Multifunctional Devices Research Articles

High-Throughput Computing of Janus Chalcogenides as Photocatalysts and Piezoelectric Materials for Overall Water Splitting.

The presence of the intrinsic fields in two-dimensional (2D) materials holds promise for photocatalysts, as it diminishes the band gap requirements of 1.23 eV and accelerates the separation of the photogenerated carriers. Inspired by the extensive application in MA2X4 families, we predict Janus ZMXAY derived from MA2X4 materials to introduce intrinsic fields suitable for photocatalysts from 512 candidates. These monolayers also exhibit high mobilities up to ∼104 cm2V-1s-1 with strong anisotropy, and are accompanied by the inherent piezoelectric properties. Notably, all monolayers, except Janus SMoPGeAs, SeMoPSiAs, and SeMoPGeAs, demonstrate suitable band gaps (0.88-1.43 eV) and appropriate band edge positions without the need for any external potential to drive spontaneous overall water splitting. It also demonstrates visible optical absorption capacity and high solar-to-hydrogen conversion efficiency (16.06-41.08%). Our work identifies ideal candidates for multifunctional devices and provides theoretical guidance for future experimental research and application development.

Fabrication of broadband-emissive micro/nanostructures using two-photon lithography.

The development of broadband emissive micro/nanoscale structures has enabled unprecedented opportunities to innovate multifunctional devices with applications in lighting, display, sensing, biomedical, photovoltaics, and optical communication. Realization of these micro/nanostructures require multi-step processing, and depends on sophisticated, complex, time-consuming, expensive, and conventional nanofabrication techniques such as mask-based photolithography, electron beam lithography, reactive ion etching. Precise control over z-axis features with a subwavelength resolution for the fabrication of 3D features is a challenge using these methods. Thus, the traditional methods often fall short of meeting these requirements simultaneously. Fabrication of emissive structures demand techniques that offer material compatibility, high resolution, and structural complexity. Here, we report single-step fabrication of 1D, 2D, and 3D broadband emissive micro/nanostructures using two-photon lithography (TPL). The broadband emissive resin used for fabricating these structures is made by combining synthesized functionalized carbon quantum dots (CQDs) with a commercially available acrylate-based resin. The resulting structures demonstrate excellent broadband emissive properties in the visible range under UV-Vis excitation.We have observed consistent emission across the fabricated structures along with good thermal and optical stability. Furthermore, we can tune the emission properties of the micro/nanostructures by modifying the functionalization/doping of the quantum dots. These micro/nanostructures have the potential to be used as fundamental components in photonics, particularly in the fields of biophotonics, sensing, and optoelectronics, and could drive new innovations in these areas.

Self-assembly of 1T/1H superlattices in transition metal dichalcogenides

Heterostructures and superlattices composed of layered transition metal dichalcogenides (TMDs), celebrated for their superior emergent properties over individual components, offer significant promise for the development of multifunctional electronic devices. However, conventional fabrication techniques for these structures depend on layer-by-layer artificial construction and are hindered by their complexity and inefficiency. Herein, we introduce a universal strategy for the automated synthesis of TMD superlattice single crystals through self-assembly, exemplified by the NbSe2-xTex 1T/1H superlattice. The core principle of this strategy is to balance the formation energies of T (octahedral) and H (trigonal prismatic) phases. By adjusting the Te to Se stoichiometric ratio in NbSe2-xTex, we reduce the formation energy disparity between the T and H phases, enabling the self-assembly of 1T and 1H layers into a 1T/1H superlattice. The resulting 1T/1H superlattices retain electronic characteristics of both 1T and 1H layers. We further validate the universality of this strategy by achieving 1T/1H superlattices through substituting Nb atoms in NbSe2 with V or Ti atoms. This self-assembly for superlattice crystal synthesis approach could extend to other layered materials, opening new avenues for efficient fabrication and broad applications of superlattices.

