Formulations containing a mixture of at least two different solvents

1. A formulation comprising at least one organic functional material, and organic solvents, wherein said formulation comprises a mixture of at least three different solvents, a first, a second, and a third organic solvent, wherein the first organic solvent exhibits a lower boiling point than the second organic solvent and said first organic solvent exhibits a higher viscosity than said second organic solvent, and wherein the third organic solvent has a higher boiling point and a higher viscosity than the second organic solvent;

wherein the at least one organic functional material has a molecular weight of at most 5,000 g/mol;

wherein the first organic solvent has a boiling point of from 150 to 320° C. at 760 mm Hg;

wherein the first organic solvent has a viscosity of from 3.5 to 50 mPas at 25.0° C.;

wherein the second organic solvent has a boiling point of from 180 to 350° C. at 760 mm Hg; and

wherein the second organic solvent has a viscosity of from 0.8 to 20 mPas at 25.0° C.;

wherein the at least one organic functional material is selected from the group consisting of hole-injecting, hole-transporting, emitting, electron-transporting, and electron-injecting materials;

wherein the at least one organic functional material has a solubility in the first and the second organic solvent of at least 5 g/l at 25.0° C.; and

wherein the content of the at least one organic functional material in the formulation is in the range from 0.01 to 5 weight % based on the total weight of the formulation.

2. The formulation according to claim 1 , wherein said second solvent exhibits a viscosity in the range of 1 to 15 mPas at 25.0° C.

3. The formulation according to claim 1 , wherein the difference between the viscosities of said second solvent and said first solvent is in the range of 1 to 50 mPas at 25.0° C.

4. The formulation according to claim 1 , wherein said second organic solvent has a boiling point in the range from 230° C. to 320° C., wherein the boiling point is given at 760 mm Hg.

5. The formulation according to claim 1 , wherein the difference between the boiling point of said first organic solvent and the boiling point of said second organic solvent is in the range of 5° C. to 100° C.

6. The formulation according to claim 1 , wherein the formulation comprises at least 20% of the first and second solvent.

7. The formulation according to claim 1 , wherein said first organic solvent comprises parameters of H d in the range of 15.5 to 22.0 MPa 0.5 , H p in the range of 0.0 to 12.5 MPa 0.5 and H h in the range of 0.0 to 15.0 MPa 0.5 .

8. The formulation according to claim 1 , wherein said second organic solvent comprises Hansen Solubility parameters of H d in the range of 15.5 to 22.0 mPa 0.5 , H p in the range of 0.0 to 12.5 MPa 0.5 and H h in the range of 0.0 to 15.0 MPa 0.5 .

9. The formulation according to claim 1 , wherein said first organic solvent is selected from aldehydes, ketones, ethers, esters, amides, sulfur compounds, nitro compounds, hydrocarbons, halogenated hydrocarbons, aromatic or heteroaromatic hydrocarbons, halogenated aromatic or heteroaromatic hydrocarbons and/or (cyclic)siloxanes, terpenes, epoxides, ketones, ethers and esters.

10. The formulation according to claim 1 , wherein said second organic solvent is selected from aldehydes, ketones, ethers, esters, amides, sulfur compounds, nitro compounds, hydrocarbons, halogenated hydrocarbons, aromatic or heteroaromatic hydrocarbons, halogenated aromatic or heteroaromatic hydrocarbons and/or (cyclic)siloxanes, terpenes, epoxides, ketones, ethers and esters.

11. The formulation according to claim 1 , wherein the formulation has a viscosity in the range from 1 to 50 mPas at 25.0° C.

12. A method comprising utilizing the formulation according to claim 1 as coating or printing ink for the preparation of organic electronic devices.

13. A process for the preparation of a formulation according to claim 1 , comprising mixing at least first and second solvent and the at least one organic functional material.

14. A process for the preparation of an electroluminescent device, comprising preparing at least one layer of an electronic device by depositing the formulation according to claim 1 on a surface and subsequently drying.

15. The formulation according to claim 1 , wherein the at least one organic functional material is not a polymer.

16. The formulation according to claim 1 , wherein the at least one organic functional material has a molecular weight of at most 3,000 g/mol.