EP2218122A1

EP2218122A1 - Structuring of conductive polymer layers by means of the lift-off process

Info

Publication number: EP2218122A1
Application number: EP08855145A
Authority: EP
Inventors: Andreas Elschner; Wilfried Loevenich; Kerstin Pollok
Original assignee: HC Starck Clevios GmbH
Current assignee: Heraeus Deutschland GmbH and Co KG
Priority date: 2007-11-28
Filing date: 2008-11-03
Publication date: 2010-08-18
Also published as: US20110076464A1; TW200943321A; WO2009068415A1; KR20100126268A; DE102007057650A1; JP2011505059A

Abstract

The invention relates to a method for producing conductive structured polymer layers by means of the lift-off process, and conductive structured polymer layers produced by said method.

Description

Structuring of conductive polymer layers by means of the lift-off process

The invention relates to a method for the production of conductive structured polymer layers by means of the lift-off process and to the conductive patterned polymer layers produced by this method.

Conductive polymers have gained economic importance in recent years due to an improved property profile. By increasing the electrical conductivity on the one hand and improving the chemical stability to environmental influences on the other hand, many new applications have been developed. Thus, conductive polymers are used, for example, as antistatic layers, transparent electrodes, Lochänjektäonsschichten, counter electrodes in capacitors or sensors with growing success.

For many applications in which conductive polymers are or could be used, it is necessary to pattern the conductive polymer layer. By structuring a polymer layer is meant that the layer is not homogeneously over the whole surface on a support, such as e.g. a film or a glass plate, but consists of individual segments, e.g. from individual tracks, which are spatially separated from each other and thus electrically isolated from each other. The challenge now is to apply these spatial, lateral structures on a support with the highest possible spatial resolution. By this is meant that the regions in which the conductive polymer is present as a layer and the regions in which no polymer is present are sharply delimited from one another. The step created at the boundary of the areas determines the spatial resolution, which can be characterized by two variables, the step height h and the step width b. The step height corresponds to the thickness of the polymer layer and is typically 30 nm <h <10 μm. The step width corresponds to the width of the polymer layer, wherein for many applications a step width b <20 microns, preferably of b <5 microns, is necessary. These include e.g. Electrodes for Organic Light Emitting Diodes "OLEDs" (Organic Light Emitting Devices, Ed. Joseph Shinar, 2004 Springer-Verlag) or Electrodes for Organic Field Effect Transitors "OFETs" (Organic Electronics, Ed. Hagen Klauk, 2006 Wiley ~ VCH, p.3ff ), which are only a few microns apart.

In order to apply laterally structured conductive polymers on a support, various printing processes are currently being developed. Among the printing processes considered to be particularly suitable include ink jet, screen, Fϊexo-, tampon, offset and gravure printing (Organic Electronics, Ed Hagen Klauk, 2006 Wiley-VCH, p.297 ff). These printing processes are well established and have proven useful in the deposition of suitable printing inks or inks. Since these printing techniques were developed primarily for the visualization of printed images, their lateral resolution is limited to the selectivity of the naked eye, ie the step width is typically b> 20 microns here. However, for many interesting applications of conductive polymers, a step width b <20 μm is necessary. In particular, the structures discussed under the heading "polymer electronics", in which, inter alia, field-effect transistors are constructed entirely from polymers, require much finer structures than the established printing techniques are currently able to afford.

Furthermore, the established printing methods listed above result in print images in which the deposited inks or inks have surfaces that are often inhomogeneous and microscopically rough. For example, screen printing, flexographic printing, pad printing, offset printing and gravure printing require highly viscous colors per se, which then can no longer run adequately during drying and thus form rough surfaces. However, rough surfaces of conductive polymer layers with an average roughness Ra> 5 nm are undesirable, in particular in the case of OLEDs or OFETs, since they can lead to electrical short circuits here. In contrast, in ink-jet printing, although low-viscosity and well-flowing inks are used, the so-called "coffee-drop effect" (Tekϊn, Emine, de Gans, Berend-Jan, Schubert, Ulrich S., Journal of Materials Chemistry (2004) , 14 (17), 2627-2632), the layer thickness at the edge of the deposited drop is significantly higher than at the center, which also makes the production of homogeneous conductive polymer layers, such as areas or lines, difficult.

