Patent Application
20100297337
The present invention relates to a process for the preparation of coatings exhibiting increased conductivity which contain polythiophene and its optionally substituted derivatives, optionally together with further conductive polymers.
It is known to increase the conductivity of polythiophenes by adding polar solvents. Thus e.g. B. F. Louwet et al. describe in Synth. Met. 2003 135-136, 115 increasing the conductivity of PEDT/PSSH (PEDT=polyethylene dioxythiophene; PSSH=polystyrene sulphonic acid or its anion, also called “PSS” in abbreviated form) by adding NMP. In the literature, the addition of NMP (=N-methylpyrrolidone), DMSO (=dimethyl sulphoxide) or diethylene glycol is preferentially described, wherein the corresponding solvents of the aqueous dispersion or solution of the PEDT-PSSH are added, in most cases in the range up to 10%, before coatings are then formed from the dispersions/solutions which then contain corresponding quantities of the solvents.
J. Ouyang et al. describe in Polymer 2004, 45, 8443 the results of their investigations into the causes of the increase in conductivity. In the Journal of Polymer Science: Part B: Polymer Physics, Vol. 41, 2561-2583 (2003) X. Crispin et al. give in their review a comprehensive overview of properties of conductive polymers based on polythiophenes or thiophene derivatives, with the emphasis on PEDT-PSSH, and report in a corresponding section on the results of the investigations into the causes of the increase in conductivity when polar solvents are added. They ascribe the phenomenon to the phenomena described by MacDiamid and Epstein in Synth. Met. (Special Issue) Vol. 65, Nos. 2-3, August 1994, pp. 103-116 for polyaniline and called “secondary doping”. MacDiamid and Epstein are cited in this publication with the following disclosure: “In phenomenological terms a secondary doping agent is a seemingly “inert” substance which induces a further increase in the conductivity of a primarily doped conjugated polymer. It differs from a primary doping agent in that the improved properties remain even after the complete removal of the secondary doping agent.” J. Ouyang et al. further disclose:
“Chemically prepared PEDT/PSS displays a significant increase in conductivity from 0.8 to 80 S/cm when inert solvents are added. According to the definition given above this effect can be classified as secondary doping, although the mechanism seems to differ from that for polyaniline. The temperature dependence of the resistance shows that the PEDT/PSS system is close to the critical range (insulator-metal transition) if organic solvents (dimethyl sulphoxide (DMSO), N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) are used. On the basis of these new data we suggest an explanation for the secondary doping of PEDT/PSS with DEG. In the emulsion, the solvent DEG is present both in water and in the PEDT/PSS-particles. A weight ratio of 0.5 for DEG to PEDT/PSS represents a limit for the quantity of DEG needed in the PEDT/PSS particles to have a separation between the excess insulating PSS and the conductive PEDT/PSS. This phase separation is possible because DEG takes up PEDT/PSS after evaporation of water due to weakening of the electrostatic bonds.”
In all these cases the polar solvent such as e.g. DMSO and others is added to the aqueous dispersion (or often also called solution) before the layer is formed. The polar solvents thus seem to bring about a change in the morphology, which Crispin et al. also describe in Chem. Mater. 2006, 18, 4354-4360. They explain the increase in the conductivity of PEDT/PSSH dispersions by 3 orders of magnitude due to the addition of diethylene glycol by the formation of a 3-dimensional network which the PEDT/PSSH dispersion forms when diethylene glycol is added. In this connection it is interesting to note that aqueous polyaniline dispersions which contain PSSH as counterion do not react to the addition of the corresponding polar solvents with an increase in conductivity. Rather, this phenomenon is limited to polyaniline with the counterion camphorsulphonic acid and the addition of phenols.
There is also a corresponding procedure in the patent literature, and there is a series of patents in which special versions of the addition of different polar solvents to aqueous polythiophene dispersions are described, e.g. U.S. Pat. No. 6,692,662 B2 discloses according to claim 1 a composition comprising a combination of an aqueous dispersion of an optionally substituted poly-3,4-alkylenedioxythiophenate ion and an associated polyanion and 1% (weight/volume) to 100% (weight/volume) of at least one of dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), ethylene glycol or mixtures thereof, wherein at least 30% (weight/volume) of the water of the aqueous dispersion is removed from the combination.
