DE102014213978A1 - Process for producing an organic semiconductor device and organic semiconductor device - Google Patents

Abstract

The invention relates to a method for producing an organic semiconductor component (2), in particular an OPV module, which is manufactured as a multilayer structure, comprising an upper electrode (4), a lower electrode (6) and a between the electrodes (4, 6). arranged active layer (8), wherein for the electrical connection of the two electrodes (4, 6) a through-contact (18) is formed, characterized in that the through-hole (18) from a in a predetermined pressure range (D) printed ink (22) is trained. Furthermore, the invention relates to an organic semiconductor component (2) produced by means of such a method.

Description

The invention relates to a method for producing an organic semiconductor device which is produced as a multilayer structure comprising an upper electrode, a lower electrode and an active layer arranged between the electrodes, wherein a through contact is formed for the electrical connection of the two electrodes. Furthermore, the invention relates to a manufactured according to such a method organic semiconductor device. The organic semiconductor device is in particular an OPV module.

Such a method and such an OPV module are, for example, the US 2011/0277655 A1 or the US 8,129,616 B2 refer to.

A preferred field of use of such an OPV module, that is, an organic photovoltaic element is the generation of electrical energy by means of sunlight. For this purpose, an OPV module has an active layer made of an organic semiconductor material in which charge carriers are generated by absorption of sunlight. The active layer is typically arranged as a thin layer between an upper and a lower electrode each formed as a thin layer. This results in a multi-layer structure, which may also include other layers. For example, the active layer may additionally be arranged between so-called barrier layers. In the following, therefore, such a or similar combination is referred to simplifying as an active layer.

The available current and the voltage supplied by the OPV module depend, among other things, on the structure of the OPV module. The current intensity generated by an OPV module is essentially defined by the area covered by the semiconductor material; By contrast, the voltage is essentially defined by the band gap of the semiconductor material and, accordingly, material-dependent. Therefore, in order to achieve a certain voltage, an OPV module often comprises several cells that are connected in series with one another. For this purpose, it is necessary in particular first to divide the upper and lower electrodes into mutually insulated upper and lower sub-electrodes and to form a plurality of cells in this way. To produce a series connection, the upper part electrode of a first cell is then usually connected in an electrically conductive manner to the lower part electrode of a second cell. For this purpose, the layers lying between the electrodes and in particular the active layer have a number of interruptions, in which a suitable conductive material is arranged, by means of which the subelectrodes are correspondingly electrically conductively connected. In this way, a via is formed between two cells, which extends from a lower part electrode to an upper part electrode through the intermediate active layer.

From the US 2011/0277655 A1 For example, a method is known in which a substrate having a conductive structure and a first dielectric layer are provided. In this case, the conductive structure comprises a through contact extending from one to the other side of the substrate. Further, a first conductive pattern is printed on the first dielectric layer, thereby forming a first pre-printed layer which is bonded to the one side of the substrate. In this case, a first conductive material is applied such that the conductive structure is connected to the first conductive pattern. In a development of the method, a second dielectric layer is provided similar to the first dielectric layer and printed with a second conductive pattern. In this way, a second pre-printed layer is formed, which is now connected to the other side of the substrate. In this case, a second conductive material is additionally applied in such a way that the conductive structure is connected to the second conductive pattern.

Furthermore, from the US 8,129,616 B2 a method is known in which a photovoltaic cell is formed with a semitransparent electrode, with an organic semiconductor layer and with a counter electrode by means of a roller coating method. In particular, a plurality of strip-shaped cells are formed on a carrier foil and connected in series by means of suitably applied electrodes. For this purpose, the upper electrode of one of the cells overlaps with the lower electrode of an adjacent cell such that a series connection is realized. In this case, at least one sacrificial layer is formed to form this configuration, which is removed again in the further course of the process.

The formation of a plated through hole inevitably creates a dead zone in which no active material is present and thus can not be used to generate energy. The ratio of usable surface area of the OPV module to non-usable area defines a geometric fill factor, which in particular also represents a measure of the efficiency of the OPV module. The larger the usable area compared to the non-usable area, the more energy per unit area can be generated with the OPV module, that is, the more efficient the OPV module is.

In addition, the OPV modules are usually thin and the multi-layer structure has a height of several orders of magnitude is less than the width and length of the OPV module. For example, the layer thickness of the electrodes is about 0.1 μm to 10 μm in each case. However, such thin layers usually have poor conductivity compared to thicker layers, which in turn limits the size of the individual cells of an OPV module. In order to achieve lower losses, therefore, the cell size must be reduced, which in turn has a negative effect on the fill factor and correspondingly the efficiency due to the additionally necessary plated-through holes. The conductivity of at least one of the electrodes is furthermore often reduced by the fact that this at least one electrode is made of a transparent, conductive material whose conductivity is often poor.

