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2D materials have garnered significant research attention due to their unique electrical and optical properties. Various photodetectors (PDs) based on 2D materials have been demonstrated to possess a high photoresponse, achieve specific light detection, and construct flexible devices. Among these, photoelectrochemical‐type (PEC) PDs are attracting increasing attention due to their facile fabrication processes, self‐powered capability, and high sensitivity. Compared with transitional solid‐state PDs based on 2D materials, research on 2D material‐based PEC PDs is still in its initial stages but exhibits promising potential for various applications. This paper comprehensively reviews recent advancements in 2D material‐based PEC PDs. The 2D materials for PEC PDs are first classified, and then the synthesis methods employed for their fabrication are briefly summarized. Later, the performance and performance optimization strategies of various 2D material‐based PEC PDs are discussed. Finally, the challenges and opportunities for developing high‐performance 2D material‐based PEC PDs are highlighted. [ABSTRACT FROM AUTHOR]

The optical synaptic device is a novel nonvolatile memory device that combines optical sensing function with synaptic plasticity to simulate the basic biomimetic behaviors of the human visual system. It shows a great potential application in artificial vision. However, most of the current optical synaptic devices are either structurally special or complex, which are quite difficult to prepare especially for mass production. In this work, a submillimeter single‐crystal Bi2O2Se flake with selenium vacancies (Bi2O2Se‐VSe) grown by physical vapor deposition is presented. Upon the Bi2O2Se‐VSe flake, an optical synaptic device is designed with the persistent photoconductivity (PPC) effect induced by selenium vacancies. The device can simulate the biological synapses with an obvious synaptic plasticity. Moreover, an artificial vision system consisting of a 3 × 4 array of optical synaptic devices has been fabricated. The intensity of the image pattern can keep at a high memory level of 54.64% and 19.31% for 532 and 1060 nm waiting for 400 s after illumination of 100 s, which demonstrates the devices exhibit excellent image sensing, learning, and memory storage. This work opens up a new route for fabricating the optical synaptic device with a simple structure and provides new ideas for studying artificial vision systems. [ABSTRACT FROM AUTHOR]

A wearable sensor capable of directly detecting cytokines in external secretions external to the human body is pivotal for gauging the intensity of the immune response and circumventing inflammatory storms, a significant clinical concern. The detection of low‐concentration cytokines is often hampered due to interference from impurities in secretions. Addressing this challenge, a wearable detection system is developed by integrating a Janus membrane with water auto‐collection/filtering capabilities, and aptamer‐modified graphene field‐effect transistor sensors, enabling the detection of low‐concentration cytokines in undiluted sweat samples. The Janus membrane can automatically filter external secretions and transport them to the sensor surface, effectively eliminating impurity interference and enhancing the sensor's detection capabilities. The device can sensitively detect cytokines (such as TNF‐α, a marker for inflammation and cancer) in undiluted sweat, with a detection range spanning 0.5 to 500 pM, and a detection limit reaching 0.31 pM. The ultra‐flexibility of the sensor is also verified, maintaining stable electrical properties even after enduring up to 50 extreme deformations. These findings indicate that the wearable detection system has the potential to realize low‐concentration cytokines monitoring in the sweat of inflammatory patients, to assist the healthcare system in controlling the body's immune status. [ABSTRACT FROM AUTHOR]

