Exciton
A neutral quasiparticle consisting of a conduction electron bound to a valence band hole by electrostatic Coulomb attraction.
Governing formula
E_exciton = E_g - E_b (where E_b = μ e⁴ / (8 ε² h² n²))
SI unit
eV (Binding Energy)
In depth
Formed when a photon is absorbed in a semiconductor or insulator. Excitons can transport energy through a crystal lattice without transporting net electric charge. Recombination of the electron and hole results in light emission.
Examples in the real world
Wannier-Mott excitons in inorganic semiconductors and Frenkel excitons in organic OLED materials.