Benzothiadiazole‐Fused Cyanoindone: A Superior Building Block for Designing Ultra‐Narrow Bandgap Electron Acceptor with Long‐Range Ordered Stacking

AbstractThere are great demands of developing ultra‐narrow bandgap electron acceptors for multifunctional electronic devices, particularly semi‐transparent organic photovoltaics (OPVs) for building‐integrated applications. However, current ultra‐narrow bandgap materials applied in OPVs, primarily based on electron‐rich cores, exhibit defects of high‐lying energy levels and inferior performance. We herein proposed a novel strategy by designing the benzothiazole‐fused cyanoindone (BTC) unit with ultra‐strong electron‐withdrawing ability as the terminal to synthesize the acceptor BTC‐2. The BTC unit imparts red‐shifted absorption up to 1000 nm to BTC‐2, attributed to enhanced intramolecular charge transfer and the quinoid resonance effect. Additionally, BTC‐2 features deep‐lying energy levels with the highest occupied molecular orbital level of −5.81 eV, due to the ultra‐strong electron‐withdrawing ability of BTC. Furthermore, BTC‐2 exhibits long‐range ordering in both molecular packing and macroscopic blend morphology, resulting from shoulder‐to‐shoulder packing of two BTC units, leading to an ultra‐long exciton lifetime over 1.1 ns. These superiorities facilitated a 17.17 % efficiency in the binary OPV device with an extremely high photocurrent of 30.34 mA cm−2, representing the best performance for ultra‐narrow bandgap electron acceptors, and a record light utilization efficiency of 4.88 % in binary semi‐transparent systems. Overall, BTC is a superior building block for designing ultra‐narrow bandgap electron acceptors.

An On-Chip Second-Order Elastic Topological Insulator for Demultiplexing Out-of-Plane and In-Plane Corner Modes.

Second-order elastic topological insulators (SETIs) with tightly localized corner states present a promising avenue for manipulating elastic waves in lower dimensions. However, existing SETIs typically support corner states of only a single mode, either out-of-plane or in-plane. In this work, an on-chip SETI that simultaneously hosts both high-frequency out-of-plane and in-plane corner states at ≈0.2MHz is introduced. The presence of these corner states is experimentally validated, and their selective excitation by tuning the excitation frequency is demonstrated. This capability to demultiplex out-of-plane and in-plane corner states positions the SETI as a potential platform for developing multifunctional elastic devices and enhancing the communication capacities of elastic waves. Furthermore, due to its structural simplicity, the SETI can be readily scaled and integrated into on-chip elastic circuits, making it suitable for applications in micro-electromechanical systems.

Flexible Photoacoustic Device Integrating Electroluminescence, Piezoelectric Vibration, and Pressure Sensing.

Marine organisms rely on the integration of light, sound, and pressure sensing for essential activities such as communication, hunting, and predator evasion. Current bioinspired devices, however, are limited by independent sensing modules, leading to complex designs and reduced adaptability. This study addresses these challenges by developing a multifunctional flexible photoacoustic device (MFPAD) that integrates electroluminescence, piezoelectric vibration, and pressure sensing into a single structure. Using airflow-assisted electrospinning, the device's fibrous layers were fabricated to optimize mechanical properties and enable synchronized responses to luminescence, sound, and pressure. Evaluations showed that MFPAD is highly sensitive to pressure changes, with corresponding light emissions, and efficient sound output modulated by input voltage and frequency. The device also enabled real-time posture tracking in robotic fish using an image recognition algorithm based on luminescence. Additionally, deep learning models allowed for the reconstruction of missing key points during motion. These findings demonstrate the promising potential of MFPAD for advancing bioinspired systems with multimodal sensing capabilities, offering a scalable solution for complex environments.

Multifunctional III-nitride optoelectronic system on a tiny chip

Multi-quantum well (MQW) diodes exhibit simultaneous emission and detection, allowing them to serve as multifunctional devices, including light emitters, receivers, energy transmitters, and information transmitters. Leveraging this capability, we designed a Multifunctional Energy Transfer Information System (METIS) that integrates contactless control, energy harvesting, and information transfer. At the core of this system, the multifunctional energy communication chip operates effectively across a broad range of extreme temperatures and in various solution environments. As the ambient temperature varies from −60 to 120 °C, the peak emission wavelength shifts from 465 to 476 nm, and even with further temperature changes from −70 to 150 °C, the communication function remains stable. Encapsulated for durability, METIS functions reliably in extreme conditions such as ice, water, salt solutions, and other light-transmitting fluids without needing external circuitry. Additionally, we demonstrate passive control of analog switches via MQW diodes. The MQW diodes also enable contactless energy and optical information transfer, ensuring stable and controllable information reconstruction at the receiving end. This approach offers an innovative solution for energy and information transmission in extreme environments.

