title: Tunneling Electrical Connection to the Interior of Metal-Organic Frameworks.
abstract: Metal-organic frameworks (MOFs) are typically poor electrical conductors, which limits their uses in sensors, fuel cells, batteries, and other applications that require electrically conductive, high surface area materials. Although metal nanoclusters (NCs) are often added to MOFs, the electrical properties of these hybrid materials have not yet been explored. Here, we show that adding NCs to a MOF not only imparts moderate electrical conductivity to an otherwise insulating material but also renders it photoconductive, with conductivity increasing by up to 4 orders of magnitude upon light irradiation. Because charge transport occurs via tunneling between spatially separated NCs that occupy a small percent of the MOF's volume, the pores remain largely open and accessible. While these phenomena are more pronounced in single-MOF crystals (here, Rb-CD-MOFs), they are also observed in films of smaller MOF crystallites (MIL-53). Additionally, we show that in the photoconductive MOFs, the effective diffusion coefficients of electrons can match the typical values of small molecules diffusing through MOFs; this property can open new vistas for the development of MOF electrodes and, in a wider context, of electroactive and light-harvesting MOFs.
authors.forename: Shuangbing
authors.initials: S
authors.lastname: Han
authors.affiliation: §Department of Chemistry and Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Warren
authors.affiliation: ∥IBS Center for Soft and Living Matter and the Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea.
authors.forename: Seok Min
authors.initials: SM
authors.lastname: Yoon
authors.forename: Christos D
authors.initials: CD
authors.lastname: Malliakas
authors.forename: Xianliang
authors.initials: X
authors.lastname: Hou
authors.forename: Yanhu
authors.initials: Y
authors.lastname: Wei
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis
authors.affiliation: ∥IBS Center for Soft and Living Matter and the Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea.
authors.forename: Bartosz A
authors.initials: BA
authors.lastname: Grzybowski