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ZrS3/MS2 and ZrS3/MXY (M Mo, W; X, Y S, Se, Te; X?≠?Y) type-II van der Waals hetero-bilayers: Prospective candidates in 2D excitonic solar cells
摘要： Excellent photovoltaic abilities in a 2D excitonic solar cell based on staggered type-II van der Waals (vdW) hetero-bilayers comprising of semiconducting ZrS3 monolayer and monolayers of MS2 & MXY (M=Mo, W; X, Y=S, Se, Te; X≠Y) are reported herewith, using DFT-D2 and HSE06 functional. Studies on vdW hetero-bilayers of MX3/MX2 and MX3/M’Y2 have so far been conveniently avoided on account of their large lattice mismatch. The present work is the first attempt to address such hetero-bilayers constituted by monolayers of transition metal dichalcogenides and trichalcogenides. The nature of the band edges in ZrS3 and MS2 monolayers induces high electron and hole mobility in these individual monolayers, respectively, which has been combined synergistically in the hetero-bilayers consisting of them. The Power Conversion Efficiency (PCE) in ZrS3/MoS2, ZrS3/WS2, ZrS3/MoSeTe, ZrS3/WSTe, and ZrS3/WSeTe hetero-bilayers, calculated within the Anderson-limit, are found to reach as high as ~12%, 8%, 16%, 14%, and 14% respectively. The PCE of the hetero-bilayers reported herewith are much higher than the efficiency in MoS2/p-Si heterojunction solar cells (5.23%) and comparable to that of the theoretically proposed PCBM fullerene/BCN system (10?20%) and g-SiC2-based systems (12?20%) and the recently predicted TiNF/TiNBr (18%), TiNCl/TiNBr (19%), TiNF/TiNCl (22%) bilayer solar cell systems.
关键词： 2D materials,transition metal dichalcogenides,photovoltaic,van der Waals hetero-bilayers,transition metal trichalcogenides,power conversion efficiency
更新于2025-09-11 14:15:04
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Diffusion-Driven Al-Doping of ZnO Nanorods and Stretchable Gas Sensors Made of Doped ZnO Nanorods/Ag Nanowires Bilayers
摘要： A crystal-damage-free nano-doping method, which utilized the vacuum drive-in diffusion of Al into ZnO nanorods, was developed. In this method, vertical ZnO nanorod arrays that were grown by chemical bath deposition beforehand were deposited with Al thin film and subsequently heat-treated under a high vacuum. At an optimum condition, the surface Al atoms were completely diffused into ZnO nanorods, resulting in Al-doped ZnO nanorods. Stretchable gas sensors were fabricated by sequentially drop-casting Al-doped ZnO nanorods and silver nanowires on PDMS substrate. The resistance and response of the sensor could be optimized through the elaborate control of relative densities of Al-doped ZnO nanorods and silver nanowires. The sensor showed a high response of 32.3% to 10 ppm of NO2 gas at room temperature, even under a large strain of 30%. The NO2-sensing mechanism of Al-doped ZnO nanorods/silver nanowires bilayer sensors is discussed on the basis of synergistic interplay of Al-doped ZnO nanorods and silver nanowires.
关键词： Al-doped ZnO nanorods,Stretchable gas sensors,bilayers,drive-in diffusion,silver nanowires
更新于2025-09-09 09:28:46
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Relaxation and domain formation in incommensurate two-dimensional heterostructures
摘要： We introduce con?guration space as a natural representation for calculating the mechanical relaxation patterns of incommensurate two-dimensional (2D) bilayers. The approach can be applied to a wide variety of 2D materials through the use of a continuum model in combination with a generalized stacking fault energy for interlayer interactions. We present computational results for small-angle twisted bilayer graphene and molybdenum disul?de (MoS2), a representative material of the transition-metal dichalcogenide family of 2D semiconductors. We calculate accurate relaxations for MoS2 even at small twist-angle values, enabled by the fact that our approach does not rely on empirical atomistic potentials for interlayer coupling. The results demonstrate the ef?ciency of the con?guration space method by computing relaxations with minimal computational cost. We also outline a general explanation of domain formation in 2D bilayers with nearly aligned lattices, taking advantage of the relationship between real space and con?guration space. The con?guration space approach also enables calculation of relaxations in incommensurate multilayer systems.
