Electrical Doping of Organic Semiconductors with Molecular Oxidants and Reductants

This chapter examines the basic doping process in organic molecular and polymeric materials, discusses factors to be considered in selecting a dopant, and describes some of the molecules that have been used as dopants. It explains some case studies of the use of doping to improve device performance. The chapter explores how air-stable, or at least less air-sensitive, yet useful, n-dopants can be obtained by identifying reductants in which the electron-transfer process leading to doping is coupled to a chemical reaction. Electrical doping has long played a role in studies of conjugated polymers. The most conceptually simple way to achieve electrical p-or n-doping in organic materials is by introducing neutral one-electron oxidants or reductants. Strong n-dopants that operate via one-electron transfer necessarily have low Ionization energy and so tend to be sensitive to oxidation by oxygen and/or water. Doping in molecular or polymeric organic semiconductors is somewhat different from that in traditional crystalline inorganic semiconductors.