Nonvolatile Unipolar and Bipolar Bistable Memory Characteristics of a High Temperature Polyimide Bearing Diphenylaminobenzylidenylimine Moieties

Methyl Methacrylate Copolymer with Pendant Thioxanthenone Groups as Active Layer for Resistive Memory Devices

An electro-active copolymer of methyl methacrylate and 2-((4-acroylpiperazine-1-yl)methyl)-9H-thioxanthene-9-one (poly(MMA-co-ThS)) was synthesized by radical polymerization. The copolymer has good solubility in most organic solvents, thermal stability up to 282 °C and excellent ability to form thin films on silicon wafers. Poly(MMA-co-ThS) films exhibited an electrochemical and electrochromic activity resulting in the formation of long-lived radical anion states of pendant thioxanthone groups inside the film. These states exhibit optical transitions in the visible region as a broad optical absorption band, 500<λ<900 nm (1.38 Collapse

Key Words

• Charge transport
• Memristor
• Organic polymers
• Pendant groups
• Spectroelectrochemistry

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MESH Headings Collapse

Grants

• 22-13-00108 Russian Science Foundation
• 3616/6-2 Deutsche Forschungsgemeinschaft

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Affiliation(s)

Danila S Odintsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Andrei A Gismatulin Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Inna K Shundrina Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Alexandra D Buktoyarova Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Irina A Os'kina Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Jens Beckmann Institute for Inorganic Chemistry and Crystallography, University of Bremen, 28359, Bremen, Germany
Ivan A Azarov Novosibirsk State University, 630090, Novosibirsk, Russian Federation
Ekaterina V Dementeva 194021, Saint Petersburg, Russian Federation
Leonid A Shundrin Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
Vladimir A Gritsenko Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation Novosibirsk State Technical University, 630073, Novosibirsk, Russian Federation

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Main chain copolysiloxanes with terthiophene and perylenediimide units: synthesis, characterization and electrical memory

A main chain donor–acceptor copolysiloxane PBIClSi-alt-PTSi for resistor type memory has been designed and synthesized. The PBIClSi-alt-PTSi possesses high thermal stability and shows nonvolatile write-once-read many times (WORM) memory characteristics.

Design and synthesis of hyperbranched polyimide containing multi-triphenylamine moieties for memory devices

A hyperbranched polyimide (HBPI) was synthesized from a designed triamine monomer and the HBPI based memory device presented SRAM (static random access memory) behavior with a low switch voltage and high ON/OFF current ratio.

Digital memory versatility of fully π-conjugated donor-acceptor hybrid polymers

The fully π-conjugated donor-acceptor hybrid polymers Fl-TPA, Fl-TPA-TCNE, and Fl-TPA-TCNQ, which are composed of fluorene (Fl), triphenylamine (TPA), dimethylphenylamine, alkyne, alkyne-tetracyanoethylene (TCNE) adduct, and alkyne-7,7,8,8-tetracyanoquinodimethane (TCNQ) adduct, were synthesized. These polymers are completely amorphous in the solid film state and thermally stable up to 291-409 °C. Their molecular orbital levels and band gaps vary with their compositions. The TCNE and TCNQ units, despite their electron-acceptor characteristics, were found to enhance the π-conjugation lengths of Fl-TPA-TCNE and Fl-TPA-TCNQ (i.e., to produce red shifts in their absorption spectra and significant reductions in their band gaps). These changes are reflected in the electrical digital memory behavior of the polymers. Moreover, the TCNE and TCNQ units were found to diversify the digital memory modes and to widen the active polymer layer thickness window. In devices with aluminum top and bottom electrodes, the Fl-TPA polymer exhibits stable unipolar permanent memory behavior with high reliability. The Fl-TPA-TCNE and Fl-TPA-TCNQ devices exhibit stable unipolar permanent memory behavior as well as dynamic random access memory behavior with excellent reliability. These polymer devices were found to operate by either hole injection or hole injection along with electron injection, depending on the polymer composition. Overall, this study demonstrated that the incorporation of π-conjugated cyano moieties, which control both the π-conjugation length and electron-accepting power, is a sound approach for the design and synthesis of high-performance digital memory polymers. The TCNE and TCNQ polymers synthesized in this study are highly suitable active materials for the low-cost mass production of high-performance, polarity-free, programmable, volatile, and permanent memory devices that can be operated with very low power consumption, high ON/OFF current ratios, and high reliability.