One way of making conductive polymers in high spatial resolution structures, i. with a step width b <20μm, the polymer surfaces being smooth, i. the average roughness Ra is less than 5 nm, is described in EP-A-1079397. Therein homogeneous layers of a conductive polymer, which are applied by means of a Lackschleudcr, structured by means of a laser beam. The laser beam of an excimer or Nd.YAG laser is guided over the places where the polymer must be removed and decomposes the organic layer at the appropriate places (laser ablation). This process is currently used only for the removal of polymer layers from glass substrates and has the disadvantage that it is slow and expensive due to the acquisition and operating costs of the laser. Another disadvantage is that ablated fragments of the polymer deposit on the surface of the adjacent polymer layer, i. contaminate, and these can change the electrical properties and surface properties of the conductive polymer. It is also disadvantageous that the laser ablation of conductive polymers on polymeric substrates, e.g. Polyethylene terephthalate (PET) films are difficult to control because the desired removal of the conductive polymer also ablates the substrate material simultaneously. The resolving power of laser sintering is limited to the focusability of the laser beam and is 1 to 5 μm.

DE-A-10340641 describes the structuring of conductive polymers by means of photolithography. Here, a positive photoresist layer is applied to the conductive polymer layer and applied over a shadow illuminated. The photoresist can be removed at the exposed areas with a developer, thus exposing the underlying conductive polymer layer. This can then be removed by placing it in a suitable solvent. The desired conductive polymer structures are exposed by solubilizing the overlying insoluble photoresist by large-area UV irradiation, the so-called flood exposure, and then removing it by rinsing with the developer. This method has the following disadvantages: The conductive polymer layer comes in direct contact with the photoresist, ie. the photoresist may contaminate the conductive polymer layer and thus alter its electronic properties, eg, the work function. Another disadvantage is that the corridor exposure can damage the conductive polymer by Fotooxi- dation sustainable and thereby the conductivity is lowered.

Another way of structuring conductive polymers is described by Hohnholz, Okuzaki and MacDi-aπnid ("Plastic Electronic Devices Through Line Patterning of Conducting Polymers", Advanced Materials, 2005, 15, 51-56), in which polyethylenedioxythiophene / polystyrenesulfonic acid (PEDOT / PSS), in which this conductive polymer is coated on foil previously provided with a burned-in toner pattern by means of a laser printer, and the toner is removed in toluene or acetone to remove the overlying PEDOT / PSS layer but the conductive polymer remains on the areas of the film that do not contain any toner.This method is simple, but has the disadvantage that, due to the graininess of the toner particles, only coarse structures with a step width b of> 50 μm are realized to let.

Dong. Zhong, Chi and Fuchs describe a different approach to conductive polymers in Patterning of Conducting Polymers Based on a Random Copolymer Strategy: Toward the Facilc Fabrication of Nanosensors Exclusively Based on Polymers (Advanced Materials, 2005, 17, 2736-2741) The method used here is the lift-off processing known from photolithography (compare "Lithography Processes", brochure of the company MicroChemicals GmbH from 2005, see Fig. 1). In this process, a photo positive resist is first applied to the substrate and exposed at the sites with an electron beam, at which later no conductive polymer is to cover the surface. The unexposed photoresist is then removed with solvent. Then, the exposed photoresist is thermally cured to form a negative of the later desired structure. Now, pyrroles or anilines in the presence of the oxidant FeCl _{3 are} spun from solution as a thin film and polymerize on the substrate. This film then lies both on the cured photoresist as well as on the areas of the substrate freed from the photoresist. By rinsing in toluene or acetone, the cured photoresist can now be removed again so that the overlying layer of conductive polymer is also removed. The toluene or acetone-insoluble conductive polymer adheres to the photoresist exposed sites on the substrate. Structures can be created with the lift-off process conductive polymers are realized with a step width of <1 micron. A disadvantage of the method described, however, is that the conductive polymers must be polymerized in situ on the substrate, ie a chemical reaction takes place on the substrate, which can be realized industrially only with great effort. In addition, in-situ polymerized layers have the disadvantage that they form only moderately smooth surfaces and tend to flake off due to their tension.