Wearable Multifunctional Bilayer Nanofiber Films for Human Motion Energy Harvesting and Photothermal Therapy

AbstractIn light of the escalating requisites for portability, functionality, comfort, and health in electronic apparatus, the imperative advancement of sophisticated multifunctional textile‐based triboelectric nanogenerators (textile‐TENGs) is underscored. This research delineates the fabrication of an innovative multifunctional textile‐TENG, comprising a photosensitive stratum aimed at thermal regulation and photothermal therapy, alongside a tribo‐negative nanofiber film adorning its verso. Exhibiting superlative electrical prowess, the textile‐TENG generates remarkably elevated outputs over a wide temperature range, thereby facilitating the efficacious conversion of kinetic energy derived from human motion into electrical energy. Concurrently, the device manifests an exceptional photothermal conversion efficiency, achieving instantly modifiable saturation temperatures (41.52–60.97 °C) under diverse solar exposures, rendering it eminently suitable for a broad spectrum of applications in thermal therapy and regulation domains. Significantly, within cold environments, the textile‐TENG demonstrates a capability to augment temperature by approximately 7.4 °C, markedly surpassing conventional cotton textiles in performance. In summation, the textile‐TENG is characterized by its unparalleled electromechanical attributes and photothermal conversion efficacies, concurrently facilitating thermal regulation, therapy, and electricity generation. This investigation not only furnishes a referential methodology for the development of advanced multifunctional textile devices but also substantially expands the conceivable application ambit of textile‐based technologies.

Multi-functional spin-caloritronic device based on co-doped zigzag silicene nanoribbon heterojunction

The discovery of graphene has sparked significant interest in two-dimensional (2D) materials within the research community. Graphene’s discovery has led to the exploration of several 2D-materials with varied properties. Silicene, a silicon-based analogue of graphene, is one of the newer 2D-materials. Silicene is a promising material for electronic applications and novel fields like spintronics. In this study, we propose a spin-caloritronic device based on zigzag silicene nanoribbons (ZSiNRs). The device features a heterojunction between two ZSiNRs, one of which is doped with boron (B) and nitrogen (N) atoms. The ZSiNRs’ edges are terminated with hydrogen (H) atoms for both the nanoribbons in the heterojunction. We utilize the density functional theory (DFT) combined with non-equilibrium Green’s function (NEGF) to investigate the thermal-spin transport properties of this device under the influence of a thermal gradient. Notably, the device operates without any external bias, with spin transport driven solely by the thermal gradient. We find that a thermal colossal magnetoresistance (CMR) effect may be produced by modulating thermally generated spin currents by changing the magnetic configuration. Furthermore, the proposed device has superior transport properties, displaying phenomena including the spin-Seebeck diode effect (SSD), spin filtering effect (SFE), and spin-Seebeck effect (SSE). These characteristics position the proposed device as a strong candidate for multi-functional spin-caloritronic applications.

Ag@MXene-cellulose nanofiber composite for electromagnetic interference shielding, sensing, and actuating

With the development of flexible electronic devices, the development of flexible and multi-functional materials becomes increasingly important. In this study, we prepared Ag@MXene-cellulose nanofiber (AMC) multi-functional composites with a three-dimensional (3D) conductive network structure, which can be used for electromagnetic interference (EMI) shielding, pressure sensing, and actuating. AMC has good electrical conductivity (18.04 S cm-1) and EMI shielding effectiveness (37.7dB). The microstructure of the AMC surface gives it the potential to be applied in the pressure sensor. AMC is humidity-sensitive and has excellent electrical/photo-thermal conversion properties. Thus, AMC can be used to fabricate humidity-driven actuators and electrical/light-driven actuators. Finally, three multi-functional devices/systems have been carefully designed to achieve the fabrication of multi-functional devices/systems that rely on only one raw material, which significantly simplifies the preparation of multi-functional devices. We hope this research will open up new ways for artificial muscles, soft robots, and EMI shielding devices.

