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A photovoltaic photodetector based on a hybrid dimensional WSe2/WS2/p-Si dual-vdW heterojunction is constructed, which can realize the coupling of the photovoltaic effect and photogating effect.

High-performance visible and near-infrared photodetection and single-pixel imaging can be achieved by our γ-InSe/Ge photodiode at zero bias. Meanwhile, a maximum polarization sensitivity of 3.01 is obtained under 635 nm among the broadband spectrum.

The capabilities to manipulate light-matter interaction at the nanoscale lie at the core of many promising photonic applications. Optical nanoantennas, made of metallic or dielectric materials, have seen a rapid development for their remarkable optical properties facilitating the coupling of electromagnetic waves with subwavelength entities. However, high-throughput and cost-effective fabrication of these nanoantennas is still a daunting challenge. In this work, we provide a versatile nanofabrication method capable of producing large scale optical nanoantennas with different shapes. It is developed from colloidal lithography with no dry etching required. Furthermore, both metallic and all-dielectric nanoantennas can be readily fabrication in a high-throughput fashion. Au and Si nanodisks were fabricated and employed to assemble heterostructures with monolayer tungsten disulfide. Strong coupling is observed in both systems between plasmon modes (Au nanodisks) or anapole modes (Si nanodisks) with excitons. We believe that this nanofabrication method could find a wide range of applications with the diverse optical nanoantennas it can engineer.

The Te/SnS2 tunneling heterojunctions possess interesting type-III band alignment and reverse rectification feature, which can work as high-performance photodetector with excellent self-powered performance.

Different forms of saturable absorbers based on PtTe2 nanosheets were applied in Er-doped fiber lasers for Q-switched and mode-locked pulse generation.

Two-dimensional (2D) polarization-sensitive detection as a new photoelectric application technology is extensively investigated. However, most devices are mainly based on individual anisotropic materials, which suffer from large dark current and relatively low anisotropic ratio, limiting the practical application in polarized imaging system. Herein, we design a van der Waals (vdWs) p-type SnS/n-type InSe vertical heterojunction with proposed type-II band alignment

A solution-fabricated Te/Si mixed-dimensional vdWH can function well as a high-performance broadband self-powered photodetector, achieving an ultrahigh responsivity of 6.49 A W−1 at 0 V.

A Te/Si heterojunction photodetector array has been in situ constructed by performing pulsed-laser deposition of a Te nanofilm on a pre-patterned 2-inch SiO2/Si wafer, exhibiting ultra-broadband photosensitivity from ultraviolet to infrared.

A hierarchical SnS/ZnIn2S4 heterostructure with optical regulation and band tailoring is developed for high-performance broadband integrated optoelectronics.

Constructing mixed dimensional materials have been regarded as an outstanding approach to maximum the advantages from materials of different dimensions. In this work, we prepared a mixed dimensional photocatalyst based on Formamidinium lead bromide (FAPbBr3 ) perovskite and 2D materials (2DMs). The aim of this work is to utilize distributions of the active sites in 2DMs, through growing FAPbBr 3 on the different position of 2DMs, the concentration of photogenerated charges is manipulated, thus conducting different reactions. A pre-treatment using HBr to increase the unsaturated bonds in MoS2 presents significant influence on the FAPbBr3 growth and its photocatalytic product. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) confirm that the perovskite nanoparticles were well loaded on the 2D materials. The photocatalytic process and the heterojunction arrangement are demonstrated by X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence (TRPL), electron paramagnetic resonance (EPR) and surface photovoltage microscopy (SPVM). By adjusting the weight ratios and growth of FAPbBr3 on the top of 2DMs, the optimized composite photocatalyst (with 30 wt% of FAPbBr3) exhibits remarkable photoactivity for oxidation of benzyl alcohol into benzaldehyde (30 wt% FAPbBr3@WS2 performed 75.9% conversion in 4 h, approximately 9-fold than the pure 2DMs). Meanwhile, by growing FAPbBr3 on the edge of 2DMs, benzoic acid is obtained as the product. Although longer reaction time is needed, the photocatalyst performs outstanding activity (30 wt% FAPbBr 3@MoS2 reached 84.5% conversion in 5 h).

