DE102014202945A1 - Method for producing an organic electronic component and organic electronic component - Google Patents

Abstract

A method for producing an organic electronic component comprises, in a first step, providing a substrate layer with an electrically conductive material. In a second step, the method comprises arranging a passivation layer in passivation regions by means of flexographic printing. In a third step of the method, an organic semiconductor material is arranged. In a fourth step, an electrode layer is arranged such that the passivation layer and the organic semiconductor material are arranged between the substrate layer and the electrode layer.

Description

The invention relates to a method for producing an organic electronic component and to an organic electronic component produced by the method.

In manufacturing methods of planar electronic components, in particular organic electronic components, such as organic solar cells, organic light emitting diodes (OLED) or organic field effect transistors (OFET), there is a need for structuring or passivation of certain surface areas of the layers of the respective component ,

In [1], for example, a method for the production of grid structures with electrically conductive metal pastes by means of the flexographic printing process [2] is described. In [3] a method for the production of antennas with electrically conductive metal pastes by means of flexo printing is named.

In [4] a pre-wetting of a component surface with N-octanol to improve the wetting of the surface with poly (3,4-ethylenedioxythiophene) poly (styrene sulfonates) - abbreviated as PEDOT: PSS - for the production of solar cells is described. The pre-wetting takes place by means of a flexographic printing process.

In [5] the flexographic printing process for the generation of organic field effect transistors (OFET) by means of pressure of a strongly hydrophobic material for self-alignment of PEDOT: PSS using targeted dewetting is described.

In [6] a process for the preparation of hydrophobic barrier structures for sensor elements by means of flexographic printing is described.

Flat organic light-emitting diodes can currently be arranged on a polymer or plastic substrate. The plastic substrate has an anode layer in addition to barrier layers. The anode layer may be a transparent conductive layer such as a transparent and conductive oxide (TCO). Structuring of barrier films with a transparent conductive layer can take place by means of additive or subtractive methods.

Structuring or passivation of certain surface areas of the layers of an organic electronic component can be carried out by means of additive or subtractive methods.

For example, in additive processes, passivation may apply insulating materials to the anode to prevent current flow from the anode to a cathode in the passivated regions. In subtractive methods, for. B. the anode in the passivated or to be structured areas are removed to prevent the flow of current.

In [7] a subtractive method is described in which the anode is partially removed by laser and thus the light surfaces of organic light-emitting diodes are separated from each other. However, the process causes particles that can contaminate the remaining active elements or areas. The process is also difficult to roll-to-roll for plastic barrier films because only the TCO coating can be removed without damaging the barrier layer. This leads to the highest demands on all process parameters, such as a web guide of the substrate, a thickness tolerance of the substrate, a thickness tolerance of the barrier layer and the TCO coating or a depth of focus of the laser.

In additive processes, a partial passivation of the anode can take place by application of a structured dielectric. In [8] a photolithographic process for the deposition of the structured dielectric is described. However, photolithographic processes are complex, expensive and not or only insufficiently compatible with role-to-role (RzR) processes.

So-called inkjet printing processes are also difficult to RZR-compatible and, in particular, uneconomical for large surfaces to be passivated. Drops that have been mismatched during the process can also reach the active elements or areas of the component and impair their function. Furthermore, only low-viscosity liquids are printable in inkjet processes.

In screen-printing processes, a printing plate comes into contact with both the passivating and non-passivating regions, and thus also the active elements, and can scratch or load them with particles, as described, for example, in US 5,256,467. Further, screen printing methods other than rotary screen printing are difficult to be RzR compatible.

Although intaglio printing is RzR-compatible, a used printing plate comes into contact with the active elements and can scratch or load them with particles and thus impair the function of the components. Furthermore, passivation residues not scraped off by a printing cylinder can remove the active elements contaminate. Most low-pressure printing processes use low-viscosity printing materials and absorbent substrates. For a passivation layer, which is possibly viscous, and non-absorbent substrates such as plastic or metal foils, such a method is unsuitable.