Comparative Morphology of the Extrinsic and Intrinsic Leg Musculature in Dictyoptera (Insecta: Blattodea, Mantodea).

Insect legs, as primarily locomotory devices, can show a tremendous variety of morphological modifications providing a multitude of usages. The prehensile raptorial forelegs of praying mantises (Mantodea) are a prominent example of true multifunctionality since they are used for walking while being efficient prey-capturing and grasping devices. Although being mostly generalist arthropod predators, various morphological adaptations due to different environmental conditions occur across Mantodea. Recently, the general mantodean morphology, and particularly their raptorial forelegs, received an increased interest. Yet, knowledge about the evolutionary transition from walking to prey-grasping legs is still scarce. From evolutionary and functional perspectives, the question arises: what changes were necessary to achieve the strongly modified raptorial forelegs-while keeping walking ability-and how does the foreleg morphology differ from the remaining four walking legs? In this context, we investigated the musculature of the raptorial forelegs in seven phylogenetically distant mantodeans, including pterothoracic legs in four of them, using high-resolution microcomputed tomography and dissection. To understand the results from an evolutionary perspective, we additionally examined all three pairs of unmodified walking legs of the closest sister group-Blattodea. We updated the knowledge of blattodean morphology, revealing differences in cuticle structures of the coxal articulation of the first pair of legs between the two orders and a shared musculature set-up in all pairs of legs among later-branching mantodeans. Interestingly, the early branching species Metallyticus splendidus and Chaeteessa sp. show several muscular characteristics, otherwise found exclusively in one or the other order, with a few procoxal muscles showing an intermediate state between the two orders. Studying the evolutionary transition from a walking leg to a raptorial leg will help to understand the character evolution of this highly specialized biomechanical system from a purely locomotory appendage to a multi-functional device with all related amenities and constraints.

Benzothiadiazole-Fused Cyanoindone: A Superior Building Block for Designing Ultra-Narrow Bandgap Electron Acceptor with Long-Range Ordered Stacking.

There are great demands of developing ultra-narrow bandgap electron acceptors for multifunctional electronic devices, particularly semi-transparent organic photovoltaics (OPVs) for building-integrated applications. However, current ultra-narrow bandgap materials applied in OPVs, primarily based on electron-rich cores, exhibit defects of high-lying energy levels and inferior performance. We herein proposed a novel strategy by designing the benzothiazole-fused cyanoindone (BTC) unit with ultra-strong electron-withdrawing ability as the terminal to synthesize the acceptor BTC-2. The BTC unit imparts red-shifted absorption up to 1000 nm to BTC-2, attributed to enhanced intramolecular charge transfer and the quinoid resonance effect. Additionally, BTC-2 features deep-lying energy levels with the highest occupied molecular orbital level of -5.81 eV, due to the ultra-strong electron-withdrawing ability of BTC. Furthermore, BTC-2 exhibits long-range ordering in both molecular packing and macroscopic blend morphology, resulting from shoulder-to-shoulder packing of two BTC units, leading to an ultra-long exciton lifetime over 1.1 ns. These superiorities facilitated a 17.17 % efficiency in the binary OPV device with an extremely high photocurrent of 30.34 mA cm-2, representing the best performance for ultra-narrow bandgap electron acceptors, and a record light utilization efficiency of 4.88 % in binary semi-transparent systems. Overall, BTC is a superior building block for designing ultra-narrow bandgap electron acceptors.

A multi-functional platform for stimulating and recording electrical responses of SH-SY5Y cells.