Next-generation imaging systems require photodetectors with high sensitivity, polarization sensitivity, miniaturization, and integration. By virtue of their intriguing attributes, emerging 2D materials offer innovative avenues to meet these requirements. However, the current performance of 2D photodetectors is still below the requirements for practical application owing to the severe interfacial recombination, the lack of photoconductive gain, and insufficient photocarrier collection. Here, a tunneling dominant imaging photodetector based on WS

The tunneling heterojunctions made of two-dimensional (2D) materials have been explored to have many intriguing properties, such as ultrahigh rectification and on/off ratio, superior photoresponsivity, and improved photoresponse speed, showing great potential in achieving multifunctional and high-performance electronic and optoelectronic devices. Here, we report a systematic study of the tunneling heterojunctions consisting of 2D tellurium (Te) and Tin disulfide (SnS

Two-dimensional (2D) materials have attracted widespread research attention toward multiple optoelectronic applications, owing to their promising sensitivity to light. However, the weak light absor...

Elemental two-dimensional (2D) tellurium (Te) possesses fascinating properties such as high mobility, strong anisotropy and strong infrared response, which show great potential for various applications. However, the fabrication of large-area and high-quality 2D Te flakes by vapor deposition remains challenging. Herein, we developed a strategy of using In2Te3 powder as the source for high-temperature vapor deposition of 2D tellurium flakes. The synthesized regular Te flakes have a lateral length larger than 100 μm and possess excellent optoelectronic properties. The thin Te flakes exhibit a low electrical resistivity down to 42 μΩ m and a high field-effect hole mobility up to 850 cm2 V s−1. The photodetector based on 2D Te flakes shows a wide response to visible light, with an ultrahigh photoresponsivity of 1.04 × 104 A W−1 under illumination of a 405 nm laser. These figures-of-merits of the 2D Te device are prominent compared with those of previously reported Te devices, indicating the very high material quality of our Te flakes synthesized by the proposed growth strategy.

With the fast development of semiconductor technology, self-driven devices have become an indispensable part of modern electronic and optoelectronic components. In this field, in addition to traditional Schottky and p–n junction devices, hybrid 2D/3D semiconductor heterostructures provide an alternative platform for optoelectronic applications. Herein we report the growth of 2D SnS1−xSex (x = 0, 0.5, 1) nanosheets and the construction of a hybrid SnS0.5Se0.5/GaAs heterostructure based self-driven photodetector. The strong anisotropy of 2D SnS1−xSex is demonstrated theoretically and experimentally. The self-driven photodetector shows high sensitivity to incident light from the visible to near-infrared regime. At the wavelength of 405 nm, the device enables maximum responsivity of 10.2 A W−1, high detectivity of 4.8 × 1012 Jones and fast response speed of 0.5/3.47 ms. Impressively, such a heterostructure device exhibits anisotropic photodetection characteristics with the dichroic ratio of ∼1.25 at 405 nm and ∼1.45 at 635 nm. These remarkable features can be attributed to the high-quality built-in potential at the SnS0.5Se0.5/GaAs interface and the alloy engineering, which effectively separates the photogenerated carriers and suppresses the deep-level defects, respectively. These results imply the great potential of our SnS0.5Se0.5/GaAs heterostructure for high-performance photodetection devices.