5 shows a photograph of an OLED 1005 comprising a substrate structured by gravure printing, the passivation areas being indicated by the words "COMEDD" and "R2flex", as well as the (dark) areas between luminous areas 1006a -C are recognizable. The OLED 1005 has spotty OLED lighting areas (active areas) 1006a -C, which are caused by contamination of the active elements by Passivierungsreste.

Accordingly, it would be desirable to have a process for passivating regions in organic electronic devices that enables high throughput, reliable passivation, and high quality of the active regions of the device.

The object of the present invention is to provide a method for producing organic electronic components and in particular organic light-emitting diodes, so that active regions have a low degree of damage and / or contamination and can be produced at high throughput rates.

This object is achieved by the method according to claim 1 and an organic electronic component according to claim 8.

Exemplary embodiments of the present invention provide a method for producing an organic electronic component, in which a passivation layer is arranged in passivation regions between a flat anode and a cathode by means of flexographic printing. The method further comprises arranging an organic semiconductor material and arranging an electrode layer, such that the passivation layer and the organic semiconductor material are arranged between the substrate layer and the electrode layer.

An advantage of this embodiment is that by means of flexographic printing (method) contamination of active areas can be minimized or prevented, and that by spacing a printing form from the substrate in spacing areas outside the passivation areas, contact between the substrate and the printing plate in these spacing areas is prevented and so damage to the active surfaces or areas can be minimized or prevented. The method can be implemented as an RzR method, so that a production throughput by means of the method can be high. Furthermore, the method can be implemented as a continuous process.

Alternative embodiments provide methods of making organic light emitting diodes by flexographic printing.

An advantage of these exemplary embodiments is that luminous regions of the organic light emitting diodes can have a homogeneous luminous surface.

Further embodiments of the present invention provide a method for producing an organic electronic component, wherein the substrate or the base electrode is a metallic foil.

An advantage of this embodiment is that an electrical conductivity of a metallic foil, a thermal conductivity, a mechanical strength and / or a barrier property compared to TCO substrates can be increased.

Further advantageous embodiments are the subject of the dependent claims.

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings. Show it

1 a schematic flow diagram of a method for producing an organic device according to an embodiment of the present invention;

2 a schematic side sectional view of an organic light emitting diode having a base electrode, a passivation layer, which in passivation regions an organic semiconductor material from the substrate, according to an embodiment of the present invention;

3 a top view of a structured organic light-emitting diode, which can be produced by a method according to the invention;

4 a schematic diagram of a flexographic printing method according to an embodiment of the present invention; and

5 a photograph of a structured organic light-emitting diode, which have a substrate structured by means of gravure printing process and having passivation of contaminated lighting surfaces according to the prior art.

Before below embodiments of the present invention in detail with reference to the Drawings are explained in more detail, it is pointed out that identical, functionally identical or equivalent elements, objects and / or structures are provided in the different figures with the same reference numerals, so that the description of these elements shown in different embodiments is interchangeable or applied to each other can be.

Hereinafter, the term substrate layer is to be understood as meaning a layer which has a base electrode. The substrate layer may be, for example, a metallic foil made of aluminum, steel, silver, copper or another metal. The substrate layer can be the base electrode, for example if it is designed as a metal foil. Alternatively, the substrate layer may also be a (possibly transparent) polymer barrier film with a transparent electrically conductive layer or a flexible glass with a transparent electrically conductive layer such as a TCO layer or a metal layer. If the substrate layer is a polymer barrier film or a flexible glass having a transparent electrically conductive layer, the substrate layer may be a transparent electrically conductive substrate. The transparent electrically conductive layer may comprise a TCO layer, nanowires (or nanowires) and / or carbon nanotubes (CNTs). The transparent electrically conductive layer or the metal layer can be used as a base electrode. For example, the base electrode may have silver. The silver can be arranged, for example, by vapor deposition or sputtering (cathode sputtering) on the substrate layer. The substrate layer may be both the substrate of the base electrode (eg plastic film with TCO) and the base electrode itself (eg metal foil). The terms base electrode and substrate layer are used below as a synonym and are to be understood as interchangeable.

1 shows a schematic flow diagram of a method 100 for producing an organic component. The procedure 100 indicates a first step 110 in which a substrate layer is provided with an electrically conductive material.

