Selenium-Substitution Strategy for Enhanced Mobility, Tunable Bandgap, and Improved Electrochemical Energy Storage in Semiconducting Conjugated Coordination Polymers.

Conjugated coordination polymers (c-CPs), a novel class of organic-inorganic hybrid materials, are distinguished by their unique structural characteristics and exceptional charge transport properties. The electronic properties of these materials are critically determined by the constituting coordination atoms, with electron-rich selenol ligands emerging as promising candidates for constructing high-mobility semiconducting c-CPs. Currently, c-CPs incorporating selenium-substituted ligands remain scarce. In this study, we successfully synthesized a new tetraseleno-hydroxyquinone (TSHQ) ligand using a "4+2" design strategy and developed a semiconducting three-dimensional Ag-Se coordination polymer, Ag4TSHQ. Ag4TSHQ exhibits room-temperature electrical conductivity of up to 1.6 S/m and shares the same structural topology as Ag4TTHQ (TTHQ = tetrathiol-hydroxyquinone), enabling precise bandgap modulation from 0.6 eV to 1.5 eV via a mixed-ligand approach. Time-resolved terahertz spectroscopy reveals that the charge mobility of Ag4TSHQ in the dc limit is ~350 cm2/V⋅s, which is twice that of its sulfur counterpart, Ag4TTHQ. Furthermore, our evaluations of their electrochemical energy storage capabilities demonstrate that Ag4TSHQ effectively utilizes its redox potential, achieving a remarkable specific capacitance of up to 340 F/g-significantly outperforming Ag4TTHQ, which has a capacitance of 294 F/g. These findings underscore the potential of selenium-ligand-based c-CPs for optoelectronic applications and energy storage technologies.