Opto-Electrochemical Synaptic Memory in Supramolecularly Engineered Janus 2D MoS2

Engineering the Interfacing of Molecules with 2D Transition Metal Dichalcogenides: Enhanced Multifunctional Electronics

ConspectusEngineering all interfaces between different components in electronic devices is the key to control and optimize fundamental physical processes such as charge injection at metal-semiconductor interfaces, gate modulation at the dielectric-semiconductor interface, and carrier modulation at semiconductor-environment interfaces. The use of two-dimensional (2D) crystals as semiconductors, by virtue of their atomically flat dangling bond-free structures, can facilitate the tailoring of such interfaces effectively. In this context, 2D transition metal dichalcogenides (TMDs) have garnered tremendous attention over the past two decades owing to their exclusive and outstanding physical and chemical characteristics such as their strong light-matter interactions and high charge mobility. These properties position them as promising building blocks for next-generation semiconductor materials. The combination of their large specific surface area, unique electronic structure, and properties highly sensitive to environmental changes makes 2D TMDs appealing platforms for applications in optoelectronics and sensing. While a broad arsenal of TMDs has been made available that exhibit a variety of electronic properties, the latter are unfortunately hardly tunable. To overcome this problem, the controlled functionalization of TMDs with molecules and assemblies thereof represents a most powerful strategy to finely tune their surface characteristics for electronics. Such functionalization can be used not only to encapsulate the electronic material, therefore enhancing its stability in air, but also to impart dynamic, stimuli-responsive characteristics to TMDs and to selectively recognize the presence of a given analyte in the environment, demonstrating unprecedented application potential.In this Account, we highlight the most enlightening recent progress made on the interface engineering in 2D TMD-based electronic devices via covalent and noncovalent functionalization with suitably designed molecules, underlining the remarkable synergies achieved. While electrode functionalization allows modulating charge injection and extraction, the functionalization of the dielectric substrate enables tuning of the carrier concentration in the device channel, and the functionalization of the upper surface of 2D TMDs allows screening the interaction with the environment and imparts molecular functionality to the devices, making them versatile for various applications. The tailored interfaces enable enhanced device performance and open up avenues for practical applications. This Account specifically focuses on our recent endeavor in the unusual properties conferred to 2D TMDs through the functionalization of their interfaces with stimuli-responsive molecules or molecular assemblies. This includes electrode-functionalized devices with modulable performance and charge carriers, molecular-bridged TMD network devices with overall enhanced electrical properties, sensor devices that are highly responsive to changes in the external environment, in particular, electrochemically switchable transistors that react to external electrochemical signals, optically switchable transistors that are sensitive to external light inputs, and multiresponsive transistors that simultaneously respond to multiple external stimuli including optical, electrical, redox, thermal, and magnetic inputs and their application in the development of unprecedented memories, artificial synapses, and logic inverters. By presenting the current challenges, opportunities, and prospects in this blooming research field, we will discuss the powerful integration of such strategies for next-generation electronic digital devices and logic circuitries, outlining future directions and potential breakthroughs in interface engineering.

Optoelectronic Devices for In-Sensor Computing

The demand for accurate perception of the physical world leads to a dramatic increase in sensory nodes. However, the transmission of massive and unstructured sensory data from sensors to computing units poses great challenges in terms of power-efficiency, transmission bandwidth, data storage, time latency, and security. To efficiently process massive sensory data, it is crucial to achieve data compression and structuring at the sensory terminals. In-sensor computing integrates perception, memory, and processing functions within sensors, enabling sensory terminals to perform data compression and data structuring. Here, vision sensors are adopted as an example and discuss the functions of electronic, optical, and optoelectronic hardware for visual processing. Particularly, hardware implementations of optoelectronic devices for in-sensor visual processing that can compress and structure multidimensional vision information are examined. The underlying resistive switching mechanisms of volatile/nonvolatile optoelectronic devices and their processing operations are explored. Finally, a perspective on the future development of optoelectronic devices for in-sensor computing is provided.

Organic iontronic memristors for artificial synapses and bionic neuromorphic computing

To tackle the current crisis of Moore's law, a sophisticated strategy entails the development of multistable memristors, bionic artificial synapses, logic circuits and brain-inspired neuromorphic computing. In comparison with conventional electronic systems, iontronic memristors offer greater potential for the manifestation of artificial intelligence and brain-machine interaction. Organic iontronic memristive materials (OIMs), which possess an organic backbone and exhibit stoichiometric ionic states, have emerged as pivotal contenders for the realization of high-performance bionic iontronic memristors. In this review, a comprehensive analysis of the progress and prospects of OIMs is presented, encompassing their inherent advantages, diverse types, synthesis methodologies, and wide-ranging applications in memristive devices. Predictably, the field of OIMs, as a rapidly developing research subject, presents an exciting opportunity for the development of highly efficient neuro-iontronic systems in areas such as in-sensor computing devices, artificial synapses, and human perception.