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Hybrid dual-channel phototransistor based on 1D t-Se and 2D ReS2 mixed-dimensional heterostructures
摘要： The combination of mixed-dimensional semiconducting materials can provide additional freedom to construct integrated nanoscale electronic and optoelectronic devices with diverse functionalities. In this work, we report a high-performance dual-channel phototransistor based on one-dimensional (1D)/two-dimensional (2D) trigonal selenium (t-Se)/ReS2 heterostructures grown by chemical vapor deposition. The injection and separation efficiency of photogenerated electron–hole pairs can be greatly improved due to the high-quality interfacial contact between t-Se nanobelts and ReS2 films. Compared with bare ReS2 film devices, the dual-channel phototransistor based on t-Se/ReS2 heterostructure exhibits considerable enhancement with the responsivity (R) and detectivity (D*) up to 98 A·W–1 and 6 × 1010 Jones at 400 nm illumination with an intensity of 1.7 mW·cm?2, respectively. Besides, the response time can also be reduced by three times of magnitude to less than 50 ms due to the type-II band alignment at the interface. This study opens up a promising avenue for high-performance photodetectors by constructing mixed-dimensional heterostructures.
关键词： phototransistor,van der Waals heterostructures,ReS2,trigonal selenium (t-Se) nanobelt
更新于2025-09-23 15:23:52
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Variation in Structural, Electrical and Optical Properties of Selenium Nanowires After Irradiation with Ni6+ Ions
摘要： The effect of Ni ion irradiation on selenium nanowires of 80 nm diameter is studied in the present work. Se nanowires were prepared by using electrodeposition technique in polycarbonate membrane. Changes in the structural, optical and electrical properties are studied using XRD, UV/Vis spectroscopy and current–voltage characteristics, of the pristine and irradiated samples. X-ray diffraction study confirms the variation in peak intensity without any shifting in peak position. Variation in texture coefficient and grain size was clearly observed which is a consequence of changing plane orientation, irradiation induced grain growth and grain fragmentation. A decrease in the optical band gap takes place due to interstitial energy band states in the vicinity of conduction and valence band. IVC also shows variation in the conductivity which is due to the generation of current carriers with the passage of energetic ions.
关键词： Ion irradiation,Optical analysis,Selenium nanowires,Impedance,Electrical properties,Structural analysis
更新于2025-09-23 15:23:52
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Development of a high temperature diamond anvil cell for x ray absorption experiments under extreme conditions
摘要： X-ray absorption spectroscopy (XAS) is presently a powerful and established tool to investigate solid and liquid matter at high pressure and high temperature (HP-HT). HP-HT XAS experiments rely on high pressure technology whose continuous development has extended the achievable range up to 100 GPa and more. In high pressure devices, high temperature conditions are typically obtained by using internal and external resistive heaters or by laser heating. We have recently developed a novel design for an internally heated diamond anvil cell (DAC) allowing XAS measurements under controlled high temperature conditions (tested up to about 1300 K). The sample in the new device can be rapidly heated or cooled (seconds or less) so the cell is suitable for studying melting/crystallization dynamics when coupled with a time-resolved XAS setup (second and sub-second ranges). Here we describe the internally heated DAC device which has been realized and tested in experiments on pure selenium at the energy dispersive ODE beamline of Synchrotron SOLEIL. We also present results obtained in XAS experiments of elemental Se using a large volume Paris-Edinburgh press, as an example of the relevance of structural studies of matter under extreme conditions.
关键词： high pressure,high temperature,DAC,Selenium,XAS
更新于2025-09-23 15:23:52
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Two-Dimensional Non-Layered Selenium Nanoflakes: Facile Fabrications and Applications for Self-Powered Photo-Detector
摘要： Two-dimensional (2D) materials exhibit many interesting properties, but most of two-dimensional materials are exfoliated from layered bulk materials, limiting the development of 2D material group. Recently, non-layered 2D materials have aroused a great attention due to their excellent catalysis performance, favored compatibility with silicon substrates and highly chemically active. With high photoconductivity, high responsivity and fast response time, non-layered selenium (Se) exhibits important applications in the field of optoelectronics. In this work, we use a simple liquid phase exfoliation method to fabricated 2D Se nanoflakes from bulk Se which possesses unique chain structure. The thickness of 2D Se nanoflakes was measured to be in the range of 5-10 nm. As-fabricated Se nanoflakes was used in a photodetector by photoelectrochemical (PEC) method, showing a high photocurrent density (1.28 μA/cm2) and photoresponsivity (10.45 μA/W). In addition, the long-term photoelectric measurements indicate that the 2D Se-based photodetector has good time and cycle stability. Our results show that 2D Se have promising potential in liquid-based photo-detectors.
关键词： 2D selenium,photoelectrochemical photodetector,nonlayered 2D materials
更新于2025-09-23 15:22:29
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Effect of selenium partial pressure on the performance of Cu2ZnSn(S, Se)4 solar cells
摘要： Sputtering followed by selenization is one of the most common methods for preparing CZTSSe thin films. However, the influence of selenium partial pressure on the crystallinity of the CZTSSe film has been rarely reported. In this study, CZTSSe thin films were prepared by selenization using quartz tubes of different lengths. The influence of Se saturated vapor pressure and temperature on the structure, composition, optical, and electrical properties of CZTSSe films and solar cells was analyzed and these results were used to optimize the performance of the CZTSSe film. It was found that the maximum partial pressure of selenium was 22,542 Pa when the selenization process was carried out in a quartz tube with a length of 30 cm, which largely improved the structural and electrical properties of CZTSSe. However, quartz tube with an over-short length would bring strong partial pressure during selenization, which resulted in a generation of secondary phases. Finally, CZTSSe thin-film solar cell with a maximum efficiency of 3.27% was obtained at an optimal selenium partial pressure of 22542 Pa.