In recent years, multifunctional cell regulation on a single chip has become an imperative need for cell research. In this study, a novel multi-functional micro-platform integrating wireless electrical stimulation, mechanical stimulation and electrical response recording of cells was proposed. Controlling cell fate by photoexcited radio stimulation of cells on photosensitive films can precisely orchestrate biological activities. This is the first report of combining hydrogenated amorphous silicon (a-Si:H) photosensitive films and a 532 nm green laser for cell stimulation and electrical response recording. Remote wireless electrical stimulation of nerve cells through photoelectric effects based on photosensitive films evoked a change in membrane potential and promoted the neurite growth and neuronal differentiation. These effects were confirmed in a cell model of the human neuroblastoma cell line. The electrical response of cells demonstrated that the photocurrent generated by laser irradiation of the photosensitive film induced a redistribution of ions inside and outside the cell. Furthermore, a mechanical stimulus was applied to cells using a probe placed above them. The chip was used as a signal output to simultaneously obtain the electrical response of cells. The ability of photosensitive films to precisely excite cellular activity offers a novel prospect for wireless electrical stimulation. This work provides a promising strategy for the design of multi-functional biological devices based on a single chip.

Flexible mechano-optical dual-responsive perovskite molecular ferroelectric composites for advanced anticounterfeiting and encryption.

Hybrid organic-inorganic molecular ferroelectrics have emerged as promising materials for multifunctional piezoelectric devices. However, they present challenges in practical applications because of their inherent brittleness and poor ductility. Herein, we present a flexible mechano-optical dual-responsive molecular ferroelectric composite by incorporating trimethylchloromethyl ammonium (TMCM)-MnCl3 into styrene ethylene butylene styrene (SEBS) matrix. The SEBS/TMCM-MnCl3 exhibits excellent stretchable mechanical properties (tensile strain >1300%, thickness of 30 μm), piezoelectricity, and photoluminescence, enabling advanced visual-tactile-fused anticounterfeiting and encryption applications. Anticounterfeiting and antitampering tags are developed to judge whether the valued items are true or tampered with based on pattern recognition and piezoelectric response, respectively. Additionally, high-security password keyboards featuring triple-layer encryption are designed, offering more password combinations (524,288 times greater than those of traditional password devices relying solely on digital encryption) and enhanced security reliability against cracking attempts. This work can inspire designs of multifunctional optoelectronic materials and enable visual-tactile-fused intelligent applications in human-machine interfaces, information security, and advanced robotics.

Selective Laser Doping and Dedoping for Phase Engineering in Vanadium Dioxide Film.

Vanadium dioxide (VO2), renowned for its reversible metal-to-insulator transition (MIT), has been widely used in configurable photonic and electronic devices. Precisely tailoring the MIT of VO2 on micro-/nano-scale is crucial for miniaturized and integrated devices. However, existing tailoring techniques like scanning probe microscopy, despite their precision, fall short in efficiency and adaptability, particularly on complex or curved surfaces. Herein, this work achieves the local engineering of the phase of VO2 films in high efficiency by employing laser writing to assist in the hydrogen doping or dedoping process. The laser doping and laser dedoping technique is also highly flexible, enabling the fabrication of reconfigurable, non-volatile, and multifunctional VO2 devices. This approach establishes a new paradigm for creating reconfigurable micro/nanophotonic and micro/nanoelectronic devices.

Overview of Gas-Generating-Reaction-Based Immunoassays

Point-of-care (POC) immunoassays have become convincing alternatives to traditional immunosensing methods for the sensitive and real-time detection of targets. Immunoassays based on gas-generating reactions were recently developed and have been used in various fields due to their advantages, such as rapid measurement, direct reading, simple operation, and low cost. Enzymes or nanoparticles modified with antibodies can effectively catalyze gas-generating reactions and convert immunorecognition events into gas pressure signals, which can be easily recorded by multifunctional portable devices. This article summarizes the advances in gas-generating-reaction-based immunoassays, according to different types of signal output systems, including distance-based readout, pressure differential, visualized detection, and thermal measurement. The review mainly focuses on the role of photothermal materials and the working principle of immunoassays. In addition, the challenges and prospects for the future development of gas-generating-reaction-based immunoassays are briefly discussed.

A Ferroelastic Salt Cocrystal with Ultraviolet Emission.

