Ammonia is a harmful atmospheric pollutant that poses serious threats to human health and ecological environment. Therefore, the development of low-energy, high-performance and real-time ammonia monitoring system is imperative. In this study, p-aminobenzene sulfonic acid (pABSA) modified MoO₃/polypyrrole (PPy) composite materials were successfully prepared using an in situ chemical oxidation polymerization method with MoO₃ and pyrrole monomer (Py) as raw materials and FeCl₃ as an oxidant, along with pABSA as an anionic surfactant. Microstructure of the materials was characterized to explore influence of pABSA-modified MoO₃/PPy composite materials on the gas sensing performance. The results demonstrate that at room temperature, the response value of pABSA-modified MoO₃/PPy composite material to a mass concentration of 1×10⁵ µg/L ammonia is 188%, which is ~8 times higher than that of pure PPy (22%), exhibiting excellent selectivity and stability. The enhancement in sensing performance can be attributed to the formation of a heterojunction between MoO₃ and PPy as well as surface modification by pABSA leading to increased mobile charge carriers on the material's surface.

Electrochromic materials with dynamic color change and optical modulation have potential applications in the fields of automotive anti-glare mirror, smart window, low-power display, and electronic paper, attracting worldwide attention. NiO and MnO₂ are typical anodic coloration materials with a comfortable neutral tone. However, the low transmittance of single NiO or MnO₂ films in bleaching states leads to small optical modulation. Herein, a porous nickel-manganese layered double hydroxide (NiMn-LDH) film with neutral color for visible electrochromic application was prepared. The NiMn-LDH films were grown directly on fluorine-doped tin oxide (FTO) conductive glass substrates by a one-step solvothermal method using NiCl₂·6H₂O and MnSO₄·H₂O as the raw materials. The crystalline phase and micromorphology of the as-grown NiMn-LDH films were characterized and the electrochromic and electrochemical performances were also investigated. The results indicate that the film grown by solvothermal method is composed of NiMn-LDH nanosheets with porous surface morphology, leading to a large optical modulation of 61.9% at 550 nm. The coloration and bleaching time are calculated to be 15.8 and 13.2 s, respectively. A high coloration efficiency of 63.1 cm²·C^-1 is also achieved for the as-grown NiMn-LDH nanosheet film. Meanwhile, the NiMn-LDH film electrode demonstrates good cycle stability, retaining 87.0% of its maximum optical modulation after 160 cycles. Furthermore, the NiMn-LDH film electrode delivers an area capacitance of 10.0 mF·cm^-2 at a current density of 0.1 mA·cm^-2. These results consolidate that the as-prepared NiMn-LDH film electrode is a promising candidate for both electrochromic and energy-storage applications.

Metal sulfide Ag₂S is an attractive semiconductor due to its excellent physical and chemical property that enable it with wide applications in fields of catalysis, sensing, optoelectronics in past years. In present work, ϕ18 mm× 50 mm Ag₂S ingot was successfully prepared using zone melting method and its thermoelectric (TE) behavior was investigated. Ag₂S has standard monoclinic P2₁/c space group (α-Ag₂S phase) below 450 K and transfer to cubic structure (β-Ag₂S phase) over this temperature. Ag₂S is a n-type semiconductor as the Seebeck coefficient S is always negative due to the Ag interstitial ions in the material that can provide additional electrons. S is about -1200 µV·K^-1near room temperature, declines to -680 µV·K ^-1 at 440 K and finally decreases to ~-100 µV·K ^-1at β-Ag₂S state. The electrical conductivity (σ) of α-Ag₂S is almost zero. However, the value sharply jumps to ~40000.5 S·m ^-1 as the material just changes to β-Ag₂S at 450 K and then gradually deceases to 33256.2 S·m ^-1 at 650 K. Hall measurement demonstrates that carrier concentration n_H of Ag₂S is suddenly increased from the level of ~10 ¹⁷ cm^-3 to ~10¹⁸ cm^-3during phase transition. Total thermal conductivity κ of α-Ag₂S is ~0.20 W·m ^-1·K^-1 but is ~0.45 W·m^-1·K^-1of β-Ag₂S. Ultimately, a maximum ZT=0.57 is achieved around 580 K that means Ag₂S might be a promising middle-temperature TE material.

