A polythiophene polymer with high charge-carrier mobilities, a method for fabricating the polymer, and a semiconductor component and an organic field effect transistor including the polymer are provided. The polymer has electrical semiconductor characteristics and includes a backbone formed from thiophene groups. The thiophene groups carry a side group in the 3rd and 4th positions that can itself have semiconductor characteristics. The polymers have a high mobility of the charge carriers and are therefore suitable for fabricating electronic components such as field effect transistors.