The coexistence and coupling of photoluminescence and ferroelasticity in a single matter are vitally important for developing multifunctional materials and devices. However, the effective construction of ferroelastics with efficient photoluminescence, especially in the ultraviolet range, is a great challenge. In this work, a salt cocrystal, (DPA)(DPAH)PF6 (DPA = diphenylamine, DPAH = diphenylamine cation), with ultraviolet emission and ferroelasticity was reported by introducing the anion group PF6- in the parent DPA crystal. Besides, the thermally triggered order-disorder transition of PF6- groups leads to a ferroelastic phase transition at ∼340 K with the Aizu notation of 2/mF1̅. In addition, (DPA)(DPAH)PF6 displays a bright ultraviolet emission at 392 nm with a photoluminescence quantum yield of 49.4%. This work presents a strategy to achieve ultraviolet (UV)-emissive ferroelastic based on the luminescent organic crystal, which not only extends the luminescence of ferroelastic to the UV region but also paves a new way for the development of multifunctional ferroelastic materials and devices.

Quadruple Stimuli-Responsive Behaviour of Acylhydrazone Crystals: Mechanical, Photomechanical, Thermomechanical, and Optical Waveguide Properties.

As society advances, the demand for high-performance crystal materials with versatile stimuli-responsive capabilities has increased. However, there remains a notable shortage of simple molecular crystals that exhibit stable and swift responses to various stimuli. In this study, we synthesized a novel acylhydrazone crystal by integrating benzene-fused heterocycles and halogens, achieving a crystal material with multiple stimuli-responsive behaviours. The crystal demonstrates good mechanical flexibility, capable of with standing a strain of 2.3 % under applying mechanical force and recovering its original shape after force removal. Crystal structure analysis reveals this property is due to the strong and flexible intermolecular interactions. It also exhibits rapid photomechanical bending away from light source under UV irradiation, which could be attributed to the facile photoisomerization. Moreover, the crystal undergoes significant thermomechanical transitions, including cracking and jumping, upon heating. Additionally, the prepared crystal exhibits passive optical waveguide of red light at 640 nm, which, combining the photomechanical bending, can achieve controllable light output direction. These multi-stimuli-responsive behaviors make the acylhydrazone crystal a promising candidate for applications in multifunctional sensors, optoelectronic devices, and thermal switches. This work provides a helpful reference for the study of potential crystal material design and functionality of advanced responsive systems.

Dual-mode topological rainbow based on Kagome sandwich structure

Topological slow light offers an attractive platform for enhancing light-matter interaction because of its immunity to backscattering and robustness to defects. Most topological rainbow trapping structures are designed to support only one mode during frequency routing. However, in this work, we have designed a dual-mode topological rainbow trapping structure to enrich the functionality of frequency routing in slow light, based on Kagome sandwich structure. With the expanding perturbation index m decreasing gradually, the proposed structure supports coupled topological dual-mode edge states. Through the theoretical and numerical calculations, the group velocity of dual-mode edge states can be slowed to near-zero areas, resulting in the trapping of light at the corresponding positions. Our work introduces a new approach to utilizing coupled topological edge states for building multifunctional slow light optical devices.

Chiral Inorganic Polar BaTiO3/BaCO3 Nanohybrids with Spin Selection for Asymmetric Photocatalysis.

Chirality-dependent photocatalysis is an emerging domain that leverages unique chiral light-matter interactions for enabling asymmetric catalysis driven by spin polarization induced by circularly polarized light selection. Herein, we synthesize chiral inorganic polar BaTiO3/BaCO3 nanohybrids for asymmetric photocatalysis via a hydrothermal method employing chiral glucose as a structural inducer. When excited by opposite circularly polarized light, the same material exhibits significant asymmetric catalysis, while enantiomers present an opposite polarization preference. More importantly, the preferred circularly polarized light undergoes reversal with reversal of the CD signal. Systematic experimental results demonstrate that more photogenerated carriers are generated in chiral semiconductors under suitable circularly polarized light irradiation, including more spin-polarized electrons, which inhibits the recombination of electron-hole pairs and promotes the activation of oxygen molecules into reactive oxygen species, thus inducing this asymmetric photocatalytic feature. This study provides valuable insights for the development of highly efficient polarization-sensitive chiral perovskite nanostructures as promising candidates for next-generation, multifunctional chiral device applications.