Optically Controllable Organic Logic-in-Memory: An Innovative Approach toward Ternary Data Processing and Storage

Multifunctional In-Memory Logics Based on a Dual-Gate Antiambipolar Transistor toward Non-von Neumann Computing Architecture

In-memory computing may make it possible to realize non-von Neumann computing because the logic circuits are unified in the memory units. We investigated two types of in-memory logic operations, namely, two-input logic circuits and multifunctional artificial synapses. These were realized in a dual-gate antiambipolar transistor (AAT) with a ReS2/WSe2 heterojunction, in which polystyrene with a zinc phthalocyanine core (ZnPc-PS4) was incorporated as a memory layer. Here, reconfigurability is a key concept for both types of device operations and was achieved by merging the Λ-shaped transfer curve of the AAT and the nonvolatile memory effect of ZnPc-PS4. First, we achieved electrically reconfigurable two-input logic circuits. Versatile logic circuits such as AND, OR, NAND, NOR, and XOR circuits were demonstrated by taking advantage of the Λ-shaped transfer curve of the dual-gate AAT. Importantly, the nonvolatile memory function provided the electrical switching of the individual circuits between AND/OR, NAND/NOR, and XOR/NAND circuits with constant input signals. Second, the memory effect was applied to multifunctional artificial synapses. The inhibitory/excitatory and long-term potentiation/depression synaptic operations were electrically reconfigured simply by controlling one parameter (readout voltage), making three distinct responses possible even with the same presynaptic signals. These findings provide hints that may lead to the realization of new in-memory computing architectures beyond the current von Neumann computers.

Anti-Ambipolar Heterojunctions: Materials, Devices, and Circuits

Anti-ambipolar heterojunctions are vital in constructing high-frequency oscillators, fast switches, and multivalued logic (MVL) devices, which hold promising potential for next-generation integrated circuit chips and telecommunication technologies. Thanks to the strategic material design and device integration, anti-ambipolar heterojunctions have demonstrated unparalleled device and circuit performance that surpasses other semiconducting material systems. This review aims to provide a comprehensive summary of the achievements in the field of anti-ambipolar heterojunctions. First, the fundamental operating mechanisms of anti-ambipolar devices are discussed. After that, potential materials used in anti-ambipolar devices are discussed with particular attention to 2D-based, 1D-based, and organic-based heterojunctions. Next, the primary device applications employing anti-ambipolar heterojunctions, including anti-ambipolar transistors (AATs), photodetectors, frequency doublers, and synaptic devices, are summarized. Furthermore, alongside the advancements in individual devices, the practical integration of these devices at the circuit level, including topics such as MVL circuits, complex logic gates, and spiking neuron circuits, is also discussed. Lastly, the present key challenges and future research directions concerning anti-ambipolar heterojunctions and their applications are also emphasized.

Contributions of Light to Novel Logic Concepts Using Optoelectronic Materials

Instead of the current method of transmitting voltage or current signals in electronic circuit operation, light offers an alternative to conventional logic, allowing for the implementation of new logic concepts through interaction with light. This manuscript examines the use of light in implementing new logic concepts as an alternative to traditional logic circuits and as a future technology. This article provides an overview of how to implement logic operations using light rather than voltage or current signals using optoelectronic materials such as 2D materials, metal-oxides, carbon structures, polymers, small molecules, and perovskites. This review covers the various technologies and applications of using light to dope devices, implement logic gates, control logic circuits, and generate light as an output signal. Recent research on logic and the use of light to implement new functions is summarized. This review also highlights the potential of optoelectronic logic for future technological advancements.

Reconfigurable Logic-in-Memory Constructed Using an Organic Antiambipolar Transistor

We demonstrate an electrically reconfigurable two-input logic-in-memory (LIM) using a dual-gate-type organic antiambipolar transistor (DG-OAAT). The attractive feature of this device is that a phthalocyanine-cored star-shaped polystyrene is used as a nano-floating gate, which enables the electrical switching of individual logic circuits and stores the circuit information by the nonvolatile memory effect. First, the DG-OAAT exhibited Λ-shaped transfer curves with hysteresis by sweeping the bottom-gate voltage. Programming and erasing operations enabled the reversible shift of the Λ-shaped transfer curves. Furthermore, the top-gate voltage effectively tuned the peak voltages of the transfer curves. Consequently, the combination of dual-gate and memory effects achieved electrically reconfigurable two-input LIM operations. Individual logic circuits (e.g., OR/NAND, XOR/NOR, and AND/XOR) were reconfigured by the corresponding programming and erasing operations without any variations in the input signals. Our device concept has the potential to fulfill an epoch-making organic integration circuit with a simple device configuration.

Nanocrystal Array Engineering and Optoelectronic Applications of Organic Small-Molecule Semiconductors

Organic small-molecule semiconductor materials have attracted extensive attention because of their excellent properties. Due to the randomness of crystal orientation and growth location, however, the preparation of continuous and highly ordered organic small-molecule semiconductor nanocrystal arrays still face more challenges. Compared to organic macromolecules, organic small molecules exhibit better crystallinity, and therefore, they exhibit better semiconductor performance. The formation of organic small-molecule crystals relies heavily on weak interactions such as hydrogen bonds, van der Waals forces, and π-π interactions, which are very sensitive to external stimuli such as mechanical forces, high temperatures, and organic solvents. Therefore, nanocrystal array engineering is more flexible than that of the inorganic materials. In addition, nanocrystal array engineering is a key step towards practical application. To resolve this problem, many conventional nanocrystal array preparation methods have been developed, such as spin coating, etc. In this review, the typical and recent progress of nanocrystal array engineering are summarized. It is the typical and recent innovations that the array of nanocrystal array engineering can be patterned on the substrate through top-down, bottom-up, self-assembly, and crystallization methods, and it can also be patterned by constructing a series of microscopic structures. Finally, various multifunctional and emerging applications based on organic small-molecule semiconductor nanocrystal arrays are introduced.

A reconfigurable binary/ternary logic conversion-in-memory based on drain-aligned floating-gate heterojunction transistors

A new type of heterojunction non-volatile memory transistor (H-MTR) has been developed, in which the negative transconductance (NTC) characteristics can be controlled systematically by a drain-aligned floating gate. In the H-MTR, a reliable transition between N-shaped transfer curves with distinct NTC and monolithically current-increasing transfer curves without apparent NTC can be accomplished through programming operation. Based on the H-MTR, a binary/ternary reconfigurable logic inverter (R-inverter) has been successfully implemented, which showed an unprecedentedly high static noise margin of 85% for binary logic operation and 59% for ternary logic operation, as well as long-term stability and outstanding cycle endurance. Furthermore, a ternary/binary dynamic logic conversion-in-memory has been demonstrated using a serially-connected R-inverter chain. The ternary/binary dynamic logic conversion-in-memory could generate three different output logic sequences for the same input signal in three logic levels, which is a new logic computing method that has never been presented before.