Advanced ink printing techniques, such as printing and coating, have overcome the limitations of traditional manufacturing methods, allowing for rapid prototyping of films and electronic devices with sophisticated structures and specific functions. These techniques hold enormous potential in wearable smart identification, energy storage, electromagnetic shielding and absorption, touch display, and so on. The key to printing advanced energy and electronic devices lies in the development of cutting-edge functional inks and their corresponding printing technologies. MXene, a family of two-dimensional compounds composed of transition metal carbides, nitrides, or carbonitrides, was discovered in 2011. MXene exhibits remarkable physical and chemical properties, including high conductivity, pronounced hydrophilicity, and diverse surface chemistry, which has garnered significant attention within the research community and made it particularly suitable as inks in printing applications. Conducting research on the printing behavior and mechanisms of MXene inks is crucial not only for achieving high-precision patterns but also for establishing a solid foundation for manufacturing techniques that can precisely create multiscale, multimaterial and multifunctional films, and electronic devices. This article begins with a brief discussion of MXene flakes’ synthesis and colloidal stability, followed by a detailed examination of its rheological characteristics, printable ink formulation, and printing methods. Additional, special attention is given to the latest advances of MXene ink in energy, health, and sensing applications. The perspective concludes with a summary of current research challenges and future directions in this area, offering new perspectives and insights for researchers.

In recent years, pressure sensors have been widely applied in the fields of smart wearable textile, health detection, and electronic skin. The emergence of the two-dimensional nanomaterial MXene has brought a brand-new breakthrough for pressure sensing. Ti₃C₂T_x is the most popular studied MXene in the field of pressure sensing and shows good mechanical, electrical properties, excellent hydrophilicity, and extensive modifiability, enabling it an ideal material for pressure sensing. Hence, researchers have conducted a lot of explorations and studies on design and application of MXene in pressure sensors in recent years. Herein, the preparation technologies and antioxidant methods are summarized. Design of MXene-based microstructures is also introduced, including aerogels/porous structural materials, hydrogels, flexible substrates, and films, which are beneficial to improve the response range, sensitivity, and flexibility of pressure sensors, and promote the rapid development of pressure sensors. The mechanisms of MXene pressure sensors are further broached, including piezoresistive, capacitive, piezoelectric, triboelectric, battery typed and nanofluidic. MXene has been applied in a wide range of sensors for various mechanisms due to its excellent characteristics. Finally, the chance and challenge in the synthesis, properties, and pressure sensing performance of MXene materials are prospected.

Two-dimensional transition metal carbon/nitride MXenes show promising applications in various fields due to their remarkable electrical and mechanical properties. Recently, the research of high performance MXenes nanocomposites (including one-dimensional fibers, two-dimensional films and three-dimensional blocks) has made remarkable progress. However, the mechanical properties are still far lower than the intrinsic mechanical properties of MXenes nanosheets, mainly due to the key scientific problems of voids, misalignment of MXenes nanosheets and weak interfaces. In order to solve the above problems, the intrinsic mechanical properties of MXenes nanosheets are firstly discussed in this work, then the development of high performance MXenes nanocomposites are summarized, and the latest research progress of high performance MXenes nanocomposites is discussed in detail, including how to eliminate void, improve the orientation of MXene nanosheets and enhance the interface interaction. Meanwhile, the applications of high performance MXenes nanocomposites in the fields of electric heating, thermal camouflage, electromagnetic shielding, sensing and energy storage are introduced. Finally, the challenges and future development directions of high performance MXenes nanocomposites are proposed.

