Dielectric and Ferroelectric Surface-Mounted Metal-Organic Frameworks (SURMOFs) as Sensor Devices

• Applicants: Professor Dr. Michael Huth; Dr. Martin Kind; Professor Dr. Rochus Schmid
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 316711251

Tunability, porosity and conformational flexibility are key properties of metal-organic frameworks (MOFs). An emerging application field of this material class is their use in highly miniaturized sensor structures. The main goal of this project is the development of a novel sensor concept up to a proof-of-concept stage. The adsorption of analyte guest molecules in surface-mounted MOFs (SURMOFs), causing changes in their dielectric properties, is detected via associated modulations of the conductivity of a nanogranular metal (NGM) sensing layer. This sensing layer is part of a SURMOF/NGM heterostructure. NGMs are artificial materials comprising metallic nano-particles which are embedded in a non-conducting matrix. Their conduction mechanism is based on thermally assisted tunneling and depends sensitively on the dielectric environment. Pillared SURMOF systems with rotatable dipolar linker molecules will be grown onto the NGM, with defined crystallographic orientation to mediate a stabilized ferroelectric order. In another approach, the SURMOFs serve themselves as a non-conducting matrix for two-dimensional ordered arrays of metallic nano-dots. This design will facilitate the occurrence of sizable variations in the frequency-dependent dielectric permittivity of the SURMOF upon interaction with polar (and non-polar) guest molecules. In order to achieve this ambitious goal, the competence of three groups focusing on the synthesis and characterization of SURMOFs, the fabrication and electrical characterization of NGMs and the theoretical atomistic simulation of MOFs have been combined.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1928: Coordination Networks: Building Blocks for Functional Systems
• International Connection: Belgium, USA
• Cooperation Partners: Professor Dr. Igor Beloborodov; Toon Verstraelen