Broadband, sensitive, and spectrally distinctive photodetectors show great applications in multifunction optoelectronic devices, which usually integrate multiple photodetectors for distinguishing different spectra. Recently, UV‐induced photocurrent polarity‐switching in individual photoelectrochemical photodetectors (PEC PDs) has been demonstrated by tuning the interfacial physical/chemical processes. However, broadband and spectrally distinctive PEC PDs are still scarce. Here, mosaic t‐Se/InSe heterojunctions are used for designing broadband and spectrally distinctive PEC PDs. Mosaic t‐Se/InSe photoelectrodes are fabricated by one‐step electrochemical deposition with annealing treatment. t‐Se/InSe self‐powered PEC PDs show a broadband photoresponse from UV to near‐infrared (NIR). The photocurrent is negative for UV‐visible spectra and turns positive under NIR irradiation. The light‐induced photocurrent polarity‐switching originates from the competition of different redox reactions at the t‐Se/InSe photoelectrode/electrolyte interface. The responsivity is −22.5, −10.93, −4.18, and 2.48 mA W−1 for 365, 525, 630, and 850 nm light, respectively, exceeding most spectrally distinctive solid‐state PDs. The boosted photoresponse of t‐Se/InSe is attributed to the synergistic effect of stronger light absorption, faster carrier transport, and accelerated interfacial charge transfer. Moreover, the devices show great potential for applications in encrypted optical communications. This work provides a way for designing broadband and spectrally distinctive PEC PDs and demonstrates their potential applications. [ABSTRACT FROM AUTHOR]

Photoelectrochemical‐type ultraviolet photodetectors (PEC UV PDs) with simple fabrication processes and high sensitivity have attracted ever‐growing attention. However, the self‐powered performance of PEC UV PDs is still unsatisfying. Herein, the SnO2 nanosheet array (NSA) photoanodes are fabricated and their good self‐powered UV detection capability is demonstrated. The 3D structure of SnO2 NSA not only improves the interfacial charge transfer and carrier transport but also enhances UV absorption. Therefore, the self‐powered SnO2 NSA‐based PEC UV PDs exhibit excellent performance with an ultrahigh responsivity of 207.12 mA W−1, an excellent UV–visible rejection ratio (R254/R455 of 3395), a fast response time (25 ms), and good stability under 254 nm illumination, demonstrating one of the recorded‐high‐performance in the recently reported PEC UV PDs. This work provides more options for developing high‐performance PEC UV PDs. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) synaptic devices have attracted great attention in the field of NIR vision sensors due to their highly parallel sensing and memory functions, which emulate the basic biomimetic behaviors of the human visual system. However, it is a great challenge for the 2D material to achieve NIR light response and integration, which obstructs the progress of NIR synaptic devices. Hence, a two‐terminal NIR synaptic device based on a multilayer MoSe2 moiré superlattice is reported. The moiré structure dominated by interlayer excitons significantly enhances the interlayer coupling of multilayer MoSe2, resulting in a narrower band gap nearly to that of bulk to achieve NIR light response and broadband absorption from 240 nm to 1700 nm. The existence of Se vacancies in MoSe2 moiré superlattice makes the device show the fundamental synaptic performance. Furthermore, a 10×10 integrated retinal morphologic device array is constructed. Under the 100 s light pulse stimulation of 1060 nm, the pattern obtained after attenuation of 50 s still has a memory level of 14.84%, reflecting the excellent storage function under NIR illumination. This research opens up a new avenue for the realization of NIR artificial retina and bionic eye based on 2D materials. [ABSTRACT FROM AUTHOR]

Multifunctional capability and low coupling electronic skin (e‐skin) is of great significance in advanced robot systems interacting with the human body or the external environment directly. Herein, a multifunctional e‐skin system via vertical integrated different sensing materials and structures is presented. The multifunctional e‐skin has capacity sensing the proximity, pressure, temperature, and relative humidity simultaneously, with scope of 100–0 mm, 0–30 N, 20–120 °C and 20–70%, respectively. The sensitivity of the four kinds of sensors can be achieved to 0.72 mm−1, 16.34 N−1, 0.0032 °C−1, and 15.2 pF/%RH, respectively. The cross‐coupling errors are less than 1.96%, 1.08%, 2.65%, and 1.64%, respectively, after temperature compensation. To be state‐of‐the‐art, a commercial robot is accurately controlled via the multifunctional e‐skin system in the complicated environment. The following and safety controlling exhibit both accuracy and high dynamic features. To improve the sensing performance to the insulating objects, machine learning is employed to classify the conductivity during the object approaching, leading to set the threshold in dynamic. The accuracy for isolating the insulator increases from 18% to 88%. Looking forward, the multifunctional e‐skin system has broader applications in human–machine collaboration and industrial safety production technology. [ABSTRACT FROM AUTHOR]