The procedure 100 comprises a second step, in which a passivation layer is arranged in passivation regions by means of flexographic printing, ie by means of a flexographic printing process. The passivation regions may be surface regions of the substrate layer, such that the substrate layer in the passivation regions is covered with the passivation layer. Alternatively or additionally, it is also conceivable that material layers, such as organic or inorganic conductive or semiconducting functional materials are arranged on the substrate, so that passivation regions can cover surface regions of the functional materials.

The procedure 100 comprises a third step in which an organic semiconductor material is arranged. For example, the organic semiconductor material can be arranged wholly or partially over a surface of the substrate layer, so that the organic electronic material is in contact with the base layer in active regions of the substrate layer and is spaced from the substrate layer in the passivation regions by means of the passivation layer.

The procedure 100 indicates a fourth step 140 in which an electrode layer is arranged, so that in the passivation regions, the passivation layer and the organic semiconductor material are arranged between the substrate layer and the electrode layer. The electrode layer may have one or more counterelectrodes, that is to say that an electric potential can be applied flatly to the electrode layer or in different regions (of the counterelectrodes). In other words, the electrode layer may be made in one piece or in several pieces. If the electrode layer is embodied in several parts, then an electrical potential can be applied to one or more subareas of the electrode layer, that is, the plurality of counterelectrodes can be driven jointly or separately from one another.

The organic semiconductor material may enable current flow between an anode and a cathode in the active regions. One by the method 100 manufactured component may be about an OLED, an organic solar cell or an OFET.

Based on a polarity between the base electrode and the electrode layer, the base electrode or the electrode layer can be used as the anode and the respectively oppositely disposed electrode layer or base electrode as the cathode. This means that the electrically conductive material of the substrate layer can form both an anode and a cathode. The passivation layer may be disposed at the anode or the cathode. In other words, the passivation layer can be arranged on the substrate layer or on the electrode layer, so that the third step 130 on the second step 120 can follow or, so the second step 120 on the third step 130 can follow.

The passivation layer may be, for example, a resin or a passivation paste. The passivation layer can have a layer thickness of, for example, more than 1 micron, more than 15 microns or more than 20 microns.

A high viscosity of passivation pastes allows the same after application, i. H. Arranging on the substrate layer or the organic electronic material, can "run" and so close (pin holes) and / or as well as a uniformly thick and / or smooth, d. H. having a low surface roughness, can form a layer. An average surface roughness may be in a range of 5-1000 nm, 50-800 nm or 200-500 nm.

The passivation paste may be, for example, a polyurethane resin or an epoxy resin, and / or have a viscosity in a range between 500 and 5,000, 600 and 2,500 or 1,000 and 3,000 m / Pas at 20 ° C and with a contact pressure in a range of, for example -100 N / mm, 5-50 N / mm or 7-20 N / mm, preferably 10 N / mm ± 10% during the flexographic printing process on the substrate.

Alternatively or additionally, the passivating paste may be, for example, an ultraviolet (UV) light-curing resin. Alternatively, the resin may cure, for example, upon reaching an annealing temperature. An annealing temperature may, for example, be more than 50 °, 120 ° or 400 ° Celsius. For example, in an initial state, before curing, the resin may have a solvent that exits the resin during a curing time, for example, so that it cures.

Heretofore, a person skilled in the art would have used a process other than a flexographic printing process as known in the art because the pattern of an inking roll (anilox roll) of an apparatus for performing a flexographic printing process may also be visible in the print result, and thus a closed completely closed layer can be prevented.

Passivation material of the passivation layer may "bleed" based on the properties described above, thus allowing a uniform layer thickness.

In contrast to printing with electrically conductive materials, as it is used, for example, with inkjet methods in antenna structures, defects in Passivierungsbereiche may possibly lead to short circuits between the cathode and anode, whereas local defects in conductive materials possibly lead to increased line resistance. For example, while increased line resistances may reduce device efficiency, shorting may result in complete failure of the device such that a requirement for a passivation layer may be higher with respect to a closed surface than with a conductive layer.

