Research articles

A two-terminal self-rectfying TaO_y/Nanoporous TaO_x memristor synapse was fabricated based on anodization process. The device exhibits high non-linearity, low synapse-coupling (S.C), acceptable endurance, sweeping and retention stability, as well as essential synaptic functions such as long-term plasticity and spiking-timing-dependent-plasticity. Furthermore, crossbar array consisting of the only designed device without any selector shows relatively well-defined switching parameters with acceptable cell uniformity and capability of suppressing undesired pathways. The effect of S.C on recognition accuracy of MNIST patterns was also simulated for the first time. Based on experimental average S.C value, the device exhibited the high accuracy comparable to S.C = 0

In textile electronics, micro to millimeter-scaled misalignment is commonly occurred during the high-throughput and bulk-scaled textile manufacturing process, thus the exact performance control of the fiber-based active devices is very difficult in low-cost wearable electronics. In this research, we developed novel single-strand organic electrochemical transistors and proposed dimension-independent characterization method (i.e., the current variation ratio in variation of logarithmic concentration of electrolyte) for ion concentration sensing. Furthermore, we demonstrated the pseudo two-terminal transistor operation by incorporating electrochemical gate electrode onto the surface of the source electrode, leading to single-strand fiber device platform.

Flexible perovskite solar cell with an efficiency of 15.8 % via tailoring of vacuum-deposited PbI₂ growth morphology has been achieved. We demonstrated superior mechanical bending stability using amorphous TCO (retaining 80 % of the initial efficiency after 1000 bending cycles at 4 mm bending radius). Flexible NIR-transparent perovskite solar cell with an efficiency of 14.0 % and average transmittance of ~74 % between 800 and 1000 nm has been developed. Eventually, we proved a flexible perovskite/CIGS tandem solar cell with an efficiency of 19.6 % measured in four-terminal configuration.

We report on the anisotropic friction domains of MoS2 not only grown by chemical vapor deposition (CVD) under various sulfur pressure conditions, but also by mechanical exfoliation process. The 180° periodicity of each domain and the 60° shift between adjacent domains indicate the presence of linearly aligned structures along the armchair direction of MoS2. The universality of anisotropic frictional behaviors of 2D materials, including graphene, hBN, and WS2 with stacking honeycomb lattices supports our assumption based on linearly aligned ripples along the crystallographic axes, which result from an inhomogeneous strain field.

Helicoidally stacked polymer networks constructed by coating and curing the chirophotonic crystal paints has great potential to fabricate flexible mirrors with macroscopic dimensions and broad bandwidth.

Gas filled nanobubbles are fabricated by surface-engineered progress with forming folate-mediated, gadolinium (Gd³⁺)-labelled and IR-780/5-FU loaded hollow structures. The nanobubbles progress capacity of NIR-/MR-/US-imaging in vitro. Importantly, the nanobubbles present charge-switchable behaviors when pH values changed from 7.4 to 5.0 and demonstrate pH-/light-sensitive drug release behaviors. Coupled with FA-targeting, the nanobubbles can be employed for efficient tri-modal imaging in vivo with selective tumor accumulation, long tumor retention time, and present enhanced anti-tumor activity with combined chemo-/photothermal therapy. Therefore, nanobubbles can act as excellent nanocarriers for active tumor targeting theranostics.

A graphene based quasi-solid state rechargeable Li-O₂ battery is developed by utilizing 3D nanoporous graphene cathode, TTF modified quasi-solid state GPE and porous graphene/Li anode. This integrated prototype battery simultaneously addresses the major challenges of Li-O₂ batteries in energy efficiency, lifetime and safety and present an important progress in practical implementation of full performance Li-O₂ battery.

This work first reports the finding of a re-entrant relaxor–ferroelectric composite (RRFC) which solves a long-standing challenge: a combination of low hysteresis and large electrostrain over a broad temperature range (i.e., 168 K temperature window for hysteresis <20% and strain >0.1%) in sufficiently disordered (Ba_0.925Bi_0.05)(Ti_1−x/100Sn_x/100)O₃ ceramics. This exceptional combination is achieved by the RRFC designing strategy; i.e., introducing sufficient disorder to enable a re-entrant transition and thereby creating a relaxor–ferroelectric coexisting microstructure over a broad temperature range. Our finding does not only solve the incompatibility of electromechanical properties but also may open a way to develop thermally stable high-performance materials.

A new electron-accepting π-conjugated compound containing fluorinated naphthobisthiadiazole (FNTz) is designed and synthesized for application as an acceptor in organic solar cells (OSCs). Physical measurements show that the introduction of fluorine atoms in the naphthobisthiadiazole (NTz) unit has considerable influence on the absorption behavior and frontier orbital energy levels of molecules. In OSCs, the FNTz-based acceptor in combination with poly(3-hexylthiophene) (P3HT) as a donor exhibits a significant improvement in power conversion efficiency compared to the corresponding nonfluorinated NTz-based acceptor. This study demonstrates the potential of FNTz as an electron-accepting unit in organic semiconductors.

We experimentally observe that D, the strength of the Dzyaloshinskii–Moriya interaction (DMI), is correlated with the difference of work function W of Co and nonmagnetic material X in Pt/Co/X trilayer system. The spin–orbit-scattering-mediated spin–chiral effect may plays leading role in this system, and this phenomena may be affected by work function difference which may be linked to electrostatic potential that may affect the scattering potential at the interface. Such correlation with the intrinsic material parameter provides a guideline for material selection to engineer the DMI and helps control properties for applications of chiral objects such as magnetic skyrmion.

