title: Orbital occupation in electron-charged CdSe quantum-dot solids.
abstract: We have prepared high-quality assemblies of monodisperse CdSe quantum dots and employed a combination of electrochemical gating and electrical and optical techniques to study orbital occupation in these quantum-dot solids. Electron occupation in localized states is important in some cases and can be unambiguously distinguished from occupation of the nanocrystal eigenstates. In addition, all excitonic transitions show a red-shift in the transition energy, due to the presence of electron charge. We infer that the energy of the S electrons is determined by the quantum-confinement energy and by Coulomb repulsions of the S electron with all other electrons in the assembly. By using a simple electron-repulsion model, we explain observed differences in the electron-addition energy for different samples, the broadening of the electron occupation as a function of electrochemical potential, and the strong dependence of the electron-addition energy on nanocrystal diameter.
authors.affiliation: Debye Institute, University Utrecht, POB 80000, 3508 TA Utrecht, The Netherlands. a.j.houtepen@phys.uu.nl
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: Houtepen
authors.forename: Daniël
authors.initials: D
authors.lastname: Vanmaekelbergh