Rheoreversible metallosupramolecular soft-nanostructure of Cd(II) for fabricating thin-film based semiconducting device

Abstract

Self-assembly based supramolecular soft-network of Cd(II)-metallogel (i.e., Cd-PDCA) of Cd(II)-acetate salt and 2,6-pyridinedicarboxylic acid (PDCA) has been successfully achieved through instant mixing protocol at ordinary conditions. 2,6-pyridinedicarboxylic acid is used as a low molecular weight gelator (LMWG) and DMF is utilized as a gel-immobilized polar aprotic solvent for the preparation of mechanically-stable Cd-PDCA. A specific stoichiometry of Cd(II) and PDCA (i.e., 1:1, having [Cd(II)-salt] = 0.02 mM and [PDCA] = 0.02 mM) was maintained by experimentally obtained minimum critical gelation (MCG) concentration values. The mechanical properties of the synthesized Cd-PDCA metallogel are explored through rheological measurements (involving frequency sweep, strain sweep, and thixotropic measurements). The strain sweep based rheological study explores that experimentally determined value of critical shear strain for the Cd-PDCA metallogel is 1.56 %. The material shows excellent thixotropic features with multiple cycles as found in time sweep-based experimental observation. Morphological features of the xerogel sample of metallogel are opened through collecting FESEM image depicting the nano-structural patterns of the metallogel-forming network. EDAX elemental detection is also performed to know the involvement of all chemical components playing crucial role in the construction of metallogel soft-scaffold. Critical effect by pyridylamine-mediated chemo-responsiveness of Cd-PDCA metallogel is also tested through visual observation and FESEM morphological imaging. Moreover, the stimuli-responsiveness of the metallogel is also executed by applying various external stimuli such as ultra-sonication, mechanical agitation through vortex, followed by subsequent rest, heating effect, UV-light exposure, and repercussion by diverse chemicals like ammonia and acetic acid. FT-IR, and ESI-Mass spectrometric analyses are performed to establish the metallogel-fabricating mechanistic technique. Schottky barrier diode aptitudes of the Cd-PDCA metallogel are also examined by means of Al/Cd-PDCA metallogel/ITO sandwich type device-fabrication strategy. The metallogel-based device effectively shows excellent I-V features with conductivity as 1.002 ×10-5 Sm-1 and a high ON/OFF ratio of 27.78 at dark conditions. The fabricated device shows a remarkable ideality factor of 2.30. Charge transport parameter like carrier mobility (μeff) of the device is found as 3.86×10-6 m2v-1s-1.