The present invention relates to 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 polythiophene and a composition Z2 comprising 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 it is ensured that, following completion of method step III), the content of non-polymerised thiophene monomer in the composition Z3 is in the range from 1 ppm to 100 ppm, based on the total weight of the composition Z3. The present invention also relates to a composition obtainable as the composition Z3 produced with this method, a composition comprising a polythiophene, a layer construction, an electronic component and the use of a composition.