WO-A-02/072660 discloses in particular in claim 1 a process for the preparation of dispersions or solutions which contain optionally substituted polythiophenes in organic solvents which is characterized in that
WO-A-2004/021366 discloses in claim 1 a mixture comprising:
The aqueous formulations, containing different polythiophene derivatives, described in the state of the art have achieved a certain limited importance in the market, but still suffer from various disadvantages, among which are the following:
The object forming the basis of the present invention was thus to overcome the above disadvantages and provide a generally applicable process for increasing the conductivity of layers (coatings) by means of polar solvents (“secondary doping”) which contain conductive polymers based on optionally substituted thiophenes (e.g. PEDT), wherein the layers should be able to be formed from dispersions that are aqueous or predominantly based on organic media (e.g. containing less than 1% water).
Surprisingly, the above object was solved by a process for the preparation of a coating displaying an increased conductivity wherein at least one polar solvent as defined herein is not added to the dispersion which contains the constituents of the coating to be produced. Instead, according to the invention, the at least one polar solvent is contacted with the coating after the actual coating step, i.e. after deposition of the coating, i.e. after or during drying of the coating formed.
According to another aspect, the present invention relates to a process for the preparation of a coating displaying an increased conductivity, wherein the coating contains a first conductive polymer and at least one further conductive polymer, wherein the first conductive polymer is derived from optionally substituted thiophene, in which process
The present invention also relates to a process for the preparation of an aqueous or organic dispersion or solution which contains a first conductive polymer and at least one further conductive polymer, wherein the first conductive polymer is derived from optionally substituted thiophene, in which process
Finally the present invention relates to a process for the preparation of an article selected from the group consisting of transparent substrates, flexible or rigid conductive sub-strates such as films (based on e.g. polymethylmethacrylate, polycarbonate, polyethyleneterephtalate etc.), in particular films for touch panels, digital paper, organic LEDs (OLEDs), electroluminescence displays, rechargeable batteries, capacitors, supercapacitors, light-emitting diodes, sensors, electrochrome disks, copier drums, cathode ray tubes, antistatic or electromagnetically screening plastic films and moulded parts and photographic materials, in which a coating prepared according to the invention is used, i.e. in which one or more areas or parts of the article is or are provided with a coating according to the invention.
Further preferred versions of the present invention are disclosed in the appended dependent claims.
The terms “layer” and “coating” are used synonymously herein.
The invention can be carried out in different ways, the decisive factor being that the at least one polar solvent is not added to the (aqueous or organic) dispersion which contains the constituents of the layer to be produced. Instead, according to the invention the at least one polar solvent can be brought into contact with the further forming layer, i.e. the as a rule still drying layer, or with the already fully-formed layer, i.e. the as a rule completely dried layer, separately after the actual coating, i.e. after the substrate to be coated is no longer in direct contact with the reservoir of the dispersion/solution. The dispersion/solution is further prepared as described herein.
The bringing into contact with the at least one polar solvent can in particular take place by the polar solvent(s) of the coating being supplied either from the vapour phase, as a spray mist or as an additional thin coating (for example by spin coating).
Surprisingly, the conductivity values achieved using comparatively smaller quantities of polar solvent (relative to the quantity of same incorporated into the layer) are at least comparable with those which are achieved when the corresponding solvents are added in quantities of several percent to the starting dispersion before the layer forms.
In some cases, however, clearly better values can be achieved:
In the case of the optionally substituted thiophene polymers according to the invention, one is preferably used which has repeat units of the following formula
in which Y represents —(CH2)n—CR1R2(CH2)n— or an optionally substituted 1,2-C3 to C8 cycloalkylene residue and
R1 and R2 independently of each other represent hydrogen, hydroxymethyl, an optionally substituted C1 to C20 alkyl residue or an optionally substituted C6 to C14 aryl residue,
and
m, n are the same or different and are an integer from 0 to 3.
The layer according to the invention preferably contains polythiophene (PTh), poly(3,4-ethylene dioxythiophene) (PEDT) and/or polythienothiophene (PTT), in particular PEDT.
The dispersion/solution from which the layers according to the invention is deposited thus contains a conductive polymer based on optionally substituted thiophene, as defined above, alone or, preferably, together with at least one other conductive polymer, as explained in more detail below. This can take place in the form of chemical compounds, such as e.g. copolymers or graft copolymers, or physical mixtures. Mixtures of two or more different polymers derived from optionally substituted thiophene can also be used.