Multiinformation tactile perception is highly important for detecting the change of external environment and realizing the compliant control of the robot. However, the integration of dual‐mode or multimode sensors with low coupling remains a challenge. Herein, a dual‐function tactile sensor with linear pressure and temperature perception is reported. The pressure detection part contains the pyramid conductive film and flexible hemispherical electrode, which works as the piezoresistive material. A spiral nickel film works as a temperature‐sensitive material for sensing the temperature of objects during approaching and while contacting. As a result, the dual‐function sensor can detect the pressure in 0–100 kPa with a sensitivity of 11.5 kPa−1, while the temperature is in 25–65 °C with a sensitivity of 0.0032 °C −1. To be state of the art, the tactile sensor array is used for an active safety control of robotic arms, which can realize the perception and timely avoidance of sudden changes in external temperature and object collisions. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO2) is an n‐type wide‐bandgap semiconductor with the merits of superior electron transport properties and good stability, making it an attractive candidate for solar‐blind ultraviolet photodetectors (SBUV PDs). However, it is still challenging to design high‐performance SnO2‐based photoelectrochemical (PEC)‐type SBUV PDs. In this study, oxygen vacancies (OVs) engineering is proposed to manipulate the photoresponse of SnO2 nanosheets (NSs) and high‐performance SnO2‐based PEC SBUV PDs are developed. SnO2 NSs with different OVs are prepared by hydrothermal method with annealing process. PEC PDs consisting of SnO2 NSs annealed at 550 °C show record high responsivity and specific detectivity of 269.40 mA W−1 and 2.38 × 1012 Jones at a bias voltage of 0.2 V, respectively, surpassing all aqueous‐type PEC UV PDs. OVs simultaneously accelerate the carrier recombination in the SnO2 NSs and charge transfer at the interface of the SnO2 NSs and electrolyte, indicating that both excess OVs and too few OVs reduce the PEC photoresponse. Therefore, an appropriate OV's content is vital to designing high‐performance SnO2 NSs PEC PDs. Moreover, the SnO2 NSs PEC PDs have good self‐powered capability, excellent wavelength‐selectivity, multicycle and long‐term stability. The results of this study demonstrate that OVs engineering is a powerful strategy for designing high‐performance SnO2‐based PEC PDs. [ABSTRACT FROM AUTHOR]

Flexible and wearable sensors are highly desired for health monitoring, agriculture, sport, and indoor positioning systems applications. However, the currently developed wireless wearable sensors, which are communicated through radio signals, can only provide limited positioning accuracy and are often ineffective in underwater conditions. In this paper, a wireless platform based on flexible piezoelectric acoustics is developed with multiple functions of sensing, communication, and positioning. Under a high frequency (≈13 MHz) stimulation, Lamb waves are generated for respiratory monitoring. Whereas under low‐frequency stimulation (≈20 kHz), this device is agitated as a vibrating membrane, which can be implemented for communication and positioning applications. Indoor communication is demonstrated within 2.8 m at 200 bps or 4.2 m at 25 bps. In combination with the sensing function, real‐time respiratory monitoring and wireless communication are achieved simultaneously. The distance measurement is achieved based on the phase differences of transmitted and received acoustic signals within a range of 100 cm, with a maximum error of 3 cm. This study offers new insights into the communication and positioning applications using flexible acoustic wave devices, which are promising for wireless and wearable sensor networks. [ABSTRACT FROM AUTHOR]

