FORMULATIONS AND ELECTRONIC DEVICES

Abstract

The present invention relates to a formulation comprising at least one organofunctional material which can be employed for the production of functional layers of electronic devices, and at least one aromatic compound. The present invention furthermore relates to electronic devices which are obtainable from these formulations.

Claims

1.-20. (canceled)

21. A formulation comprising at least one organofunctional material which can be employed for the production of functional layers of electronic devices, and at least one aromatic compound having a structure of the formula (1) or (2) ##STR00050## where the following applies to the symbols used: X is on each occurrence, identically or differently, CR or N, where in total at most 2 radicals X stand for N; R is on each occurrence, identically or differently, H, D, F, N(R.sup.1).sub.2, CN, NO.sub.2, C(═O)N(R.sup.1).sub.2, Si(R.sup.1).sub.3, C(═O)R.sup.1, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.1, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.1C═CR.sup.1, C≡C, Si(R.sup.1).sub.2, C═O, NR.sup.1, O, S or CONR.sup.1 and where one or more H atoms is optionally replaced by D, F, NO.sub.2 or CN, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.1, or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1; two adjacent radicals R here may also form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system with one another; R.sup.1 is on each occurrence, identically or differently, H, D, F, N(R.sup.2).sub.2, CN, NO.sub.2, Si(R.sup.2).sub.3, C(═O)R.sup.2, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.2, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.2C═CR.sup.2, C≡C, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2 and where one or more H atoms is optionally replaced by D, F, CN or NO.sub.2, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.2, or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; two or more adjacent radicals R.sup.1 with one another or R.sup.1 with R here may form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system; R.sup.2 is on each occurrence, identically or differently, H, D, F or an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, one or more H atoms is optionally replaced by F; two or more substituents R.sup.2 here may also form a mono- or polycyclic, aliphatic ring system with one another; Y is on each occurrence, identically or differently, a group CR, wherein the adjacent groups Y in the structure of the formula (1) or (2) together form a ring of one of the following formulae (3), (4), (5), (6), (7), (8) and (9): ##STR00051## where R.sup.1 has the meaning given above, the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2), and furthermore: A.sup.1, A.sup.3 are, identically or differently on each occurrence, C(R.sup.3).sub.2, O, S, NR.sup.3 or C(═O); A.sup.2 is C(R.sup.1).sub.2, O, S, NR.sup.3 or C(═O); G is an alkylene group having 1, 2 or 3 C atoms, which is optionally substituted by one or more radicals R.sup.2, or is —CR.sup.2═CR.sup.2— or an ortho-linked arylene or heteroarylene group having 5 to 14 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; R.sup.3 is, identically or differently on each occurrence, F, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms, a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, each of which is optionally substituted by one or more radicals R.sup.2, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.2C═CR.sup.2, C≡C, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2 and where one or more H atoms is optionally replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.2, or an aryloxy or heteroaryloxy group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or an aralkyl or heteroaralkyl group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; two radicals R.sup.3 which are bonded to the same carbon atom may form an aliphatic or aromatic ring system with one another here and thus form a spiro system; furthermore, R.sup.3 may form an aliphatic ring system with an adjacent radical R or R.sup.1; with the proviso that two identical heteroatoms in the above-mentioned groups are not bonded directly to one another and two groups C═O are not bonded directly to one another.

22. The formulation according to claim 21, wherein the organofunctional material which can be employed for the production of functional layers of electronic devices is selected from the group consisting of fluorescent emitters, phosphorescent emitters, host materials, matrix materials, electron-transport materials, exciton-blocking materials, electron-injection materials, hole-conductor materials, hole-injection materials, n-dopants, p-dopants, wide-band-gap materials, electron-blocking materials and hole-blocking materials.

23. The formulation according to claim 21, wherein the proportion of the aromatic compound having a structure of the formula (1) or (2) in the formulation is at least 0.1% by weight based on the formulation.

24. The formulation according to claim 21, wherein the proportion of the aromatic compound having a structure of the formula (1) or (2) in the formulation is at least 20% by weight based on the formulation.

25. The formulation according to claim 21, wherein the aromatic compound having a structure of the formula (1) or (2) has a surface tension of at most 40 mN/m.

26. The formulation according to claim 21, wherein the aromatic compound having a structure of the formula (1) or (2) has a boiling point of at most 300° C.

27. The formulation according to claim 21, wherein the aromatic compound having a structure of the formula (1) or (2) has a viscosity of at least 3 mPas.

28. The formulation according to claim 21, wherein the aromatic compound having a structure of the formula (1) or (2) has a viscosity of at least 5 mPas, the proportion of the aromatic compound having a structure of the formula (1) or (2) in the formulation is at least 80% by weight, based on the formulation the aromatic compound having a structure of the formula (1) or (2) has a surface tension of at most 30 mN/m, the aromatic compound having a structure of the formula (1) or (2) has a boiling point of at most 280° C., and the aromatic compound having a structure of the formula (1) or (2) is employed as solvent.

