Low-Noise Dual-Band Polarimetric Image Sensor Based on 1D Bi2 S3 Nanowire

A high-performance broadband polarization-sensitive photodetector based on BiSeS nanowires

Bismuth selenide (Bi2Se3) has emerged as a promising material for high-performance photodetectors due to its wideband spectral response, strong in-plane anisotropy, narrow bandgap, high absorption coefficient, and carrier mobility. However, inherent defects and states in Bi2Se3-based devices reduce optical conversion efficiency and stability. To address these challenges, we report the design and preparation of Bi2Se2.33S0.67 nanowires by a facile chemical vapor transport method. The individual Bi2Se2.33S0.67 nanowire photodetectors exhibit remarkable photoresponse over a broadband wavelength region ranging from ultraviolet C (254 nm) to near-infrared (1064 nm) with a low dark current of 0.015 nA and the measured maximum photoresponsivity of 2.52 A W-1 at 532 nm, together with a detectivity of around 5.2 × 1011 Jones. Furthermore, the photoresponse of photodetectors exhibits polarization angle sensitivity within a broadband range of 355 to 808 nm. The structural anisotropy of the Bi2Se2.33S0.67 crystal leads to a maximum dichroic ratio of about 1.8 at 355 nm. Additionally, cat images produced by this device further demonstrate the potential of the high-performance devices, and the effectiveness of photodetectors in deep learning image recognition validates their wide-spectrum, high-responsivity, and superior polarization-sensitive detection capabilities.

A broadband polarization-sensitive photodetector and an infrared encoder based on high crystallinity 1D Bi2(Se,S)3 ternary nanowires

The realization of multifunctionality and integration in one device is of great significance for the development of current information technologies. However, it often requires the design of heterojunctions or external conditions, which leads to complex fabrication processes and increased power consumption. Besides, the study and utilization of the special negative photoconductivity (NPC) effect is still in its early stage and remains limited. One-dimensional (1D) nanowires have great potential in the optoelectronic application field due to their unique chain structure, strong anisotropy, and possible NPC characteristics. Herein, an alloying strategy was proposed to synthesize 1D Bi2(Se,S)3 ternary nanowires with high crystallinity and uniformity via a chemical vapor deposition method. The photodetector based on a single Bi2(Se,S)3 nanowire shows broadband response (405-1550 nm), high responsivity (5.31 A W-1), excellent specific detectivity (1.87 × 1011 Jones) and fast response speed (0.43/0.47 ms). Furthermore, it exhibits strong polarization sensitivity with anisotropy ratios of 2.25 (638 nm), 1.76 (980 nm) and 1.54 (1550 nm), and achieves polarization-sensitive imaging capability. Notably, an infrared encoder was simulated based on the NPC effect under a 1550 nm laser which can be modulated effectively by laser power intensity for the first time. The NPC phenomenon is due to the photogenerated carriers which are trapped by recombination centers in the deep trap energy levels (Etrap) at lower power intensity. These findings provide a promising strategy for the study of the NPC phenomenon, and the development of high-performance multifunctional photodetection and communication encryption.

Oriented Epitaxial Growth of Mixed-Dimensional van der Waals Heterostructures with One-Dimensional (1D) Bi2S3 Nanowires and Two-Dimensional (2D) WS2 Monolayers for Performance-Enhanced Photodetectors

The synthesis of mixed-dimensional van der Waals heterostructures with controlled alignment by chemical vapor deposition (CVD) technique remains a big challenge due to the complex epitaxial growth mechanism. Herein, we report the epitaxial growth of mixed-dimensional Bi2S3/WS2 heterostructures by a two-step CVD method. Bi2S3 crystals grown on 2D WS2 monolayers exhibit 1D feature with the preferred orientation, indicating a strong epitaxial growth behavior at the 1D/2D interface. Furthermore, the heterostructure was carefully characterized by transmission electron microscopy, which reveals the preferential growth of Bi2S3 nanowires along the zigzag edge of WS2 monolayers. The experimental results are also consistent with the theoretical calculations by DFT, where the preferred orientation possesses minimal surface energy. The strong interaction between Bi2S3 and WS2 enables efficient charge transfer of photogenerated carriers at the heterointerface, which leads to a largely improved light harvesting capability with the highest responsivity of ∼48.1 AW-1 and detectivity of ∼5.9 × 1012 Jones.