To form an interruption of the active layer disposed between the electrodes for subsequent formation of a via, the layer is either directly patterned, that is applied with a corresponding interruption, or the interruption is formed by subsequent removal of material from the layer. In a further method step, the through-connection is then formed. In this case, the formation of the via at the position of the interruption must take place, which disadvantageously results in a corresponding adjustment effort with regard to the various process steps. Alternatively, the via is formed in common with the upper electrode and thus must be made of the same material as this one.

To form interruptions of the active layer, the use of a laser is also known. Here, however, the selection of the operating parameters of the laser, such as wavelength and power is critical and in particular material dependent. The operating parameters must in particular be selected such that only the active layer lying between the electrodes is selectively processed and the electrodes remain intact. Therefore, this method is not very flexible. In addition, the use of a laser is often expensive.

The invention has for its object to provide a simplified method for producing an OPV module. The method should also allow the production of an OPV module with a larger geometric fill factor. Furthermore, the method should have the greatest possible design freedom with regard to the production of the OPV module. Another object is to specify an OPV module which can be produced by means of the method.

The object is achieved by a method having the features of claim 1 and an organic semiconductor device having the features of claim 13. Advantageous embodiments, developments and variants are the subject of the dependent claims. In this case, the refinements and advantages cited in connection with the method also apply analogously to the organic semiconductor component.

In a method for producing an organic semiconductor device, this is fabricated as a multilayer structure and comprises an upper electrode, a lower electrode and an active layer disposed between the electrodes. For electrical connection of the two electrodes, a via is formed, which is formed from an ink printed in a predetermined pressure range. In particular, at first one of the two electrodes is formed as a lower electrode. On these the active layer is applied. The ink for making the via is printed either before or after the application of the active layer. For this purpose, a printing method is used in particular.

The advantages achieved by the invention are in particular that the production of the organic semiconductor device and in particular the formation of the via through the printing of the ink is particularly simplified. The formation of the through-connection by means of printed ink makes it possible in particular to use a printing method by means of which a plated-through hole with particularly small dimensions, in particular with a particularly small width and length, can be produced. In particular, it is thus possible to manufacture an organic semiconductor device with an improved filling factor and, correspondingly, with improved efficiency. The printing of the ink, that is to say in particular the printing of the plated-through hole, also advantageously makes possible a free design of the plated-through hole, in particular its shape and shape, as a result of which the organic semiconductor component as a whole is particularly free to design. Furthermore, it is advantageously possible to dispense with the use of a laser.

Preferably, the organic semiconductor device is an OPV module, that is, an organic photovoltaic element. This is particularly suitable for the preparation by means of the above-mentioned method. In the following, therefore, without limiting the generality, it is assumed that an organic semiconductor component designed as an OPV module is used. The description applies mutatis mutandis to any organic semiconductor devices. It is conceivable, for example, an embodiment as an organic light-emitting diode, organic electrochemical cell, organic field effect transistor, organic thin film transistor, organic photodetector, laser diode, Schottky diode, photoconductor, photodetector or thermoelectric device.

The OPV module comprises at least two cells each having an upper cell electrode and a lower cell electrode, the upper cell electrodes being formed as sub-electrodes of the upper electrode and the lower cell electrodes being sub-electrodes of the lower electrode. In particular, first, the lower electrode comprising a number of lower sub-electrodes is formed. This is preferably done on a suitable substrate, for example PET. Subsequently, the active layer and the via are applied.

The application of the ink and thus in particular of the via is effected by means of a printing process, in particular a high-resolution printing process, for example by means of ink jet printing, gravure printing, flexographic printing, screen printing, transfer printing or slot die coating, so-called slot-die coating. In this case, the ink is preferably printed exclusively in a predetermined printing area, in which the through-connection is to be formed. Subsequently, the upper electrode comprising a number of upper sub-electrodes is formed. In this case, in particular, the upper part electrode for forming a series connection of a number of cells are suitably connected electrically conductively to the lower part electrode by means of the plated-through holes.

The substrate serves in particular for improved handling of the OPV module and is comparatively thick with respect to the electrodes and the active layer. The lower electrode is preferably made of a transparent, conductive oxide, for example, indium tin oxide, the upper electrode, for example made of silver.

