Tunable Electrical Conductivity in Metal-Organic Framework Thin-Film Devices

Abstract

We report a strategy for realizing tunable electrical conductivity in metal-organic frameworks (MOFs) in which the nanopores are infiltrated with redox-active, conjugated guest molecules. This approach is demonstrated using thin-film devices of the MOF Cu3(BTC)2 (also known as HKUST-1; BTC, benzene-1,3,5-tricarboxylic acid) infiltrated with the molecule 7,7,8,8-tetracyanoquinododimethane (TCNQ). Tunable, air-stable electrical conductivity over six orders of magnitude is achieved, with values as high as 7 siemens per meter. Spectroscopic data and first-principles modeling suggest that the conductivity arises from TCNQ guest molecules bridging the binuclear copper paddlewheels in the framework, leading to strong electronic coupling between the dimeric Cu subunits. These ohmically conducting porous MOFs could have applications in conformal electronic devices, reconfigurable electronics, and sensors.

A Dual−Ion Battery Cathode via Oxidative Insertion of Anions in a Metal–Organic Framework

“…Unfortunately, the large ionic radii of these weakly coordinating anions necessitate substantial changes in the unit cell volume of the electrode material upon oxidative insertion. For graphite, 15,16, and 20% increases in cell volume were observed upon intercalation of BF 4 − , PF 6 − , and TFSI − , respectively. 8 Certain conducting organic polymers can not only be reversibly oxidized through a similar mechanism but also swell substantially upon insertion.…”

Chemical principles for electroactive metal–organic frameworks

“…A related process is the ability to "rewire" an insulating MOF though an auxiliary electroactive linker. The champion system in this regard is HKUST-1 modified with the molecule TCNQ (7,7,8,8-tetracyanoquinododimethane) that provided a route to tunable conductivity 42 . In the recent work of Allen and Cohen, cross-linking in a series of isorecticular MOFs was demonstrated 21 , which could be extended to install conductive pathways for a wider range of MOF topologies.…”

(TTF)Pb2I5: A Radical Cation-Stabilized Hybrid Lead Iodide with Synergistic Optoelectronic Signatures

“…9 Metal-organic-frameworks (MOFs), a related class of hybrid materials, generally possess poor electronic functionality, but attempts to prepare electrically conductive MOFs have recently been made. Examples include incorporating a conjugated molecule within the framework directly, 10 as a guest that electronically couples metal atoms in the framework using (TCNQ), 11 or post-synthetic modification of an insulating MOF via chemical leaching. 12,13 Stavila et al 14 have recently reviewed this topic.…”