Aqueous zinc‐ion batteries (AZIBs) have attracted considerable attention as promising next‐generation power sources because of the abundance, low cost, eco‐friendliness, and high security of Zn ...resources. Recently, vanadium‐based materials as cathodes in AZIBs have gained interest owing to their rich electrochemical interaction with Zn2+ and high theoretical capacity. However, existing AZIBs are still far from meeting commercial requirements. This article summarizes recent advances in the rational design of vanadium‐based materials toward AZIBs. In particular, it highlights various tactics that have been reported to increase the intercalation space, structural stability, and the diffusion ability of the guest Zn2+, as well as explores the structure‐dependent electrochemical performance and the corresponding energy storage mechanism. Furthermore, this article summarizes recent achievements in the optimization of aqueous electrolytes and Zn anodes to resolve the issues that remain with Zn anodes, including dendrite formation, passivation, corrosion, and the low coulombic efficiency of plating/stripping. The rationalization of these research findings can guide further investigations in the design of cathode/anode materials and electrolytes for next‐generation AZIBs.
This article highlights various tactics for increasing intercalation space, structural stability, and guest Zn2+ diffusion capacity for vanadium‐based materials, as well as exploring their structure‐dependent electrochemical properties and corresponding energy storage mechanisms. Furthermore, it summarizes recent achievements in the optimization of aqueous electrolytes and Zn anodes to resolve the issues that remain with Zn anodes.
Battery‐type materials are promising candidates for achieving high specific capacity for supercapacitors. However, their slow reaction kinetics hinders the improvement in electrochemical performance. ...Herein, a hybrid structure of P‐doped Co3O4 (P‐Co3O4) ultrafine nanoparticles in situ encapsulated into P, N co‐doped carbon (P, N‐C) nanowires by a pyrolysis–oxidation–phosphorization of 1D metal–organic frameworks derived from Co‐layered double hydroxide as self‐template and reactant is reported. This hybrid structure prevents active material agglomeration and maintains a 1D oriented arrangement, which exhibits a large accessible surface area and hierarchically porous feature, enabling sufficient permeation and transfer of electrolyte ions. Theoretical calculations demonstrate that the P dopants in P‐Co3O4@P, N‐C could reduce the adsorption energy of OH− and regulate the electrical properties. Accordingly, the P‐Co3O4@P, N‐C delivers a high specific capacity of 669 mC cm−2 at 1 mA cm−2 and an ultralong cycle life with only 4.8% loss over 5000 cycles at 30 mA cm−2. During the fabrication of P‐Co3O4@P, N‐C, Co@P, N‐C is simultaneously developed, which can be integrated with P‐Co3O4@P, N‐C for the assembly of asymmetric supercapacitors. These devices achieve a high energy density of 47.6 W h kg−1 at 750 W kg−1 and impressive flexibility, exhibiting a great potential in practical applications.
A hybrid structure of P‐doped Co3O4 ultrafine nanoparticles in situ encapsulated into P, N co‐doped carbon nanowires is designed via a pyrolysis–oxidation–phosphorization of metal–organic frameworks derived from Co‐layered double hydroxide as self‐template and reactant. The incorporated P dopants in P‐doped Co3O4@P, N co‐doped carbon reduce the adsorption energy of OH− and regulate the electrical property, boosting the electrochemical performance.
Heterojunction based on two-dimensional (2D) layered materials is an emerging topic in the field of nanoelectronics and optoelectronics. Here, molybdenum sulfide (MoS2)-based Schottky diodes were ...fabricated using the field-effect transistor configuration with asymmetric metal contact structure. Gold and chromium electrodes were employed as drain and source electrodes to form Ohmic and Schottky contact with MoS2, respectively. The devices exhibited electrical rectifying characteristic with the current rectifying ratio exceeding 103 and an ideal factor of 1.5. A physics model of the band diagram was proposed to analyze the gate-tunable rectifying behavior of the device. The dynamic rectification based on the diode circuit was further realized with the operating frequency up to 100 Hz. The devices were also demonstrated to show different sensitivities to the light under external biases in the opposite directions, with the highest photoresponsivity reaching 1.1 × 104 A/W and specific detectivity up to 8.3 × 1012 Jones at a forward drain bias of 10 V. This kind of 2D material-based Schottky diodes have the advantage of simplicity in design and fabrication, as well as superior electrical rectifying and photosensing characteristics, which have great potential for future integrated electronic and optoelectronic applications.
