Tuning the Electrical Conductivity of a Flexible Fabric-Based Cu-HHTP Film through a Novel Redox Interaction between the Guest-Host System.

Integration of metal-organic frameworks (MOFs) and flexible fabrics has been recently considered as a promising strategy applied in wearable electronic devices. We synthesized a flexible fabric-based Cu-HHTP film consisted of Cu2+ ions and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) via a self-sacrificial template method. The obtained Cu-HHTP film displays an outstanding nanostructured surface and uniformity. Iodine molecules are first introduced into the pores of Cu-HHTP to investigate the influence of guest molecules on electrical conductivity in a 2D guest-host system. After doping, the conductivity of the Cu-HHTP film shows an increased dependent on the doping time, and the maximum value is more than 30 times that of the original MOFs. The enhanced electrical conductivity results from an intriguing redox interaction occurred between the confined iodine molecules and the framework. The organic ligands are oxidized by iodine molecules, and generating new ions allows for subsequent participation in the regulation of the mixed valence bands of copper ions in MOFs, changing the ratio of Cu2+/Cu+, promoting the charge transport of the framework, and then synergistically enhancing the electronic conductivity. This study successfully prepared a flexible fabric-based conductive I2@Cu-HHTP film and presented insights into revealing the behavior of iodine molecules after entering the Cu-HHTP pores, expanding the possibilities of Cu-HHTP used in flexible wearable electronics.

Greatly increased electrical conductivity of PBTTT-C14 thin film via controllable single precursor vapor phase infiltration.

Doping is an important strategy for effectively regulating the charge carrier concentration of semiconducting materials. In this study, the electronic properties of organic-inorganic hybrid semiconducting polymers, synthesized viain situcontrolled vapor phase infiltration (VPI) of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT-C14) with the metal precursors molybdenum pentachloride (MoCl5) and titanium tetrachloride (TiCl4), were altered and characterized. The conductivities of the infiltration-doped PBTTT-C14 thin films were enhanced by up to 9 and 4 orders of magnitude, respectively. The significantly improved electrical properties may result from interactions between metal atoms in the metal precursors and sulfur of the thiophene rings, thus forming new chemical bonds. Importantly, VPI doping has little influence on the structure of the PBTTT-C14 thin films. Even if various dopant molecules infiltrate the polymer matrix, the interlayer spacing of the films will inevitably expand, but it has negligible effects on the overall morphology and structure of the film. Also, Lewis acid-doped PBTTT-C14 thin films exhibited excellent environmental stability. Therefore, the VPI-based doping process has great potential for use in processing high-quality conductive polymer films.