There was therefore still a need for a method for the production of conductive structured polymer layers, in which the conductive polymer can be deposited from solution or dispersion on a substrate, in which the structures of the conductive polymer layer give a high lateral lateral resolution and in which the surfaces of the conductive Polymer layer are smooth. In addition, there has been a need for a process for structuring highly conductive polymers, i. Polymers having a conductivity of σ> 100 S / cm, e.g. for the production of field effect transistors or sensors. Here the distance between adjacent electrodes d must be as small as possible, preferably d <500 μm.

The object was therefore to provide a process for the production of conductive structured polymer layers, in which the conductive polymer can be deposited from solution or dispersion on a substrate, in which the structures of the conductive polymer layer yield a high lateral spatial resolution and in which the surfaces conductive polymer layer are smooth. Another object was to provide a method for patterning highly conductive polymers, i. Polymers with a conductivity of σ>] 00 S / cm.

Surprisingly, it has now been found that conductive structured polymer layers which fulfill the abovementioned conditions can be produced using the lift-off process and applying at least one conductive polymer as polycarbonate and at least one polyanion to the substrate.

The present invention therefore provides a process for the preparation of conductive structured polymer layers using the lift-off process, characterized in that at least one conductive polymer as polycation and at least one polyanion having an average molecular weight M _w in a range of 1000 to 100 000 g / mol, is applied to the substrate.

Here, the lift-off process comprises the steps shown in Fig. 1. With this process, structures with a step width b <5μm can be generated. In the context of the invention, conductive polymers as polycation may represent an optionally substituted polythiophene, polyaniline or polypyrrole. It may also be that mixtures of two or more of these conductive polymers are used as a polycation.

In a preferred embodiment, the polycation represents an optionally substituted polythiophene containing repeating units of the general formula (I)

(I)

where

A represents an optionally substituted C ₁ -C 8 -alkylene radical, preferably an optionally substituted C ₂ -C ₃ -alkylene radical,

Y stands for O or S,

R is a linear or branched, optionally substituted. C 1 -C 6 -alkyl radical, preferably linear or branched, optionally substituted C ₁ -C ₆ -alkyl radical, an optionally substituted C 1 -C 12 -cycloalkyl radical, an optionally substituted C ₆ -C ₄ -aryl radical, an optionally substituted C ₇ -C ₈ -aralkyl radical, is an optionally substituted Ci-Gj-hydroxyalkyl radical or a hydroxyl radical,

x is an integer from 0 to 8, preferably 0, 3 or 2, more preferably 0 or 1, and

in the event that several radicals R are attached to A, they may be the same or different.

The general formula (I) is to be understood such that the substituent R can be bonded to the alkylene radical A x times. In further preferred embodiments, the polycation may contain a polythiophene containing recurring units of the general formula (I) those containing recurring units of the general formula (Ia) and / or the general formula (Ib)

be in which

R and x have the abovementioned meaning.

In still further preferred embodiments, the polycation represents a polythiophene containing repeating units of the general formula (I) those containing polythiophenes of the general formula (I-aa) and / or the general formula (I-ba)

For the purposes of the invention, the prefix Poϊy- means that more than one identical or different repeating unit is contained in the polythiophene. The polythiophenes contain a total of n repeating units of the general formula (I), where n can be an integer from 2 to 2000, preferably 2 to 100. The repeating units of general formula (I) may be the same or different within each polythiophene. Preference is given to polythiophenes containing in each case identical recurring units of the general formula (I).

At the endgrappen, the polythiophenes preferably carry H.

In particularly preferred embodiments, the polycation is a polythiophene having repeating units of the general formula (I) poly (3,4-ethylenedioxythiophene) or poly (3 ₅ 4- ethyleneoxythiathiophene), ie a horaopoiethiophene from recurring units of the formula (I-aa) or (I-ba).

In further particularly preferred embodiments, the polycation represents a polythiophene having repeating units of the general formula (I) a copolymer of recurring units of the formula (I-aa) and (I-ba).

C _r C ₃ -Aykyϊenreste A are in the context of the invention methylene, ethylene, n-propylene, n-butylene or n-pentylene, C _r Cis-alkyl in the context of the invention for linear or branched Ci-Cjg- alkyl radicals such as methyl , Ethyl, n- or iso-propyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1 , 2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl _; n- Undecy !, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl, _{_C5-1r} cycloalkyl of _{_C5-Ci2} cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, Ce-C 1-4 -aryl radicals, for example phenyl or naphthyl, and C ₇ -C ₈ -aralkyl, for Cy-C 18 -aralkyl radicals, for example benzyl, o-, m-, p-tolyl, 2,3-, 2, 4, 2.5, 2.6 ™, 3,4-, 3,5-xylyl or mesityl. C ₁ -C ₄ hydroxyalkyl group in the context of the invention the above-mentioned Ci-C ₄ alkyl radicals having a hydroxy group. The preceding list serves to exemplify the invention and is not to be considered as exhaustive.