Low-Symmetry 2D t-InTe for Polarization-Sensitive UV-Vis-NIR Photodetection

Polarization-sensitive photodetection grounded on low-symmetry 2D materials has immense potential in improving detection accuracy, realizing intelligent detection, and enabling multidimensional visual perception, which has promising application prospects in bio-identification, optical communications, near-infrared imaging, radar, military, and security. However, the majority of the reported polarized photodetection are limited by UV-vis response range and low anisotropic photoresponsivity factor, limiting the achievement of high-performance anisotropic photodetection. Herein, 2D t-InTe crystal is introduced into anisotropic systems and developed to realize broadband-response and high-anisotropy-ratio polarized photodetection. Stemming from its narrow band gap and intrinsic low-symmetry lattice characteristic, 2D t-InTe-based photodetector exhibits a UV-vis-NIR broadband photoresponse and significant photoresponsivity anisotropy behavior, with an exceptional in-plane anisotropic factor of 1.81@808 nm laser, surpassing the performance of most reported 2D counterparts. This work expounds the anisotropic structure-activity relationship of 2D t-InTe crystal, and identifies 2D t-InTe as a prospective candidate for high-performance polarization-sensitive optoelectronics, laying the foundation for future multifunctional device applications.

Polarimetric Imaging for Robot Perception: A Review

In recent years, the integration of polarimetric imaging into robotic perception systems has increased significantly, driven by the accessibility of affordable polarimetric sensors. This technology complements traditional color imaging by capturing and analyzing the polarization characteristics of light. This additional information provides robots with valuable insights into object shape, material composition, and other properties, ultimately enabling more robust manipulation tasks. This review aims to provide a comprehensive analysis of the principles behind polarimetric imaging and its diverse applications within the field of robotic perception. By exploiting the polarization state of light, polarimetric imaging offers promising solutions to three key challenges in robot vision: Surface segmentation; depth estimation through polarization patterns; and 3D reconstruction using polarimetric data. This review emphasizes the practical value of polarimetric imaging in robotics by demonstrating its effectiveness in addressing real-world challenges. We then explore potential applications of this technology not only within the core robotics field but also in related areas. Through a comparative analysis, our goal is to elucidate the strengths and limitations of polarimetric imaging techniques. This analysis will contribute to a deeper understanding of its broad applicability across various domains within and beyond robotics.

Review on synthetic approaches and PEC activity performance of bismuth binary and mixed-anion compounds for potential applications in marine engineering

Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds.

Highly Polarization-Deep-Ultraviolet-Sensitive β-Ga2O3 Epitaxial Films by Disrupting Rotational Symmetry and Encrypted Solar-Blind Optical Communication Application

Ultrawide bandgap semiconductor β-Ga2O3 (4.9 eV), with its monoclinic crystal structure, exhibits distinct anisotropic characteristics both optically and electrically, making it an ideal material for solar-blind polarization photodetectors. In this work, β-Ga2O3 epitaxial films were deposited on sapphire substrates with different orientations, and the mechanisms underlying the anisotropy of these epitaxial films were investigated. Compared to c-plane sapphire, the lattice mismatch between m- or r-plane sapphire and β-Ga2O3 is more pronounced, disrupting the rotational symmetry of the films and rendering them anisotropic. Thanks to the improved anisotropy, the polarization ratio of the photodetector based on β-Ga2O3 films grown on r-plane substrates is 0.24, nearly ten times higher than that on c-plane substrates. Finally, by utilizing these polarization-sensitive photodetectors, we developed an encrypted solar-blind ultraviolet optical communication system. Our work provides a new approach to facilitate the fabrication and application of high-performance polarization-sensitive solar-blind photodetectors.

