Design and Synthesis of Solution-Processable Donor–Acceptor Dithienophosphole Oxide Derivatives for Multilevel Organic Resistive Memories

Abstract

A class of solution-processable, donor–acceptor-decorated dithienophosphole oxide derivatives has been successfully synthesized and employed to fabricate solution-processed resistive memory devices with a simple indium–tin oxide/active layer/aluminum structure. The intramolecular charge transfer (ICT) characters of the donor–acceptor dithienophosphole oxide derivatives were established from photophysical, solvatochromic, and computational studies. The number of conductance states in the organic memory devices was found to be altered by slight changes in molecular structures. The mechanism for the tristable memory property of the devices was proposed based on the correlation of the extent of ICT characters and the computed structural parameters of the compounds, current–voltage characteristics of the devices and the fitting to theoretical conduction models. These findings offer important insights for the realization of multilevel resistive memory devices through the modification of the ICT character of the active compounds.

Synthesis, Characterization, Supramolecular Self-Assembly, and Organic Resistive Memory Applications of BODIPY Derivatives

“…Similar XRD patterns have been observed in the thin film of compound 6 , in which an intense peak at 1.68° corresponding to a d -spacing of 52.52 Å and two broad peaks from 17.68° to 24.23° and from 27.04° to 29.58° corresponding to d -spacings from 5.01 Å to 3.67 Å and from 3.29 Å to 3.02 Å, respectively, are observed. Such strong intermolecular alkyl–alkyl and π–π stacking interactions are believed to contribute to the facilitation of better molecular packing and film formation, leading to smoother surface of the films, which can be beneficial to the resistive memory performance (vide infra). , In-plane and out-of-plane grazing incidence X-ray diffraction (GIXRD) measurements have also been employed to investigate the orientation of the molecules in the spin-coated films of the representative compounds (Figures S23c–S23f in the Supporting Information). An intense peak at 1.47° and two broad peaks at 21.42° and 28.26°, corresponding to d -spacings of 60.02, 4.1, and 3.2 Å, respectively, for compound 3 , and an intense peak at 1.59° and two broad peaks at 21.68° and 27.33°, corresponding to d -spacings of 55.49, 4.1, and 3.3 Å for compound 6 in the out-of-plane diffraction patterns have been observed, similar to those observed in the XRD experiments for the thin films of compounds 3 and 6 .…”

Exploiting coordination geometry to tune the dimensions and processability of metallosupramolecular polymers

“…18,19 Nevertheless, some major challenges still hamper the progress of supramolecular polymers towards application, particularly in terms of finding the right balance between aggregation and solubility, 13,20,21 which largely controls processability. 22,23 Accordingly, design strategies that can attenuate initial steric hindrance and allow for a more controllable self-assembly process while preserving solubility and desired functional properties are a central goal in supramolecular chemistry. 24,25 Recently, we have demonstrated that the coordination geometry serves to control molecular preorganization events that, in turn, regulate the packing modes, energy landscapes and luminescence of metallosupramolecular polymers (Scheme S3 †).…”

Synthesis of benzo[b]phosphole‐based alkynylgold(I) complexes with resistive memory properties modulated by donor–acceptor chromophores

“…On the other hand, phosphole, being an organic molecular compound or as a ligand for coordination to various transition metal centers, has received increasing research interests in the past decade 14,44–60 . Desirable properties, such as tunable electrochemical characteristics, facile molecular functionalization and intermolecular packing have been observed in various classes of phosphole moieties, allowing the design of smart materials in the fields of organic electronics, 14,52,59,60 photochromism, 44,54 chemosensing, 50,51,56 and supramolecular chemistry 48,53,55,57 .…”

“…On the other hand, phosphole, being an organic molecular compound or as a ligand for coordination to various transition metal centers, has received increasing research interests in the past decade 14,44–60 . Desirable properties, such as tunable electrochemical characteristics, facile molecular functionalization and intermolecular packing have been observed in various classes of phosphole moieties, allowing the design of smart materials in the fields of organic electronics, 14,52,59,60 photochromism, 44,54 chemosensing, 50,51,56 and supramolecular chemistry 48,53,55,57 . Recent examples have also shown that the incorporation of electron‐accepting phosphole oxide unit can lead to favorable effect on the resultant organic resistive memories, including the lowering of turn‐on voltage ( V th ), stabilization of the resistive states and generation of multilevel memory behavior 14,59,60 .…”

“…Desirable properties, such as tunable electrochemical characteristics, facile molecular functionalization and intermolecular packing have been observed in various classes of phosphole moieties, allowing the design of smart materials in the fields of organic electronics, 14,52,59,60 photochromism, 44,54 chemosensing, 50,51,56 and supramolecular chemistry 48,53,55,57 . Recent examples have also shown that the incorporation of electron‐accepting phosphole oxide unit can lead to favorable effect on the resultant organic resistive memories, including the lowering of turn‐on voltage ( V th ), stabilization of the resistive states and generation of multilevel memory behavior 14,59,60 . These attractive spectroscopic properties and potential functionalization by the integration of the gold(I) metal center and alkynyl moieties into the phosphole framework may warrant an exploration of this class of complexes to function as resistive memory materials, given the tunability of the phosphole acceptor ability by the Lewis acidity of Au(I) and its possible perturbation and fine‐tuning via the incorporation of various auxiliary alkynyl ligands.…”