A bioinspired nanosystem of cancer cell membrane-camouflaged SPIO@DOX-ICG nanoparticles was fabricated to realize precise cancer treatment by simultaneous chemotherapy, hyperthermia-therapy, and radiotherapy. The nanosystem achieved synergistic anticancer effects by antagonizing tumor hypoxia and reprograming the polarization of tumor associated macrophages to anti-tumor M1 phenotype, without causing toxic side effects on major organs.

The key in engineering functional excitable tissues is to develop advanced conductive biomaterials that could guide cells to form electrically interconnected networks. This study aims to develop reduced graphene oxide functionalized silk nanofibrous biomaterials with controllable surface deposition. The composites exhibit uniform nanolayer of reduced graphene oxide, and well controlled conductivity and nanofibrous morphology. The scaffolds promote formation and functionalities of engineered cardiac tissues, and electrical stimulation further enhances these promotion effects. This research provides guidance for using reduced graphene oxide to fabricate conductive nanofibrous biomaterials for the regeneration of functional excitable tissues.

In this study, we present a new type of spatially modified ECM composed of type 1 collagen whose properties differ from those of a collagen matrix. Using this ECM, we developed a stable human mammary epithelium with a lumen structure that exhibited a barrier function in a microfluidic platform, produced laminin, and formed a basement membrane. This reconstructed mammary duct can serve as a model for investigating breast cancer and may be adapted to other types of epithelium for in vitro studies.

An intrinsically stretchable and highly conductive graphene electrode based on vertically oriented graphene/Au bilayer flakes are successfully fabricated by a direct-laser-patterning at a very high-repetition rate and fast scanning speed of laser with a femtosecond pulse, allowing micro-supercapacitors to be integrated with the complete soft electronics systems that can be standalone and be customized by user’s circuit designs.

We visualize an electric-field-induced collective propagation of oxygen vacancies spontaneously contained in Ca-substituted BiFeO₃ films, using the fact that the oxygen-rich and poor regions have different color contrasts and thus they are optically distinguishable forming a sharp boundary. We quantitatively determine the drift velocity to be of the order of 100 μm s⁻¹ with an activation barrier of 0.79 eV indicating a significantly large ionic mobility 2 × 10⁻⁶ cm² s⁻¹ V⁻¹ at a remarkably low temperature of 390 °C. Furthermore, U-shaped propagation and turbulence under backward electric field provide insights into fluidic defects in crystalline solids.

The modulation of interfacial coupling of (La_0.67Sr_0.33MnO₃)_n/(SrTiO₃)_n superlattices with n unit cells of SrTiO₃ and n unit cells La_0.67Sr_0.33MnO₃, offers an effective opportunity to control charge transfer and orbital hybridization. The easy axis of magnetic anisotropy rotates ~45° towards the out-of-plane direction from n = 10 to n = 2 at reduced temperature T_Re = T/T_S = 0.87 (T_S is onset of magnetization). Orbital hybridization accompanying the charge transfer results in preferred occupancy of \(3d_{3z_{2} - r_{2}}\) orbital at the interface, and induces stronger electronic hopping integral and interfacial magnetic anisotropy along perpendicular direction, useful to tailor properties in device applications.

We observed huge magnetoresistance (~ 10¹⁵% in 90 kOe external magnetic field and 10¹³% in 30 kOe external magnetic field) at 10 K by engineering electronic phase separation in charge-ordered half-doped manganites. The observed huge value of magnetoresistance is explained by double-exchange model Hamiltonian calculations. Moreover, our electronic phase-controlled material, namely Sm_0.5Ca_0.25Sr_0.25MnO₃, shows an ultrasharp metamagnetic transition below 10 K, which is martensitic in nature. The many order of magnitudes higher magnetoresistance in Sm_0.5Ca_0.25Sr_0.25MnO₃ than any other magnetoresistive materials reported so far will motivate further experimental work.

A thermoresponsive smart colorimetric patch was fabricated by embedding thermoresponsive plasmonic microgels in a stretchable hydrogel film. The stretchable and wearable colorimetric patches exhibited vivid color change, fast response time, outstanding thermal resolution, and high durability. Potential applications in wearable smart sensors and soft robotics were demonstrated through a spatial temperature scanner and a colorimetric thermometer for thermoresponsive actuators.

A novel synthesis protocol for fabrication of micron-sized multi-compartmentalized mesoporous silica spheres is developed, which is exemplified by successful synthesis of a family of unprecedented multi-compartmentalized mesoporous silica microspheres (MSMs) including hollow MSMs, hollow nanosphere-containing MSMs, nanosphere-containing MSMs, yolk-shell-structured MSMs, and “solid” MSMs. These microspheres exhibit not only significantly enhanced performances in CO₂ capture and catalysis but also the superiority in technical applications.

An approach towards kirigami metamaterials with reconfigurable toroidal circular dichroism is presented. Inspired by the kirigami concept, kirigami-based chiral metamaterials are proposed to switch the electromagnetic performance between non-chiral and chiral states. When transforming the 2D metasurface to 3D kirigami patterns, the resonant modes exhibit gradually enhanced chiroptical response, from single-band, dual-band to broad-band functionalities.