Brain-inspired neuromorphic computing refers to simulation of the structure and functionality of the human brain via the integration of electronic or photonic devices. Artificial synapses are the most abundant computation element in the brain-inspired system. Memristors are considered to be ideal devices for artificial synapse applications because of their high scalability and low power consumption. Based on Ohm’s law and Kirchhoff’s law, memristor crossbar arrays can perform parallel multiply-accumulate operations in situ, leading to analogue computing with greatly improved speed and energy efficiency. Oxides are most widely used in memristors due to the ease of fabrication and high compatibility with CMOS processes. This work reviews the research progress of oxide memristors for brain-inspired computing, mainly focusing on their resistance switching mechanisms, device structures and performances. These devices fall into three categories: electrical memristors, memristors controlled via both electrical and optical stimuli, and all-optically controlled memristors. The working mechanisms of electrical memristors are commonly related to microstructure change and Joule heat that are detrimental to device stability. The device performance can be improved by optimizing device structure and material composition. Tuning the device conductance with optical signals can avoid microstructure change and Joule heat as well as reducing energy consumption, thus making it possible to address the stability problem. In addition, optically controlled memristors can directly response to external light stimulus enabling integrated sensing-computing-memoring within single devices, which are expected to be used for developing next-generation vision sensors. Hence, the realization of all-optically controlled memristors opens a new window for research and applications of memristors.

Wearable instruments are functional devices that can be worn on human body, sensing, transmitting and processing body or environmental information in real time, and show broad application prospects in medical health, especially artificial intelligence, sports and entertainment. With the development of wearable instruments, various flexible sensors have emerged. Flexible mechanical sensors based on piezoelectric effect have attracted much attention because of their advantages of wide sensing frequency, fast response, good linearity, and self-power supply. However, traditional piezoelectric materials are mostly brittle ceramics and crystalline materials, which limit their application in flexible devices. With the deepening of research, more and more flexible piezoelectric materials and piezoelectric composites continue to emerge, injecting new development vitality into flexible wearable mechanical devices. This article mainly summarizes the cutting-edge progress of flexible wearable piezoelectric devices, including piezoelectric principle, preparation and performance improvement methods of flexible piezoelectric materials. In addition, the main application directions of flexible wearable piezoelectric devices, including medical health and human-computer interaction, as well as the challenges and opportunities encountered, are summarized.

The outbreak of corona virus disease 2019 (COVID-19) has aroused great attention around the world. SARS-CoV-2 possesses characteristics of faster transmission, immune escape, and occult transmission by many mutation, which caused still grim situation of prevention and control. Early detection and isolation of patients are still the most effective measures at present. So, there is an urgent need for new rapid and highly sensitive testing tools to quickly identify infected patients as soon as possible. This review briefly introduces general characteristics of SARS-CoV-2, and provides recentl overview and analysis based on different detection methods for nucleic acids, antibodies, antigens as detection target. Novel nano-biosensors for SARS-CoV-2 detection are analyzed based on optics, electricity, magnetism, and visualization. In view of the advantages of nanotechnology in improving detection sensitivity, specificity and accuracy, the research progress of new nano-biosensors is introduced in detail, including SERS-based biosensors, electrochemical biosensors, magnetic nano-biosensors and colorimetric biosensors. Functions and challenges of nano-materials in construction of new nano-biosensors are discussed, which provides ideas for the development of various coronavirus biosensing technologies for nanomaterial researchers.

The pandemic outbreak of COVID-19 has posed a threat to public health globally, and rapid and accurate identification of the viruses is crucial for controlling COVID-19. In recent years, nanomaterial-based electrochemical sensing techniques hold immense potential for molecular diagnosis with high sensitivity and specificity. In this review, we briefly introduced the structural characteristics and routine detection methods of SARS-CoV-2, then summarized the associated properties and mechanisms of the electrochemical biosensing methods. On the above basis, the research progress of electrochemical biosensors based on gold nanomaterials, oxide nanomaterials, carbon-based nanomaterials and other nanomaterials for rapid and accurate detection of virus were reviewed. Finally, the future applications of nanomaterial-based biosensors for biomolecular diagnostics were pointed out.

