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

The mechanism behind electrical memory behavior of carbazole-containing polyimides (PIs) in nanoscale thin films was investigated. For this investigation, a series of poly(3,3'-dihydroxy-4,4'-biphenylene-co-3,3'-bis(N-ethylenyloxycarbazole)-4,4'-biphenylene hexafluoro-isopropylidenedi-phthalimide)s (6F-HAB-HABCZn PIs) with various compositions was synthesized as a model carbazole-containing polymer system. The thermal properties, band gaps, and molecular orbital levels of the PIs were determined. Furthermore, the chemical compositions, as well as the nanoscale thin film morphologies and electron densities, were analyzed, providing detailed information on the population and positional distribution of carbazole moieties in thin films of the PIs. PI Devices were fabricated with aluminum electrodes and tested electrically. The PI thin film layers in the devices exhibited electrically permanent memory behavior, which was driven by trap-limited space-charge limited conduction and ohmic conduction. The permanent memory characteristics were found to be attributed to the incorporated carbazole moieties rather than from the other chemical components. Furthermore, the memory characteristics depended significantly on the population and positional distribution of carbazole moieties in the PI layer, as well as the film thickness. Considering that the backbone is not conjugated, the present results collectively indicate that the electrical switching behavior of the PI films is driven by the carbazole moieties acting as charge traps and a hopping process using the carbazole charge-trap sites as stepping-stones.

Nowadays, RFID is used to identify a wide range of work pieces or individual products for tracking their movements during the product life cycle. For future purposes the idea of storing only a single ID must be extended to a "Digital Product Memory". A Digital Product Memory provides a digital diary of the complete product life cycle and is embedded in the product itself. It records all relevant ambient parameters in digital form. Sensors note where and when an interaction with a product takes place. People can access these digital product diaries at any time. The autonomous behavior of the product memory makes it additionally possible to monitor and control the production and logistics of the product. In this paper we describe a flexible approach for product-driven manufacturing using a digital product memory to achieve minimum lot sizes and a reduced time to market.

Since the introduction of a concept of memristor by Leon Chua in 1971 as the fourth fundamental passive component in electronic circuits, and its functional prototype introduced by HP Lab in 2008, research has increasingly concentrated on exploring its application ability in electronic circuits. First, the memristor principles have been exploited in various memory devices within a classical von Neumann computer architecture. The properties of memristor were found particularly suitable for resistive random-access memories (ReRAM).1 Contrary to the classical von Neumann architecture based on the binary logic, advanced methods like neuromorphic computing require an electronic element with continuously varying states depending on previous input signals. The input signal consists of a sequence of voltage spikes that stimulate the device, similarly as a neural synapse does in biological systems. These trains of spikes change the output state of the device continuously to a lower resistance state, mimicking a learning process. Having these functionalities, memristors are considered to be possible building blocks of brain-inspired neuromorphic computing and artificial neural networks.2 Memristors with neurosynaptic functionality take a continuity of resistance values with synaptic weights modulated by the number and frequency of homogeneous spikes. In order to mimic the neural synapse, memristors must exhibit analog properties including non-abrupt switching transitions, memory loss, continuously variable resistance states, and predictable response. We present such functionality on thin films of two kinds of organic materials:(i) A newly synthesized poly(methacrylamide) derivative with carbazole charge transporting group separated from the polymer backbone by an alkyl chain, was synthesized recently and found to behave as a bistable resistive memory.3 Thin films of the polymer, sandwiched between Al and ITO electrodes, exhibit rewritable flash memory behavior with bistable conductivity, with the set switching voltage ranging from 2 to 4.5 V, and the current ON/OFF ratio exceeding 100. The device demonstrates a remarkable lifetime and remains persistent for more than 104 seconds under the static voltage of 0.5 V. The main physical mechanisms driving the resistive switching have been attributed to the electric field-induced reorientation of heterocycles, which modulates charge transport, and trapping/detrapping of charges in localized states within the bulk of the polymer. Memory persistence is strengthened by the physical crosslinking caused by hydrogen bonds between amide and carbonyl groups in the side chains. Depending on the layer thickness, electrode material and applied voltage range the electrical characteristics can change from bistable to analog behavior showing memristive properties.(ii) Ditopic π-conjugated bis-terpyridine (tpy-) ligands form supramolecular structures in which the ligands are interconnected by complexation with metal ions. These molecules offer a low energy operation with improved reproducibility of memristive characteristics. They possess low-lying molecular energy levels and relatively narrow bandgap enabling the low-power consuming resistive switching and longer stability. We used a newly synthesized bis-terpyridine ligands based on 9-phenyl carbazole, Cbz, and its complex with cobalt Co2+ as an active layer of a memristor device. A two-terminal memristor architecture was employed, consisting of the ligand or its cobalt complex deposited on an ITO substrate, and aluminum, gold, or gallium as a top electrode. We show that Cbz as a memristor active layer exhibits an excellent nonvolatile bistable memory behavior, while Co-Cbz exhibits both electronic memory and synaptic plasticity. The ligand exhibited bi-stable conduction and non-volatile memory effect with persistence over 18 hours, while its cobalt complex displayed a synaptic effect characterized by subsequent potentiation and depression cycles. Voltage-induced modulation of synaptic weight was observed with a low applied voltage below 500 mV and short pulse duration below 20 ms. Pair pulse facilitation and pair pulse depression demonstrated significant synaptic weight changes, showing the cobalt complex ability to emulate biological neurons. The operational mechanism was attributed to a combination of the redox effect in the ligand and complex, and to the voltage-induced migration of perchlorate counter ions and subsequent redox processes, altering the metal-to-ligand charge transfer band and changing the conducting state of the active layer.Acknowledgments: The work was financially supported by the Czech Science Foundation, project 24-10384S, and MEYS of the Czech Republic, project LUAUS24032. Strukov, D. B., Snider, G. S., Stewart, D. R. & Williams, R. S. The missing memristor found. Nature 453, 80–83 (2008).Chang, T., Jo, S. H. & Lu, W. Short-term memory to long-term memory transition in a nanoscale memristor. ACS Nano 5, 7669–7676 (2011).Panthi, Y.R, Pfleger, J., Vyprachticky, D., Pandey, A., Thottappali, M.A., Sedenkova, I., Konefal, M. & Foulger, S.H. Rewritable resistive memory effect in poly[N-(3-(9H-carbazol-9-yl)propyl)-methacrylamide] memristor. Mater. Chem. C 11, 17093 (2023).