Because of the in-gap defect levels, high deep ultraviolet (DUV) light absorption and low leakage current, the incorporation of a 4H-silicon carbide (SiC) substrate has been confirmed to enhance the optoelectrical properties of two-dimensional (2D) layered materials in recent years. Tin disulfide (SnS2) is a post-transition metal dichalcogenide (PTMD) with high light absorption coefficient and thickness-dependent band gap modulation, leading to potential applications in solar cells, DUV-visible photodetectors (PDs), and flexible wearable devices. Here, we first transferred SnS2 nanosheets onto a SiO2 layer and epitaxial n−-type 4H-SiC substrate, respectively. The optoelectrical performance of the SnS2/4H-SiC structure is improved under the UV and visible light. In particular, under 325 nm illumination, the photocurrent density significantly increased by ∼44 times, the response time is shortened to 17 ms, and the specific detectivity (D*) increases to 7.3 × 1013 Jones. Moreover, the responsivity (R325 nm) of 2.42 × 104 A W−1 is increased by one order of magnitude, which outperforms most of 2D materials DUV PDs reported up to date. In particular, the enhancement of mobility, decreased trap density, and suppression of dark current can be also obtained in the SnS2/SiC structure compared with the SnS2/SiO2 structure. This work provides a facile route toward 2D materials/SiC-based PDs with high performance, facile processing, and simple architecture for future applications in industrial, environmental, and even biological fields.

In recent years, two-dimensional material-based tunneling heterojunctions are emerging as a multi-functional architecture for logic circuits and photodetection owing to the flexible stacking, optical sensitivity, tunable detection band, and highly controllable conductivity behaviors. However, the existing structures are mainly focused on transition or post-transition metal chalcogenides and have been rarely investigated as topological insulator (such as Bi2Se3 or Bi2Te3)-based tunneling heterostructures. Meanwhile, it is challenging to mechanically exfoliate the topological insulator thin nanoflakes because of the strong layer-by-layer interaction with shorter interlayer spacing. Herein, we report Au-assisted exfoliation and non-destructive transfer method to fabricate large-scale Bi2Se3 thin nanosheets. Furthermore, a novel broken-gap tunneling heterostructure is designed by combing 2H-MoTe2 and Bi2Se3via the dry-transfer method. Thanks to the realized band alignment, this ambipolar-n device shows a clear rectifying behavior at Vds of 1 V. A built-in potential exceeding ∼0.7 eV is verified owing to the large band offsets by comparing the numerical solution of Poisson's equation and the experimental data. Carrier transport is governed by the majority carrier including thermionic emission and the tunneling process through the barrier height. At last, the device shows an ultralow dark current of ∼0.2 pA and a superior optoelectrical performance of Ilight/Idark ratio ≈106, a fast response time of 21 ms, and a specific detectivity of 7.2 × 1011 Jones for a visible light of 405 nm under zero-bias. Our work demonstrates a new universal method to fabricate a topological insulator and paves a new strategy for the construction of novel van der Waals tunneling structures.

The excellent semiconducting properties and ultrathin morphological characteristics allow van der Waals (vdW) heterostructures based on 2D materials to be promising channel materials for the next-generation optoelectronic devices, especially in photodetectors. Although various 2D heterostructure-based photodetectors have been developed, the unavoidable trade-off between responsivity and detectivity remains a critical issue for these devices. Here, an ingenious phototransistor based on WSe

Yarn supercapacitors have attracted significant attention for wearable energy storage due to their ability to be directly integrated with garments. Conducting polymer polypyrrole (PPy) based yarn supercapacitors show limited cycling stability because of the huge volume changes during the charge-discharge processes. In addition, laundering may cause damage to such yarn supercapacitors. Here, the fabrication of PPy-based re-stickable yarn supercapacitors is reported with good cycling stability by employing vapor phase polymerization (VPP) and water-soluble polyethylene oxide (PEO) film as the adhesive layer. VPP duration and cycle are controlled to achieve multi-layered PPy electrodes. The assembled yarn supercapacitors show a good cycling stability with capacitance retention of 79.1% after 5000 charge-discharge cycles. The energy stored in the yarn supercapacitor is sufficient to power a photodetector. After gluing the yarn supercapacitors onto a PEO film, the devices can be stunk on and peeled off the garment to avoid the mechanical stresses during the washing process. Three yarn supercapacitors connected in parallel on PEO film show negative changes in electrochemical performance after 5 sticking-peeling cycles. This work provides a facile way to fabricate PPy-based re-stickable energy storage devices with high cycling stability for smart garments.