Flexible sensors have wide applications in various fields such as biomedicine, environmental monitoring and smart wearable devices, as they can adapt to diverse complex environments and curved surfaces. This study aimed to develop resilient and flexible oxygen sensors based on fluorescence quenching. A flexible oxygen sensing component was prepared, comprising aluminum silicate fibers as the support, polydimethysiloxane (PDMS) as the matrix, and platinum tetrakis pentafluorophenyl porphyrin (PtTFPP) as the oxygen probe. The component exhibited superhydrophobicity with a water contact angle of 152°, which was beneficial for maintaining integrity in humid atmospheres and aqueous solutions. It showed the fluorescence quenching effect towards gaseous oxygen and dissolved oxygen in water, which could be well fitted by the Stern-Volmer equation with K_SV constants of 0.020 h·Pa^-1 for the gaseous oxygen and 2.94 L·mmol^-1 for the dissolved oxygen. The component also demonstrated good reversibility and fast response in rapidly altered atmosphere, with a response time of 0.9 s from nitrogen switching to oxygen and a recovery time of 2.7 s from oxygen switching to nitrogen. Additionally, the PtTFPP-PDMS component displayed remarkable stability concerning its relative fluorescence intensity and water contact angle even after exposure to 100 ℃ steam for 15 h, soaking in pH 1-10 aqueous solutions, and enduring 400 bending cycles. The aluminum silicate fiber-supported PtTFPP-PDMS film developed in this study exhibited excellent fluorescent oxygen sensing properties and stability, making it a promising candidate for oxygen sensors, and suitable for determination of gaseous and dissolved oxygen in challenging environments.

Mechanoluminescent (ML) materials, due to their unique mechanical-to-optical energy conversion, hold significant promise in stress sensing and are poised to become the next generation of visual strain-sensing materials. Currently, expanding ML material systems and enhancing their performance remain focal points of research. In this study, a series of Tb³⁺-doped green ML phosphors was synthesized using BaSrGa₄O₈ matrix (hexagonal crystal system, space group P6₃, with a non-centrosymmetric structure) via high-temperature solid-state synthesis. These materials emitted bright green light under various mechanical excitations (tension, compression, and torsion). Clear note mappings were observed by writing B, S, G, O, T, and b on the prepared ML elastomer with a glass rod. By analyzing the colormap, the stress conditions during the writing process could be traced. This is the first observation of ML phenomenon in the above-mentioned matrix doping system. Under 254 nm ultraviolet (UV) excitation, BaSr_1-xGa₄O₈: xTb³⁺ phosphors exhibited bright green emission at 543 nm, which was attributed to ⁵D₄-⁷F₅ transition of Tb³⁺, and shared the same luminescent center as ML. The samples continued to display strong long persistent luminescence after UV irradiation was removed. By combining ML, photoluminescence (PL), and long persistent luminescence (LPL) with thermoluminescence (TL) analysis, further insights into their intrinsic connections were elucidated. In conclusion, this study broadens the range of high-performance ML material systems, showcasing potential applications in visual strain sensing, information security, and anti-counterfeiting.

In recent years, copper iodide (CuI) is an emerging p-type wide bandgap semiconductor with high intrinsic Hall mobility, high optical absorption and large exciton binding energy. However, the spectral response and the photoelectric conversion efficiency are limited for CuI-based heterostructure devices, which is related to the difficulty in fabrication of high-quality CuI thin films on other semiconductors. In this study, a p-CuI/n-Si photodiode has been fabricated through a facile solid-phase iodination method. Although the CuI thin film is polycrystalline with obvious structural defects, the CuI/Si diode shows a high weak-light sensitivity and a high rectification ratio of 7.6×10⁴, indicating a good defect tolerance. This is because of the unilateral heterojunction behavior of the formation of the p⁺n diode. In this work, the mechanism of photocurrent of the p⁺n diode has been studied comprehensively. Different monochromatic lasers with wavelengths of 400, 505, 635 and 780 nm have been selected for testing the photoresponse. Under zero-bias voltage, the device is a unilateral heterojunction, and only visible light can be absorbed at the Si side. On the other hand, when a bias voltage of -3 V is applied, the photodiode is switched to a broader “UV-visible” band response mode. Therefore, the detection wavelength range can be switched between the “Visible” and “UV-visible” bands by adjusting the bias voltage. Moreover, the obtained CuI/Si diode was very sensitive to weak light illumination. A very high detectivity of 10¹³-10¹⁴ Jones can be achieved with a power density as low as 0.5 μW/cm², which is significantly higher than that of other Cu-based diodes. These findings underscore the high application potential of CuI when integrated with the traditional Si industry.