Possible further substituents of the preceding radicals are numerous organic groups, for example alkyl, cycloalkyl, aryl, halogen, ether, thioether, disulfide, sulfoxide, sulfone, sulfonate, amino, Aldehyde, keto, carboxylic acid ester, carboxylic acid, carbonate, carboxylate, cyano, alkylsilane and alkoxysilane groups and Carboxylamidgrup- pen.

The polycations, especially the polythiophenes, are cationic, with "cationic" referring only to the charges located on the polythiophene backbone Depending on the substituent on the R radicals, the polythiophenes may carry positive and negative charges in the structural unit, with the positive ones Charges on the Polythiophenhauptkette and the negative charges may be located on the substituted by sulfonate or carboxylate groups R. In this case, the positive charges of the polythiophene main chain can be partially or completely saturated by the optionally present anionic groups on the radicals R. Overall, the polythiophenes however, they are all considered cationic polythiophenes in the context of the invention, since the positive charges on the polythiophene backbone are critical. because their exact number and position can not be determined correctly. However, the number of positive charges is at least 1 and at most n, where n is the total number of all repeating units (equal or different) within the polythiophene. To compensate for the positive charge, as far as this is not already done by the sulfonate or carboxylate-subsaturated and thus negatively charged radicals R, the polycations or cationic polythiophenes require anions as counter ions.

As counterions are preferably polymeric anions, hereinafter also referred to as polyanions, in question.

Examples of suitable polyanions are anions of polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acid or polymaleic acids, or anions of polymeric sulfonic acids, such as polystyrenesulfonic acids and polyvinylsulfonic acids. These polycarboxylic and -sulfonic acids can also be copolymers of vinylcarboxylic and vinylsulfonic acids with other polymerizable monomers, such as acrylic acid esters and styrene. These may, for example, also be partially fluorinated or perfluorinated polymers containing SCVM ⁺ or COO ^" M ⁺ groups, where M ^{+ is} , for example, Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ or NH4 ^4" , preferably H ⁺ , Na ⁺ or K ⁺ stands.

Particularly preferred as the polymeric anion is the anion of polystyrene sulfonic acid (PSS). Cationic polythiophenes which contain anions as counterions for charge compensation are also often referred to in the art as polythiophene / (poly) anion complexes.

In particularly preferred embodiments of the invention, the polycation is 3,4 ^" (ethylenedioxythiophene) and the polyanion is polystyrenesulfonate.

The average molecular weight M _w (weight average) of the polyanionic polyacids, preferably of polystyrenesulfonic acid, is preferably in a range of from 20,000 to 70,000 g / mol, more preferably in a range of from 30,000 to 60,000 g / mol. The polyacids or their alkali salts are commercially available which can be prepared (for example polystyrene sulfonic acids and polyacrylic acids, or by known processes see eg Houben _Weyl? Methods of Organic Chemistry, Vol. E 20 Macromolecular Materials, Part 2 (1987), p 1141 uf ).

The average molecular weight M _w is determined by aqueous gel permeation chromatography (GPC) using a phosphate buffer as eluent and a column combination MCX. The detection takes place here by means of an RI detector. The signals are evaluated by means of a polystyrene sulfonic acid calibration at 25 ° C.

In yet another preferred embodiment, the conductive polymer layers containing at least one polycation and at least one polyanion can be applied to the substrate in the form of a dispersion or solution. For example, processes such as spin coating, knife coating, immersion and spray coating are suitable for applying the conductive polymer layers or printing processes, such as ink-jet, offset, gravure and flexo printing, preference is given to spin-coating,

Suitable substrates are glass, silicon wafers, paper and plastic films such as polyester, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyacrylate, polsulfone or polyimide films.

