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Strain Effect Enhanced Ultrasensitive MoS2 Nanoscrolls Avalanche Photodetector
摘要： 2D materials and their derived quasi one-dimensional structure bring incredible possibilities for the field of photoelectric detection due to the intrinsic optical and electrical properties. However, the photo-generated carriers in atomically thin media are poor due to the low optical absorption, which extremely limits the performance. Here, in the MoS2 nanoscrolls photodetector, we meticulously investigated the avalanche multiplication effect. The results show that by employing the nanoscrolls structure, the required threshold electrical field to trigger avalanche multiplication is significantly lowered compared with MoS2 flake due to the modulation of energy band and intervalley scattering through the strain effect. Consequently, the avalanche multiplication could efficiently enhance the photoresponsivity exceeding 104 A/W. Furthermore, enhanced avalanche multiplication could be generalized to other TMDCs through theoretical prediction. The results are not only significant for the understanding of intrinsic nature in 2D materials but also exhibit meaningful advance in high performance and low-power consumption photodetection.
关键词： Ultra-sensitivity,Nanoscrolls,2D materials,Avalanche multiplication effect,Photodetector
更新于2025-09-23 15:21:01
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A hydrothermally synthesized MoS <sub/>2(1a??x)</sub> Se <sub/>2x</sub> alloy with deep-shallow level conversion for enhanced performance of photodetectors
摘要： Photoelectric detectors based on binary transition metal chalcogenides have attracted widespread attention in recent years. However, due to the high-temperature synthesis of binary TMD, high-density deep-level defect states may be generated, leading to poor responsiveness or a long response time. Besides, the addition of an alloy will change the DLDSs from deep to shallow energy levels caused by S vacancies. In this paper, MoS2(1?x)Se2x nanostructures were synthesized by a hydrothermal method, and a novel type of photodetector was fabricated by using the synthesized material as a light sensitive material. The MoSSe-based photodetector not only has a high photocurrent, but also exhibits a wide spectral response in the range of 405 nm to 808 nm. At the same time, it can achieve a responsivity of 1.753 mA W?1 under 660 nm laser irradiation of 1.75 mW mm?2. Therefore, this work can be considered as a method of constructing a new type of photodetector with a simple process and low cost.
关键词： MoS2(1?x)Se2x,photoelectric detectors,photodetector,transition metal chalcogenides,hydrothermal synthesis
更新于2025-09-23 15:21:01
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Few-layer PdSe2-based field-effect transistor for photodetector applications
摘要： We demonstrate a multilayer palladium diselenide (PdSe2) high-performance photodetector. The photodetector exhibits the photodetectivity of 0.15 ? 1010 Jones under laser illumination (λ ? 655 nm and power of 0.057 mWmm(cid:0) 2). The negative threshold voltage shift in transfer characteristics upon laser illumination is mainly attributed to the photogating effect. Systematic analysis of experimental data indicates that the photogating effect and space charge limited conduction are simultaneously involved in the conduction mechanism. We observe that the photogenerated current increases logarithmically as the light intensity increases, and it persists (~200 s) even after stopping the illumination. The slow decrease in current was attributed to the trapping of photogenerated charge carriers at the PdSe2/SiO2 interface and the defects in the structure of PdSe2. We also observe a reproducible and stable time-resolved photoresponse with respect to the incident laser power. We believe that this study can be an important source of information and can help researchers to continue to investigate methods that would allow them to maximise the potential of PdSe2 for photodetector applications.
关键词： Palladium diselenide,Photodetector,Field effect transistor,Two-dimensional materials,Photoresponse
更新于2025-09-23 15:21:01
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Cd(OH)2@ZnO nanowires thin-film transistor and UV photodetector with a floating ionic gate tuned by a triboelectric nanogenerator
摘要： The adsorbed ions on the surface of nanowires thin-film, such as O2-, are acted as a floating gate, modulating significantly the thin-film’s electronic and optoelectronic properties. However, due to the lack of tuning means for surface ions, the floating ionic gate has not been applied in developing electronic and optoelectronic nanodevices. Here, based on the gas discharge induced by a triboelectric nanogenerator (TENG), the tuning of surface ions on Cd(OH)2@ZnO nanowires thin-film is achieved, and the thin-film transistor (TFT) and thin-film photodetector (TFP) have been fabricated by using the surface ions as a floating ionic gate. In the TFT with a floating ionic gate, the current can be tuned step-by-step as the operation cycles of TENG is controlled, and the maximum on-off ratio of current reaches 4.0×105. In the UV light TFP with a floating ionic gate, the on-off ratio and recovery time constant of photocurrent reach 2.7×107 and 0.53 s, achieving a simultaneous enhancement of sensitivity and recovery speed by a factor of 1350 and 946 times, respectively. O2- is identified as the surface ions on the nanowire thin-film, and the tuning mechanism has been discussed. Because of the low cost and easy operation of the TENG, the floating ionic gate technology based on TENG provides a promising strategy for developing novel electronic and optoelectronic nanodevices with enhanced performances by constructing a device system.
