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2D Schottky Junction between Graphene Oxide and Transition-Metal Dichalcogenides: Photoresponsive Properties and Electrocatalytic Performance
摘要： 2D graphene is conductor and not a semiconductor. 2D transition—metal dichalcogenides (TMD) is a semiconductor and not a conductor. Preparing 2D composite material that simultaneously possesses both advantages of graphene and TMD has proven to be challenging. In this work, both 2D-WS2/2D-GO and 2D-MoS2/2D-GO composites with few layer thickness are synthesized. The electronic structure indicates a high content of Mo4+ 3d5/2 and W4+4f7/2 with lower binding energy in the 2D composite, which is ascribed to partial loss of surface sulfur atoms in 2D composites and the newly formed heteroatomic bond of CWS and CMoS. The Schottky junction between 2D-GO and 2D-TMD (2D G-T junction) is established and exhibits obvious photoelectric responses. Superior electrocatalytic properties of the two 2D-composites are attributable to the 2D Schottky Junction between 2D-TMDs and 2D-GO. Interlayer electronic coupling in 2D Schottky Junction (2D G-T junction) activates inert sites on the 2D surface of 2D-TMDs or GO. The power conversion efficiency of dye-sensitized solar cells (DSCs) based on 2D-WS2/2D-GO is 9.54% under standard solar illumination intensity (AM1.5, 100 mW cm?2). The value is one of the highest reported efficiencies for DSCs based on Pt-free counter electrodes. Finally, 2D-WS2/2D-GO composites exhibit excellent stability as counter electrode of DSCs.
关键词： photoresponse,interlayer electronic coupling,2D,electrocatalyst,graphene,transition-metal dichalcogenides,Schottky junction
更新于2025-09-23 15:23:52
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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52
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Photoelectricity and thermoelectricity in organic chlorophyll phototransistors
摘要： As one kind of organic semiconductor materials, Chlorophyll has been attracted great attention with remarkable optical properties. Here, we demonstrate photoresponse and thermoelectric current in the biological Chlorophyll A field effect phototransistors (FEpTs). Meanwhile, it exhibits excellent performances including high responsivity (5×1013 A/W) and relatively fast response time (rise time ~ 20.3 s, fall time ~ 28.2 s) under illumination by 405 nm. Utilizing thermionic emission theory and typical Arrehenius plot, Schottky barrier B is found to be 76.6 meV. The biological phototransistor via low-cost, simple, and scalable fabrication processes opens up new opportunities to realize flexible, transparent organic electronic, and biologically optoelectronic devices.
关键词： Schottky junction,photoelectricity and thermoelectricity,Chlorophyll,Organic phototransistor
更新于2025-09-23 15:21:21
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Colloidal Quantum-Dots/Graphene/Silicon Dual-Channel Detection of Visible Light and Short-Wave Infrared
摘要： Integration of infrared detectors with current silicon-based imagers would not only extend their spectral sensing range but also enables numerous applications including thermal imaging, machine vision, and spectrometers. Here, we report the development of a dual-channel photodetector by depositing a colloidal quantum dot (CQDs) infrared photodiode onto a graphene/p-Silicon Schottky diode to provide simultaneous visible and infrared photoresponse channels. The HgTe photodiode is patterned into a semitransparent mesh-structure so that the visible light reaches the Silicon substrate with varying fill factors. The graphene/silicon Schottky junction has a responsivity of ~0.9 A/W in the visible and the infrared CQDs photodiode has a detectivity of ~5×109 Jones at 2.4μm, for a filling factor of 0.1.
关键词： Photodetectors,Graphene/silicon Schottky junction,Visible/infrared,Colloidal quantum dots
更新于2025-09-23 15:21:01
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Solar cell based on vertical graphene nano hills directly grown on silicon
摘要： We demonstrate a solar cell application based on vertical graphene nano hills (VGNH) directly grown without using a catalyst. The photovoltaic device based on VGNH grown on top of interfacial layer Al2O3 is compared with that on top of bare silicon by critically analyzing its electrical properties. The role of the interfacial layer is to minimize surface recombination and enhance its built-in potential. Our key process is simple to fabricate large-area devices, avoiding an unreliable transfer process. In addition, the thickness of VGNH is optimized and the surface texturing of silicon is performed to overcome the crucial problem of the high reflectivity of silicon. A low reflectivity of thick layers of VGNH is achieved with low series resistance despite of the vertical structure, which is beneficial for high photocurrent. A higher work function of VGNH ~ 4.7 eV is measured by KPFM. The conversion efficiency of 10.97% is achieved with an active area of 0.9 cm2 by co-doping with PEDOT: PSS and inorganic acid HNO3. Moreover, the photo-responsivity of the VGNH-based device is estimated as 1.196 AW-1 under deep ultraviolet light.
关键词： vertical graphene,graphene doping,graphene nano hills,directly grown graphene,solar cell,anti-reflecting coating,Schottky junction
更新于2025-09-23 15:21:01
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Improved photovoltaic performance of graphene-based solar cells on textured silicon substrate
摘要： Graphene has attracted much interest as an active layer in heterojunction solar cells due to its outstanding properties such as flexibility, transparency, mechanical strength and elevated carrier mobility. In this research, a new technique was presented in order to enhance the efficiency of graphene–based heterojunction solar cells by employing a textured silicon (Si) substrate. Here, two sets of devices were fabricated based on flat and pyramidal structure of Si and the photovoltaic properties of graphene/Si heterojunction solar cells were compared. Selective chemical dissolution of Si wafers was carried out in order to produce pyramidal skeleton. Reduced graphene oxide (rGO) was then transferred on pyramidal Si through electrophoretic deposition (EPD) technique. The evidence of graphene layers on Si substrates was studied using Raman spectroscopy, X–ray diffractometry (XRD) and atomic force microscopy (AFM) analysis. The morphology of samples indicated an enhancement in rGO/Si interface area when the pyramidal structure is applied. Moreover, the enhanced surface area of this sample which is due to elevated roughness of pyramidal structure and wrinkles of graphene layers promotes its antireflective behavior which was proven using reflectance spectroscopy. The average reflectance of the graphene layer on the textured Si was ~14% in the wavelength range of 400–800 nm which is lower than that of rGO on flat Si. The improved optical properties of graphene on pyramidal silicon can broaden its potential applications in optoelectrical devices such as high-efficiency solar cells. In order to study the photovoltaic properties of rGO/Si samples, a passive layer was formed on Si substrate and a square frame of Ag was coated on it which was acted as a top contact. The current–voltage characteristics showed that the efficiency of rGO/Si heterojunction solar cells was improved when textured silicon was applied.