The deposited conductive polymer layers form homogeneous layers with average surface roughness typically <5nm Ra. This value can be determined by means of a scanning force microscope (Digital Instruments) on an area of] μm ² . The electrical conductivity of the layers is preferably σ = 500 S / cm. This value can be calculated from the measured surface resistance R _sq and the layer thickness d corresponding to U R ^ -d) ^"1. For this purpose, two parallel Ag electrodes are evaporated onto the layer and the electrical resistance R between them is measured R _sq = R-W / L, where L is the electrode spacing and W is the electrode length The layer thickness d is determined using a stylus profuometer (Tencor 500) at the level of a scratch in the polymer layer.

In the context of the invention, the dispersion or solution may be aqueous or alcoholic. By alcohol it is meant that a mixture containing water and alcohol (s) is used. As alcohols, for example, aliphatic alcohols such as methanol, ethanol, i-propanol and butanol are suitable.

These dispersions or solutions may additionally contain at least one polymeric binder. Suitable binders are polymeric, organic binders, for example polyvinyl alcohols, polyvinylpyrolidones, polyvinyl chlorides, polyvinyl acetates, polyvinyl butyrates, polyacrylic acid esters, polyacrylic acid amides, polymethacrylic acid esters, polymethacrylic acid amides, polyacrylonitriles, styrene / acrylic acid ester, vinyl acetate / acrylic acid ester and ethylene / vinyl acetate copolyyrinates, poly butadienes, polyisoprenes, polystyrenes, polyethers, polyesters, polycarbonates, polyurethanes, polyamides, polyimides, polysulfones, melamine-formaldehyde resins, epoxy resins, silycon resins or celluloses. The solids content of polymeric binder is between 0 and 3 percent by weight (wt.%), Preferably between 0 and 1 wt.%.

The dispersions or solutions may additionally comprise adhesion promoters such as, for example, organofunctional silanes or their hydrolyzates, for example 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-metacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane. In order to increase the conductivity of the abovementioned dispersions or solutions, conductivity-increasing agents, such as dimethyl sulfoxide, can be added in the context of the invention. However, other conductivity enhancing agents, such as disclosed in EP 0686662 or Oυyang et al., Polymer, 45 (2004), pp. 8443-8450, can be used within the scope of the invention as conductivity-increasing agents. Suitable conductivity-increasing agents are especially compounds containing ether groups, for example tetrahydrofuran, compounds containing lactone groups, such as γ-butyrolactone, γ-valerolactone, compounds containing amide or lactam groups, such as caprolactam, N-methylcaprolactam, N, N-dimethylacetamide, N-methylacetamide, N ₅ ND imethylformamide (DMF), N-methylformamide, N-methylformanea, N-methylpyrrolidone (NMP), N-octylpyrrolidone, pyrrolidone, sulfones and sulfoxides such as sulfolane (tetramethylene sulfone), dimethylsulfoxide (DMSO), sugars or sugar derivatives such as For example, sucrose, glucose, fructose, lactose, sugar alcohols such as sorbitol, mannitol, furan derivatives such as 2-furancarboxylic acid, 3-furancarboxylic acid, and / or di- or polyalcohols such as ethylene glycol, glycerol, di- or triethylene glycol. Particular preference is given to using tetrahydrofuran, N-methylformamide, N-methylpyrrolidone, dimethyl sulfoxide or sorbitol as additives capable of increasing the yield strength.

In the context of the invention, the polycarbonate and polyanion (s) can be used in a weight ratio (weight ratio) of from 1: 2 to 1: 7, preferably from 1: 2.5 to 1: 6.5, and more preferably from 1: 3 to 1: 6. The weight of the polycation corresponds to the initial weight of the monomers used, assuming that complete conversion of the monomer takes place during the polymerization.

A further subject of the present invention are the conductive structured polymer layers produced by the process according to the invention.

The step width b of the conductive polymer layer produced by the method according to the invention is preferably less than 5 μm, more preferably less than 1 μm. The achieved step widths can be determined with a stylus profilometer (Tencor 500). The steps of the structured, conductive polymer layers produced according to the method according to the invention had a width b <5 μm. Since this width corresponds to the lateral resolution of the stylus filoiϊteter, it can be assumed that the true step width is actually still less than 5.