Sub-micron pixel polarization-sensitive photodetector based on silicon nanowire

Silicon nanowire is a potential candidate to be used as polarization-sensitive material, but the relative mechanism of polarization response must be carried out. Herein, a sub-micron metal-single silicon nanowire-metal photodetector exhibits polarization-sensitive characteristics with an anisotropic photocurrent ratio of 1.59 at 780 nm, an excellent responsivity of 24.58 mA/W, and a high detectivity of 8.88 × 109 Jones at 980 nm. The underlying principle of optical anisotropy in silicon nanowire is attributed to resonance enhancement verified by polarizing light microscopy and simulation. Furthermore, Stokes parameter measurements and imaging are all demonstrated by detecting the characteristics of linearly polarized light and imaging the polarizer array, respectively. Given the maturity of silicon processing, the sub-micron linearly polarized light detection proposed in this study lays the groundwork for achieving highly integrated, simplified processes, and cost-effective on-chip polarization-sensitive optical chips in the future.

A high-performance and self-powered polarization-sensitive photoelectrochemical-type Bi2O2Te photodetector based on a quasi-solid-state gel electrolyte

Among the two-dimensional (2D) Bi2O2X (X = S, Se, and Te) series, Bi2O2Te has the smallest effective mass and the highest carrier mobility. However, Bi2O2Te has rarely been investigated, most likely due to the lack of feasible methods to synthesize 2D Bi2O2Te. Herein, 2D Bi2O2Te nanosheets are successfully synthesized by low-temperature oxidation of Bi2Te3 nanosheets synthesized using a solvothermal method. The performance of a quasi-solid-state photoelectrochemical-type (PEC-type) photodetector based on 2D Bi2O2Te nanosheets is systematically investigated. Remarkably, the device has a high responsivity of 20.5 mA W-1 (zero bias) and fast rise/fall times of 6/90 ms under 365 nm illumination, which is superior to the majority of PEC-type photodetectors based on bismuth-based compounds. More importantly, due to the strong anisotropy of 2D Bi2O2Te nanosheets, the device achieves a dichroic ratio as high as 52, which belongs to the state-of-the-art polarized photodetectors. Besides, the capacity of 2D Bi2O2Te for high-resolution polarization imaging is demonstrated. This work provides a promising strategy for the synthesis of 2D Bi2O2Te nanosheets to fabricate a high-performance and polarization-sensitive photodetector.

Sensitive organic/inorganic polarized photodetectors enhanced by charge transfer with image sensing capacity

Organic photodetectors (OPDs) have attracted increasing attention in the future wearable sensing and real-time health monitoring, due to their intrinsic features including the mechanical flexibility, low-cost processing and cooling-free operations; while their performances are lagging as the results of inferior carrier mobility and small exciton diffusion coefficient of organic molecules. Graphene exhibits the great photoresponse with wide spectral bandwidth and high response speed. However, weak light absorption and the absence of a gain mechanism have limited its photoresponsivity. Here, we report a sensitive organic/inorganic phototransistor with fast response speed by coupling PTCDA organic single crystal with the monolayer graphene. The long range exciton diffusion in highly ordered π-conjugated molecules, efficient exciton dissociation and charge transfer at the PTCDA/graphene heterointerfaces, and the high mobility of graphene enable a high responsivity (8 × 104A/W), short response time (220 µs) and excellent specific detectivity (>1011 Jones), which is higher than the level of commercial on-chip device. This interfacial photogating effect is verified by the high-resolution spatial photocurrent mapping experiment. In addition, the high sensitivity to polarization is clear and the ultrahigh photoconductive gain enables a near-infrared (NIR) response for 980 and 1550 nm. Finally, high-speed visible and NIR imaging applications are successfully demonstrated. This work suggests that high quality organic single crystal/graphene is a promising platform for future high performance optoelectronic systems and imaging applications.

Low-Dimensional-Materials-Based Photodetectors for Next-Generation Polarized Detection and Imaging

The vector characteristics of light and the vectorial transformations during its transmission lay a foundation for polarized photodetection of objects, which broadens the applications of related detectors in complex environments. With the breakthrough of low-dimensional materials (LDMs) in optics and electronics over the past few years, the combination of these novel LDMs and traditional working modes is expected to bring new development opportunities in this field. Here, the state-of-the-art progress of LDMs, as polarization-sensitive components in polarized photodetection and even the imaging, is the main focus, with emphasis on the relationship between traditional working principle of polarized photodetectors (PPs) and photoresponse mechanisms of LDMs. Particularly, from the view of constitutive equations, the existing works are reorganized, reclassified, and reviewed. Perspectives on the opportunities and challenges are also discussed. It is hoped that this work can provide a more general overview in the use of LDMs in this field, sorting out the way of related devices for "more than Moore" or even the "beyond Moore" research.