关键词： incommensurate,domain formation,MoS2,bilayers,two-dimensional,relaxation,graphene
更新于2025-09-09 09:28:46
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Particle-in-cell simulation of ultrafast hot-carrier transport in Fe/Au heterostructures
摘要： We present a theoretical approach for spin-polarized hot-electron transport, as it occurs after excitation by ultrafast optical pulses in heterostructures formed by ferromagnetic and normal metals. We formulate a spin-dependent particle-in-cell model that solves the Boltzmann equation for excited electrons. It includes lifetimes and transmission coefficients as parameters, which can be taken from ab initio calculations or experiment, and can be easily extended to multilayer systems. This approach is capable of describing electron transport in the ballistic, superdiffusive, and diffusive regime including secondary-carrier generation. We apply the model to optically excited carriers in Fe/Au bilayers and Fe/Au/Fe spin-valve structures and analyze theoretically the hot-electron transport dynamics probed in recent experiments on spin valves. We find contributions to the demagnetization dynamics induced in Fe/Au/Fe trilayers regardless of the parallel or antiparallel magnetic alignment of the Fe layers.
关键词： ferromagnetic and normal metals,ultrafast optical pulses,Fe/Au/Fe spin-valve structures,Fe/Au bilayers,Boltzmann equation,spin-polarized hot-electron transport
更新于2025-09-04 15:30:14
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Microwave photocurrent from the edge states of InAs/GaInSb bilayers
摘要： We measure microwave photocurrent in devices made from InAs/GaInSb bilayers where both the insulating bulk state and conducting edge state were observed in the inverted-band regime, consistent with the theoretical prediction for a quantum spin Hall (QSH) insulator. It has been theoretically proposed that microwave photocurrent could be a unique probe in studying the properties of QSH edge states. To distinguish a possible photoresponse between a bulk state and helical edge state, we prepare a Hall bar and Corbino disk from the same wafer. Results show that the Corbino-disk samples have a negligible photocurrent in the bulk gap, while clear photocurrent signals from the Hall-bar samples are observed. This finding suggests that the photocurrent may carry information concerning the electronic properties of the edge states.
关键词： quantum spin Hall insulator,microwave photocurrent,helical edge states,InAs/GaInSb bilayers
更新于2025-09-04 15:30:14
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Nanoparticles at Biomimetic Interfaces: A Combined Experimental and Simulation Study on Charged Gold Nanoparticles/Lipid Bilayers Interfaces
摘要： The poor understanding of the interaction of nanomaterials with biologically relevant interfaces is recognized as one of the major issues currently limiting the development of nanomedicine. The central purpose of this study is to compare experimental (Confocal Microscopy, Fluorescence Correlation Spectroscopy, X-ray Reflectivity) and computational (Molecular Dynamics simulations) results to thoroughly describe the interaction of cationic gold nanoparticles (AuNP) with mixed zwitterionic/anionic lipid membranes. The adhesion of AuNPs to the lipid membrane is investigated on different length scales from a structural and dynamical point of view; with this approach, a series of complex phenomena, spanning from lipid extraction, localized membrane disruption, lateral phase separation and slaved diffusion, are characterized and interpreted from a molecular level to macroscopic observations.
关键词： Nanoparticles,Gold Nanoparticles,Molecular Dynamics,X-ray Reflectivity,Fluorescence Correlation Spectroscopy,Lipid Bilayers,Biomimetic Interfaces,Confocal Microscopy
更新于2025-09-04 15:30:14
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Charge and Coordination Directed Liposome Fusion onto SiO2 and TiO2 Nanoparticles
摘要： TiO2 and SiO2 are very useful materials for building biointerfaces. A particular interesting aspect is their interactions with lipid bilayers. Many past research efforts focused on phosphocholine (PC) lipids, which form supported lipid bilayers (SLB) on SiO2 at physiological conditions but are adsorbed as intact liposomes on TiO2. Low pH was required to form PC SLBs on TiO2. This work intends to understand the surface forces and chemistry responsible for such differences. Two charge neutral lipids: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl ethyl phosphate (DOCPe); and two negatively charged lipids: 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) and 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl hydrogen phosphate (DOCP) were used. Using calcein leakage assays, adsorption measurement, cryo-TEM, and washing, we concluded that charge is the dominating factor on SiO2. The two neutral lipids form SLB on SiO2 at pH 3 and 7, but the two negatively charged ones cannot form. On TiO2, both charge and coordination chemistry are important. The two anionic lipids formed SLB from pH 3 to 10. DOCP had stronger affinity than DOPS likely due to the tighter terminal phosphate binding of the former. The two neutral liposomes formed SLB only at pH 3, where phosphate interaction and van der Waals force are deemed important. The pH 3 prepared TiO2 DOPC SLBs are destabilized at neutral pH, indicating reversible nature of the interaction. This work has provided new insights into two important materials interacting with common liposomes, which are important for reproducible biosensing, device fabrication, and drug delivery applications.
关键词： coordination chemistry,liposome fusion,SiO2,TiO2,charge,supported lipid bilayers
更新于2025-09-04 15:30:14