A new type of quasiparticle has been predicted by Anna Kauch and colleagues at Technical University Vienna in Austria. Using computer simulations, the team concluded that the “π-ton” (pronounced pie-ton) is created by the bonding between two electron-hole pairs in semiconductor-like materials. The researchers now hope that π-tons could soon be studied in real experiments and even put to work in photovoltaics.
Quasiparticles are particle-like excitations that emerge from the collective behaviour of electrons and other entities in solids. They include polaritons, which arise from the interaction between electrons and light and excitons that are created when an electron in a semiconductor’s valence band is excited by a photon to the conduction band. In the electron’s place, a positively charged “hole” is left behind in the valence band, which the electron remains strongly attracted to. The electron-hole pair behaves like a particle – an exciton.
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