29. The formulation according to claim 21, wherein, in the ring structures of one of the formulae (3), (4), (5), (6), (7), (8) or (9), at least one of the groups A.sup.1 and A.sup.3 stands, identically or differently, for O or NR.sup.3 and A.sup.2 stands for C(R.sup.1).sub.2.

30. The formulation according to claim 21, wherein, in the ring structures of one of the formulae (3), (4), (5), (6), (7), (8) or (9), the groups A.sup.1 and A.sup.3 stand, identically or differently on each occurrence, for C(R.sup.3).sub.2 and A.sup.2 stands for C(R.sup.1).sub.2.

31. The formulation according to claim 21, wherein two adjacent radicals Y in the structure of the formula (1) or formula (2) form a ring structure of one of the following formulae (3-A) to (3-F): ##STR00052## where A.sup.1, A.sup.2 and A.sup.3 stand, identically or differently on each occurrence, for O or NR.sup.3, the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2), and R.sup.1 and R.sup.3 have the meaning indicated in claim 21.

32. The formulation according to claim 21, wherein two adjacent radicals Y in the structure of the formula (1) or formula (2) form a ring structure of one of the following formulae (4-A) to (4-F): ##STR00053## where A.sup.1, A.sup.2 and A.sup.3 stand, identically or differently on each occurrence, for O or NR.sup.3, the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2), and R.sup.1 and R.sup.3 have the meaning indicated in claim 21.

33. The formulation according to claim 21, wherein two adjacent radicals Y in the structure of the formula (1) or formula (2) form a ring structure of one of the following formulae (5-A) to (5-E): ##STR00054## where A.sup.1, A.sup.2 and A.sup.3 stand, identically or differently on each occurrence, for O or NR.sup.3, the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2), and R.sup.1 and R.sup.3 have the meaning indicated in claim 21.

34. The formulation according to claim 21, wherein two adjacent radicals Y in the structure of the formula (1) or formula (2) form a ring structure of one of the following formulae (6-A) to (6-C): ##STR00055## where the symbols used have the meanings indicated in claim 21, and the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2).

35. The formulation according to claim 21, wherein two adjacent radicals Y in the structure of the formula (1) or formula (2) form a ring structure of one of the following formulae (7-A), (8-A) or (9-A): ##STR00056## where the symbols used have the meanings indicated in claim 21, and the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2).

36. The formulation according to claim 21, wherein the aromatic compound having a structure of the formula (1) or (2) is selected from compounds of the formulae (10), (11) and (12), ##STR00057##

37. A process for the production of an electronic device comprising applying the formulation according to claim 21 to a substrate and/or to a layer applied indirectly or directly to a substrate.

38. The process according to claim 37, wherein the formulation is applied to a substrate or one of the layers applied to the substrate by flood coating, dip coating, spray coating, spin coating, screen printing, relief printing, gravure printing, rotary printing, roller coating, flexographic printing, offset printing or nozzle printing, preferably ink-jet printing.