With regard to the thiophene-based polymer according to the invention or the further conductive polymers which can be incorporated into the layer according to the invention, the following applies: described as conductive polymers, which are also called “intrinsically conductive polymers” or “organic metals”, are substances which are derived from low-molecular compounds (monomers), are at least oligomeric through polymerisation, i.e. contain at least 3 monomer units which are linked by chemical bonding, display a conjugated n-electrons system in the neutral (non-conductive) state and can be converted by oxidation, reduction or protonation (often called “doping”) into an ionic form which is conductive. The conductivity is at least 10−7 S/cm.
Most conductive polymers display a more or less marked increase in conductivity as the temperature rises, which shows them to be non-metallic conductors. A few representatives of this class of substances display a metallic behaviour, at least in a temperature range close to room temperature, inasmuch as conductivity falls as temperature rises. A further method of recognizing metallic behaviour is to plot the so-called “reduced activation energy” of the conductivity against the temperature at low temperatures (down to nearly 0 K). Conductors with a metallic contribution to conductivity display a positive slope of the curve at low temperature. Such substances are called “organic metals”.
The term “conductive polymer” as used in the present case covers both intrinsically conductive polymers and the so-called organic metals, as discussed above.
Examples of the intrinsically conductive polymers or organic metals according to the invention which, in addition to polythiophene or its derivatives, are constituents of the layers according to the invention are in particular polyaniline (PAni), polydiacetylene, polyacetylene (PAc), polypyrrole (PPy), polyisothianaphthene (PITN), polyheteroarylene vinylene (PArV), wherein the heteroarylene group can be e.g. thiophene, furan or pyrrole, poly-p-phenylene (PpP), polyphenylene sulphide (PPS), polyperinaphthalene (PPN), polyphthalocyanine (PPc) and others, and their derivatives (which are formed e.g. from monomers substituted with side chains or groups), their copolymers and their physical mixtures. Polyaniline (PAni) and its derivatives are particularly preferred. Polyaniline is most preferred.
Preferred binary mixtures are those comprised of PAni and PTh, PAni and PEDT, PEDT and PPy and also PEDT and PTh.
The layers can also contain further additives, wetting aids, antioxidants, lubricants and optionally non-conductive polymers. In particular a thermoplastic polymer can be used. For example polyethylene terephthalate copolymer, commercially available from Eastman Kodak, or a polymethyl methacrylate (PMMA) from Degussa can be used.
There are numerous ways for preparing the dispersions for forming the coatings which are to be contacted with the polar solvents of the present invention.
For example, commercially available PEDT dispersion such as Baytron P HCV4 or PH 500 may be used, or EDT or other optionally substituted thiophene monomers may be polymerized in accordance with methods known in the art and the resulting products be dispersed in water. Chemical or physical mixtures of the optionally substituted thiophene polymers with other conductive polymers such as optionally substituted polyaniline may also be used.
According to a preferred aspect of the invention, to prepare the dispersions/solutions from which the layers according to the invention can then be deposited, monomers are polymerized which lead to the conductive polymers described above. The polymerization procedure is e.g. as described above, i.e. according to alternatives (i) to (iii). Optionally polymerization takes place in the presence of suitable doping acids.
Dispersions which are prepared by polymerizing EDT (ethylene dioxythiophene) in an aqueous dispersion of polyaniline (e.g. ORMECON® D 1012 or D 1022 W from Ormecon GmbH) or by polymerizing aniline in an aqueous PEDT dispersion (e.g. in Baytron PH500) are preferred and particularly suitable for carrying out the invention. A simultaneous polymerization of EDT and aniline in the presence of the doping acid is also possible.
The ratio of the first conductive polymer, in particular PEDT (or optionally substituted thiophene polymer) to the at least one further conductive polymer, if present, in particular polyaniline, can be freely chosen and is determined according to transparency requirements, the ratio of the optionally substituted thiophene polymer to polyaniline lying preferably between 1:10 and 10:1, preferably 1:1 to 8:1, such as about 2:1, in each case relative to mols of monomer units.
It is known to a person skilled in the art that such dispersions of conductive polymers, depending on the degree of oxidation and protonation of the respective polymer, contain anions suitable for charge equalization of e.g. poly acids such as PSSH or other sulfonic acids such as methanesulfonic acid. The latter are not always expressly mentioned in the present description.
Copolymers or graft copolymers from the monomers which form the basis of the above-named polymers are also suitable.