In recent years, humidity sensors have attracted widespread attention from researchers in fields such as food safety and soil monitoring. Traditional humidity sensors exhibit the advantages of good stability and high sensitivity. However, most humidity sensing systems convert humidity signals into recognizable waveforms through wired connections and large external devices, making it impossible to achieve real-time visual monitoring of changes in humidity information. Currently, direct conversion of humidity information into visible color signals by eyes provides an ideal solution to the aforementioned problems but still lacks intelligent monitor capacity. This study integrated humidity sensors and electrochromic devices (ECDs) to prepare an intelligent visual humidity monitoring system. By converting humidity signals into voltage signals to drive ECDs, stable and reversible color change in the system could be achieved. The ECDs were prepared using tungsten trioxide (WO₃) as the negative electrode and zinc foil (Zn) as the positive electrode. Based on the output voltage of the humidity sensor, it achieves transitions between different working states, thereby generating color signals that can be observed by the naked eyes. Electrochemical performance and electrochromic performance of ECDs were tested and characterized by using a UV-visible spectrophotometer and an electrochemical workstation. Subsequently, the performance of the conditioning circuit was analyzed using an oscilloscope and a humidity generation platform. The results show that the intelligent electrochromic humidity indicator has good stability and rapid response performance, where the coloring time and fading time are only 7.5 s and 4.5 s, respectively. After 300 cycles, the optical modulation (ΔT) is basically maintained the same as the initial value, and the retention rate can reach more than 95%. Therefore, this visual humidity indication system which possesses novel design and simple structure has promising broad application in fields such as artificial intelligence and intelligent agriculture.

Photochromic windows are considered an effective and energy-efficient smart window due to their simple structure, passive light modulation, and zero-energy input. However, the research on photochromic smart windows has rarely addressed the mid-infrared (MIR) bands, which greatly limits energy-saving efficiency. Here, we report that rare-earth oxygen-containing hydrides (ReO_xH_y) films grown on ITO substrates have the ability to be broadband modulated. The developed photochromic smart window is capable of automatically adjusting emissivity by sensing light intensity while maintaining visible and near-infrared (NIR) modulation (ΔT_sol = 35.1%, ΔT_lum = 37%, and Δε_{8-13 μm} = 0.12). We also achieved one-step preparation of GdO_xH_y with improved stability by optimising the preparation atmosphere. The photochromic mechanism was analyzed by comprehensive characterization. In conclusion, this passive and synergistic modulation method across the visible-NIR-MIR is expected to greatly advance the field of photochromic smart windows.

Nickel molybdate (NiMoO₄) is a material with excellent performance in the field of energy storage and catalysis, but lacking of further explorations in the field of electrochromism. In this work, porous NiMoO₄ films were grown on transparent conductive glasses by hydrothermal method without using seed layer. Crystalline phase and micromorphology of NiMoO₄ nanosheet films were characterized by grazing incidence X-ray diffractometer (GIXRD) and field-emission scanning electron microscope (FESEM), and the electrochromic and electrochemical properties were also investigated by using a UV-Vis-NIR spectrophotometer and an electrochemical workstation. The results show that the NiMoO₄ electrochromic films have a porous structure, which can provide sufficient channels for ion migration and reactive sites for the dynamic process of ion intercalation/deintercalation into NiMoO₄ film. Therefore, the NiMoO₄ films exhibit excellent electrochromic performance, including large optical modulation of 79.6% at 480 nm and high coloring efficiency of 86.2 cm²·C^-1. Meanwhile, the coloration and bleaching response time of the NiMoO₄ films are 9.5 and 12.7 s, respectively. Interestingly, there is a two-step process in the bleached process of NiMoO₄ electrochromic films, including a fast process and a slow process. And the optical modulation can still be maintained at 99.7% of the maximum optical modulation after 100 cycles. In addition, the NiMoO₄ films exhibit a large area specific capacitance of 49.59 mF·cm^-2 at 0.3 mA·cm^-2. These excellent properties support NiMoO₄ nanosheet films with promising application in high-performance electrochromic devices. And the next step is to focus on finding the suitable electrolyte and matched counter electrodes in the device assembly.