In other words, printing a passivation layer in the flexographic printing process, such as the process 100 enables a roll-to-roll patterning of sheet-like, flexible, organic electronic components with non-conductive passivation material (insulating layer) by printing a passivation layer in the flexographic printing process.

An advantage of this method is that it is an additive method and a base electrode of the substrate layer, for example the anode (such as the TCO layer on a polymer barrier film or a metal foil) remains undamaged compared to subtractive methods.

The procedure 100 In particular, in contrast to a subtractive method, in which the anode is partially removed, for example by means of laser, has the advantage that the method 100 can also be applied when the substrate layer is a metal foil.

In particular, the method can 100 be used to passivate large areas of the electronic component. A resolution, ie an accuracy of the arrangement of the passivated surfaces, can be, for example, 50 μm, 200 μm or 1000 μm. The method can be used to fabricate flat, flexible, organic electronic components in a roll-to-roll (RzR) process by printing a passivation layer in flexographic printing.

2 shows a schematic side sectional view of an organic light emitting diode 10 with a base electrode 12 and a passivation layer 14 in passivation areas 16 an organic semiconductor material 18 from the bottom electrode 12 spaced. The passivation layer 14 can, for example, by means of the step 120 to be ordered. On the organic semiconductor material 18 is a counter electrode layer 22 arranged. The bottom electrode 12 , the passivation material 14 , the organic semiconductor material 18 and the counter electrode layer 22 are from an encapsulation layer 24 covered. The encapsulation layer 24 is designed to be mechanically impaired by, for example, mechanical contact or contact with the counterelectrode layer 22 , the semiconductor material 18 and / or the passivation layer 14 with external objects to prevent and / or to prevent ingress of water and oxygen.

The bottom electrode 12 of the organic electronic component 10 is with a first electrical contact 26a connected. counter electrodes 22a and 22b the counter electrode layer 22 of the organic electronic component 10 are with electrical contacts 26b and 26c connected to the counter electrode layer 22 are coupled so that between sections (counter electrode) 22a the counter electrode layer 22 that with the electrical contact 26b are coupled and the electrode 26a or the base electrode 12 , a first electrical potential can be applied. In areas (counter electrode) 22b the electrode layer 22 that with the electrical contact 26c coupled, and the bottom electrode 12 a second electrical potential can be applied.

This means that the organic light emitting diode 10 in one area 28a and in one area 28b by means of electrical contact 26b and 26c can be controlled independently of each other, wherein a voltage which is connected to the electrical contact 26a can be applied, a common (reference) potential for the areas 28a and 28b forms. Based on a sign of a potential difference, for example, the electrically conductive material of the base electrode 12 the anode and the electrode layer 22 the cathode of the organic device 10 be or vice versa.

Metal foils or polymer barrier films with a transparent electrically conductive layer or a flexible glass with a transparent electrically conductive layer can form a basic electrical contact for organic electronic components. The substrate or the substrate layer with the base electrode 12 can be flexible to allow for compatibility with a roll-to-roll process. The functionality of, for example, an overlying organic electronic (semiconductor) layer is made possible by a heterojunction between an electron-conducting and a hole-conducting organic material. To delineate the active surfaces, the electrical ground contact is selectively separated in places by an insulating layer (passivation) of the organic electronic mating contact. The insulating layer, ie the passivation layer, is subject to the requirements that it has a closure, that is to say no pinholes, in order to ensure an effective separation (isolation) of the ground and mating contact. Furthermore, it may be necessary for the passivation layer to have a low roughness and a small thickness in order to minimize or not impair the subsequent coating and encapsulation processes. Alternatively, a high thickness may be desirable, such as to obtain a predetermined height of the organic electronic device.

Advantageously, the non-passivated regions, such as the active regions or elements, may not be mechanically damaged, loaded with particles, or contaminated with passivation material to provide unrestricted functionality.

3 shows a plan view of a structured organic light emitting diode 30 , by means of a method according to the invention, such as the method 100 , can be produced. Opposite the organic light emitting diode 1005 of the 5 has the organic light emitting diode 30 homogeneous illuminated areas 32a -C and a minimized extent of defects and structuring residues on the luminous surfaces.