An optionally desired conversion of the aqueous dispersions which in particular contain PEDT, optionally in combination with other conductive polymers, into organic solvent systems can take place by known methods, e.g. according to the process described by Nissan Chemicals Industries in EP 1 849 815 A1. The procedure according to the invention is that in step a) an aqueous dispersion is prepared which before step b) is first converted into a dispersion based on at least one organic dispersant with a water content of less than 1%, relative to the weight of the whole dispersion. Suitable organic solvents are for example primary or secondary monohydric or polyhydric alcohols, in particular those with 1 to 4 C atoms, such as methanol, ethanol, propanol, 2-propanol, propanediol etc.
It is essential that the layers according to the invention containing (optionally substituted) thiophene polymers which may contain further conductive polymers such as e.g. (optionally substituted) polyaniline are brought into contact during or after the drying of the layer with the polar solvents according to the invention.
Organic solvents with a dielectric constant (DE) of >25 are preferably considered as polar solvents which increase the conductivity of the layers. Solvents with a DE of 30 to 55 are preferred.
In particular the polar solvents according to the invention have a boiling point above 100° C. at normal pressure.
The solvents according to the invention are preferably selected from the group consisting of aliphatic, cycloaliphatic, aromatic, heterocyclic (saturated and unsaturated) and heteroaromatic solvents and also substituted derivatives thereof with a total of 1 to 10 C atoms, in particular 1 to 6 C atoms. For example the solvents according to the invention are selected from the group consisting of formic and acetic acid derivatives such as formamides and acetamides, in particular formamides and acetamides which display single or double methyl substitution at the nitrogen of the amide group and also sulphoxides. There may be further mentioned as preferred aromatic solvents nitrogen-substituted benzene derivatives, in particular benzene derivatives substituted with a nitro group such as nitrobenzene. According to the invention nitrogen-containing mononuclear heterocycles are also suitable, for example N-methylpyrrolidone. Halogen-substituted phenols such as chlorophenol can also be used and are preferred according to the invention. Furans, in particular tetrahydrofuran, are also suitable.
Solvents that are suitable according to the invention are preferably amidic solvents based on formic and acetic acid such as in particular formamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam and N-methylformamide.
Alcohols and ethers such as ethylene glycol, glycerol, ethylene glycol dimethylether, ethylene glycol monomethylether, ethylene glycol monobutylether or dioxan are also suitable according to the invention. Sulphur-containing organic solvents such as dimethyl sulphoxide are also suitable and preferred according to the invention.
In particular, DMSO, NMP, diethylene glycol, DMA (=dimethylacetamide), DMF and/or nitrobenzene are preferred. DMSO is particularly preferred.
Furthermore, organic acids may be used as the polar solvent of the present invention. For example, acids meeting the above criteria for the dielectric constant and boiling point may be used. In particular, sulfonic acid derivatives such as substituted or unsubstituted C1 to O3 methanesulfonic acid derivatives may be used, in particular halogen substituted, more preferably fluorine substituted acids. Particularly preferred is trifluoromethanesulfonic acid.
After the bringing into contact and drying of the coatings according to the invention the obtained layer thicknesses were about 50 to 80 nm. Compared with the layer thicknesses immediately after the preparation of the coatings, i.e. before bringing into contact with the solvent according to the invention, they had surprisingly reduced by roughly 25% to 70%.
The conductivity of the coatings prepared and treated in accordance with the present invention is preferably higher than 100 S/cm, in particular higher than 30.0 S/cm or higher than 350 S/cm, and can e.g. be in the range of from 100 or 300 or 350 to 3000 S/cm. The conductivity is measured in accordance with the four-point probe method of van der Pauw.
The coatings prepared according to the invention can be used in general for transparent substrates, inter alia for flexible or rigid conductive substrates such as films, e.g. for touch panels, for “digital paper”, organic LEDs (OLEDs), electroluminescence displays, or in the manufacture of rechargeable batteries, capacitors, supercapacitors, light-emitting diodes, sensors, electrochrome disks, as coatings on copier drums, cathode ray tubes, as antistatic or electromagnetic screening finishes for plastic films and moulded parts or on photographic materials.
The following examples are intended to explain the procedure according to the invention by way of example compared with the results which can be achieved according to the state of the art, and without limiting the scope of the invention. The conductivity was determined by means of four-point measurement, and the layer thicknesses determined using a Dektak Profilometer.
