Electrical Transport in Colloidal Quantum Dot Films

In nanocrystal solids, the small density of states of quantum dots makes it difficult to achieve metallic conductivity without band-like transport However, to achieve band-like transport, the energy scale of the disorder should be smaller than the coupling energy. This is unlikely with the present systems due to the size polydispersivity. Transport by hopping may nevertheless lead to an increased mobility with decreasing temperature for some temperature range; and such behavior at finite temperature is not proof of band like conduction. To date, at low temperature, variable range hopping in semiconductor or weakly coupled metal nanocrystal solids dominates transport, as in disordered semiconductors.