Formulation and method for preparation of organic electronic devices
The present invention relates to novel formulations comprising an organic semiconductor (OSC) and one or more organic solvents. The formulation comprises a viscosity at 25° C. of less than 15 mPas and the boiling point of the solvent is at most 400° C. Furthermore, the present invention describes the use of these formulations as inks for the preparation of organic electronic (OE) devices, especially organic photovoltaic (OPV) cells and OLED devices, to methods for preparing OE devices using the novel formulations, and to OE devices, OLED devices and OPV cells prepared from such methods and formulations.
1. Formulation comprising one or more organic semiconducting compounds (OSC), and one or more organic solvents, wherein:
one or more organic semiconducting compound has a molecular weight of 2000 g/mol or less and is of the formula P6:
wherein
n is an integer >1,
R on each occurrence identically or differently denotes H, F, Cl, Br, I, CN, a straight-chain, branched or cyclic alkyl group having from 1 to 40 C atoms, in which one or more C atoms are optionally replaced by O, S, O—CO, CO—O, O—CO—O, CR 0 ═CR 0 or C≡C such that O— and/or S-atoms are not linked directly to each other, and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, or denotes an aryl or heteroaryl group having from 4 to 20 ring atoms that is unsubstituted or substituted by one or more non-aromatic groups R s , and wherein one or more groups R may also form a mono- or polycyclic aliphatic or aromatic ring system with one another and/or with the ring to which they are attached,
R s on each occurrence identically or differently denotes F, Cl, Br, I, CN, Sn(R 00 ) 3 , Si(R 00 ) 3 or B(R 00 ) 2 a straight-chain, branched or cyclic alkyl group having from 1 to 25 C atoms, in which one or more C atoms are optionally replaced by O, S, O—CO, CO—O, O—CO—O, CR 0 ═CR 0 , C≡C such that O—and/or S-atoms are not linked directly to each other, and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, or R s denotes an aryl or heteroaryl group having from 4 to 20 ring atoms that is unsubstituted or substituted by one or more non-aromatic groups R s , and wherein one or more groups R s may also form a ring system with one another and/or with R,
R 0 on each occurrence identically or differently denotes H, F, Cl, CN, alkyl having from 1 to 12 C atoms or aryl or heteroaryl having from 4 to 10 ring atoms,
R 00 on each occurrence identically or differently denotes H or an aliphatic or aromatic hydrocarbon group having from 1 to 20 C atoms, wherein two groups R 00 may also form a ring together with the hetero atom (Sn, Si or B) to which they are attached,
the formulation has a viscosity at 25° C. of less than 15 mPas and
the boiling point of one or more organic solvent is at most 400° C.
2. Formulation according to claim 1 , wherein the formulation has a viscosity at 25° C. in the range of 0.5 to 9.5 mPas.
3. Formulation according to claim 1 , wherein said formulation is a solution.
4. Formulation according to claim 1 , wherein the formulation has a surface tension in the range of 22 mN/m to 50 mN/m.
5. Formulation according to claim 1 , wherein one or more organic solvent has Hansen Solubility parameters of H d in the range of 17.0 to 23.2 MPa 0.5 , H p in the range of 0.2 to 12.5 MPa 0.5 and H h in the range of 0.0 to 20.0 MPa 0.5 .
6. Formulation according to claim 5 , wherein one or more organic solvent has Hansen Solubility parameters of H d in the range of 17.0 to 23.2 MPa 0.5 , H p in the range of 0.2 to 10.5 MPa 0.5 and H h in the range of 0.0 to 5.0 MPa 0.5 .
7. Formulation according to claim 5 , wherein one or more organic solvent comprises one or more of an aromatic and/or heteroaromatic compound.
8. Formulation according to claim 5 , wherein one or more organic solvent comprises of one or more aromatic hydrocarbon compound.
9. Formulation according to claim 8 , wherein said aromatic hydrocarbon compound comprises a cycloalkyl group.
10. Formulation according to claim 8 , wherein said aromatic hydrocarbon compound comprises an alkyl group having 1 to 8 carbon atoms.
11. Formulation according to claim 1 , wherein said organic solvent comprises a mixture of hydrocarbon aromatic compounds.
12. Formulation according to claim 1 , wherein one or more organic solvent has a boiling point of at least 130° C.
13. Formulation according to claim 1 , wherein said organic solvent is a mixture of compounds having different boiling points and the boiling point of the compound with the lowest boiling point is at least 10° C. below the boiling point of the compound with the highest boiling point.
14. Formulation according to claim 1 , wherein said organic solvent is a mixture of compounds having different boiling points and the boiling point of the compound with the lowest boiling point is at most 100° C. below the boiling point of the compound with the highest boiling point.
15. Formulation according to claim 1 , wherein said formulation comprises at least 80% by weight of said organic solvents.
16. Formulation according to claim 1 , wherein one or more organic solvent has a partition ratio log P of at least 1.5.
17. Formulation according to claim 1 , wherein said formulation comprises at least one inert binder.
18. Formulation according to claim 17 , wherein said inert binder is a polymer comprising repeating units derived from styrene monomers and/or olefins.
19. Formulation according to claim 17 , wherein said inert binder is a polymer comprising at least 80% by weight of repeating units derived from styrene monomers and/or olefins.
20. Formulation according to claim 17 , wherein said inert binder is a polymer having a weight average molecular weight of at least 200,000 g/mol.
21. Formulation according to claim 1 , wherein one or more organic semiconducting compound is an organic light emitting material and/or charge transporting material.
22. Formulation according to claim 1 , wherein one or more organic semiconducting compound has a molecular weight of 1000 g/mol or less.
23. Formulation according to claim 1 , wherein the formulation further comprises a host material.
24. Formulation according to claim 1 , wherein the formulation comprises 0.1 to 5% by weight of organic semiconducting compounds.
25. Formulation according to claim 17 , wherein the weight ratio of said semiconducting compound to said inert binder is in the range of 5:1 to 1:1.
26. Formulation according to claim 1 , wherein the formulation comprises at least one wetting agent.
27. Formulation according to claim 26 , wherein said wetting agent is volatile and is not capable of chemically reacting with said organic semiconducting compound.
28. A coating or printing ink for the preparation of OE devices, comprising a formulation according to claim 1 .
29. Process of preparing an organic electronic (OE) device, comprising the steps of
a) depositing the formulation according to claim 1 onto a substrate to form a film or layer, and
b) removing the solvent(s).
30. Process according to claim 29 , wherein the formulation is applied by gravure printing, doctor blade coating, roller printing, reverse roller printing, flexographic printing, or web printing.
31. Process according to claim 29 , wherein the formulation is applied by a printing process with a printing device and the cell etch of the printing device is in the range of 4 cm 3 /m 2 to 18 cm 3 /m 2 .
32. Process according to claim 29 , wherein the formulation is applied by a printing process with a printing device having a print speed of 100 m/minute or less.
33. Process according to claim 29 , wherein the surface on which the formulation is applied has a surface energy in the range of 25 to 130 mN m −1 .
34. Process according to claim 29 , wherein removing of the solvent is by evaporation and the evaporation of the solvent is achieved below the boiling point of the solvent.
35. An organic electronic (OE) device prepared by a process according to claim 29 .
36. An organic electronic (OE) device according to claim 35 , which is an organic light emitting diode (OLED), an organic field effect transistor (OFET) or an organic photovoltaic (OPV) device.
37. An organic electronic (OE) device according to claim 35 , which has a top gate design.
38. An organic electronic (OE) device according to claim 35 , which has a bottom gate design.