The dispersions ORMECON D 1031 W, D 1032 W and D 1033 W (which contain PEDT and polyaniline) commercially available from Ormecon GmbH were reacted with 5% DMSO in each case compared with the dispersions Baytron P HCV4 and Baytron P HS00 commercially available from H.C. Starck and processed into a thin layer by spin coating on glass and then dried (10 min at 120° C.). The layer thicknesses were between 50 and 100 nm.
In accordance with the instructions of EP 1 849 815 A1, D 1033 W was converted into methanol or ethanol, DMSO was added to the dispersion and the mixture likewise processed into a thin layer and dried. The layer thicknesses were between 50 and 100 nm.
The following results were obtained:
The addition of these or other polar solvents to dispersions which do not contain PEDT, but only polyaniline, e.g. to ORMECON D 1012 or D 1021 W (conductivity 0.1 S/cm), did not lead to an increase in conductivity.
Dispersion ET 574 is a dispersion which was prepared by polymerization of aniline in Baytron P HCV4 and has a PEDT-to-aniline ratio of 2:1 (relative to mols monomer units).
Firstly, dispersions were prepared as described in Example 1, but without the addition of DMSO to the respective dispersion. Proceeding in accordance with the invention, the dispersion was then applied to the substrate, and only then was DMSO or another suitable solvent with a dielectric constant >25 brought into contact with the forming layer, i.e. during the drying, or with the fully formed layer, i.e. after the substantially complete drying. This was carried out as follows:
a) During the drying:
The substrate was coated with the dispersion (for example by means of spin coating), and then placed, in a box which has an opening to an outlet, on a heating plate which was set at 50° C. There was an open vessel with DMSO on the same heating plate, with the result that the layer was exposed to a gas atmosphere which had a partial pressure of DMSO corresponding to this temperature. After 24 hours the sample was removed and the conductivity determined.
b) After the drying:
Firstly, the dispersion applied to the substrate was dried (e.g. 10 min at 120° C.). The coated substrate was then kept in a sealed vessel, e.g. a glass flask, for 1 hour in the gas space above the level of the liquid of the DMSO or other polar solvents, while the respective solvent was heated e.g. to 100° C.
c) By means of spin coating:
The layer dried according to b) on the substrate was brought into contact with DMSO (or another solvent) in a spin coater, the excess DMSO/solvent was removed by spinning and then drying was carried out (10 min at 120° C.).
The layer thicknesses obtained were about 50 to 100 nm. Compared with the layer thicknesses immediately after the preparation of the coating, i.e. before the addition of the solvent according to the invention, they had reduced by about 25% to 70%. The layer thicknesses were measured with a Dektak profilometer.
The following conductivity values resulted:
The bringing into contact of layers that had been formed from dispersions that did not contain PEDT, but only polyaniline, e.g. from ORMECON D 1012 or D 1021 W (conductivity 0.1 S/cm), with DMSO or other polar solvents during or after the drying or by means of spin coating did not lead to an increase in conductivity.
Various polar solvents were used according to the procedure as described in Example 2, variant a), during the drying of layers that had been formed from the dispersions named below. The following results were obtained (the conductivity is given in S/cm in each case):
814 g PEDT-PSSH dispersion (Clevios PHCV4) and 370 μL aniline were placed in a 1 L reaction vessel equipped with a cooling jacket and a stirrer. The batch was stirred and cooled for 15 min at a temperature of the cooling liquid of 0° C. A solution of 925 mg ammonium peroxodisulphate in 89.5 mL water was added to the batch in four portions, each separated by a time interval of 15 min, wherein each of the first three portions had a volume of 15 mL and the final portion was comprised of the balance of the solution. After completion of the addition, the batch was stirred at a cooling temperature of 0° C. Subsequently, the batch was stirred for 16 h at 20° C.
The greenish-blue dispersion was cooled to 6° C. using stirring in a vessel equipped with a cooling jacket, and treated for 30 min with a 1000 W sonotrode while stirring.
Subsequently, the dispersion was passed though a column filled with beads of a cationic-exchange material (diameter of the column: 3 cm; filling height: 14 cm), and subsequently though a column filled with beads of an anion-exchange material (diameter of the column: 3 cm; filling height: 14 cm). Thereby, the ion conductivity was reduced from 350 μS/cm prior to ion exchange to 150 μS/cm after ion exchange. In order to measure the ion conductivity 1 g of dispersion was mixed with 24 g deionized water.