Self‐powered photodetectors have attracted widespread attention due to their low power consumption which can be driven by the built‐in electric field instead of external power, but it is very difficult to achieve high responsivity and fast response speed concurrently. Here, a self‐powered photodetector with light‐induced electric field enhancement based on a 2D InSe/WSe2/SnS2 van der Waals heterojunction is designed. The light‐induced electric field derived from the photo‐generated electrons of SnS2 accumulated at the SnS2/WSe2 interface produces an additional negative gate voltage applied to the WSe2 layer, which enhances the built‐in electric field in the InSe/WSe2/SnS2 heterojunction. Accordingly, the photocurrent and photoresponse speed of the heterostructure device are largely improved. The self‐powered photodetector based on the InSe/WSe2/SnS2 heterostructure exhibits a high responsivity of 550 mA W−1, which is a 50 times increase compared to the InSe/WSe2 photodetector, and the response speed (110/120 µs) is one order of magnitude faster than that of the InSe/WSe2 photodetector. The high responsivity and fast speed are caused by the stronger built‐in electric field modulated by a light‐induced electric field, which can separate carriers effectively and reduce drift times. This device architecture can provide a new avenue to fabricate high‐responsivity, fast self‐power photodetectors by utilizing the van der Waals heterojunction. [ABSTRACT FROM AUTHOR]

Selenium (Se) is a p‐type semiconductor with a narrow bandgap, that holds great potential for application in the field of photodetectors because of its good optical properties. However, the photodetection performance of Se‐based photoelectrochemical photodetectors (PEC PDs) fabricated by the drop‐casting (DC) method is still far below the expected value. In this work, in situ grown t‐Se microrod array films (IS‐Se MAFs) are prepared on fluorine‐doped tin oxide (FTO) by a simple electrodeposition method at 353 K. PEC PDs consisting of IS‐Se MAFs as photocathodes show excellent self‐powered photodetection capability with a high responsivity of 10.38 mA W−1, which is a 358‐fold increase over that of DC‐Se PEC PDs. The boosted photoresponse originates from the synergistic effect of the larger electrochemically active surface area and stronger light absorption of IS‐Se MAFs. Moreover, IS‐Se MAFs PEC PDs have a broadband photoresponse ranging from ultraviolet to near‐infrared, fast response speed, good multicycle, and long‐term stability. All the merits confirm the promising application of IS‐Se MAFs in high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

2D materials, with their extraordinary physical and chemical properties, have gained extensive interest for physical, chemical and biological sensing applications. However, 2D material‐based devices, such as field effect transistors (FETs) often show high contact resistance and low output signals, which severely affect their sensing performance. In this study, a new strategy is developed to combine metallic and semiconducting polymorphs of transition‐metal dichalcogenides (TMDCs) to solve this critical issue. Such a phase engineering methodology to integrate large‐scale and spatially assembled multilayers of 2H MoTe2 FETs with coplanar metallic 1T′ MoTe2 contacts is applied. Such in‐plane heterophase‐based FETs exhibit an ohmic contact behavior with an extremely low contact resistance due to the coplanar and seamless connections between 2H and 1T′ phases of MoTe2. These 1T′/2H/1T′ based FETs are successfully demonstrated for detecting NH3 with high current outputs increased up to microamp levels without using any conventional interdigital electrodes, which is compatible with the current CMOS circuits for practical applications. Furthermore, the as‐fabricated sensors can detect NH3 gas concentrations down to 5 ppm at room temperature. This study demonstrates a new strategy of applying the heterophase MoTe2‐based nanoelectronics for high‐performance sensing applications. [ABSTRACT FROM AUTHOR]

With the rapid development of wireless electronic facilities, the demand for high‐performance electromagnetic shielding films has swiftly increased. Graphene is a desirable electromagnetic interference (EMI) shielding material due to its excellent electrical conductivity and light transmittance. Previous studies mostly focus on polycrystalline graphene sheets and the performances are far below the theoretical value due to poor crystal quality. In this paper, the authors demonstrate a flexible ultrathin transparent EMI film based on large‐area single crystal graphene (SCG), which is grown on single crystalline Cu substrates by chemical vapor deposition. Their flexible transparent EMI films show ultrahigh electromagnetic shielding effectiveness (SE). This can be attributed to the high crystalline quality and outstanding electronic conductivity of the as‐used graphene film. The electromagnetic shielding effectiveness of the SCG/MgF/SCG sandwiched structure can reach over 8.10 dB, and the normalized electromagnetic SE is up to 5.5 × 107 dB cm2 g−1, much higher than the recorded materials. Moreover, their large area single‐crystal graphene EMI films exhibit a high and broad wavelength transmittance from visible to infrared range (e.g., infrared transmittance of 94% at 5000 nm). A flexible EMI lid of SCG has been investigated for effectively blocking WIFI signals and phone radiation. [ABSTRACT FROM AUTHOR]

