Electronic Transport through Electron‐Doped Metal Phthalocyanine Materials

FePc, and MnPc—that were investigated as a function of potassium concentration and temperature. For all of these systems, insulating in the pristine state, we found that the electrical conductivity can be increased to a value in excess of r= 100 Scm –1 upon potassium intercalation. In this state, the conductivity of all compounds remains high at cryogenic temperatures, indicating the existence of metallic behavior. Increasing the potassium concentration further brings all MPcs back into an insulating state. We will focus on one of these molecular systems, CuPc, to address the electronic and structural properties of this compound in more detail. We discuss scanning tunneling spectroscopy (STS) experiments that show the presence of a finite density of states in the metallic state and of a gap in the insulating states, thus confirming, at a local level, the occurrence of an insulator–metal–insulator transition. We also present structural investigations demonstrating the formation of intercalated phases and Raman spectroscopy measurements, which provide an independent microscopic