The resulting dispersion had a solid content of 1% (measured as non-volatile content at 120° C. using a residual moisture analyzer). A spin-coated layer of the dispersion on a glass substrate had a layer thickness of 85 nm and a conductivity of 1 S/cm.
By using different post-treatment methods, inter alia subsequent spin coating of the layer with DMSO, a conductivity of more than 500 S/cm was obtained.
455 g PEDT-PSSH dispersion (Clevios PHCV4) and 104 μL aniline were placed in a 1 L reaction vessel equipped with a cooling jacket and a stirrer. The batch was stirred and cooled for 15 min at a temperature of the cooling liquid of 0° C. A solution of 266 mg ammonium peroxodisulphate in 50 mL water was added to the batch in four portions, each separated by a time interval of 15 min, wherein each of the first three portions had a volume of 10 mL and the final portion was comprised of the balance of the solution. After completion of the addition, the batch was stirred at a cooling temperature of 0° C. Subsequently, the batch was stirred for 16 h at 20° C.
The greenish-blue dispersion was cooled to 6° C. using stirring in a vessel equipped with a cooling jacket and treated for 30 min with a 1000 W sonotrode while stirring.
Subsequently, the dispersion was passed though a column filled with beads of a cationic-exchange material (diameter of the column: 3 cm; filling height: 14 cm), and subsequently though a column filled with beads of an anion-exchange material (diameter of the column: 3 cm; filling height: 14 cm). Thereby, the ion conductivity was reduced from 240 μS/cm prior to ion exchange to 150 μS/cm after ion exchange. In order to measure the ion conductivity 1 g of dispersion was mixed with 24 g deionized water.
The resulting dispersion had a solid content of 1% (measured as non-volatile content at 120° C. using a residual moisture analyzer). A spin-coated layer of the dispersion on a glass substrate had a layer thickness of 62 nm and a conductivity of 0.3 S/cm.
By using different post-treatment methods, inter alfa subsequent spin coating of the layer with DMSO, a conductivity of more than 500 S/cm was obtained.
455 g PEDT-PSSH dispersion (Clevios PHCV4) and 139 μL aniline were placed in a 1 L reaction vessel equipped with a cooling jacket and a stirrer. The batch was stirred and cooled for 15 min at a temperature of the cooling liquid of 0° C. A solution of 355 mg ammonium peroxodisulphate in 50 mL water was added to the batch in four portions, each separated by a time interval of 15 min, wherein each of the first three portions had a volume of 10 mL and the final portion was comprised of the balance of the solution. After completion of the addition, the batch was stirred at a cooling temperature of 0° C. Subsequently, the batch was stirred for 16 h at 20° C.
The greenish-blue dispersion was cooled to 6° C. using stirring in a vessel equipped with a cooling jacket, and treated for 30 min with a 1000 W sonotrode while stirring.
Subsequently, the dispersion was passed though a column filled with beads of a cationic-exchange material (diameter of the column: 3 cm; filling height: 14 cm), and subsequently though a column filled with beads of an anion-exchange material (diameter of the column: 3 cm; filling height: 14 cm). Thereby, the ion conductivity was reduced from 300 μS/cm prior to ion exchange to 150 μS/cm after ion exchange. In order to measure the ion conductivity 1 g of dispersion were mixed with 24 g deionized water.
The resulting dispersion had a solid content of 0.9% (measured as non-volatile content at 120° C. using a residual moisture analyzer). A spin-coated layer of the dispersion on a glass substrate had a layer thickness of 55 nm and a conductivity of 0.4 S/cm.
By using different post-treatment methods, inter alia subsequent spin coating of the layer with DMSO, a conductivity of more than 500 S/cm was obtained.
455 g PEDT-PSSH dispersion (Clevios PHCV4) and 52 μL aniline were placed in a 1 L reaction vessel equipped with a cooling jacket and a stirrer. The batch was stirred and cooled for 15 min at a temperature of the cooling liquid of 0° C. A solution of 133 mg ammonium peroxodisulphate in 50 mL water was added to the batch in four portions, each separated by a time interval of 15 min, wherein each of the first three portions had a volume of 10 mL and the final portion was comprised of the balance of the solution. After completion of the addition, the batch was stirred at a cooling temperature of 0° C. Subsequently, the batch was stirred for 16 h at 20° C.
The greenish-blue dispersion was cooled to 6° C. using stirring in a vessel equipped with a cooling jacket, and treated for 30 min with a 1000 W sonotrode while stirring.
