Abstract
An electron and an electron hole are attracted to each other by electrostatic Coulomb
force and combine. This bound state of electron-hole pair is known as an exciton. It can carry
energy without transferring net electric charge because it is an electrically neutral quasiparticle. Excitons exist in semiconductors, insulators and some liquids. Frenkel exciton and
Wannier-Mott exciton are the two types of excitons. In this section, the origin of excitons, types
of excitons, and the relaxation and thermalization behavior of excitons with some research
results have been discussed.