From Material to Cameras: Low-Dimensional Photodetector Arrays on CMOS

The last two decades have witnessed a dramatic increase in research on low-dimensional material with exceptional optoelectronic properties. While low-dimensional materials offer exciting new opportunities for imaging, their integration in practical applications has been slow. In fact, most existing reports are based on single-pixel devices that cannot rival the quantity and quality of information provided by massively parallelized mega-pixel imagers based on complementary metal-oxide semiconductor (CMOS) readout electronics. The first goal of this review is to present new opportunities in producing high-resolution cameras using these new materials. New photodetection methods and materials in the field are presented, and the challenges involved in their integration on CMOS chips for making high-resolution cameras are discussed. Practical approaches are then presented to address these challenges and methods to integrate low-dimensional material on CMOS. It is also shown that such integrations could be used for ultra-low noise and massively parallel testing of new material and devices. The second goal of this review is to present the colossal untapped potential of low-dimensional material in enabling the next-generation of low-cost and high-performance cameras. It is proposed that low-dimensional materials have the natural ability to create excellent bio-inspired artificial imaging systems with unique features such as in-pixel computing, multi-band imaging, and curved retinas.

Polarization-Sensitive Photodetector Based on High Crystallinity Quasi-1D BiSeI Nanowires Synthesized via Chemical Vapor Deposition

Bismuth chalcohalides (BiSeI and BiSI), a class of superior light absorbers, have recently garnered great attention owing to their promise in constructing next-generation optoelectronic devices. However, to date, the photodetection application of bismuth chalcohalides is still limited due to the challenge in controllable preparation. Herein, the synthesis of large-scale quasi-1D BiSeI nanowires via chemical vapor deposition growth is reported. By precisely tuning the growth temperature and the Se supply, it can effectively control the growth thermodynamics and kinetics of BiSeI crystal, and thus achieve high purity quasi-1D BiSeI nanowires with high crystal quality, uniform diameter, and tunable domain length. Theory and optical characterizations of the quasi-1D BiSeI nanowires reveal an indirect bandgap of 1.57 eV with prominent optical linear dichroism. As a result, the quasi-1D BiSeI nanowire-based photodetector demonstrates a broadband photoresponse (400-800 nm) with high responsivity of 5880 mA W-1 , fast response speed of 0.11 ms and superior air stability. More importantly, the photodetector displays strong polarization sensitivity (anisotropic ratio = 1.77) under the 532 nm light irradiation. This work will provide important guides to the synthesis of other quais-1D metal chalcohalides and shed light on their potential in constructing novel multifunctional optoelectronic devices.

Quantum tailoring for polarization-discriminating Bi2S3 nanowire photodetectors and their multiplexing optical communication and imaging applications

In this study, cost-efficient atmospheric pressure chemical vapor deposition has been successfully developed to produce well-aligned high-quality monocrystalline Bi2S3 nanowires. By virtue of surface strain-induced energy band reconstruction, the Bi2S3 photodetectors demonstrate a broadband photoresponse across 370.6 to 1310 nm. Upon a gate voltage of 30 V, the responsivity, external quantum efficiency, and detectivity reach 23 760 A W-1, 5.55 × 106%, and 3.68 × 1013 Jones, respectively. The outstanding photosensitivity is ascribed to the high-efficiency spacial separation of photocarriers, enabled by synergy of the axial built-in electric field and type-II band alignment, as well as the pronounced photogating effect. Moreover, a polarization-discriminating photoresponse has been unveiled. For the first time, the correlation between quantum confinement and dichroic ratio is systematically explored. The optoelectronic dichroism is established to be negatively correlated with the cross dimension (i.e., width and height) of the channel. Specifically, upon 405 nm illumination, the optimized dichroic ratio reaches 2.4, the highest value among the reported Bi2S3 photodetectors. In the end, proof-of-concept multiplexing optical communications and broadband lensless polarimetric imaging have been implemented by exploiting the Bi2S3 nanowire photodetectors as light-sensing functional units. This study develops a quantum tailoring strategy for tailoring the polarization properties of (quasi-)1D material photodetectors whilst depicting new horizons for the next-generation opto-electronics industry.

