Redox Switching Behavior in Resistive Memory Device Designed Using a Solution-Processable Phenalenyl-Based Co(II) Complex: Experimental and DFT Studies

Abstract

We herein report a novel square-planar complex [Co II L], which was synthesized using the electronically interesting phenalenyl-derived ligand LH 2 = 9,9′-(ethane-1,2-diylbis-(azanediyl))bis(1H-phenalen-1-one). The molecular structure of the complex is confirmed with the help of the single-crystal X-ray diffraction technique. [Co II L] is a mononuclear complex where the Co(II) ion is present in the square-planar geometry coordinated by the chelating bis-phenalenone ligand. The solid-state packing of [Co II L] complex in a crystal structure has been explained with the help of supramolecular studies, which revealed that the π•••π stacking present in the [Co II L] complex is analogous to the one present in tetrathiafulvalene/tetracyanoquinodimethane charge transfer salt, well-known materials for their unique charge carrier interfaces. The [Co II L] complex was employed as the active material to fabricate a resistive switching memory device, indium tin oxide/Co II L/Al, and characterized using the write-read-erase-read cycle. The device has interestingly shown a stable and reproducible switching between two different resistance states for more than 2000 s. Observed bistable resistive states of the device have been explained by corroborating the electrochemical characterizations and density functional theory studies, where the role of the Co II metal center and π-conjugated phenalenyl backbone in the redox-resistive switching mechanism is proposed.

A closed-shell phenalenyl-based dinuclear iron(iii) complex as a robust cathode for a one-compartment H2O2 fuel cell

“…28 Furthermore, we utilized a Co( ii ) complex with a closed-shell cationic state of PLY to construct a resistive switching memory device. 33 As a part of our continued interest in exploring PLY-based metal complexes, we herein report a new PLY precursor moiety, 9-hydrazineyl-1 H -phenalen-1-one (Hz-PLY), which is further functionalized to design the first PLY-based Schiff base ligand, ( E )-9-(2-(2-hydroxy-3-methoxybenzylidene)hydrazineyl)-1 H -phenalen-1-one (hmbh-PLYH 2 ). Utilizing this approach, we introduced the PLY moiety into the class of Schiff base ligands in this report.…”

Designing one-compartment H2O2 fuel cell using electroactive phenalenyl-based [Fe2(hnmh-PLY)3] complex as the cathode material

“…24,25 Indeed, the high resonance stabilization energy associated with the highly symmetrical (D 3 h) PLY framework contributes to observed unique redox states. 26 In addition, the presence of a unique NBMO (nonbonding molecular orbital) and interesting molecular orbital overlap, which facilitate intermolecular charge transfer in the solid state, make PLY a suitable candidate for designing electronic devices 27,28 and cathode materials. [29][30][31] The cationic form of PLY, also known as closed-shell PLY, can form via metal coordination, which under an applied potential can accept electrons and generate in situ PLY radical species (open-shell).…”

Coexistence of Electrochromism and Bipolar Nonvolatile Memory in a Single Viologen

“…A resistive random-access memory (RRAM) device can change its electrical resistance from high to low values or vice versa in response to an applied bias. − Though the dicationic viologens are employed for integrating RRAM devices, however, monocationic radicals that are formed in response to the electric field are prone to dimerization due to the π–π stacking and pairing of the electron spins of each monomer unit, thus hampering the multifunctional activities including memory switching and electrochromic functions . This prompts us to design and synthesize different viologens with bulky substituents to suppress the dimer formation in response to an electric field.…”