The active layer is preferably applied flat in the printing area, whereby in particular a more complex, structured application can be avoided and the OPV module can be manufactured more easily. Structured application means that the active layer is not applied as a continuous layer but as a plurality of subregions separated from one another by means of at least one interruption. The interruption is used in this case, in particular for preparing the formation of the via. In contrast, flat is understood in particular that the active layer in the area of the subsequent vias continuously, that is initially applied without interruption.

In a preferred embodiment, an ink which penetrates the active layer in the printing area is used on the surface-applied active layer for printing the through-connection. This makes it possible, in particular, to dispense with additional structuring, that is to say the formation of at least one interruption for introducing the through-connection. Instead, the formation of the interruption and the formation of the via, in particular, takes place simultaneously during the printing of the ink. This penetrates the active layer and in particular also possible further provided between the electrodes and already applied layers, whereby in particular a contacting takes place with the lower electrode. In this way, the production of the OPV module is particularly simplified.

Conveniently, the ink contains a solvent for penetrating the active layer in the printing area. The solvent is in particular also a solvent for the material of the active layer and dissolves it accordingly in the pressure range. In this way, in particular, an interruption of the active layer in the pressure region arises. The ink includes, for example, silver particles as a conductive material and a methanol / anisole mixture as a solvent. In order to achieve a particularly good wetting of the lower electrode, in particular after penetration of the active layer, the ink expediently has a low surface tension, preferably in the range from 10 to 100 mN / m. A suitable viscosity of the ink is in the range of 1 to 30 mPas in ink jet printing. However, with another printing method, other ranges of values may be more appropriate. For example, the value of the viscosity in a screen printing method is preferably significantly higher than in inkjet printing.

In an alternative preferred embodiment, the ink is first printed in the areas provided for the vias prior to the application of the active layer. From the printed ink, the via is formed. The active layer is thus applied subsequently and in particular over the ink over the entire surface. In the area of the ink, the active layer is broken, so that the via is formed.

Preferably, prior to the application of the active layer, a thermal treatment of the ink, for example a sintering process, is carried out first. As a result, the ink forms a somewhat stronger conductor structure. In particular, the conductor structure is therefore formed directly on the lower electrode and before the application of the active layer and the upper electrode. Thereafter, the active layer is applied flat and in the pressure range displaced by the via. For example, the active layer is applied in a gravure printing method in which excess material is removed by means of a doctor blade so that the conductive ink or the conductor structure is exposed, thereby forming the via and is subsequently connectable to the upper electrode. Such a procedure is also referred to as doctor blading. The OPV module is therefore particularly easy to manufacture. In addition, it is in particular possible to dispense with a separate structuring of the active layer, that is to say forming at least one interruption for introducing the through-connection.

In an advantageous embodiment, dewetting takes place when the active layer is applied in the printing region, which ensures in a particularly simple manner that the plated through hole is not covered by the active layer. In a further advantageous embodiment, the ink has a plurality of particles with a predetermined mean particle size and the active layer is applied with a predetermined layer thickness, wherein the average particle size is greater than the layer thickness. The ink comprises, for example, silver clusters, with an average size of approximately between 0.5 μm and 5 μm, and the active layer is applied at a layer thickness of approximately between 50 nm and 500 nm. This ensures, in particular, that the conductor structure formed by means of the ink projects sufficiently beyond the active layer and is not covered by it.

The ink is applied in particular only in the smallest possible pressure range, whereas the electrodes are formed in particular over a large area and thereby extend large parts of the OPV module. In order to use an optimally suitable method for printing the ink and for forming the electrodes, the ink is preferably applied in a separate process step from the formation of the electrodes.

Conveniently, an ink is used which contains a material with good conductivity, for example silver or gold. However, since these materials are expensive, the particularly more material-intensive electrodes are preferably made of a different material than the through-hole. This makes it possible to manufacture the electrodes in particular less expensive than when using the same material. It is also possible to select particularly suitable materials for the electrodes and for the through-connection.

In order to further simplify the process, in addition to the via, the two electrodes and the active layer are advantageously also formed by means of a printing process. In combination with the formation of the via by means of printing on the ink, the method is therefore expediently a multi-stage printing process in which, in particular, all layers are produced in each case by means of a printing process. Advantageously, the method is a roll application method, whereby the OPV module can be manufactured particularly inexpensively.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show:

1 schematically the construction of an OPV module in sectional view,

2 schematically the OPV module according to 1 in supervision,

3A to C show schematically a method step of a method for producing the OPV module according to 1 , and

4A to D each schematically a process step of another method for producing the OPV module according to 1 ,

The 1 and 2 show an organic semiconductor device 2 that's here as an OPV module 2 is formed, wherein 1 clearly shows its multi-layer structure. The OPV module 2 includes an upper electrode 4 , a lower electrode 6 and one between the electrodes 4 . 6 arranged active layer 8th , In this case, this stands in particular generally for a functional layer stack which contains at least one active layer, but in addition also functional layers, not shown here, such as barrier layers, for example.