Ternary GePdS3: 1D van der Waals Nanowires for Integration of High-Performance Flexible Photodetectors

One-dimensional (1D) van der Waals (vdW) materials are anticipated to leverage for high-performance, giant polarized, and hybrid-dimension photodetection owing to their dangling-bond free surface, intrinsic crystal structure, and weak vdW interaction. However, only a few related explorations have been conducted, especially in the field of flexible and integrated applications. Here, high-quality 1D vdW GePdS₃ nanowires were synthesized and proven to be an n-type semiconductor. The Raman vibration and band gap (1.37-1.68 eV, varying from bulk to single chain) of GePdS₃ were systemically studied by experimental and theoretical methods. The photodetector based on a single GePdS₃ nanowire possesses fast photoresponse at a broadband spectrum of 254-1550 nm. The highest responsivity and detectivity reach up to ∼219 A/W and ∼2.7 × 10¹⁰ Jones (under 254 nm light illumination), respectively. Furthermore, an image sensor with 6 × 6 pixels based on GePdS₃ nanowires is integrated on a flexible polyethylene terephthalate (PET) substrate and exhibits sensitive and homogeneous detection at 808 nm light. These results indicate that the ternary noble metal chalcogenides show great potential in flexible and broadband optoelectronics applications.

Broadband Polarization-Sensitive Photodetection of Magnetic Semiconducting MnTe Nanoribbons

2D materials with low symmetry are explored in recent years because of their anisotropic advantage in polarization-sensitive photodetection. Herein the controllably grown hexagonal magnetic semiconducting α-MnTe nanoribbons are reported with a highly anisotropic (100) surface and their high sensitivity to polarization in a broadband photodetection, whereas the hexagonal structure is highly symmetric. The outstanding photoresponse of α-MnTe nanoribbons occurs in a broadband range from ultraviolet (UV, 360 nm) to near infrared (NIR, 914 nm) with short response times of 46 ms (rise) and 37 ms (fall), excellent environmental stability, and repeatability. Furthermore, due to highly anisotropic (100) surface, the α-MnTe nanoribbons as photodetector exhibit attractive sensitivity to polarization and high dichroic ratios of up to 2.8 under light illumination of UV-to-NIR wavelengths. These results demonstrate that 2D magnetic semiconducting α-MnTe nanoribbons provide a promising platform to design the next-generation polarization-sensitive photodetectors in a broadband range.

Growth of quasi-1 dimensional (Bi1-xSbx)2S3nanowires on fluorine-doped tin oxide glass substrate by vapor transport

(Bi_1-xSb_x)₂S₃solid solution nanowires (0≤x≤0.73) are grown on fluorine-doped tin oxide (FTO) glass via physical vapor transport. The compositions were controlled by varying the Sb₂S₃source temperature (300 °C-453 °C) by changing the upstream locations of the Sb₂S₃source in the furnace while keeping the Bi₂S₃source at the center of the furnace (497 °C). Defect-free nanowires with phase-pure orthorhombic and quasi-1 dimensional crystal structures were grown under a modified vapor-solid mechanism affected by FTO at initial growth stage. The aspect ratios of the nanowires reached the minimum at compositionx∼0.6.As the Sb₂S₃source approached the Bi₂S₃source,xincreased owing to the increase in the Sb₂S₃source temperature.x/(1-x), which is proportional to the evaporation flux of the Sb₂S₃source, could be well-fitted with a thermally activated equation with an apparent activation energy (105kJmol-1). However, at the distance between the Sb₂S₃and Bi₂S₃sources, with the Sb₂S₃source at temperatures higher than 410 °C, the compositions reduced despite the increased Sb₂S₃evaporation flux. Such retrograde behavior was confirmed by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Raman studies. This retrograde behavior is ascribed to the loss due to the reaction of gaseous Sb species with the Bi₂S₃source.