39. An electronic device obtainable by the process according to claim 36.

40. An electronic device having at least one layer comprising at least one organofunctional material and at least one aromatic compound having a structure of the formula (1) or (2) ##STR00058## where the following applies to the symbols used: X is on each occurrence, identically or differently, CR or N, where in total at most 2 radicals X stand for N; R is on each occurrence, identically or differently, H, D, F, N(R.sup.1).sub.2, CN, NO.sub.2, C(═O)N(R.sup.1).sub.2, Si(R.sup.1).sub.3, C(═O)R.sup.1, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.1, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.1C═CR.sup.1, C≡C, Si(R.sup.1).sub.2, C═O, NR.sup.1, O, S or CONR.sup.1 and where one or more H atoms is optionally replaced by D, F, NO.sub.2 or CN, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.1, or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1, or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.1; two adjacent radicals R here may also form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system with one another; R.sup.1 is on each occurrence, identically or differently, H, D, F, N(R.sup.2).sub.2, CN, NO.sub.2, Si(R.sup.2).sub.3, C(═O)R.sup.2, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 C atoms, each of which is optionally substituted by one or more radicals R.sup.2, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.2C═CR.sup.2, C≡C, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2 and where one or more H atoms is optionally replaced by D, F, CN or NO.sub.2, or an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.2, or an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; two or more adjacent radicals R.sup.1 with one another or R.sup.1 with R here may form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system; R.sup.2 is on each occurrence, identically or differently, H, D, F or an aliphatic, aromatic and/or heteroaromatic hydrocarbon radical having 1 to 20 C atoms, in which, in addition, one or more H atoms is optionally replaced by F; two or more substituents R.sup.2 here may also form a mono- or polycyclic, aliphatic ring system with one another; Y is on each occurrence, identically or differently, a group CR, wherein the adjacent groups Y in the structure of the formula (1) or (2) together form a ring of one of the following formulae (3), (4), (5), (6), (7), (8) and (9): ##STR00059## where R.sup.1 has the meaning given above, the dashed lines represent the bonds from the two carbon atoms of group Y to the radicals X of the aromatic or heteroaromatic ring in the structure of the formula (1) or formula (2), and furthermore: A.sup.1, A.sup.3 are, identically or differently on each occurrence, C(R.sup.3).sub.2, O, S, NR.sup.3 or C(═O); A.sup.2 is C(R.sup.1).sub.2, O, S, NR.sup.3 or C(═O); G is an alkylene group having 1, 2 or 3 C atoms, which is optionally substituted by one or more radicals R.sup.2, or is —CR.sup.2═CR.sup.2— or an ortho-linked arylene or heteroarylene group having 5 to 14 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; R.sup.3 is, identically or differently on each occurrence, F, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms, a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, each of which is optionally substituted by one or more radicals R.sup.2, where one or more non-adjacent CH.sub.2 groups is optionally replaced by R.sup.2C═CR.sup.2, C≡C, Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2 and where one or more H atoms is optionally replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.2, or an aryloxy or heteroaryloxy group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2, or an aralkyl or heteroaralkyl group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R.sup.2; two radicals R.sup.3 which are bonded to the same carbon atom may form an aliphatic or aromatic ring system with one another here and thus form a spiro system; furthermore, R.sup.3 may form an aliphatic ring system with an adjacent radical R or R.sup.1; with the proviso that two identical heteroatoms in the above-mentioned groups are not bonded directly to one another and two groups C═O are not bonded directly to one another.

41. The electronic device according to claim 39, wherein the electronic device is selected from the group consisting of organic electroluminescent devices, organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light-emitting electrochemical cells and organic laser diodes.

Description

WORKING EXAMPLES

[0257] For the tests, five OLED components having the layer sequence described in FIG. 1 are produced. The solvent of the formulation for the emitter layer (G-EML) is varied here. 3-Phenoxytoluene is used for the reference component, a mixture of hexamethylindane (HMI) and butyl benzoate (BB) in the mixing ratio 60:40 (ratio by weight) is used for Example 1, a mixture of HMI and BB in the ratio 50:50 is used for Example 2, a mixture of HMI and cyclohexylbenzene (CHB) in the ratio 50:50 is used for Example 3, and a mixture of HMI and CHB in the ratio 60:40 is used for Example 4. Table 1 summarises the concentration, viscosity and surface tension of the formulations used.

TABLE-US-00001 TABLE 1 Measurement values of the formulations used for the emitter layer Surface tension Layer Formulation Conc. (g/l) Viscosity (mPas) (mN/m) G-EML Reference 14 4.8 37.6 G-EML Example 1 14 5.7 30.6 G-EML Example 2 14 5.5 30.9 G-EML Example 3 14 4.7 31.5 G-EML Example 4 14 5.5 31.4

Measurement of the Viscosity and Surface Tension

[0258] The viscosity of the formulations used is measured using a rheometer with cone-and-plate measurement geometry. The viscosities indicated in Table 1 are determined at a temperature of 23.4° C. and a shear rate of 500 s.sup.−1.

[0259] The surface tension is determined by means of an optical method (pendant drop). In this measurement method, the surface tension of the liquid is calculated from the deformation of a hanging drop due to gravity. The surface tension is measured at room temperature, usually in the range from 22° C. to 24° C.

Production of the Test Components:

[0260] In a clean room, glass substrates coated with ITO and a bank structure are cleaned in an ultrasound bath using DI water, dried and subsequently subjected to a plasma treatment (oxygen plasma for 5 s, followed by CF.sub.4 plasma for 40 s). An 80 nm layer of PEDOT (PEDOT is a polythiophene derivative (Baytron PJET HC V2) from H. C. Starck, Goslar, which is supplied as an aqueous dispersion) is then applied, likewise in the clean room, by ink-jet printing. In order to remove residual water from the layer, the substrates are dried by heating on a hotplate at 180° C. for 10 minutes. 20 nm of an interlayer (typically a hole-dominated polymer, here HL-X026 from Merck) are then applied from mesitylene solution (concentration 5 g/l) under an inert-gas atmosphere (nitrogen or argon). The layer is dried by heating at 180° C. for at least 60 minutes. The emission layer (G-EML) is subsequently applied to the hole-transport layer by means of ink-jet printing, dried in vacuo and subsequently dried by heating on a hotplate at 160° C. for 10 minutes.