The upper electrode 4 is in a number of upper sub-electrodes 4 ' divided, that is, in sections, which are in particular electrically separated from each other. Each of these upper sub-electrodes 4 ' includes a narrow bus bar 10 , which is made of silver, for example, and a corresponding grid on the top O of the OPV module 2 forms. Alternatively, the busbar is 10 no separate part but a part of the upper electrode 4 , Furthermore, each of the upper sub-electrodes comprises 4 ' one compared to the common rail 10 wide surface contact 12 that is about a given section 8th' the active layer 8th extends. The surface contact 12 is designed for example as a grid electrode. The lower electrode 6 is by means of a number of isolation points 14 in a number of mutually electrically separate, lower part electrodes 6 ' divided.

In each case one of the upper part electrodes 4 ' forms with one of the lower part electrodes 6 ' and a section 8th' the active layer 8th a cell 16 , For interconnecting several cells 16 with each other are in the active layer 8th a number of vias 18 introduced through the entire active layer 8th and from the lower electrode 6 to the upper electrode 4 extend. In this case, in the embodiment shown here in each case connects a via 18 the upper part electrode 4 ' a first cell 16 with the lower part electrode 6 ' one to the first cell 16 adjacent second cell 16 , In this way, a series connection is formed. Alternatively or additionally, it is possible to have two or more cells 16 interconnect in parallel.

In 2 is the OPV module 2 according to 1 shown in supervision. Clearly recognizable are those in comparison to the collective leaders 10 wide surface electrodes 12 , These extend here, in particular in the conveying direction F of a web-fed printing press not shown here in detail, which is used to manufacture the OPV module 2 serves. Alternatively, however, there is a different orientation. The vias 18 are here in particular not continuously formed in the conveying direction F, but only in sections. In a variant of the OPV module 2 are the vias 18 however, executed consistently.

In the 3A to C is in each case a method step of a method for producing the OPV module 2 according to 1 shown. It is in a first, in the 3A illustrated step provided a semifinished product, the lower electrode 6 and the active layer applied thereon 8th includes. On a more detailed representation of the lower sub-electrodes 6 ' is omitted here. The active layer 8th However, it is planar, that is, continuous and not divided into sections isolated from each other, whereby the active layer 8th is particularly easy to produce. In the embodiment shown here, the active layer 8th made of the polymers P3HT and PCBM, the lower electrode 6 ' from a transparent, conductive metal oxide.

In a second step, a via becomes 18 imprinted, as in 3B shown. For this purpose, in a printing area D by means of a printer head 20 an ink 22 on the active layer 8th printed. The ink 22 contains in particular a solvent containing the active layer 8th dissolves in the pressure range D and in this way the formation of a through the active layer 8th through reaching through hole 18 allows. This is thus in particular directly with the lower electrode 6 connected. In the embodiment shown here, the ink contains 22 as solvent, a mixture of methanol and anisole. In this mixture, silver clusters are dispersed as a conductive material. When introducing the ink 22 will now be an interruption of the active layer 8th created and in particular at the same time a conductive material for the production of the via 18 provided. By printing, for example by means of an ink jet printing process, also referred to as inkjet printing, it is particularly possible a through-hole 18 to produce particularly small dimensions, for example, a width B of about 60 microns.

In a third, in the 3C The step shown becomes the upper electrode 4 applied and by means of the via 18 with the lower electrode 6 connected. With corresponding, but not shown here embodiment of the two electrodes 4 . 6 as a plurality of sub-electrodes 4 ' . 6 ' it is then possible, by means of several vias 18 the partial electrodes 4 ' . 6 ' according to the electrical requirements of the OPV module 2 connect to. For the production of the upper electrode 4 For example, silver is vapor-deposited. Alternatively, it is possible to use the upper electrode 4 in particular by means of a screen printing process in a suitable grid pattern.

In the 4A to D is in each case a method step of an alternative method for producing the OPV module 2 shown. It is first, as in 4A shown a lower electrode 6 For example, provided from indium tin oxide, directly on the number of vias 18 is printed, for example by means of a screen printing process. The vias 18 then form on the lower electrode 6 in particular a freestanding ladder structure 24 , After printing the ink 22 In the printing area D, a thermal treatment, for example a sintering process by means of which, in particular, the electrical conductivity of the printed ink is suitably carried out 22 is adjustable.

