Dispersions comprising polythiophenes with a defined content of thiophene monomer

1. A method for producing a composition comprising polythiophene, comprising the method steps:

I) provision of a composition Z1 comprising thiophene monomers and an oxidising agent;

II) oxidative polymerisation of the thiophene monomers by reducing the oxidising agent to a reduction product and oxidation of the thiophene monomer, to form a composition Z2 comprising a polythiophene and the reduction product;

III) at least partial removal of the reduction product from the composition Z2 obtained in method step II), to obtain a composition Z3;

wherein the composition Z3 has a content of non-polymerised thipohene monomer in the range from 5 ppm to 100 ppm, based on the total weight of the composition Z3.

2. The method according to claim 1 , wherein following completion of method step III), the content of non-polymerised thiophene monomer in the composition Z3 is in a range from 5 ppm to 50 ppm, based on the total weight of the composition Z3.

3. The method according to claim 1 , wherein following completion of method step III), the content of non-polymerised thiophene monomer in the composition Z3 is in the range from 5 ppm to 30 ppm, based on the total weight of the composition Z3.

4. The method according to claim 1 , wherein the thiophene monomer is 3,4-ethylenedioxythiophene (EDT) and the polythiophene is poly(3,4-ethylenedioxythiophene) (PEDOT).

5. The method according to claim 1 , wherein, in addition to the thiophene monomer and the oxidising agent, the solution provided in method step I) also comprises a polyanion.

6. The method according to claim 5 , wherein the polyanion is a polystyrene sulfonic acid (PSS).

7. The method according to claim 1 , wherein the composition Z3 obtained in method step III) is a PEDOT/PSS dispersion.

8. The method according to claim 1 , wherein the oxidising agent in method step I)

a) in the case of an oxidising agent absorbing one electron per molecule is used in a molar ratio of oxidising agent : thiophene monomer of less than 2.33:1,

b) and in the case of an oxidising agent absorbing two electrons per molecule is used in a molar ratio of oxidising agent : thiophene monomer of less than 1.16:1.

9. The method according to claim 1 , wherein the at least partial removal of the reduction product in method step III) takes place through the treatment of the composition Z2 with an ion exchanger.

10. A composition obtained as composition Z3 using a method comprising:

I) provision of a composition Z1 comprising thiophene monomers and an oxidising agent;

II) oxidative polymerisation of the thiophene monomers by reducing the oxidising agent to a reduction product and oxidation of the thiophene monomer, to form a composition Z2 comprising a polythiophene and the reduction product;

III) at least partial removal of the reduction product from the composition Z2 obtained in method step II), to obtain a composition Z3;

wherein the composition Z3 has a content of non-polymerised thipohene monomer in the range from 5 ppm to 100 ppm, based on the total weight of the composition Z3.

11. A composition comprising a polythiophene, wherein, in addition to the polythiophene, the composition comprises in the range from 5 ppm to 100 ppm of the thiophene monomer on which the polythiophene is based, based on the total weight of the composition.

12. The composition according to claim 11 , wherein the composition comprises in the range of from 5 ppm to 50 ppm of the thiophene monomer on which the polythiophene is based, based on the total weight of the composition.

13. The composition according to claim 11 , wherein the composition comprises in the range from 5 ppm to 30 ppm of the thiophene monomer on which the polythiophene is based, based on the total weight of the composition.

14. The composition according to claim 11 , wherein the composition comprises less than 500 ppm of inorganic anions, based on the total weight of the composition.

15. The composition according to claim 11 , wherein the polythiophene is poly(3,4-ethylenedioxythiophene) and the thiophene monomer is 3,4-ethylenedioxythiophene.

16. The composition according to claim 11 , wherein, in addition to the polythiophene, the composition comprises a polyanion.

17. The composition according to claim 16 , wherein the polyanion is a polystyrene sulfonic acid.

18. The composition according to claim 11 , wherein the composition is a PEDOT/PSS dispersion.

19. The composition according to claim 11 , wherein, the composition has at least one of the following properties:

i) a conductivity of at least 500 S/cm;

ii) a PEDOT/PSS content in the range from 0.8% to 2% by weight, based on the total weight of the composition.

20. A layer construction, comprising

A) a substrate with a substrate surface and

B) a layer at least partially covering the substrate surface,

wherein the layer is formed from the solid comprised in a composition according claim 10 .

21. The layer construction according to claim 20 , wherein the layer B) has the following properties:

B1) the internal transmission of the layer is greater than 80%;

B2) the conductivity of the layer is at least 500 S/cm.

22. An electronic component comprising a layer construction according to claim 20 .

23. A method for producing an electrically conductive layer in an electronic component, the method comprising applying the composition of claim 10 to a substrate surface.