Strong Anisotropic Two-Dimensional In2Se3 for Light Intensity and Polarization Dual-Mode High-Performance Detection

Detecting the light from different freedom is of great significance to gain more information. Two-dimensional (2D) materials with low intrinsic carrier concentration and highly tunable electronic structure have been considered as the promising candidate for future room-temperature multi-functional photodetectors. However, current investigations mainly focus on intensity-sensitive detection; the multi-dimensional photodetection such as polarization-sensitive photodetection is still in its early stage. Herein, the intensity- and polarization-sensitive photodetection based on α-In₂Se₃ is studied. By using angle-resolved polarized Raman spectroscopy, it is demonstrated that α-In₂Se₃ shows an anisotropic phonon vibration property indicating its asymmetric structure. The α-In₂Se₃-based photodetector has a photoelectric performance with a responsivity of 1936 A/W and a specific detectivity of 2.1 × 10¹³ Jones under 0.2 mW/cm² power density at 400 nm. Moreover, by studying the polarized angle-resolved photoelectrical effect, it is found that the ratio of maximum and minimum photocurrent (dichroic ratio) reaches 1.47 at 650 nm suggesting good polarization-sensitive detection. After post-annealing, α-In₂Se₃ in situ converts to β-In₂Se₃ which has similar in-plane anisotropic crystallinity and exhibits a dichroic ratio of 1.41. It is found that the responsivity of β-In₂Se₃ is 6 A/W, much lower than that of α-In₂Se₃. The high-performance light intensity- and polarization-detection of α-In₂Se₃ enlarges the 2D anisotropic materials family and provides new opportunities for future dual-mode photodetection.

Starch-Assisted Synthesis of Bi2S3 Nanoparticles for Enhanced Dielectric and Antibacterial Applications

Starch [(C₆H₁₀O₅) _n ]-stabilized bismuth sulfide (Bi₂S₃) nanoparticles (NPs) were synthesized in a single-pot reaction using bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O) and sodium sulfide (Na₂S) as precursors. Bi₂S₃ NPs were stable over time and a wide band gap of 2.86 eV was observed. The capping of starch on the Bi₂S₃ NPs prevents them from agglomeration and provides regular uniform shapes. The synthesized Bi₂S₃ NPs were quasispherical, and the measured average particle size was ∼11 nm. The NPs are crystalline with an orthorhombic structure as determined by powder X-ray diffraction and transmission electron microscopy. The existence and interaction of starch on the NP's surface were analyzed using circular dichroism. Impedance spectroscopy was used to measure the electronic behavior of Bi₂S₃ NPs at various temperatures and frequencies. The dielectric measurements on the NPs show high dielectric polarizations. Furthermore, it was observed that the synthesized Bi₂S₃ NPs inhibited bacterial strains (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) and demonstrated substantial antibacterial activity.

Ultraviolet Photodetectors Based on Polymer Microwire Arrays toward Wearable Medical Devices

Polymer micro/nanoarchitectures have attracted intense interest for wearable medical applications due to their excellent mechanical flexibility, solution processability, and tunable optoelectronic properties. Based on polymer micro/nanostructures, high-performance ultraviolet (UV) photodetectors can not only functionalize the accurate image sensing but also sustain the biocomfortable flexible devices for real-time health monitoring. The main challenges are focused on the integration of medical wearable devices, which requires large-scale assembly of polymer micro/nanostructures with controlled morphology and strict alignment. Herein, we utilized a confined assembly system through the cautious regulation for the growth of high-quality polymer 1D arrays. UV photodetectors based on these polymer microwire arrays perform a high on/off ratio of 137 and responsivity of 19.1 mA W^-1. Polymer microarray photodetectors facilitate the scale-up fabrication of 14 × 18 multiplexed image sensors for highly accurate capturing the signals of Arabic numerals "1," "2," and "3." Flexible UV photodetectors based on these arrays present excellent flexibility and bending durability, maintaining 97% of their original on/off ratio after 4000 cycles with a 10 mm bending radius. UV photodetection signals were also collected from the attached flexible devices on the back skin of the mouse, demonstrating the great potential in wearable medical photodetection.