关键词： Schottky junction solar cell,Heterojunctions,Thin films,Reduced graphene oxide,Silicon pyramids,Electrophoretic deposition
更新于2025-09-23 15:19:57
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High responsivity ZnO based p-n homojunction UV-photodetector with series Schottky Barrier
摘要： In the present article, we proposed a p-n homojunction photodetector with a series Schottky barrier and a high value of responsivity in the ultraviolet region. The thin-film photodetector makes use of a junction between an RF-sputtered n-type ZnO nanostructure and a p-type CZO thin film derived through the spin coating process on an ITO coated glass substrate. Palladium metal contacts have been deposited to form the Schottky barrier in series with p-n homojunction. The device has been simulated, fabricated, and tested only after ensuring the stability of the p-type CZO thin film. The measured I-V characteristics of fabricated photodetector under illuminated and dark conditions showed excellent UV response and good rectification property. The device exhibits a peak responsivity of 13.2 A/W for a reverse biasing voltage of 3 V. This value is much above the values reported by others for ZnO based photodetector.
关键词： CZO,photodiode,U-V illumination,ZnO,Schottky junction
更新于2025-09-23 15:19:57
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Enhanced solar- photocatalytic activity for the simultaneous degradation and detoxification of multiple chlorophenols by embedding plasmonic Pt into TiO2/H3PW12O40 nanopore
摘要： A novel Pt-TiO2/H3PW12O40 film was fabricated, which showed a considerable nonselective degradation and detoxification efficiency towards multiple chlorophenols (CPs), owing to the enhanced yield and separation efficiency of photogenerated electrons and holes. Based on the Mott-Schottky analysis, the carrier density of as-prepared Pt-TiO2/H3PW12O40 film reached 9.72 × 1022 cm?1, which was higher than that of Pt-TiO2, TiO2/H3PW12O40, and TiO2. The outstanding properties were attributed to the SPR effect and the formation of electrons traps from Pt0 (which was well protected by the nanopores that were formed by Ti-O-W and Ti-O-P); and H3PW12O40 that can efficiently transport electrons via its self-generated redox cycle. Meanwhile, the Pt-TiO2/H3PW12O40 film considerably lowers ecological risks of multiple CPs because O2?, as the primary radicals, can largely avoid the generation of products with a quinoid structure. The degradation pathways of multiple CPs were similar to those of single CP because the same hydroxyl substitution intermediate products were detected during the degradation, all of which followed the first-order reaction kinetics. Moreover, the excellent recycling performance of the Pt-TiO2/H3PW12O40 film guaranteed the reduction in economic cost and risks of secondary pollution. Therefore, the Pt-TiO2/H3PW12O40 film showed a considerable application potential in the removal of organic contaminants in aqueous environments.
关键词： Acute toxicity,Schottky junction,SPR effect,Multiple CPs,Degradation pathway
更新于2025-09-23 15:19:57
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Tuneable efficiency of direct growth graphene solar cells
摘要： Direct growth technique could produce low-cost, high-efficiency graphene-on-silicon Schottky junction solar cells. The team from Sejong University, Korea, report on their latest development – a low cost fabrication technique, which allows different thicknesses of graphene to be grown directly onto bare silicon. The efficiency of the cell was further increased to 9.18 % by adding and doping a polymer (PMMA) layer. The authors say that their direct growth technique is 'compatible for industrial-level applications,' and suggest that it offers a simpler and more reliable alternative to manually transferring CVD-grown graphene onto a silicon surface.
关键词： solar cells,graphene,efficiency,Schottky junction,direct growth
更新于2025-09-19 17:13:59
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Plasmonic MoO2 as co-catalyst of MoS2 for enhanced photocatalytic hydrogen evolution
摘要： Generally, photocatalytic water splitting on MoS2 nanomaterials is restricted owing to the high carrier recombination and limited utilization of the visible light. This study describes the enhancement of the MoS2-catalysed hydrogen evolution by incorporating metallic MoO2 as a co-catalyst introduced by coupling with MoS2 nanosheets through a facile calcination strategy, forming a Schottky junction between MoO2 and MoS2. The localized surface plasmon resonance effect induced by the oxygen vacancies and favourable Fermi lever position of MoO2 lead to a broad spectral response and a significant improvement in the exciton generation and dissociation. The electron gets transferred from the conduction band (CB) of MoS2 to MoO2, wherein MoO2 acts as an ‘electron pool’ that gathers the photoexcited electrons, which are rapidly shuttled to the surface of MoO2, where the redox reaction occurs due to its great metallic conductivity. Resultantly, a 242% increment in the production of hydrogen gas by MoS2/MoO2 is achieved in comparison with that of the MoS2 nanosheets.
关键词： Photocatalytical hydrogen production,co-catalysts,MoS2/MoO2,LSPR effect,Schottky junction
更新于2025-09-19 17:13:59