Coupling of gate-induced superconducting polythiophene layers through an insulating part

We report on the enhancement of the critical temperature $T_c$ for gate-induced superconductivity in polythiophene thin films using superconductor-insulator-superconductor stacks. The increase of $T_c$ is ascribed to the coupling of the superconducting layers through an insulating barrier. This might be explained by an effective screening of the Coulomb interaction of charge carriers within different layers. Using a combination of superconducting polythiophene and lead layers evidence is found for coupling of charges of the two different layers via phonons.