An ultra-sensitive laccase/polyaziridine-bismuth selenide nanoplates modified GCE for detection of atenolol in pharmaceuticals and urine samples

The analysis of β-blockers in pharmaceutical, biological and environmental samples has gained much interest due to their wide applications. The aim of this study was to develop an enzyme-based biosensor using hexagonal-shaped low-dimensional Bi₂Se₃ NPs decorated with laccase through polyaziridine (PAZ) modified glassy carbon electrode (Lac/PAZ-Bi₂Se₃ NPs/GCE). Surface properties were examined using SEM, TEM, EDX, XRD, XPS, FTIR, UV-Visible, and zeta potential. Electrochemical studies were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The enzymatic biosensor exhibited excellent catalytic activity towards the oxidation of ATN at +1.05 V (vs Ag/AgCl). Under the optimum experimental conditions, I_p (µA) was linearly related to the concentrations of ATN in the range of 3 to 130 µM (R² = 0.9972) with an LOD of 0.15 µM and 0.21 µM with and without Lac enzyme. Additionally, the validation of the biosensor was tested to determine ATN on within a day and between-day basis. The biosensor was applied successfully to detect ATN in real samples. The obtained recoveries range from 98.5 % to 99.2 % with an RSD (n = 5) of 0.95 (±0.02). The findings of this study have potential biomedical applications in drug detection employing a promising nano electrode sensor of Lac/PAZ-Bi₂Se₃ NPs/GCE.

2D Ultrawide Bandgap Semiconductors: Odyssey and Challenges

2D ultrawide bandgap (UWBG) semiconductors have aroused increasing interest in the field of high-power transparent electronic devices, deep-ultraviolet photodetectors, flexible electronic skins, and energy-efficient displays, owing to their intriguing physical properties. Compared with dominant narrow bandgap semiconductor material families, 2D UWBG semiconductors are less investigated but stand out because of their propensity for high optical transparency, tunable electrical conductivity, high mobility, and ultrahigh gate dielectrics. At the current stage of research, the most intensively investigated 2D UWBG semiconductors are metal oxides, metal chalcogenides, metal halides, and metal nitrides. This paper provides an up-to-date review of recent research progress on new 2D UWBG semiconductor materials and novel physical properties. The widespread applications, i.e., transistors, photodetector, touch screen, and inverter are summarized, which employ 2D UWBG semiconductors as either a passive or active layer. Finally, the existing challenges and opportunities of the enticing class of 2D UWBG semiconductors are highlighted.

Polarimetric Image Sensor and Fermi Level Shifting Induced Multichannel Transition Based on 2D PdPS

2D materials have been attracting high interest in recent years due to their low structural symmetry, excellent photoresponse, and high air stability. However, most 2D materials can only respond to specific light, which limits the development of wide-spectrum photodetectors. Proper bandgap and the regulation of Fermi level are the foundations for realizing electronic multichannel transition, which is an effective method to achieve a wide spectral response. Herein, a noble 2D material, palladium phosphide sulfide (PdPS), is designed and synthesized. The bandgap of PdPS is around 2.1 eV and the formation of S vacancies, interstitial Pd and P atoms promote the Fermi level very close to the conduction band. Therefore, the PdPS-based photodetector shows impressive wide spectral response from solar-blind ultraviolet to near-infrared based on the multichannel transition. It also exhibits superior optoelectrical properties with photoresponsivity (R) of 1 × 10³ A W^-1 and detectivity (D*) of 4 × 10¹¹ Jones at 532 nm. Moreover, PdPS exhibits good performance of polarization detection with dichroic ratio of ≈3.7 at 808 nm. Significantly, it achieves polarimetric imaging and hidden-target detection in complex environments through active detection.

Self-driven SnS1-xSex alloy/GaAs heterostructure based unique polarization sensitive photodetectors

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 SnS_1-xSe_x (x = 0, 0.5, 1) nanosheets and the construction of a hybrid SnS_0.5Se_0.5/GaAs heterostructure based self-driven photodetector. The strong anisotropy of 2D SnS_1-xSe_x 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 SnS_0.5Se_0.5/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 SnS_0.5Se_0.5/GaAs heterostructure for high-performance photodetection devices.