The following examples are merely illustrative of the invention and are not to be construed as limiting in any way. Examples:

Example 1:

A 50mm x 50mm glass substrate was first cleaned with acetone, then with muconic solution in an ultrasonic bath and finally in a UV / ozone reactor (UPV, Inc, PR-100). The photoresist AZ 1512 HS (Micro Chemicals GmbH) was then treated with a spin coater (Carl Süss, RC8) at 1000 U / min for 30 seconds (sec.) At an acceleration of 200U / sec ² and the lid open spun down on the glass substrate. The forming film was first dried on a hot plate 3 minutes (min.) At 100 ⁰ C and at 115 ° C for 30 minutes in a drying cabinet. After drying, the layer thickness d = 2.8 μm (see Fig. 1-1).

The substrate coated with photoresist was covered with a shadow mask consisting of a thick aluminum foil with milling cutouts of 100-400 μm width and held in a photoresist (Walter Lemmen, Kreuzwertheim, Aktina E) for 80 seconds (sec.) UV light applied. The substrate was then placed for 120 seconds with stirring in a developer solution consisting of 1 part of AZ 35 IB (MicroChemicals GmbH) and 3 parts of water (see Fig. 1-2 and Fig. 1-3).

The glass substrates were then covered with patterned photoresist, exposing areas previously exposed by the shutter mask to photoresist and covering the shaded areas with photoresist. The height profile of the photoresist structures is shown schematically in Fig. 2-1.

Example 2:

The preparation of the PEDOT / PSS dispersion was carried out in aqueous solution by a known method (L. Groenendaal, F. Jonas, D, Freitag, H. Pielartzik & J.R. Reynolds, Adv. Mater. 12 (2000) 481-494):

895.2 g of deionized water and 323 g of an aqueous polystyrenesulfonic acid solution having a weight average M _w of 490000 g / mol and a solids content of 5.52% by weight were initially introduced into a 2 l three-necked flask with stirrer and internal thermometer. The determination of the molecular weight was carried out by means of aqueous gel permeation chromatography (GPC). The solution was treated with 0.075 g of iron (OΙ) sulfate. The reaction temperature was maintained between 20 and 25 ° C. While stirring, 2.97 g of 3,4-ethylenedioxythiophene (EDT, Baytron® M, HC Starck GmbH) were added. The solution was stirred for 30 minutes. Subsequently, 6.9 g of sodium persulfate were added and the solution was stirred for a further 24 hours. After completion of the reaction, 60 g of a cation exchanger (Lewatit SlOO H, Lanxess AG) and 80 g of an anion exchanger (Lewatit MP 62, Lanxess AG) were added to remove inorganic salts and the solution was stirred for a further 2 hours. Subsequently, the ion exchanger was filtered off. The weight ratio of PEDOT to PSS in the solution was 1: 6. In order to obtain a better wetting of the photoresist surface, 3 drops of a fluoride surfactant solution (F09108 Zonyl FSN, Fluorinated Surfactant 10% in water, ABCR GmbH) were added to 1 μl of the PEDOT / PSS solution. The solution was spin-coated onto the photoresist-structured substrate from Example 1 at 850 rpm for 30 seconds with an acceleration of 200 U / sec ² and an open lid, and then dried for 15 minutes at 130 ^° C. on a hotplate. The layer thus produced homogeneously covered both the photoresist coated and uncoated areas of the glass surface. The layer thickness was d = 100 nm and the conductivity σ = 2.2 mS / cm. By rinsing the layer in acetone, the crosslinked photoresist was completely dissolved. This dissolution process could be followed visually, since the photoresist had a yellow-brownish intrinsic color. However, the PEDOT / PSS layer lying on the photoresist was not lifted off, but remained as a coherent loose skin on the substrate. This manifested itself in a diffuse elevation profile with no clear boundaries between detached and remaining areas, as shown in Fig. 2-3.

The desired lift-off of the conductive polymer layer, as shown in Fig. 1-5, thus did not take place.

Example 3 according to the invention) The procedure was analogous to that in Example 2 with the difference that this time in the polymerization of EDT the PSS with a weight average M _w of 47 000 g / mol was used. As in Example 2, the weight ratio of PEDOT to PSS in the solution was also 1: 6. The solution was spin-coated at 500 rpm for 30 seconds and an acceleration of 200U / sec ² with the lid open. The layer thickness was d - 100 nm and the conductivity σ = 17 mS / cm.

In contrast to example 2, the polymer layer on the crosslinked photoresist was rinsed off in acetone together with the crosslinked photoresist. On the other hand, the PEDOT / PSS layer sticks to the substrate. The transitions between remaining and detached areas were sharp, as the step formed here shows a narrow step width of b <5μm in the height profile (see Fig. 2-2).