[0261] The emission layer here consists of the following three materials TH-1, TH-2 and TE-1, which are employed in the ratio 40:40:20, more precisely in a concentration of 14 g/l, based on the respective solvent mixture. The thickness of the emission layer is 60 nm.

##STR00048##

[0262] All ink-jet printing operations are carried out in air, as is the drying of the hole-injection layer by heating. The drying of the hole-transport layer and emitter layer by heating is carried out under inert gas (N.sub.2) in a glove box.

[0263] The substrates printed in this way are then transferred into a vacuum vapour-deposition chamber, where a 20 nm thick electron-transport layer (ETL) comprising the two following materials ETM-1 and ETM-2 in the ratio 50:50 is applied by thermal co-evaporation.

##STR00049##

[0264] The Al cathode is then applied by vapour deposition through a vapour-deposition mask; vapour-deposition units from Lesker or others, typical vacuum level 5×10.sup.−6 mbar. In order to protect, in particular, the cathode against air and atmospheric moisture, the device is finally encapsulated and then characterised.

Measurement Results and Discussion:

[0265] Table 2 shows in the ‘Efficiency’ column that an efficiency of 46.9 cd/A is achieved at a luminance of 1000 cd/m.sup.2 for the reference component, an efficiency of 48.0 cd/A is achieved for the component in accordance with Example 1, an efficiency of 48.1 cd/A is achieved for the component in accordance with Example 2, an efficiency of 47.5 cd/A is achieved for the component in accordance with Example 3, and an efficiency of 48.1 cd/A is achieved for the component in accordance with Example 4.

[0266] Table 2 shows in the ‘EQE’ column that an external quantum efficiency (EQE) of 12.7% is achieved at a luminance of 1000 cd/m.sup.2 for the reference component, an EQE of 13.2% is achieved for the component in accordance with Example 1, an EQE of 13.3% is achieved for the component in accordance with Example 2, an EQE of 12.8% is achieved for the component in accordance with Example 3, and an EQE of 13.3% is achieved for the component in accordance with Example 4.

[0267] It can be seen from Table 2, column ‘U’, that an operating voltage of 7.2 V is required at a luminance of 1000 cd/m.sup.2 for the reference component, an operating voltage of 6.8 V is required for the component in accordance with Example 1, an operating voltage of 6.5 V is required for the component in accordance with Example 2, an operating voltage of 6.9 V is required for the component in accordance with Example 3, and an operating voltage of 6.9 V is required for the component in accordance with Example 4.

[0268] The lifetime data for the components produced are shown by Table 2, column ‘LT80’. No significant difference is evident in the lifetime characteristic lines between the reference component and the components produced in accordance with Examples 1 to 4. It can be deduced from this that the use of the solvent system according to the invention does not result in impairment of the components and the use of the solvent system according to the invention does not have an adverse effect on the electro-optical performance of the components produced and their lifetime. However, the solvent system according to the invention results in greater flexibility being achieved with respect to the viscosity and the surface tension of the formulations to be used, which opens up a larger process window for meeting the requirements of different ink-jet printing machines.

TABLE-US-00002 TABLE 2 Measurement values of the test components produced Efficiency (cd/A) EQE (%) U (V) LT.sub.80 (h) Formulation at 1000 cd/m.sup.2 at 8000 cd/m.sup.2 Reference 46.9 12.7 7.2 59 Example 1 48.0 13.2 6.8 53 Example 2 48.1 13.3 6.5 52 Example 3 47.5 12.8 6.9 39 Example 4 48.1 13.0 6.9 46

[0269] In a further test series, the influence of the use of isobenzofuran as additive on the properties of formulations, such as, for example, the surface tension and the viscosity, is investigated. To this end, two formulations are prepared with different proportions of additive. The formulation in accordance with Example 5 comprises a proportion of 5% by weight of isobenzofuran in 3-PT as solvent, the formulation in accordance with Example 6 comprises a proportion of 10% by weight of isobenzofuran in 3-PT as solvent.

TABLE-US-00003 TABLE 3 Measurement values of the test formulations Proportion of additive Conc. Viscosity Surface tension Layer Formulation (% by wt.) (g/l) (mPas) (mN/m) G-EML Reference 0 14 4.8 37.6 G-EML Example 5 5 14 4.8 36.9 G-EML Example 6 10 14 4.8 36.4

[0270] It can be seen from Table 3, column ‘Viscosity’, that the viscosity of the formulation is not influenced by addition of different proportions of isobenzofuran. However, it can be seen from Table 3, column ‘Surface tension’, that the surface tension of the formulation prepared can be influenced by the addition of different proportions of additive. The use of isobenzofuran as additive in a formulation thus gives rise to the possibility of influencing the wetting ability of the formulation in accordance with the requirements of the coating method selected, without changing the rheological properties of the formulation.