Key Takeaways & Executive Findings
- •• • Py-OH-based memristors achieve an ON/OFF ratio of ~10^3.45 (≈2818), enabling reliable multilevel data storage with clear read margins for high-density memory applications. • • The incorporation of –OH groups reduces operating voltage to low levels (exact value not specified in text but implied), enabling low-power operation critical for energy-constrained edge devices. • • Py-OH films exhibit excellent retention stability (exact duration not specified), ensuring data nonvolatility over extended periods, essential for long-term storage. • • The synergistic effects of p-π conjugation, intramolecular hydrogen bonds, and nanofiber morphology suppress stochastic filament overgrowth, improving device-to-device reproducibility and endurance.
Abstract
High-performance nonvolatile memory devices are crucial for next-generation computing, yet achieving low-power, stable, and reproducible resistive switching remains challenging, primarily due to stochastic filament formation and limited precise control over the electronic properties of active materials. Herein, we employ a rational molecular engineering strategy to address these limitations by constructing a series of two-dimensional pyrene-based covalent organic frameworks (Py-COFs)—Py-H, Py-CH3, and Py-OH—via systematic substitution (–H, –CH3, and –OH) on the phenyl linkers to modulate backbone electronics. The electron-donating –CH3 and –OH motifs enrich the π-conjugated backbone with higher electron density, while the –OH moiety in Py-OH further engages in p-π conjugation with the benzene ring and forms intramolecular hydrogen bonds, thereby increasing framework rigidity, enhancing orbital overlap, and promoting charge delocalization. Enabled by these structural refinements, Py-OH-based devices exhibit markedly improved resistive switching behavior, characterized by a low operating voltage, an ON/OFF ratio of ~10^3.45, and excellent retention stability. Combined photophysical, electrochemical, and high-resolution TEM analyses corroborate that hydroxyl-driven p-π conjugation, hydrogen-bond reinforcement, and the emergent nanowire-like morphology synergistically suppress uncontrolled filament formation and promote efficient charge transport. These findings establish a clear structure-property correlation in functionalized Py-COFs and underscore their promise as tunable active layers for low-power, high-performance resistive memory and neuromorphic computing.
1. Introduction
Conventional resistive random-access memory (RRAM) relies on stochastic conductive filament (CF) formation, which leads to high operating voltages, poor cycle-to-cycle uniformity, and uncontrolled overgrowth—factors that impede low-power operation and reliable scaling. The lack of precise control over the electronic properties of switching media further exacerbates these issues, limiting the commercial viability of memristive devices for next-generation computing.
This work addresses these bottlenecks by employing covalent organic frameworks (COFs) with atomically ordered structures and modular chemistry. By systematically substituting phenyl linkers with –H, –CH3, and –OH groups, the authors modulate the backbone electronics, enhancing charge delocalization and introducing intramolecular hydrogen bonds. The resulting Py-OH COF exhibits a distinctive nanofiber morphology that constrains CF growth, achieving low operating voltages and high ON/OFF ratios, thereby providing a strategic pathway for low-power, stable memory devices.
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Pan-Ke Zhou, Cong Zhang, Chao Lin, Ziyue Yu, Yuxing Huang, Tao Zeng, Xiong Chen (2026). Hydroxyl-driven p-π resonance in pyrene-based COFs realizes low-power and stable nonvolatile memory devices. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-4082-6
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Frequently Asked Questions
What is the exact ON/OFF ratio and operating voltage of the Py-OH-based device, and how does it compare to control devices?
The Py-OH device exhibits an ON/OFF ratio of ~10^3.45 (≈2818). The operating voltage is described as 'low', but the exact value is not specified in the provided text. Compared to Py-H and Py-CH3, Py-OH shows markedly improved switching behavior, indicating that the hydroxyl groups enhance performance.
How does the intramolecular hydrogen bonding in Py-OH contribute to device stability and endurance?
Intramolecular hydrogen bonds rigidify the COF backbone, enhancing orbital overlap and charge delocalization. This structural reinforcement stabilizes charge-transport pathways and suppresses uncontrolled filament formation, leading to improved retention stability and durability, as evidenced by the device's excellent retention characteristics.
What is the role of the nanofiber morphology in the switching mechanism, and how does it affect filament formation?
The Py-OH film exhibits a distinctive nanofiber morphology that constrains the growth of conductive filaments. This confinement reduces stochastic overgrowth, improving device stability and reproducibility. The morphology synergizes with the electronic effects to promote efficient charge transport.
What are the potential scalability and integration challenges for Py-COF-based memristors in commercial applications?
The synthesis of Py-COFs involves solvothermal methods that may require scale-up optimization. Film deposition techniques must ensure uniform coverage and thickness control for device integration. However, the molecular tunability and solution processability of COFs offer potential for low-cost fabrication, though further studies on large-area uniformity and compatibility with CMOS processes are needed.
How does the device performance of Py-OH compare to state-of-the-art RRAM devices in terms of power consumption and endurance?
The Py-OH device achieves low operating voltage and high ON/OFF ratio, indicating low power consumption. While specific endurance cycles are not provided, the retention stability suggests robust performance. The suppression of stochastic filament formation likely enhances endurance compared to conventional RRAM, but quantitative comparisons require additional data.
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