Anomalous photoinduced absorption of conjugated polymer/fullerene mixtures at low temperatures and high frequencies

EDOT substitution site effect on fluorenone acceptor units: electrochemical polymerization and electrochromic properties of D-A systems

An electronic embodiment of a neural network based associative memory in the form of a binary connection matrix is described. The nature of false memory errors, their effect on the information storage capacity of binary connection matrix memories, and a novel technique to eliminate such errors with the help of asymmetrical extra connections are discussed. The stability of the matrix memory system incorporating a unique local inhibition scheme is analyzed in terms of local minimization of an energy function. The memory's stability, dynamic behavior, and recall capability are investigated using a 32-"neuron" electronic neural network memory with a 1024-programmable binary connection matrix.

Carbon quantum dots-based memristors (CQDMs) have emerged as a rising star in data storage and computing. The key constraint to their commercialization is memristance variability, which mainly arises from the disordered conductive paths. Doping methodology can optimize electron and ion transport to help construct a stable conductive mode. Herein, based on boron (B)-doped engineering strategy, three kinds of comparable quantum dots are synthesized, including carbon quantum dots (CQDs), a series of boron-doped CQDs (BCQDs) with different B contents, and boron quantum dots. The corresponding device performances highlight the superiority of BCQDs-based memristors, exhibiting a ternary flash-type memory behavior with longer retention time and more controllable memristance stability. The comprehensive analysis results, including device performance, functional layer morphology, and material simulated calculation, illustrate that the doped B elements can directionally guide the migration of aluminum ions by enhancing the capture of free electrons, resulting in ordered conductive filaments and stable ternary memory behavior. Finally, the conceptual applications of logic display and logic gate are discussed, indicating a bright prospect for BCQDs-based memristors. This work proves that modest B doping can optimize memristance property, establishing a theoretical foundation and template scheme for developing effective and stable CQDMs.

Two ambipolar and thermally stable poly(triphenylamine)s with pendent anthraquinone acceptors were readily synthesized and prepared for the investigation of side-chain and linkage-mediated effects on the memory behaviour.