Indium gallium zinc oxide (IGZO) thin‐film transistors (TFTs) are primary components in active integrated electronics, such as displays and sensor arrays, which heavily involve high‐throughput ...passivation techniques during multilayer fabrication processes. Though oxide compound semiconductors are commonly used for providing uniform and robust passivation, it usually causes performance degradation on IGZO TFTs during passivation process. Herein, a parylene‐C and aluminum oxide (AlOx) hybrid passivation approach are introduced to reduce the damage during AlOx atomic layer deposition (ALD), which results in high‐performance depletion‐mode IGZO TFT to be fabricated on polyethylene naphthalate (PEN) substrate with enhanced bias stability. Compared with parylene‐C passivation, the hybrid‐passivated IGZO TFTs exhibit excellent saturation mobility (7.9 cm2 (V s)−1), ON/OFF ratio (107), hysteresis window (0.73 V), and bias stability (1.44 and −0.27 V threshold voltage shift, Vds = 20 V). Based on systematic Mott–Schottky and X‐ray diffraction characterizations, it is found that TFT performance enhancement is originated from their doping density variation that resulted from a parylene‐C/ALD‐AlOx microstructural hybridization. Finally, this method is implemented to wafer‐scale integrated circuits with high uniformity and a flexible 10 × 10 IGZO TFT backplane matrix on a PEN substrate (2.5 cm × 2.5 cm).
A parylene‐C and aluminum oxide (AlOx) hybrid passivation approach are introduced to reduce the damage during AlOx atomic layer deposition. Based on Mott–Schottky and X‐ray diffraction characterizations, the thin‐film transistor (TFT) performance enhancement is attributed to doping density variation that results in high‐performance depletion‐mode indium–zinc–gallium–oxide TFT matrix to be operated on polyethylene naphthalate substrate with enhanced bias stability.
Electronics based on solution-processable materials are promising for applications in many fields which stimulated enormous research interest in liquid-drying and pattern formation. However, ...assembling of structure with submicrometre/nanometre resolution through liquid process is very challenging. We show a simple method to rapidly generate polymer structures with deep-submicrometre-sized features over large areas. In this method, a solution film is dried on a substrate under a suspended flexible template with groove/ridge surface topography. Upon solvent evaporation, the solution splits in the grooves and forms capillary bridges between the template and substrate, which are firmly pinned by the edges of the template grooves. This groove pinning stabilizes the contact lines, thereby allowing the formation of fine patterned structures with high aspect ratios which were used to fabricate various functional materials and electronic devices. We also produced secondary self-assembled nano-stripe patterns with resolutions of about 50 nm on the primary lines.
We developed solution-processed hybrid photodetectors with a poly (9-vinylcarbazole)/zinc oxide nanoparticle photoactive layer and a poly (vinylidene fluoride-co-trifluoroethylene) ferroelectric ...copolymer buffer layer on flexible plastic substrates. The presence of a ferroelectric-poling interface layer significantly enhanced the charge transfer and responsivity of the photodetectors under ultraviolet (UV, 365 nm) light exposure. The responsivity of the device reached 250 mA/W at a reverse bias of 5 V and incident light intensity of 27.5 μW/cm2. This responsivity was four times higher than that of a device without the ferroelectric copolymer layer (64 mA/W) under the same conditions. The response time of the device to incident UV light also improved from 322 to 34 ms with the addition of the ferroelectric copolymer layer. In addition, the flexible device exhibited a stable performance in an air environment up to a maximum strain of 0.3 under bending stress. Finally, a UV-light-responsive memory device was successfully fabricated by using the developed hybrid photodetector and liquid crystals. This device showed a colour change from white to black upon UV illumination, and the on-state of the device was maintained for 30 s without light exposure owing to the polarization of poly (vinylidene fluoride-co-trifluoroethylene).
