegradable polymer layer has a layer thickness ranging from 0.01 pm to 500 pm.

13. Substrate according to one of claims 10 to 12, wherein the polymer layer is formed such that the substrate is formed such that it has at least one first shape and can be brought into at least one second shape different from the first shape after bending, folding and / or curving the substrate, and wherein the substrate is brought from the at least second mold back into the at least first mold, preferably by heating the substrate.

14. Substrate according to one of claims 10 to 13, which is designed such that it is electrically insulating and / or which is arranged to be printable, preferably by means of inkjet printing and / or screen printing.

15. Substrate according to one of claims 10 to 14, wherein the sheet structure (10) has a three-dimensional structure, preferably wherein the three-dimensional structure has a fractal-based design.

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