关键词： TENG,UV photodetector,ZnO nanowire film,air discharge
更新于2025-09-23 15:21:01
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Photo-Thermoelectric Conversion of Plasmonic Nanohole Array
摘要： Plasmonic photo-thermoelectric conversion offers an alternative photodetection mechanism that is not restricted by semiconductor bandgaps. Here, we report a plasmonic photodetector consisting of an ultra-thin silver film with nanohole array, whose photodetection mechanism is based on thermoelectric conversion triggered by plasmonic local heating. The detector exhibits a maximum photocurrent at the wavelength of the surface plasmon polaritons, determined by the periodicity of the nanoholes. Hence, the response wavelength of the detector can be controlled via the morphological parameters of the nanohole pattern. The contribution of plasmonic local heating to thermoelectric conversion is verified experimentally and numerically, enabling discussion on the mechanisms governing light detection. These results provide a starting point for the development of other nanoscale photodetectors.
关键词： plasmon,photodetector,silver film,plasmonic local heat,thermoelectric conversion,nanohole
更新于2025-09-23 15:21:01
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A facile spray pyrolysis fabrication of Sm:CdS thin films for high-performance photodetector applications
摘要： Achievement of high-performance photodetectors based on CdS is a key field of research and challenge in the current scenario. Here, facile fabrication and characterization of novel samarium (1, 3 and 5 wt.% Sm)-doped CdS thin films for the photodetector applications have been demonstrated. The fabricated films show good crystallinity with crystallites size ranging 18–30 nm. The morphology and homogeneity of Sm-doping ingrown films were confirmed through scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX). Field emission SEM study reveals the low dimension nanograins formation and the films are free from voids and cracks. The effects of Sm-doping on linear and nonlinear optical properties of the fabricated thin films have been elucidated. The optical parameters such as refractive index, energy gap, susceptibilities were noticed to be reduced by Sm-doping in CdS thin films. An emission peak around 536 nm was observed in PL spectra of pure CdS which was found to be shifted and quenched by Sm-doping. Finally, the photodetector performance of the fabricated thin films has been investigated for 532 nm laser light. The photodetector based on the 1 wt.% Sm:CdS shows an improved performance (higher responsivity of 1.01 AW?1, higher detectivity of 2.21 × 1012 Jones, excellent photosensitivity of ～4.9 × 103, and very high external quantum efficiency (EQE) of 257 %) compared to pure CdS (responsivity of 0.213 AW?1, detectivity of 7.43 × 1011 Jones, photosensitivity of ～2.0 × 103, and EQE of 49.70 %). These results propose a much simpler route to achieve high-quality CdS films for photodetector applications.
关键词： Photoluminescence,Structural properties,CdS,Optical properties,Photodetector,Sm-doping,Thin films
更新于2025-09-23 15:21:01
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Nanoscale charge transport and local surface potential distribution to probe defect passivation in Ag doped Cu2ZnSnS4 absorbing layer
摘要： The performance of earth abundant Cu2ZnSnS4 (CZTS) material is limited by high deficit of open circuit voltage (VOC) which is mainly due to the easy formation of CuZn antisite defects. Suppression of CuZn defects is thus inevitably required for further developments in CZTS based solar cells. We studied systematic increase of Ag doping in CZTS thin film and investigated the nanoscale electrical properties using kelvin probe force microscopy (KPFM) and current sensing atomic force microscopy (CAFM) to probe CuZn defects. Crystallographic analysis indicated the successful partial substitution of Cu+ ions by large size Ag+ ions. The considerable decrease in grain boundary potential from 66.50 ± 5.44 mV to 13.50 ± 2.61 mV with Ag doping, suggesting the substantial decrease in CuZn defects. Consequently, CAFM measurement confirms the remarkable increment in minority carrier current with Ag doping and their local mobility in CZTS layer. Finally, the lower persistent photoconductivity (PPC) and fast decay response of photogenerated carriers for Ag doped CZTS photodetector further validate our results. This study provides a fresh approach of controlling deleterious CuZn defects in CZTS by tuning Ag content that may guide researchers to develop next generation high performance CZTS based solar cells.