Technologies for micro-to-nanometer patterns of solution-based materials (SBMs) contribute to a wide range of practical applications in the fields of electronics and optoelectronics. Here, ...state-of-the-art micro-to-nanometer scale patterning technologies of SBMs are disseminated. The utilisation of patterning for a wide-range of SBMs leads to a high level of control over conventional solution-based film fabrication processes that are not easily accessible for the control and fabrication of ordered micro-to-nanometer patterns. In this review, various patterning procedures of SBMs, including modified photolithography, direct-contact patterning, and inkjet printing, are briefly introduced with several strategies for reducing their pattern size to enhance the electronic and optoelectronic properties of SBMs explained. We then conclude with comments on future research directions in the field.
Technologies for micro-to-nanometer patterns of solution-based materials (SBMs) contribute to a wide range of practical applications in the fields of electronics and optoelectronics.
Owing to the tremendous demands for high-resolution pixel-scale thin lenses in displays, we developed a graphene-based ultrathin square subpixel lens (USSL) capable of electrically tuneable focusing ...(ETF) with a performance competitive with that of a typical mechanical refractive lens. The fringe field due to a voltage bias in the graphene proves that our ETF-USSL can focus light onto a single point regardless of the wavelength of the visible light-by controlling the carriers at the Dirac point using radially patterned graphene layers, the focal length of the planar structure can be adjusted without changing the curvature or position of the lens. A high focusing efficiency of over 60% at a visible wavelength of 405 nm was achieved with a lens thickness of <13 nm, and a change of 19.42% in the focal length with a 9% increase in transmission was exhibited under a driving voltage. This design is first presented as an ETF-USSL that can be controlled in pixel units of flat panel displays for visible light. It can be easily applied as an add-on to high resolution, slim displays and provides a new direction for the application of multifunctional autostereoscopic displays.
A simulation model of electrical percolation through a three-dimensional network of curved CNTs is developed in order to analyze the electromechanical properties of a highly stretchable fiber strain ...sensor made of a CNT/polymer composite. Rigid-body movement of the curved CNTs within the polymer matrix is described analytically. Random arrangements of CNTs within the composite are generated by a Monte-Carlo simulation method and a union-find algorithm is utilized to investigate the network percolation. Consequently, the strain-induced resistance change curves are obtained in a wide strain range of the composite. In order to compare our model with experimental results, two CNT/polymer composite fibers were fabricated and tested as strain sensors. Their effective CNT volume fractions are estimated by comparing the experimental data with our simulation model. The results confirm that the proposed simulation model reproduces well the experimental data and is useful for predicting and optimizing the electromechanical characteristics of highly stretchable fiber strain sensors based on CNT/polymer composites.
Conjugated polymers have emerged as promising materials for next-generation electronics. However, in spite of having several advantages, such as a low cost, large area processability and flexibility, ...polymer-based electronics have their own limitations concerning low electrical performance. To achieve high-performance polymer electronic devices, various strategies have been suggested, including aligning polymer backbones in the desired orientation. In the present paper, we report a simple patterning technique using a polydimethylsiloxane (PDMS) mold that can fabricate highly aligned nanowires of a diketopyrrolopyrrole (DPP)-based donor–acceptor-type copolymer (poly (diketopyrrolopyrrole-alt-thieno 3,2-b thiophene), DPP-DTT) for high-performance field effect transistors. The morphology of the patterns was controlled by changing the concentration of the DPP-based copolymer solution (1, 3, 5 mg mL−1). The molecular alignment properties of three different patterns were observed with a polarized optical microscope, polarized UV-vis spectroscopy and an X-ray diffractometer. DPP-DTT nanowires made with 1 mg mL−1 solution are highly aligned and the polymer field-effect transistors based on nanowires exhibit more than a five times higher charge carrier mobility as compared to spin-coated film-based devices.
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