Electron donor

In contrast to traditional reducing agents, electron transfer from a donor to an electron acceptor may be only fractional. The electron is not completely transferred, which results in an electron resonance between the donor and acceptor. This leads to the formation of charge transfer complexes, in which the components largely retain their chemical identities. The electron donating power of a donor molecule is measured by its ionization potential, which is the energy required to remove an electron from the highest occupied molecular orbital (HOMO).

The overall energy balance (ΔE), i.e., energy gained or lost, in an electron donor-acceptor transfer is determined by the difference between the acceptor's electron affinity (A) and the ionization potential (I):

${\displaystyle \mathrm{\Delta }E=A-I}$

Molecular electronics and devices

Electron donors are components of many devices such as organic photovoltaic devices. Typical electron donors undergo reversible redox so that they can serve as electron relays. Triarylamines are typical donors.