In other words shows 3 an organic light emitting diode 30 with a structured by means of flexographic printing substrate. With the naked eye, neither defects nor structuring residues are visible in the active OLED lighting areas.

4 shows a schematic diagram of a flexographic printing process. A passivation material 52 is in a squeegee bucket 54 arranged and is selfsame on an anilox roller 56 dosed. By means of the anilox roller 56 becomes the passivation material 52 on raised areas of a plate cylinder 58 or on elevated areas of a flexible printing plate 59 attached to the printing plate cylinder 58 is arranged, applied or arranged.

Adjacent to the printing form cylinder 58 is an impression cylinder 62 arranged. Between the printing plate cylinder 58 and the impression cylinder 62 becomes a substrate 64 , for example, the substrate layer or base electrode 12 out 2 be or may have, moved through. Based on mechanical contact between the flexible printing plate 59 and the substrate 64 becomes the passivation material 52 in the passivation regions on the substrate 64 arranged. The passivation areas can be enhanced by the areas that increase on the plate cylinder 58 or the flexible printing plate 59 are arranged, at least partially determined. The flexible printing form 59 can passivation material arranged at the elevated areas 52 wholly or partially to the substrate 64 transfer. This means that after a successful contact between the flexible printing plate 59 and the substrate 64 Remains of the passivation material 52 on the flexible printing plate 59 can remain.

The illustrated flexographic printing process may be implemented as a roll-to-roll process and be practicable such that the substrate 64 for example, from a first role 66 deployed (unrolled) before it is in contact with the raised areas of the flexible printing plate 59 is brought. After the arrangement of the passivation 52 on the substrate 64 and after a possible drying time or irradiation of the passivation material with UV light, the substrate may be of a second roll 68 received, ie recorded or rolled up at this. Alternatively, the flexographic printing process can also be carried out in such a way that individual flat webs of the substrate 64 in the area between the plate cylinder 58 and the impression cylinder 62 be guided and the webs, for example. In individual layers, stacked or side by side for further processing steps are provided.

In other words shows 4 a flexographic printing process for the structured transfer of insulating layers for flexible organic electronic components, in which the printing material (the passivation material 52 ) by means of a chamber doctor blade on a full-surface screened roller (anilox roller 56 ) is metered and wherein the structured passivation layer on the substrate 64 such as a transparent conductive oxide substrate, is transferred to the electrical ground contact at the points where the printing form cylinder 58 or the flexible printing form 59 with the substrate 64 comes into contact.

The advantage of this is that the substrate 64 or electrodes arranged thereon remain unchanged.

Further advantages of the presented (flexographic printing) method are, for example, that closed layers to the substrate 64 can be transmitted. The closed layers may have both a small thickness and a large thickness. The thickness and roughness may be from a grid of the anilox roll 56 , physical properties, such as a viscosity of the passivation material 52 and drying parameters. In areas which, for example, should remain active (areas not to be printed), there is contact between the printing form cylinder 58 or the flexible printing plate 59 and the substrate 64 prevented. This means that damage to the active elements or contamination or contamination of the active elements with particles or with passivation material 52 is reduced or prevented. The flexible or elastic printing form 59 allows a reduced load on the substrate 64 while the printing form cylinder 58 or the flexible printing form 59 is in contact with the same.

Further, the flexographic printing process can be implemented as a high-efficiency roll-to-roll process. This means that a production of organic electronic components with both a high throughput, d. H. can be done quickly, as well as inexpensively. In particular, based on low-cost and rapidly changing printing plates in the form of plates or sleeves (English: Sleeves) can be converted in used production equipment with a small time and / or cost, for example.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

