Control of the Electronic Structure of Organic Conductors as Exemplified by [NMP][TCNQ] Charge‐Transfer Complexes

Through replacement of cations with neutral molecules of similar shape and polarizability in a highly conducting “metal‐like” change‐transfer organic conductor, the deliberate control of the electronic structure from a quarter to a half‐filled band is possible. This goal has been achieved with the N‐methylphenazinium (NMP) salt of the tetracyanoquinodimethane (TCNQ) anion by partial replacement of the cation with phenazine. A detailed study of the optical, electrical, and magnetic properties of these conducting molecular solids has lead to the evolution of a broad understanding of the physics of one‐dimensional organic conductors and a reinterpretation of the mechanism of electron transport in such solids. Phenomena such as switching from a low coulomb repulsion two‐chain conductor to a high coulomb repulsion one‐chain conductor as well as soliton‐assisted electron transport are observed.