Electrochromic materials have been applied in energy-saving buildings, intelligent displays, and other fields, recognized as one of the most promising intelligent materials for research. Liquid phase method for preparation of WO₃ electrochromic thin filmscan construct complex polychromies structures, showing great potential in modulation amplitude and short response time, especially in large area and low cost preparation. This study aims to develop a low-cost, easy-to-scale WO₃ nanocrystalline liquid phase coating process, and improve cycle stability and preparation process. WO₃ electrochromic films with high modulation amplitude, rapid response and fatigue resistance were prepared. Optimized the annealing process, WO₃ nanopowders were synthesized with low aggregation and high crystallinity, and then WO₃ nanocrystalline coating solution was prepared by ball milling dispersion. Thin film microstructure and coating solution crystallinity were optimized. The obtained thin electrochromic films of WO₃ show high tuning amplitude (82%), short response time (t_c/t_b: 8 s/4.2 s), high colouring efficiency (81.5 cm²·C^-1), and high cycling stability (> 1000 times). In this work, the crystallization and dispersion properties of WO₃ nano-powder were modified to comprehensively improve the performance of WO₃ electrochromic films prepared by nanocrystalline liquid phase coating technology. All results above demonstrate that the WO₃ electrochromic film prepared by the liquid phase method is expected to be used in the future with high color-changing performance and cycle stability.

Electrochromic materials are energy-saving and environmentally friendly materials that can reduce energy use by adjusting sunlight and solar-heat. In particular, transition metal oxides with stable chemical properties have been widely studied as electrochromic materials. Recently, bimetallic oxides with two variable valence states of metal ions have received increasing attention due to their better electrochemical activity. In this study, Ti₂Nb₁₀O₂₉ films were successfully prepared on conductive glasses, and the effect of the atomic ratio of niobium to titanium in the precursor on the electrochromic properties of the thin films was investigated. The results show that the thin film prepared from precursors with an atomic ratio of niobium to titanium of 3 : 1 possesses the best electrochromic properties. It is worth noting that the thin film achieves a large optical modulation in the wavelength range of 300-1100 nm, and the transmittance in the bleached state is nearly 90%, appearing grayish blue under the action of −1.6 V, colorless state under the action of 0.4 V, and achieving a maximum optical modulation of 69.4% at the wavelength of 750 nm. After a square-wave potential of -1.6 V for 60 s and 0.4 V for 15 s, the film shows response time of 29.8 s for coloring and 5.9 s for bleaching. Coloration efficiency of the as-prepared film is 68.3 cm²·C^-1. The above results indicate that the successfully prepared Ti₂Nb₁₀O₂₉ thin film enriches variety of bimetallic oxide electrochromic materials and has widely application prospect.

Two-dimensional (2D) perovskite displays great potential in optoelectronic applications due to its inherent quantum well structure, large exciton binding energy and good stability. However, facile preparation of high-quality 2D perovskite films with low cost remains a huge challenge. In this work, high-quality two-dimensional perovskite (PEA)₂PbI₄ films were prepared by solution method at low annealing temperature(80 ℃) without other special treatments, and further applied in the field of photodetectors. The results show that this photodetector possessed a low dark current (10^-11 A), good responsiveness illuminated at a wavelength of 450 nm (107 mA·W^-1), high detection rate (2.05×10¹² Jones) and fast response time (250 μs/330 μs). After 1200 s continuous illumination, the device maintains 95% initial photocurrent. In addition, the photocurrent remains almost unchanged after storage for 30 d. This work provides promising strategy to develop stable and high-performance optoelectronic devices.

X-ray detection has been widely used in medical imaging, security inspection, and industrial non-destructive tests. Halide perovskite X-ray detectors have attracted increasing attention due to their high sensitivity and low detection limit, but the notorious ion migration leads to poor operational stability. It is reported that the low dimensional structure can effectively suppress the ion migration of perovskites, thus greatly improving the stability of the detectors. This review introduces the working mechanism, key performance parameters of perovskite X-ray detectors, and summarizes the recent progress of low-dimensional perovskite materials and their application in direct X-ray detectors. The relationship between the structural characteristics of low-dimensional perovskite materials and their X-ray detection performance was systematically analyzed. Low-dimensional perovskite is a promising candidate for the preparation of X-ray detectors with both high sensitivity and stability. Further optimization of detection material and device structure, preparation of large-area pixelated imaging devices, and study of working mechanism in-depth of the detector are expected to promote the practical application of perovskite X-ray detectors.

