Molecular-acceptor doping of polythiophene results in high conductivity, ca. 1 S cm(-1), in solution-processed thin films. Charge-transfer complex formation leads to new hybrid orbitals (see figure), which are derived from the highest occupied level of the donor (polythiophene) and the lowest unoccupied level of the acceptor (tetrafluorotetracyanoquinodimethane).