The lift-off process of the conductive polymer layer could thus be successfully carried out.

As the comparison of Examples 2 and 3 shows, the average molecular weight Mw of the PSS has a considerable influence on whether the structuring of the conductive polymer layer by means of the lift-off process succeeds successfully. This structuring is successful if the PEDOT / PSS dispersion used has a PSS with a mean molecular weight M _w of <100 000 g / mol, referred to as short-chain PSS. Reason for this may be that by using this short-chain PSS, the tensile strength of the conductive polymer layer is sufficiently lowered, so that a detachment of the conductive polymer layer can take place.

EXAMPLE 4 A 2 l three-necked flask with stirrer and internal thermometer was charged with 868 g of deionized water and 330 g of an aqueous polystyrenesulfonic acid solution having a weight-average M _w of 450000 g / mol and a solids content of 3.8% by weight. The determination of the molecular weight was carried out by means of aqueous gel permeation chromatography (GPC). The solution was treated with 0.075 g of ferrous sulfate. The reaction temperature was maintained between 20 and 25 ° C. With stirring, 5.1 g of 3,4-ethylenedioxythiophene was added. The solution was stirred for 30 minutes. Subsequently, 9.5 g of sodium persulfate were added and the solution was stirred for a further 24 hours. After completion of the reaction, 120 g of a cation exchanger (Lewatit SlOO H, Lanxess AG) and 80 ml of an anion exchanger (Leptit MP 62, Lanxess AG) were added to remove inorganic salts and the solution was stirred for a further 2 hours. The ion exchanger was filtered off. The weight ratio of PEDOT to PSS in the solution was 1: 2.5.

The obtained PEDOT / PSS dispersion was homogenized five times at a pressure of 900 bar with a high-pressure homogenizer; Subsequently, 95 g of this solution were mixed with 5 g of dimethyl sulfoxide.

On the photoresist-structured substrate of Example 1, this mixture was distributed. The supernatant solution was run at 1200 rpm for 30 seconds at an acceleration of

200U / sec ² and opened lid hurled. The resulting layer was at 130 ⁰ C for 10

Dried for minutes on a hot plate. The layer thickness was d = 80 nm and the conductivity σ = 350 S / cm.

By rinsing the layer in acetone, the crosslinked photoresist was completely dissolved. This dissolution process could be visually tracked due to the yellow-brownish inherent color of the crosslinked photoresist. However, the PEDOT / PSS target lying on the photoresist was not lifted off, but remains as coherently loose skin on the substrate. The desired lift-off, as shown in Fig. 1-5, thus did not take place.

Example 5 (according to the invention)

The procedure was analogous to Example 4 with the difference that in the polymerization, a polystyrene sulfonic acid having a weight average M _w of 49 000 g / mol was used. The weight ratio of PEDOT to the polymer PSS was 3: 2.5, as in Example 4. The PEDOT / PSS dispersion was homogenized five times at a pressure of 900 bar with a high-pressure homogenizer; Subsequently, 95 g of this solution were mixed with 5 g of dimethyl sulfoxide.

On the photoresist-structured substrate of Example 1, this mixture was distributed. The supernatant solution was spun at 1500 rpm for 30 seconds at 200U / sec ³ acceleration with the lid open. The resulting layer was dried at 130 ^° C. for 10 minutes on a hot plate. The layer thickness was d = 760 nra and the conductivity σ = 390 S / cm.

By rinsing the layer in acetone, the crosslinked photoresist was completely dissolved. This dissolution process could be visually tracked due to the yellow-brownish inherent color of the crosslinked photoresist. The PEDOT / PSS layer lying on the photoresist was lifted off in some places. The desired lift-off, as shown in Fig. 1-5, thus partially took place.

Example 6 (according to the invention):

The dispersion prepared according to Example 5 was diluted with additional polystyrene sulfonic acid. The PSS used had a weight average M _w of 49,000 g / mol. The mixture was set so that the ratio of PEDOT to PSS in the dispersion was 1: 3; Subsequently, 95 g of this solution were mixed with 5 g of dimethyl sulfoxide.

The solution was spun at 1500 rpm for 30 sec at an acceleration of 200U / sec ^{2 with the} lid open. Subsequently, the layer was dried at 130 ⁰ C for 15 min on a hotplate. The layer thickness was d = 76 nm ^' and the conductivity σ = 360 S / cm.

