Exciton

An exciton is an electron bound to an electron hole. It is neutrally charged (because the negative charge of the electron is balanced by the positive charge of the electron hole) and is a quasiparticle.

Exciton Media

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  Frenkel exciton, bound electron-hole pair where the hole is localized at a position in the crystal represented by black dots

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  Wannier–Mott exciton, bound electron-hole pair that is not localized at a crystal position. This figure schematically shows diffusion of the exciton across the lattice.