We report an ultra-broadband LP

As we know, binary two-dimensional (2D) IVA–VIA monochalcogenides such as stannous sulfide (SnS) and stannous selenide (SnSe) possess an asymmetric crystalline structure perpendicular to the layer-...

Functional van der Waals (vdWs) heterostructures based on layered materials have shown tremendous potential in next-generation optoelectronic devices. To date, numerous vdWs heterostructures have been investigated based on stacking or epitaxial growth technology. However, the complicated synthesis process greatly limits the large-scale integration of the heterostructure device array, which is essential for practical applications. Here, a planar photodetector array with an out-of-plane vertical In2Se3/SnSe2 heterostructure as the photosensitive channel was self-assembled through a pulsed laser deposition (PLD) technique. The vertical built-in field was exploited to suppress the dark current and separate the photogenerated carriers. The realized devices possess an ultralow dark current of 6.3 pA, combined with a high detectivity of 8.8×1011 Jones and a high signal-to-noise ratio (SNR) beyond 3×104. These performance metrics not only are one order of magnitude superior to pure In2Se3 device, but also demonstrate the unique advantage of detecting weak signals. In addition, this heterostructure photodetector array can further be constructed on flexible polyimide (PI) substrate. These flexible devices also demonstrate effective light detection capability and the photoresponse remains unchanged even after 200 cycles of bending. These findings pave a way toward the development of next-generation large area and high integration optoelectronic technologies.

Recent years have seen swift increase in the power conversion efficiency of perovskite solar cells (PSCs). Interface engineering is a promising route for further improving the performance of PSCs. Here we perform first-principles calculations to explore the effect of four candidate buffer materials (MACl, MAI, PbCl2 and PbI2) on the electronic structures of the interface between MAPbI3 absorber and TiO2. We find that MAX (X = Cl, I) as buffer layers will introduce a high electron barrier and enhance the electron-hole recombination. Additionally, MAX does not passivate the surface states well. The conduction band minimum of PbI2 is much lower than that of MAPbI3 absorber, which significantly limits the band bending of the absorber and open-circuit voltage of solar cells. On the other side, suitable bandedge energy level positions, small lattice mismatch with TiO2 surfaces, and excellent surface passivation make PbCl2 a promising buffer material for absorber/electron-transport-layer interface engineering in PSCs. Our results in this work thus provide deep understanding on the effects of interface engineering with a buffer layer, which shall be useful for improving the performance of PSCs and related optoelectronics.

Two-dimensional (2D) materials have undergone a rapid development toward real applications since the discovery of graphene. At first, graphene is a star material because of the ultrahigh mobility and novel physics, but it always suffered from zero bandgap and limited device application. Then, 2D binary compounds such as transition-metal chalcogenides emerged as complementary materials for graphene due to their sizable bandgap and moderate electrical properties. Recently, research interests have turned to monoelemental and ternary 2D materials. Among them, monoelemental 2D materials such as arsenic (As), antimony (Sb), bismuth (Bi), tellurium (Te), etc., have been the focus. For example, bismuthene can act as a 2D topological insulator with nontrivial topological edge states and high bulk gap, providing the novel platforms to realize the quantum spin-Hall systems. Meanwhile, ternary 2D materials such as Bi2O2Se, BiOX and CrOX (X=Cl, Br, I) have also emerged as promising candidates in optoelectronics and spintronics due to their extraordinary mobility, favorable band structures and intrinsic ferromagnetism with high Curie temperature. In this review, we will discuss the recent works and future prospects on the emerging monoelemental and ternary materials in terms of their structure, growth, physics and device applications.