Subsequently, the dispersion was passed though a column filled with beads of a cationic-exchange material (diameter of the column: 3 cm; filling height: 14 cm), and subsequently though a column filled with beads of an anion-exchange material (diameter of the column: 3 cm; filling height: 14 cm). Thereby, the ion conductivity was reduced from 210 μS/cm prior to ion exchange to 150 μS/cm after ion exchange. In order to measure the ion conductivity 1 g of dispersion were mixed with 24 g deionized water.
The resulting dispersion had a solid content of 0.9% (measured as non-volatile content at 120° C. using a residual moisture analyzer). A spin-coated layer of the dispersion on a glass substrate had a layer thickness of 55 nm and a conductivity of 0.2 S/cm.
By using different post-treatment methods, inter alia subsequent spin coating of the layer with DMSO, a conductivity of more than 500 S/cm was obtained.
500 μL of the ICP dispersion of Example 7 were applied on a freshly cleaned and flamed specimen slide (about 25×25 mm in size). Using a spin coater (Model P6700 of Specialty Coatings Systems Inc.; programme 3: 5 s at 500 rpm, followed by 30 s at 3000 rpm), a spin-coated layer was prepared.
The specimen slide was subsequently dried for 1 min at about 85° C.
Using a spray apparatus filled with solvent, this spin-coated layer was exposed twice to a spray mist. Then, the specimen slide was placed vertically on a paper tissue so that excess liquid was removed. Subsequently, the spin-coated layer was dried on a heater plate at about 85° C. The following solvent compositions and total spraying times were used: DMSO/MeOH (1:1): about 2 min; DMSO: about 4 min; ethylene glycol: about 6 min.
500 μL of the ICP dispersion of Example 7 were applied on a freshly cleaned and flamed specimen slide (about 25×25 mm in size). Using a spin coater ((Model P6700 of Specialty Coatings Systems Inc.; programme 3: 5 s AT 500 rpm, followed by 30 s at 3000 rpm), a spin-coated layer was prepared.
The specimen slide was subsequently dried for 1 min at about 85° C.
This spin-coated layer was dipped into the solvent (mixture) while being kept in a horizontal position, and subsequently the lower side of the specimen slide was cleaned with a paper tissue. The specimen slide was then placed for 10 s vertically on a paper tissue to remove excess liquid. Subsequently, the spin-coated layer was dried on a heater plate a about 85° C. The following solvent compositions and dipping times were used: DMSO/MeOH (1:1): about 2 min; DMSO: about 4 min; ethylene glycol: about 6 min.
500 μL of the ICP dispersion of Example 7 were applied on a freshly cleaned and flamed specimen slide (about 25×25 mm in size). Using a spin coater ((Model P6700 of Specialty Coatings Systems Inc.; programme 3: 5 s at 500 rpm, followed by 30 s at 3000 rpm), a spin-coated layer was prepared.
The specimen slide was subsequently dried for 1 min at about 85° C.
500 μL of the solvent mixture are applied on the spin-coated layer and subsequently programme 3 of the spin-coater was run (5 s at 500 rpm, then 30 s at 3000 rpm). The specimen slide was subsequently dried at about 85° C. for 1 min. The following solvent compositions were used: DMSO/MeOH (1:1); DMSO; ethylene glycol.
To a dispersion prepared as described in Example 5 were added solutions of methanesulfonic acid so that the weight ratio of the intrinsically conductive polymer (ICP) to acid was from 1:0.2 to 1:2. The weight ratio of the ICP dispersion to diluted methanesulfonic acid was about 1:0.25.
Samples of 0.5 mL of the ICP dispersion were placed on a specimen slide and uniformly dispersed by using a spin coater (5 s at 1500 rpm and 30 s at 3000 rpm). The samples were subsequently dried at about 85° C. for 1 min.
Subsequently, 0.5 mL of concentrated trifluoromethanesulfonic acid were added to the spin-coated layer and dispersed by using a spin coater (5 s at 1500 rpm and 30 s at 3000 rpm). The samples were subsequently dried at about 85° C. for 1 min.
The conductivity was measured using the 4-point probe method (electrode spacing: 2.5 cm). The thickness was determined by using a profilometer. The spin-coated layers had specific conductivities of 1200 to 1700 S/cm.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 003 251.4 | Jan 2008 | DE | national |
| 10 2008 059 389.3 | Nov 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP08/10934 | 12/12/2008 | WO | 00 | 7/2/2010 |
