Understanding the transport of electrons
in films of touching nanocrystals is of central importance for their
future use in printed electronic devices such as light emitting diodes, solar
cells, or transistors. The research team developed a new theory that describes
the transition of the electron conduction in doped nanocrystal films from a semiconducting to a
metallic behavior. The theory predicts that the transition occurs under
strikingly different conditions from those previously known for bulk
semiconductors. Associated experimental studies of the electron conduction in phosphorous-doped
silicon nanocrystal films largely support the new
theory. This study was reported in Nature Materials.
transition in nanocrystal films occurs when the spatial
spread of the electron wave function, described by the inverse Fermi vector kF-1, allows the electron to pass
through a contact with diameter 2ρ. Measurements of the electron
localization length ξ support the theory.