Safety is a core concern in human–robot collaboration (HRC), which highly relies on multi‐information collected from its environment by various sensors. Current passive solution is to isolate the robot from human by fences or cages, which is invalid for a real collaborative robot, especially for the domestic and rehabilitation robots. Herein, a capacitive and piezoresistive hybrid sensor for long‐distance proximity and wide‐range force detection in HRC is reported. The sensor composes a pair of interdigital copper foil worked as the electrode for both coplanar capacitors and resistors, while a carbon black in polymer matrix works as the piezoresistive material. As‐prepared hybrid sensor can detect the object approaching as far as 100 mm, while a contact force covers from 0 to 450 N. The maximum sensitivity is 0.65 mm−1 for object proximity, and 17.73 N−1 for contact force. Significantly, the proposed hybrid sensor is feasible and scalable integration for the electronic‐skins (e‐skins) with superior stability, mechanical flexibility and deformability, which can withstand large compression, bending and torsion in applications. Finally, the e‐skins are used for safety control in two types of commercial robots, which exhibits the long‐distance proximity and large‐range force detection capabilities, illustrating its potential usage in complex, precise, and safe requirement conditions. [ABSTRACT FROM AUTHOR]

The vertical metal‐insulator‐semiconductor (MIS) photodetectors based on van der Waals heterostructures (vdWHs), fabricated by rationally stacking different layers without the limit of lattice‐match, have attracted broad interest due to their wide wavelength monitoring range, high responsivity, high detectivity, and fast response. Here, for the first time, the control of barrier height in vdWHs MIS photodetectors is systematically investigated. Optimizing semiconducting and insulating layers enables lowering the hole barrier height to achieve a high performance of the device. Graphene/hexagonal boron nitride (h‐BN)/SnS2 device shows the best photodetection performance compared to the other common 2D semiconductors. The lowest barrier height ensures that the photo‐induced holes transfer efficiently to the graphene electrode and the dark current is highly suppressed by the h‐BN layers. Consequently, the graphene/h‐BN/SnS2 MIS photodetectors have a high photoresponsivity of 2 A W−1, a high detectivity of 1013 Jones, and a photocurrent/dark current ratio of 5.2 × 105 at a low applied bias of −0.6 V. The highest detectivity reaches 9.6 × 1013 Jones which is 100–1000 times greater than previously reported vdWHs MIS photodetectors. [ABSTRACT FROM AUTHOR]

Abstract: Novel hollow graphene flowers (HGFs) are synthesized by a Cu‐assisted chemical vapor deposition. Multilayer graphene films and vertical‐oriented graphene nanosheets are grown on hollow silica spheres successively by controlling the CH4/H2 flow and growth time. After graphene growth, HSS templates are removed to achieve HGFs. The π‐conjugated systems and unique morphology of HGFs lead to apparent adsorption ability for dyes and phenol molecules. This work provides a facile way to produce unique hollow structure graphene with massive edges for different applications in the future. [ABSTRACT FROM AUTHOR]

