On-Demand Tunable Electrical Conductance Anisotropy in a MOF-Polymer Composite

Abstract

Property optimization through orientation control of metal-organic framework (MOF) crystals that exhibit anisotropic crystal structures continues to garner tremendous interest. Herein, an electric field is utilized to post-synthetically control the orientation of conductive layered Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) crystals dispersed in an electronically insulating poly(ethylene glycol) diacrylate (PEGDA) oligomer matrix. Optical and electrical measurements are performed to investigate the impact of the electric field on the alignment of Cu3(HHTP)2 crystals and the formation of aggregated microstructures, which leads to an approximate to 5000-fold increase in the conductivity of the composite. Notably, the composite thin-films containing aligned Cu3(HHTP)2 crystals exhibit significant conductivity of approximate to 10-3 S cm-1 despite the low concentration (approximate to 1 wt.%) of conductive Cu3(HHTP)2. The use of an electric field to align Cu3(HHTP)2 crystals can rapidly generate various desired patterns that exhibit on-demand tunable collective charge transport anisotropy. The findings provide valuable insights toward the manipulation and utilization of conductive MOFs with anisotropic crystal structures for various applications such as adhesive electrical interconnects and microelectronics. Using E-field, the alignment of conductive Cu3(HHTP)2 in PEGDA yields a 5000-fold increase in the electrical conductivity of the composite. Despite a low content (approximate to 1 wt.%) of Cu3(HHTP)2, the aligned crystals provide long-range charge transport channels, resulting in a significant conductivity (approximate to 10-3 S cm-1). The technique enables facile patterning, useful for developing electrical interconnects and microelectronics based on porous conductors.image