AgBi₂I₇ thin film is one of the important candidates for constructing heterojunction ultraviolet photodetectors, due to their great optoelectronic properties and environmental stability. In this study, AgBi₂I₇ thin films were prepared by solution method and their photodetecting properties were investigated. By optimizing technological parameters such as concentration of the precursor solution and type of solvent (n-butylamine and DMSO), their photodetecting performance were investigated. AgBi₂I₇ thin films were fabricated on wide-bandgap GaN by optimal scheme to construct an AgBi₂I₇/GaN heterojunction. The heterojunction has a great selective detection of UVA-ray of which full width at half maximum is about 30 nm. Under 3 V bias and 350 nm UV irradiation, the On/Off ratio of the device exceeds 5 orders of magnitude, achieving a high responsivity of 27.51 A/W and a high detection rate of 1.53×10¹⁴ Jones. Therefore, the present research indicates that AgBi₂I₇ thin films prepared by solution method are promising to be applied to construct high-performance heterojunction ultraviolet photodetectors.

As a colossal magnetoresistance material, the perovskite manganese oxide La_1–xSr_xMnO₃ (LSMO) has broad application prospects in magnetic sensors and other fields. However, it is difficult to obtain a significant colossal magnetoresistance effect at a low magnetic field at room temperature. To improve its magnetoresistance effect and transition temperature, La_0.8Sr_0.2Mn_1–xAl_xO₃ (0≤x≤0.25) (LSMAO) polycrystalline samples were prepared by traditional solid-state reaction method in present work. Effects of Al³⁺ doping on the electrical transport property and magnetoresistance of LSMO were systematically analyzed. The X-ray diffraction (XRD) results indicate that all samples crystallize in a single rhombohedral structure with the space group of $\text{R}\bar{3}\text{C}$. Result of electrical transport property shows that resistivity of the samples increases exponentially with the increment of Al³⁺ doping amount, and the metal-insulator transition temperature is increased by an external magnetic field. This phenomenon may be attributed to dilution of the Mn³⁺/Mn⁴⁺ ions network by Al³⁺, which increases the magnetic disorder but reduces the number of carriers. In addition, the conduction mechanism of LSMAO ceramics change from the small polaron hopping model (SPH) to the variable range hopping model (VRH) after doping of Al³⁺, reflecting that the non-magnetic Al³⁺ weakens the carrier exchange between the ferromagnetic clusters. As a result, the thermally activated neighbor transition of small polarons is suppressed. Magnetoresistance effect of LSMAO is enhanced from 21.03% to 59.71% with x increasing from 0 to 0.25, which proves that the doping of Al³⁺can effectively enhance the magnetoresistance effect of LSMAO.

For the conventional von Neumann based vision systems, the sensing, memory, and processing units are separated. Shuttling of redundant data between separated image sensing, memory, and processing units causes a high latency and energy consumption. To break these limitations, the next-generation neuromorphic visual systems, which integrate light information sensing, memory, and processing, can reduce the data transfer, thus improving their time and energy efficiencies. As the basis of the hardware-implementing of neuromorphic visual systems, optoelectronic artificial synapse devices have been extensively investigated in recent years. By integrating the functions of synaptic devices and light-sensing elements, the optoelectronic artificial synapse devices pave the way for constructing new neuromorphic vision systems with low latency, high energy efficiency and good reliability. Many materials are widely utilized for optoelectronic artificial synapse devices, and operation mechanisms of the present optoelectronic artificial synapse devices mainly include the ionization and dissociation of oxygen vacancy, the trapping/detrapping of photogenerated carriers, the light-induced phase change, and the interaction between light and ferroelectric materials. In this short review, the recent progresses in optoelectronic artificial synapse devices are introduced from the perspectives of their operation mechanisms. Besides, advantages and challenges of the devices are analyzed from the view of operation mechanisms. Finally, the advanced prospect and research aspect of optoelectronic artificial synapse devices are outlined for the application.