Abstract: Well‐defined hollow spherical nanoshell arrays of 2D transitional metal dichalcogenide (TMDC) nanomaterials for MoSe2 and MoS2 are grown via chemical vapor deposition technique for the first time. The hollow sphere arrays display the uniform dimensions of ≈450 nm with the shell thickness of ≈10 nm. The unique hollow sphere architecture with increased active surface area is forecasted to supply more efficient route to improve light‐harvesting efficiency through repeated light reflection and scattering inside the hollow structure without decay of response and recovery speed, because exceptional “SP–SP” junction barriers conducting mechanism can facilitate carriers tunneling and transport during the electron transfer procedure within the present particular structure. The MoSe2 hollow sphere photodetector exhibits an outstanding responsivity (8.9 A W−1), which is tenfold higher than that for MoSe2 compact film (0.9 A W−1), fast response and recovery speed, and good durability under illumination wavelength of 365 nm. Meanwhile, MoSe2 hollow sphere arrays on flexible polyethylene terephthalate substrates reveal excellent bending stability. Therefore, this research indicates that unique hollow sphere architecture of 2D TMDC materials will be an anticipated avenue for efficient photodetector devices with far‐ranging capability. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is very attractive for green fuel energy production, but the development of active, stable, and earth-abundant catalysts for the hydrogen evolution reaction (HER) remains a major challenge. Here, core-shell nanostructured architectures are used to design and fabricate efficient and stable HER catalysts from earth-abundant components. Vertically oriented quasi-2D core-shell MoO2/MoSe2 nanosheet arrays are grown onto insulating (SiO2/Si wafer) or conductive (carbon cloth) substrates. This core-shell nanostructure array architecture exhibits synergistic properties to create superior HER performance, where high density structural defects and disorders on the shell generated by a large crystalline mismatch of MoO2 and MoSe2 act as multiple active sites for HER, and the metallic MoO2 core facilitates charge transport for proton reduction while the vertical nanosheet arrays ensure fully exposed active sites toward electrolytes. As a HER catalyst, this electrode exhibits a low Tafel slope of 49.1 mV dec−1, a small onset potential of 63 mV, and an ultralow charge transfer resistance ( Rct) of 16.6 Ω at an overpotential of 300 mV with a long cycling durability for up to 8 h. This work suggests that a quasi 2D core-shell nanostructure combined with a vertical array microstructure is a promising strategy for efficient water splitting electrocatalysts with scale-up potential. [ABSTRACT FROM AUTHOR]

2D layered MoS2 has drawn intense attention for its applications in flexible electronic, optoelectronic, and spintronic devices. Most of the MoS2 atomic layers grown by conventional chemical vapor deposition techniques are n-type due to the abundant sulfur vacancies. Facile production of MoS2 atomic layers with p-type behavior, however, remains challenging. Here, a novel one-step growth has been developed to attain p-type MoS2 layers in large scale by using Mo-containing sol-gel, including 1% tungsten (W). Atomic-resolution electron microscopy characterization reveals that small tungsten oxide clusters are commonly present on the as-grown MoS2 film due to the incomplete reduction of W precursor at the reaction temperature. These omnipresent small tungsten oxide clusters contribute to the p-type behavior, as verified by density functional theory calculations, while preserving the crystallinity of the MoS2 atomic layers. The Mo containing sol-gel precursor is compatible with the soft-lithography techniques, which enables patterned growth of p-type MoS2 atomic layers into regular arrays with different shapes, holding great promise for highly integrated device applications. Furthermore, an atomically thin p-n junction is fabricated by the as-prepared MoS2, which shows strong rectifying behavior. [ABSTRACT FROM AUTHOR]

Abstract: Covalent functionalization of graphene offers a great chance to broaden its further applications. Here we demonstrate the site‐selective chlorination of graphene through a laser‐induced in situ decomposition of 3–5 nm AgCl nanoparticles fabricated on the graphene surface by pulsed laser deposition. The chlorination process, using the laser coupled on the Raman instrument, can be monitored by in situ Raman spectroscopy. A structural disorder, which resulted from a change from sp2 to sp3 configuration due to the covalent chlorination, increases the electrical resistance of graphene by over two orders of magnitude. We believe this chlorination process from in situ decomposition of AgCl may open up a new avenue for graphene modification and bandgap modulation. [ABSTRACT FROM AUTHOR]