Polymer-based resistive memory materials and devices

Due to the advantages of good scalability, flexibility, low cost, ease of processing, 3D-stacking capability, and large capacity for data storage, polymer-based resistive memories have been a promising alternative or supplementary devices to conventional inorganic semiconductor-based memory technology, and attracted significant scientific interest as a new and promising research field. In this review, we first introduced the general characteristics of the device structures and fabrication, memory effects, switching mechanisms, and effects of electrodes on memory properties associated with polymer-based resistive memory devices. Subsequently, the research progress concerning the use of single polymers or polymer composites as active materials for resistive memory devices has been summarized and discussed. In particular, we consider a rational approach to their design and discuss how to realize the excellent memory devices and understand the memory mechanisms. Finally, the current challenges and several possible future research directions in this field have also been discussed.

Resistive switching of Au/ZnO/Au resistive memory: an in situ observation of conductive bridge formation

A special chip for direct and real-time observation of resistive changes, including set and reset processes based on Au/ZnO/Au system inside a transmission electron microscope (TEM), was designed. A clear conducting bridge associated with the migration of Au nanoparticles (NPs) inside a defective ZnO film from anode to cathode could be clearly observed by taking a series of TEM images, enabling a dynamic observation of switching behaviors. A discontinuous region (broken region) nearby the cathode after reset process was observed, which limits the flow of current, thus a high resistance state, while it will be reconnected to switch the device from high to low resistance states through the migration of Au NPs after set process. Interestingly, the formed morphology of the conducting bridge, which is different from the typical formation of a conducting bridge, was observed. The difference can be attributed to the different diffusivities of cations transported inside the dielectric layer, thereby significantly influencing the morphology of the conducting path. The current TEM technique is quite unique and informative, which can be used to elucidate the dynamic processes in other devices in the future.

Local electrical modification of a conductivity-switching polyimide film formed by molecular layer deposition

The electrical modification of a conductivity-switching polyimide film via molecular layer deposition (MLD) is studied for ultrahigh density data storage based on a scanning probe microscope (SPM). A PMDA-ODA (PMDA = 1, 2, 3, 5-benzenetetracarboxylic anhydride, ODA = 4, 4-oxydianiline) film as a recording medium is uniformly formed from a self-assembled monolayer on a Au surface by MLD. It is demonstrated that the conductivity of the film can be changed by applying a voltage between a SPM probe and the film. This conductivity-switching phenomenon is discussed by the molecular orbital approach and considered to be caused by the charge transfer effect or carrier trapping effect of PMDA-ODA.

High temperature polyimide containing anthracene moiety and its structure, interface, and nonvolatile memory behavior

A high temperature polyimide bearing anthracene moieties, poly(3,3'-di(9-anthracenemethoxy)-4,4'-biphenylene hexafluoroisopropylidenediphthalimide) (6F-HAB-AM PI) was synthesized. The polymer exhibits excellent thermal stability up to around 410 °C. This polymer is amorphous but orients preferentially in the plane of nanoscale thin films. In device fabrications of its nanoscale thin films with metal top and bottom electrodes, no diffusion of the metal atoms or ions between the polymer and electrodes was found; however, the aluminum bottom electrode had somewhat undergone oxide layer (about 1.2 nm thick) formation at the surface during the post polymer layer formation process, which was confirmed to have no significant influence on the device performance. The polymer thin film exhibited excellent unipolar and bipolar switching behaviors over a very small voltage range, less than ±2 V. Further, the PI films show repeatable writing, reading, and erasing ability with long reliability and high ON/OFF current ratio (up to 10(7)) in air ambient conditions as well as even at temperatures up to 200 °C.