Subsequently, in a second step, the active layer 8th plotted. This is in 4B shown. This is the training for the active layer 8th used material surface, that is in particular continuously applied. In 4C is then shown the result of a third step in which the active layer has been dried. Since the solution has only a low solids content, for example 1 to 10%, the applied film is correspondingly greatly reduced by drying. For example, the active layer is initially as a so-called wet film about 1 to 10 microns thick and after drying as a so-called dry film only about 50 to 500 nm. In the illustrated embodiment, the vias 18 It is also made of a material identical to that of the active layer 8th is only poorly wettable. There is accordingly a dewetting of the plated-through holes 18 such that they are at least partially exposed. This will make the in 4D shown subsequent contact with the now applied upper electrode 4 additionally simplified.

In 4C are the active layer 8th and the vias 18 although the same height, in an alternative embodiment, however, is the active layer 8th made so thin that the vias 18 protrude. As a result, in particular, the subsequent contacting with the upper electrode 4 further simplified. In a suitable embodiment, the ink comprises 22 a plurality of dispersed in a solvent particles, each made of a conductive material, for example silver clusters, with an average diameter of about 500 nm. In a variant, it is then possible, the active layer 8th As described above, only apply with a layer thickness S, which is less than the average diameter of the particles. In particular, in combination with the dewetting described above, the material of the active layer 8th then from the applied ladder structure 24 displaces and accumulates on the remaining surface.

In principle, it is possible that in addition to the active layer 8th more functional layers between the two electrodes 4 . 6 are provided, as already mentioned in the introduction. These can then be similar to the active layer 8th be applied. In addition, expediently in the 1 to 4 not shown substrate used on which the electrodes 4 . 6 and the active layer 8th be printed consecutively as a multilayer stack.

LIST OF REFERENCE NUMBERS

2

OPV module

4

upper electrode

4 '

upper part electrode

6

lower electrode

6 '

lower part electrode

8th

active layer

8th'

Section (the active layer)

10

busbars

12

surface contact

14

isolation place

16

cell

18

via

20

printhead

22

ink

24

conductor structure

B

Width (of the via)

D

pressure range

F

conveying direction

S

layer thickness

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2011/0277655 A1 [0002, 0005]
• US 8129616 B2 [0002, 0006]

Claims (14)

Method for producing an organic semiconductor device ( 2 ) manufactured as a multilayer structure comprising an upper electrode ( 4 ), a lower electrode ( 6 ) and one between the electrodes ( 4 . 6 ) arranged active layer ( 8th ), wherein for the electrical connection of the two electrodes ( 4 . 6 ) a via ( 18 ) is formed, characterized in that for the formation of the via ( 18 ) in a predetermined pressure range (D) ink ( 22 ) is printed. Method according to the preceding claim, characterized in that the organic semiconductor component ( 2 ) is an OPV module. Method according to one of the preceding claims, characterized in that the active layer ( 8th ) is applied flat in the printing area (D) Method according to one of the preceding claims, characterized in that first the active layer ( 8th ) is continuously formed and for printing the via ( 18 ) an ink ( 22 ) which is the active layer ( 8th ) penetrates in the pressure area (D). Method according to the preceding claim, characterized in that for penetrating the active layer ( 8th ) in the print area (D) the ink ( 22 ) contains a solvent. Method according to one of claims 1 to 3, characterized in that first the ink ( 22 ) and then the active layer ( 8th ) is applied flatly and this in the print area (D) of the ink ( 22 ) for the formation of the via ( 18 ) is displaced. Method according to the preceding claim, characterized in that the ink ( 22 ) before applying the active layer ( 8th ) is thermally treated. Method according to one of the two preceding claims, characterized in that during the application of the active layer ( 8th ) in the pressure range (D) a dewetting occurs. Method according to one of the preceding claims, characterized in that the ink ( 22 ) has a plurality of particles with a predetermined mean particle size and the active layer ( 8th ) is applied with a predetermined layer thickness (S), wherein the mean particle size is greater than the layer thickness (S). Method according to one of the preceding claims, characterized in that the ink ( 22 ) in one of the formation of the electrodes ( 4 . 6 ) is applied separate process step. Method according to one of the preceding claims, characterized in that the plated-through hole ( 18 ) is made of a different material than the electrodes ( 4 . 6 ). Method according to one of the preceding claims, characterized in that in addition to the via ( 18 ) also the two electrodes ( 4 . 6 ) and the active layer ( 8th ) are each formed by means of a printing process. Method according to one of the preceding claims, characterized in that this is a roll application method. Organic semiconductor device ( 2 ), in particular OPV module, which is produced by a method according to one of the preceding claims.

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