关键词： CZTSSe,thin-film solar cells,selenium partial pressure,selenization
更新于2025-09-23 15:19:57
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Heavy Atom Effect of Selenium for Metal-Free Phosphorescent Light-Emitting Diodes
摘要： Room-temperature phosphorescence from metal-free purely organic molecules has recently gained much interest. We devised metal-free organic phosphors by incorporating selenium (Se) to promote spin?orbit coupling by its nonmetal heavy atom effect. The Se-based organic phosphors showed bright phosphorescent emission in organic light-emitting diodes (OLEDs) and photo-excited phosphorescence in an amorphous film state. Large orbital angular momentum change (ΔL) during the electron transition process and heavy atom effect of Se render a PL quantum yield of 0.33 ± 0.01 and a high external quantum efficiency (EQE) of 10.7 ± 0.14% in phosphorescent LEDs. This work demonstrates the rational molecular design of metal-free organic phosphorescent emitters with Se as an alternative novel class of materials to the conventional organometallic phosphors for OLEDs.
关键词： organic light-emitting diodes,spin?orbit coupling,selenium,metal-free organic phosphors,phosphorescent LEDs,room-temperature phosphorescence
更新于2025-09-23 15:19:57
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Photocarrier relaxation pathway in selenium quantum dots and its application for UV-Vis photodetecting
摘要： Chain-like materials have recently attracted significant attention due to their unique structure and outstanding electro-optical properties. However, the photocarrier dynamics and pathways in these materials that determine the electro-optical performances of the prepared devices have barely been touched. Herein, one typical chain-like materials e quantum dots (Se QDs) were prepared via a facile liquid phase exfoliation approach. The photocarrier dynamics in selenium quantum dots were systematically investigated via ultrafast transient absorption spectroscopy in the ultraviolet-visible regime. Four photocarrier decay pathways with different lifetime times were firstly detected, endues the elucidation and reconstruction of the energy schematic diagram of Se QDs. Thanks to the broadband photo-response and fast recovery time of Se QDs, a photoelectrochemical (PEC)-typed photodetector was proposed for the first time to our knowledge, demonstrating excellent photodetection properties. Considering the feasible fabrication method and clear photocarrier pathways, the excellent photocurrent density and stability of this photodetector undoubtedly guarantee the promising of selenium for advanced photonics devices.
关键词： broadband photo-response,photocarrier dynamics,ultrafast transient absorption spectroscopy,selenium quantum dots,photoelectrochemical photodetector
更新于2025-09-23 15:19:57
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Modifying the Electronic Properties of Se/n‐Si Heterostructure Using Electrolysis
摘要： Heterostructures of dissimilar crystalline materials are key in the development of photoelectronic devices. Such structures rely on matching lattice constants for efficient transport. Nevertheless, an amorphous material, amorphous Se is becoming important in high-energy photoelectronics. Thus there is a need to understand the heterostructures it forms with conventional crystalline materials. Since the transport properties of such heterostructures will be limited by lattice mismatches, methods to improve transport are necessary. We investigated the effect of electrolysis on the electronic properties of Se based multilayer films deposited on n-type silicon (Se/n-Si) and showed that conduction and photoresponse can be changed by electrolysis processing. The Se surface of the Se/n-Si samples was used as an anode in the electrolysis of NaCl solution. Afterwards, the samples were measured using current–voltage and capacitance–voltage variations in dark conditions and under illumination. Electrolysis processed samples showed higher conduction current and photocurrent, compared to samples not used in electrolysis. This is due to the introduction of Cl into the Se, which affects carrier lifetimes: increasing hole lifetime and reducing electron lifetime. We therefore suggest that electrolysis can be applied to modify the electronic properties of Se/n-Si heterostructures.
关键词： chalcogenide semiconductor,amorphous selenium,heterostructures,electrochemical
更新于2025-09-23 15:19:57
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Polyselenides on the Route to Electrodeposited Selenium
摘要： The electrochemical oxidation of aqueous solutions of hydrogen selenide (HSe – ) and of hydrogen polyselenide ions (HSex – ) on glassy carbon electrodes at pH = 9.2 is reported. In both cases, the oxidation leads to deposits of selenium. The role of polyselenides as intermediates in the process is demonstrated. At 25 ?C amorphous selenium is formed whereas at 70 ?C crystalline selenium is deposited. The possible use of selenium ?lms for technological purposes is discussed.
关键词： polyselenides,cyclic-voltammetry,selenium,electrodeposition
更新于2025-09-19 17:15:36
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Fabrication and AFM characterization of selenium recycled nano particles by pulse laser evaporation and thermal evaporation
摘要： The feasibility of waste collection strikethrough in the traditional evaporation deposition system after preparing thin films was investigated. In this paper, first, the Selenium thin films of 0.5 μm thickness were prepared by a thermal vacuum evaporation system and an evaporation assisted laser Neodymium - Yag pulsed Nd:YAG laser system. Then, the waste materials that remain in the systems were collected and examined. The inspections include the particle size and other structural properties, taken before and after annealing at 300 °C for 30 min. Results show that the prepared thin film and particles are crystalline and the particle size of collected particles are in the range of about <50 nm, which makes this method very useful in the production of recycled nanoparticles of metals and materials that are costly or harmful, but can be an advantage and beneficial.
关键词： recycled nanoparticles,selenium,Nd: YAG laser,thin film,annealing
更新于2025-09-19 17:13:59