literature

• [1] Yu, J.-S., Kim I., Kim, J.-S., Jo, J., Larsen-Olsen, TT, Sondergaard, RR, Hosel, M., Angmo, D., Jørgensen M., Krebs , FC: Silver front electrode grids for ITO-free all printed polymer solar cells with embedded and raised topographies, prepared by thermal imprint, flexographic and inkjet roll-to-roll processes. In: Nanoscale 4, Støvring 2012: 6032-6040
• [2] Kipphan, H .: Handbook of Print Media, Technologies and Production Methods. Springer-Verlag, Berlin, Heidelberg, New York 2001
• [3] Siden, J., Nilsson, H.-E .: Line width limitations of flexographic-screen and inkjet printed RFID antennas. In: Antennas and Propagation Society International Symposium, Honolulu 2007
• [4] Krebs, FC, Fyenbo, J., Jørgensen M .: Product integration of compact roll-to-roll processed polymer solar cell modules: methods and manufacture using flexographic printing, slot-coating and rotary screen printing. In: Journal of Materials Chemistry 20, London 2010: 8994-9001
• [5] Schmidt, G .: Surface tension-structured printing for the production of polymer electronic components. Dissertation, Chemnitz 2011
• [6] Olkkonen, J., Lehtinen, K., Erho, T .: Flexographically Printed Fluidic Structures in Paper. In: Anal. Chem. 82 (24), Urbana-Champaign 2010: 10246-10250
• [7] Karnakis, D., Kearsley, A., Knowles, M .: Ultrafast Laser Patterning of OLEDs on Flexible Substrates for Solid-state Lightning. In: JLMN Journal of Laser Micro / Nanoengeniiering Vol. 4, no. 3, Osaka 2009: 218-223
• [8th] Philipp, A., Hasselgruber, M., Hild, OR, May, C .: Substrate structuring for organic light-emitting diodes by means of screen printing: Technology Day screen printing, Landshut 2010

Claims (8)

Procedure ( 100 ) for producing an organic electronic component ( 10 ) with the following steps: providing ( 110 ) a substrate layer ( 12 ; 64 ) with an electrically conductive material; Arrange ( 120 ) of a passivation layer ( 14 ; 52 ) in passivation areas ( 16 ) by flexographic printing; Arrange ( 130 ) an organic semiconductor material ( 18 ); and arranging ( 140 ) of an electrode layer ( 22 ), so that the passivation layer ( 14 ; 52 ) and the organic semiconductor material ( 18 ) between the substrate layer ( 12 ; 64 ) and the electrode layer ( 22 ) are arranged. Method according to Claim 1, in which the organic electronic component ( 10 ) is an organic light emitting diode. Method according to claim 1 or 2, wherein the step of arranging ( 120 ) of the passivation layer ( 14 ; 52 ) is carried out so that the passivation layer ( 14 ; 52 ) an extension in one direction from the substrate layer ( 12 ; 64 ) to the electrode layer ( 22 ) which is at least 1-20 μm. Method according to one of the preceding claims, in which the arranging ( 120 ) of the passivation layer ( 14 ; 52 ) comprises the steps of: providing a passivation material ( 52 ); Arranging the passivation material ( 52 ) on elevated areas of a flexible printing plate ( 59 ), which are attached to a printing plate cylinder ( 58 ) is arranged; and contacting the flexible printing form ( 59 ) with the substrate layer ( 12 ; 64 ) or a layer disposed thereon. Method according to claim 4, wherein the passivation material ( 52 ) is a resin, and further comprising the step of: curing the resin by means of UV radiation; or curing the resin by heating the resin to at least one curing temperature. Method according to one of the preceding claims, wherein the method is a roll-to-roll method and further comprises the steps of: providing the substrate layer ( 12 ; 64 ) from a first roll ( 66 ) at a time before the passivation layer ( 14 ; 52 ) to the substrate ( 12 ; 64 ) is arranged; and receiving the substrate layer ( 12 ; 64 ) with a second roll ( 68 ) at a time after the passivation layer ( 14 ; 52 ) to the substrate layer ( 12 ; 64 ) was arranged. Method according to one of the preceding claims, wherein the step of providing ( 110 ) of the substrate layer ( 12 ; 64 ) comprises either providing a metallic foil or providing a transparent electrically conductive substrate. Organic component ( 10 ) with a passivation layer ( 14 ; 52 ) by means of a flexographic printing process between a substrate layer ( 12 ; 64 ) and an electrode layer ( 22 ) is arranged.

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