Method of forming polythiophene dispersions

A process for preparing a dispersion or a solution containing a polythiophene+An− ion complex in an organic solvent, the process comprising the consecutive steps of:

• a) adding a water-miscible organic solvent or a water-miscible organic solvent mixture to an aqueous dispersion or a solution of a polythiophene+An− ion complex,
• wherein the polythiophene+ is a polymer comprising recurring units represented by formula (I)
• at least some of which are positively charged and wherein
• Y is —(CH2)m—CR1R2(CH2)n— or an optionally substituted 1,2-C3–C8-cycloalkylene radical, and
• R1 and R2, independently of one another, are hydrogen, hydroxymethyl, an optionally substituted C1–C20-alkyl radical or an optionally substituted C6–C14-aryl radical, and
• m and n are identical or different and are an integer from 0 to 3,
• and wherein
• An− is an anion of an organic polyacid,
• or wherein
• the polythiophene+An− is a polymer comprising recurring units represented by formula (II)
• wherein at least some of the thiophene rings carry a positive charge and
• wherein
• Z is —(CH2)m—CR3R4(CH2)n—,
• R3 is hydrogen or —(CH2)s—O—(CH2)p—SO3−M+,
• R4 is —(CH2)s—O—(CH2)p—SO3−M+,
• m and n are an integer from 0 to 3,
• M+ is a cation,
• s is an integer from 0 to 10, and
• p is an integer from 1 to 18;
• and
• b) removing water from the mixture resulting in step a), thereby forming the dispersion or the solution, wherein in step (b) water is removed from the mixture by means of a membrane process.