Exciton
An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force.
Explanation
It is an electrically neutral quasiparticle that exists in insulators, semiconductors and some liquids. The electron and the electron hole have opposite electrical charges. The exciton is regarded as an elementary excitation of condensed matter that can transport energy without transporting net electric charge.