In order to increase the response speed of the InSe‐based photodetector with high photoresponsivity, graphene is used as the transparent electrodes to modify the difference of the work function between the electrodes and the InSe. As expected, the response speed of InSe/graphene photodetectors is down to 120 μs, which is about 40 times faster than that of an InSe/metal device. It can also be tuned by the back‐gate voltage from 310 μs down to 100 μs. With the high response speed, the photoresponsivity can reach as high as 60 A W−1 simultaneously. Meanwhile the InSe/graphene photodetectors possess a broad spectral range at 400–1000 nm. The design of 2D crystal/graphene electrical contacts can be important for high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Tuning and characterizing the interfacial structure of organic semiconductors on graphene is essential for graphene-based devices. Regulation of the supramolecular assembling structure of oligothiophenes on graphene by changing functional groups attached to the backbone of oligothiophenes is described and the assembling behavior is compared with that on the basal plane of highly oriented pyrolytic graphite. It reveals that terminal functional groups attached to the conjugated backbone of oligothiophene can entirely change the assembling structures. Significant solvent and substrate effects have also been confirmed by comparing the assembling structures of oligothiophenes deposited from tetrahydrofuran, 1,2,4-trichlorobenzene, and octanoic acid onto graphene and graphite. [ABSTRACT FROM AUTHOR]

Ferroelectrics: Intrinsic Dipole Coupling in 2D van der Waals Ferroelectrics for Gate-Controlled Switchable Rectifier (Adv. In article number 1900975, PingAn Hu and co-workers reported a switchable ferroelectric diode based on 2D ferroelectric -In2Se3. In view of the unique multidimensional polarization correlation present in -In2Se3, the diode can be effectively reversed by gate-bias through the coupling effect between the in-plane and out-of-plane dipoles. [Extracted from the article]

Miniaturization of device elements, such as ferroelectric diodes, depends on the downscaling of ferroelectric film, which is also crucial for developing high‐density information storage technologies of ferroelectric random access memories (FeRAMs). Recently emerged ferroelectric two‐dimensional (2D) van der Waals (vdWs) layered materials bring an additional opportunity to further increase the density of FeRAMs. A lateral, switchable rectifier is designed and fabricated based on atomically thin 2D α‐In2Se3 ferroelectric diodes, thus breaking the thickness limitation of conventional ferroelectric films and achieving an unprecedented level of miniaturization. This is realized through the interrelated coupling between out‐of‐plane and in‐plane dipoles at room temperature; that is, horizontal polarization reversal can be effectively controlled through a vertical electric field. Being further explored as a switchable rectifier, the obtained maximum value of rectification ratio for the α‐In2Se3 based ferroelectric diode can reach up to 2.5 × 103. These results indicate that 2D ferroelectric semiconductors can offer a pathway to develop next‐generation multifunctional electronics. [ABSTRACT FROM AUTHOR]

Due to the nature of the aqueous operation characteristics of photoelectrochemical‐type (PEC) optoelectronic devices, it is vital to manipulate the semiconductor/electrolyte interfacial properties to synergistically regulate the photogenerated carrier separation, charge transport in semiconductors, and interfacial charge transfer. In this work, it is demonstrated that sulfur vacancy effectively manipulates the band structure of ZnS and works as electrochemical reaction active sites synchronously. ZnS with more sulfur vacancy forms a larger built‐in electric field at the ZnS/electrolyte interface, simultaneously boosting photogenerated charge separation efficiency and promoting charge transport in ZnS. The sulfur vacancy also functions as the interfacial electrochemical reaction active sites, thereby accelerating the interfacial electrochemical reaction kinetics and reducing photo‐oxidation behavior. Hence, the corresponding ZnS PEC photodetectors exhibit excellent self‐powered solar‐blind ultraviolet detection capability with ultrahigh responsivity of 241.71 mA W⁻1, fast rise/decay time of 15/15 ms, high detectivity of 8.9 × 1011 Jones, outstanding wavelength selectivity of 1343, and excellent stability (92.6% after 8‐month storage), which is one of state‐of‐the‐art PEC UV photodetectors. Furthermore, the prototype of an underwater wireless optical communication device is demonstrated using ZnS PEC photodetectors as the light signal receiver. This work endows new sight for ZnS applications in underwater optoelectronic devices. [ABSTRACT FROM AUTHOR]