In contrast to Example 5, this mixture was completely detached by means of lift-off.

Example 7 (according to the invention):

The dispersion prepared according to Example 5 was diluted with additional polystyrenesulfonic acid. The PSS used for this purpose had weight average _Mw of 49,000 g / mol. The mixture was prepared so that the ratio of PEDOT to PSS in the dispersion was 1: 3.5. Subsequently, 95 g of this solution were mixed with 5 g Dimethylsuifoxid.

The solution was spun off at 1100 rpm for 30 sec at an acceleration of 200 U / sec ² and open lid. Subsequently, the layer was dried at 130 ⁰ C for 15 min on a hotplate. The layer thickness was ά ^~ 11 nm and the conductivity σ = 310 S / cm.

In contrast to example 5, this mixture can be completely removed by means of lift-off. Example 8 (according to the invention):

The dispersion prepared according to Example 5 was diluted with additional polystyrene sulfonic acid. The PSS used had a weight average M _w of 49,000 g / mol. The mixture was adjusted so that the ratio of PEDOT to PSS in the dispersion was 1: 4. Subsequently, 95 g of this solution were mixed with 5 g of dimethyl sulfoxide.

The solution was spun at 1100 rpm for 30 sec at an acceleration of 200U / sec ^{2 with the} lid open. Subsequently, the layer at 130 ⁰ C for 15 min on a heating plate was dried. The layer thickness was d = 77 nm and the conductivity σ = 290 S / cm.

In contrast to Example 5 Hess this mixture completely dissolve by means of lift-off.

Example 9 (according to the invention):

The dispersion prepared according to Example 5 was diluted with additional polystyrene sulfonic acid. The PSS used had a weight average M _w of 49,000 g / mol. The mixture was set so that the ratio of PEDOT to PSS in the dispersion was 1: 4.5. Subsequently, 95 g of this solution were mixed with 5 g of dimethyl sulfoxide. The solution was spun at 1000 rpm for 30 sec at an acceleration of 200U / sec ^{2 with the} lid open. Subsequently, the layer was dried at 130 ° C for 15 min on a hot plate. The layer thickness was d = 77 nm and the conductivity σ = 260 S / cm.

Table 1: Summary of Results from Examples 2-9:

^: Examples according to the invention

Claims

claims

1) A process for the preparation of conductive structured polymer layers using the lift-off process, characterized in that at least one conductive polymer as a cation and at least one polyanion having an average molecular weight M _w in a range from 1000 to 100 000 g / mol, is applied to the substrate.

2) Method according to claim 1, characterized in that the polycation may be an optionally substituted polythiophene, polyaniline or polypyrrole.

3) Method according to one of claims 1 or 2, characterized in that the polycation is an optionally substituted polythiophene containing repeating units of the general formula (I),

wherein

A represents an optionally substituted C 1 -C 8 -alkylene radical,

R is a linear or branched, optionally substituted Cj-Cis ~ alkyl radical, an optionally substituted C ₅ ~ C _i2 cycloalkyl, an optionally substituted Ce-C ^ aryl, an optionally substituted C ₇ -CJ _S - aralkyl, optionally substituted Ci ~ C ₄ -Hydroxyalkylrest or a hydroxyl radical,

x stands for an integer from 0 to 8 and

4) Method according to at least one of claims 1 to 3, characterized in that the polyanion represents an anion of a polymeric carboxylic acid or sulfonic acid. 5) Method according to at least one of claims 1 to 4, characterized in that the polycation is a polythiophene containing repeating units of the general formula (Iaa)

and the polyanion is polystyrene sulfonate.

6) Method according to at least one of claims 1 to 5, characterized in that the average molecular weight M _{w of} the polyanion in a range of 20 000 - 70 000 g / mol.

7) Method according to at least one of claims 1 to 6, characterized in that the weight ratio of the polycation to the polyanion of 1: 2 to 1: 7.

8) Method according to at least one of claims 1 to 7, characterized in that the conductive polymer layer is applied from solution or from dispersion.

9) Method according to at least one of claims 1 to 8, characterized in that Leitlahigkeitssteigernde means are added thereto.

10) A conductive structured polymer layer prepared according to at least one of claims 1 ~ 9.