Self-powered photodetectors have triggered extensive attention in recent years due to the advantages of high sensitivity, fast response, low power consumption, high level of integration and wireless operation. To date, most self-powered photodetectors are implemented through the construction of either heterostructures or asymmetric electrode material contact, which are complex to process and costly to produce. Herein, for the first time, we achieved a self-powered operation by adopting a geometrical asymmetry in the device architecture, where a triangular non-layered 2D In2S3 flake with an asymmetric contact is combined with the traditional photogating effect. Importantly, the device achieves excellent photoresponsivity (740 mA W-1), high detectivity (1.56 × 1010 Jones), and fast response time (9/10 ms) under zero bias. Furthermore, the asymmetric In2S3/Si photodetector manifests long-term stability. Even after 1000 cycles of operation, the asymmetric In2S3/Si device displays negligible performance degradation. In sum, the above results highlight a novel route towards self-powered photodetectors with high performance, simple processing and structure in the future.

In the past decade, photo-detectors have been demonstrated to have very important applications in image sensing, optical communication, fire detection, environmental monitoring, space exploration, safety detection, and many other scientific research and industrial technology fields and are regarded as the key components of wearable devices. Compared to traditional fabrication approaches, pulsed-laser deposition (PLD)-grown materials for photo-detectors offer several merits. First, PLD is a clean physical vapor deposition approach. A stoichiometric amount of atoms can be transferred from the target to the substrate, avoiding complicated and potentially dangerous chemical reactions. Furthermore, the PLD process is carried out in a high-vacuum environment. Therefore, almost no contaminants, such as catalysts, precursors, surfactants and by-products, will be introduced. Also, the thickness of the films can be controlled by simply manipulating the energy and pulse number of the pulsed laser. Furthermore, the fabrication temperature is relatively low, which is available to deposit materials on various substrates, even flexible ones. Most importantly, PLD is a deposition technology with large area coverage, which can produce centimeter-scale thin films, the planar geometry of which has significant potential for compact device integration with modern semiconductor techniques. Consequently, this review introduces the recent advances on the materials, fabrication, and application of pulsed-laser deposition for a variety of high-performance photo-detectors from an overall perspective. Moreover, the challenges and future development trends are discussed.

Non-layered 2D materials exhibit intriguing properties, widening the scope of 2D libraries and promising considerable potential for applications in next-generation optoelectronics. However, due to their surface dangling bonds and weak light adsorption arising from their atomically thin thickness, their photosensitivity is still limited. Herein, we achieve an ultrasensitive 2D In2S3 photodetector by adopting strain engineering coupled with optical regulation. A SiO2 nanograting array was introduced to construct a strained morphology of 2D In2S3. This morphology induces charge localization and renders a back-to-back built-in electric field array, which efficiently suppresses the dark current and separates the photo-excited carriers. Simultaneously, the SiO2 nanograting array realizes light management and improves its light harvesting. As a result, the device presents an ultralow dark current of 3.2 pA with a high signal-to-noise ratio of up to 1.7 × 106. In particular, a prominent photoresponsivity of 1810 A W−1, an excellent detectivity of 2.09 × 1015 Jones and a fast response speed of 0.41 ms are achieved. This work depicts an effective scheme to associate photonic/electronic property manipulation for optoelectronic applications.

We present a study of all-optical light manipulation arising in a graphene-embedded side-polished fiber (SPF) with a Norland Optical Adhesives (NOA)-coated structure. With the help of the Pauli blocking effect, such an all-fiber device serves to manage the loss of transverse-electric-polarized light when the control light and the signal light are polarized along the direction parallel to the graphene surface. The insertion loss of this device can be effectively reduced with the NOA coating. An enhanced interaction between the graphene and the propagated light can be achieved via the strong evanescent field of the SPF and longer interaction length. This results in effective all-optical manipulation of light with a modulation depth of 10.4 dB (or modulation efficiency of ∼91%) and a modulation slope of ∼1.3, where the required control power is only about 14 dBm. The device has broadband operation wavelength. The insertion loss for both the signal light and the control light are only about 0.6 dB. The experimental results are well-fitting with the simulation study. Such an all-fiber device has the potential for all-optical signal processing.