Theories of electronic behavior in macromolecular solids

Abstract

AbstractMany examples of electronically conducting aperiodic polymeric solids now exist. These supply enough inherent electronic carriers to be classed as semiconductors at laboratory temperatures. Such enhanced electronic conduction arises only in the presence of either (or both) donor‐acceptor action (usually intermolecular), or ekaconjugation (intramolecular). Quantum mechanical and experimental evidence shows that conjugation can be of two types; exhalted or “ekaconjugation” and self‐limited or “rubiconjugation.” These play a strong role in organic conduction. The energetics of carrier origins, the mobilities of carriers, and the effects of morphology and impurity are critically discussed, as well as the relative roles in electrical polarization mechanisms of variously excited electrons such as (a) ground‐state electrons—contributing to normal “electronic” polarizability, (b) Frenkel (or intermolecular) excitons, (c) Mott (or intramolecular) excitons, (d) Von Hippel polarons or “quasi‐bound” electrons, and (e) “free” electrons, i.e., those in the conduction band. Mott excitons and polarons in macromolecular solids can contribute in a new and strong fashion because of the unusual size of the monopoles present in the form of delocalized charges ranging over long molecular regions. This strong type of polarizability, recently observed, is called hyperelectronic polarization.