关键词： nanoscale surface potential and current,CZTS solar cells,Ag doped CZTS,defects,photodetector
更新于2025-09-23 15:21:01
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Organic Upconversion Display with an over 100% Photon-to-photon Upconversion Efficiency and a Simple Pixelless Device Structure
摘要： Comparing to traditional near infrared (NIR) imaging devices, NIR-to-visible upconversion display which integrated a NIR photodetector with a visible light-emitting diode have merits of simple device structure, low cost, high resolution, and a simple pixelless structure. However, photon-to-photon upconversion efficiencies of these devices are typically much lower than unity. Here we report an all-organic NIR-to-visible upconversion display with a photon-to-photon upconversion efficiency higher than 100% by integrating a photomultiplying organic NIR photodetector with a high-efficiency thermally activated delayed fluorescent organic light-emitting-diode. To the best of our knowledge, this is the first report showing a photon-to-photon upconversion efficiency over 100% without using a built-in transistor for current amplification.
关键词： organic photodetector,NIR-to-visible upconversion,photon-to-photon efficiency,thermally activated delayed fluorescence,organic light-emitting diode
更新于2025-09-23 15:21:01
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In Situ Raman Investigation of TiO2 Nanotube Array-Based Ultraviolet Photodetectors: Effects of Nanotube Length
摘要： TiO2 nanotube arrays (TNAs) with tube lengths of 4, 6, and 7 μm were prepared via two-step anodization. Thereafter, ultraviolet (UV) photodetectors (PDs) with Au/TiO2/Au structures were prepared using these TNAs with different tube lengths. The effects of TNA length and device area on the performance of the device were investigated using in situ Raman spectroscopy. The maximum laser/dark current ratio was achieved by using a TNA with a size of 1 × 1 cm2 and a length of 7 μm, under a 532 nm laser. In addition, when the device was irradiated with a higher energy laser (325 nm), the UV Raman spectrum was found to be more sensitive than the visible Raman spectrum. At 325 nm, the laser/dark current ratio was nearly 24 times higher than that under a 532 nm laser. Six phonon modes of anatase TNAs were observed, at 144, 199, 395, 514, and 635 cm?1, which were assigned to the Eg(1), Eg(2), B1g(1), A1g/B1g(2), and Eg(3) modes, respectively. The strong low-frequency band at 144 cm?1 was caused by the O-Ti-O bending vibration and is a characteristic band of anatase. The results show that the performance of TNA-based PDs is length-dependent. Surface-enhanced Raman scattering signals of 4-mercaptobenzoic acid (4-MBA) molecules were also observed on the TNA surface. This result indicates that the length-dependent performance may be derived from an increase in the specific surface area of the TNA. In addition, the strong absorption of UV light by the TNAs caused a blueshift of the Eg(1) mode.
关键词： UV photodetector,Surface-enhanced Raman scattering,TiO2 nanotube arrays,SERS,Raman spectroscopy
更新于2025-09-23 15:19:57
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Nano-to-Microporous Networks via Inkjet Printing of ZnO Nanoparticles/Graphene Hybrid for Ultraviolet Photodetectors
摘要： Inkjet-printed photodetectors have gained enormous attention over the last decade. However, device performance is limited without post-processing, such as annealing and UV exposure. In addition, it is difficult to manipulate the surface morphology of the printed film using an inkjet printer due to the limited options of low viscosity ink solutions. Here, we employ a concept involving the control of the inkjet-printed film morphology via modulation of co-solvent vapor pressure and surface tension for the creation of a high-performance ZnO-based photodetector on a flexible substrate. The solvent boiling point across different co-solvent systems is found to affect the film morphology, which results in not only distinct photo-response time but also photo-detectivity. ZnO-based photodetectors were printed using different solvents which display a fast photo-response in low-boiling point solvents due to the low carbon residue and larger photo-detectivity in high-boiling point solvent systems due to the porous structure. The porous structure is obtained using both gas-liquid surface tension differences and solid-liquid surface differences, and the size of porosity is modulated from nano-size to micro-size depending on the ratio between two solvents or two nanomaterials. Moreover, the conductive nature of graphene enhances the transport behavior of the photocarrier, which enables a high-performance photodetector with high photo-responsivity (7.5*102 AW-1) and fast photo-response (0.18 s) to be achieved without the use of high-boiling point solvents.
关键词： Inkjet print,photodetector,ZnO nanoparticle (NP),flexible devices,microporous
更新于2025-09-23 15:19:57