Novel green light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide-arylamine derivatives

the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the active material with the work functions of the contacting electrodes is very important to the device performance. Electrically conductive indium tin oxide (ITO) is widely used as the electrode material in many different types of organic optoelectronic devices, such as organic light-emitting diodes (OLEDs) and organic solar cells (OSCs), due to its good light transmission property in the visible region. However, because the work function of ITO is near 4.7 eV, which usually does not match the molecular energy levels of most organic active materials, ITO electrodes generally cannot be used directly as a hole-selective (anode) or electronselective (cathode) electrodes in traditional organic devices. Instead, additional charge transporting layers are commonly deposited on top of the ITO layer to promote a more effi cient injection or extraction of holes or electrons. Typically, when ITO serves as an anode, a layer of e.g., copper phthalocyanine [ 8 ]

Recently, due to the development of semiconductor technology, high-performance memory and digital convergence technology that integrates and implements various functions into one semiconductor chip has been regarded as the next-generation core technology. In the semiconductor manufacturing process, various motors are being applied for automated processes and high product reliability. However, dust and shaft loss due to mechanical friction of a general motor system composed of motor-bearing are problematic for semiconductor wafer processing. In addition, in the edge bread remove (EBR) process after the photoresist application process, a nozzle position control system for removing unnecessary portions of the wafer edge is absolutely necessary. Therefore, in this paper, in order to solve the problems occurring in the semiconductor process, a six-degrees-of-freedom (6-DOF) magnetic levitation system without shaft and bearing was designed for application to the semiconductor process system; and an integrated driving control algorithm for 6-DOF control (levitation, rotation, tilt (Roll-Pitch), X-Y axis movement) using the force of each current component derived through current vector control was proposed. Finally, the 6-DOF magnetic levitation system with the non-contact position sensors was fabricated and the validity of the 6-DOF magnetic levitation control method proposed in this paper was verified through a performance test using a prototype.

We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 104 and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 104 s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

Memristive technologies are attractive due to their non-volatility, high-density, low-power and compatibility with CMOS. For memristive devices, a model corresponding to practical behavioral characteristics is highly favorable for the realization of its neuromorphic system and applications. This paper presents a novel flexible memristor model with electronic resistive switching memory behavior. Firstly, the Ag-Au / MoSe2-doped Se / Au-Ag memristor is prepared using hydrothermal synthesis method and magnetron sputtering method, and its performance test is conducted on an electrochemical workstation. Then, the mathematical model and SPICE circuit model of the Ag-Au / MoSe2-doped Se / Au-Ag memristor are constructed. The model accuracy is verified by using the electrochemical data derived from the performance test. Furthermore, the proposed model is applied to the circuit implementation of spiking neural network with biological mechanism. Finally, computer simulations and analysis are carried out to verify the validity and effectiveness of the entire scheme.

Using light-emitting complex Ir(mppy)3 to detect acetone from 0.5 to 100 ppm by vertical-channel gas sensor

Hole injection governs the efficiency of ultraviolet organic light-emitting diodes (UV OLEDs) due to the deep highest occupied molecular orbital level of the emissive molecule. Tungsten oxides (WOx), transition metal oxides with high work functions and good stability, cast light on solving this problem. By a low-cost, scalable and high-throughput manufacturing process, herein the facile synthesis of a WOx solution and its doping in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS + WOx) is systematically investigated for assembling efficient UV OLEDs. X-ray diffraction, atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy measurements confirm that WOx and PEDOT:PSS + WOx have good film morphology and exceptional electronic properties, such as the oxygen deficiency dominated non-stoichiometry of WOx. With PEDOT:PSS + WOx tailoring hole injection and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as the emitter, the UV OLEDs show outstanding electro-optic performance, with a radiance of 3.98 mW cm-2, external quantum efficiency of 2.30%, electroluminescence peak at 400 nm and full width at half maximum of 47 nm, which is superior to the performance of the corresponding reference materials. The mechanism of charge transfer from the PEDOT polycation to WOx, enhancing conductivity, is responsible for the robust hole injection/transport and is further elucidated by ultraviolet photoelectron spectroscopy and impedance spectroscopy, contributing to the optimization of the carrier balance and recombination zone. Our results illustrate an alternative approach for boosting UV OLED performance and advancing organic electronics.