title: Controlling band gap energies in cluster-assembled ionic solids through internal electric fields.
abstract: Assembling ionic solids where clusters are arranged in different architectures is a promising strategy for developing band gap-engineered nanomaterials. We synthesized a series of cluster-assembled ionic solids composed of [As(7)-Au(2)-As(7)](4-) in zero-, one-, and two-dimensional architectures. Higher connectivity is expected to decrease the band gap energy through band broadening. However, optical measurements indicate that the band gap energy increases from 1.69 to 1.98 eV when moving from zero- to two-dimensional assemblies. This increase is a result of the local electric fields generated by the adjacent counterions, which preferentially stabilize the occupied cluster electronic states.
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Nirmalya K
authors.initials: NK
authors.lastname: Chaki
authors.forename: Sukhendu
authors.initials: S
authors.lastname: Mandal
authors.forename: Arthur C
authors.initials: AC
authors.lastname: Reber
authors.forename: Meichun
authors.initials: M
authors.lastname: Qian
authors.forename: Hector M
authors.initials: HM
authors.lastname: Saavedra
authors.forename: Paul S
authors.initials: PS
authors.lastname: Weiss
authors.forename: Shiv N
authors.initials: SN
authors.lastname: Khanna
authors.forename: Ayusman
authors.initials: A
authors.lastname: Sen