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Au@Cu Core-Shell Nanocubes with Controllable Sizes in the Range of 20-30 nm for Applications in Catalysis and Plasmonics
摘要： Predominantly covered by a single type of {100} facets, Cu nanocubes are attractive catalytic material toward reactions such as electrochemical reduction of CO2. Here we report a seed-mediated approach to the facile synthesis of Au@Cu core-shell nanocubes with hexadecylamine and Cl- serving as capping agents toward the {100} facets of Cu and glucose as a reducing agent. The large (12%) lattice mismatch between Cu and Au led to the localized epitaxial growth of Cu shells on the Au seeds and the formation of nanocubes with randomly distributed Au cores. Compared to the same synthesis in the absence of Au seeds, the reduction of Cu(II) ions was greatly accelerated in the presence of Au seeds because of the autocatalytic surface reduction. It was also found that the structure and morphology of the products were highly dependent on the concentration of Cu(II) precursor in the reaction solution. Nanoplates rather than nanocubes were obtained when the concentration of Cu(II) precursor was reduced down to a certain level. By varying the reaction time and/or the amount of Au seeds, the size of the Au@Cu nanocubes could be tuned in a range of 20–30 nm. The as-synthesized core-shell nanocubes exhibited a strong localized surface plasmon resonance peak at 581 nm and the resonance was dominated by absorption rather than scattering. It is expected that the Au@Cu nanocubes with uniform and controllable sizes will find use in a variety of applications such as plasmonics and catalysis.
关键词： lattice mismatch,Copper nanocubes,core-shell nanocrystals,plasmonics,seed-mediated growth
更新于2025-11-19 16:56:35
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Surface-interface analysis of In <sub/>x</sub> Ga <sub/>1-x</sub> As/InP heterostructure in positive and negative mismatch system
摘要： The change of In content in the InxGa1-xAs/InP system leads to the variation of the lattice constant and thereby to the negative mismatch between the base InP and the positive mismatch. Here, we studied the surface morphology and dislocation relationship of InxGa1-xAs/InP (100) in the positive and negative mismatch system by different characterization techniques. Under the same mismatch, the surface morphology and mass effect of negative mismatch were greater than those of positive mismatch. The reason was that in the negative mismatch system, during the film growth, the disorder degree at the interface increases, leading to an increase in dislocation density, meanwhile, the dislocation in the substrate more easily moved into the film, thus increasing the film and the dislocation density in it. Moreover, the mechanism of the buffer layer was also clarified. The addition of the buffer layer first limited the dislocation movement in the substrate, and secondly reduced the mismatch between the epitaxial layer and the substrate, thereby reducing mismatch dislocation.
关键词： surface/interface,lattice mismatch,InxGa1-xAs/InP,residual stress,dislocation
更新于2025-09-23 15:23:52
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van der Waals epitaxial growth of single crystal α-MoO3 layers on layered materials growth templates
摘要： Monolayer and multilayer α-MoO3 nanosheets are successfully grown on a 2D substrate by simply evaporating amorphous molybdenum oxide thin film in ambient conditions. A single-crystal α-MoO3 nanosheet without grain boundary is epitaxially grown on various 2D substrates despite a large lattice mismatch. During growth, the quasi-stable monolayer α-MoO3 first covers the 2D substrate, then additional layers are continuously grown on the first monolayer α-MoO3. The band gap of the α-MoO3 increases from 2.9 to 3.2 eV as the thickness decreases. Furthermore, due to oxygen vacancies and surface adsorbates, the synthesized α-MoO3 is highly n-doped with a small work function. Therefore, α-MoO3 field-effect transistors (FETs) exhibit a typical n-type conductance. This work shows the great potential of ultra-thin α-MoO3 in 2D-material-based electronics.
关键词： work function,van der Waals epitaxy,band structure,vacancy,transition metal oxide,stability,2D materials,lattice mismatch,transistor,heterostructure
更新于2025-09-23 15:21:01
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Enhancement in the efficiency of Sb2Se3 solar cells by adding low lattice mismatch CuSbSe2 hole transport layer
摘要： As an excellent light absorbing material, antimony selenide (Sb2Se3) has attracted researchers to explore its application in solar cells. At present, the e?ciency of Sb2Se3 solar cells is still too low because of the low carrier concentration and high back surface recombination. In this study, we prepared an additional CuSbSe2 ?lm as hole transport layer by co-sputtering Sb2Se3 and Cu targets. It reduced the surface roughness of the absorption layer and the back surface recombination, which was bene?cial to the collection of carriers. Due to the higher carrier concentration of CuSbSe2 ?lm and proper di?usion of Cu, the carrier concentration of the absorption layer is greatly improved, thereby e?ectively increasing the Voc of the Sb2Se3 thin ?lm solar cells. Finally, we obtained a 5.87% e?ciency for the FTO/CdS/Sb2Se3/CuSbSe2/Au solar cell, which is more than 25% higher than the basic e?ciency.
关键词： Carrier concentration,CuSbSe2,Co-sputtering,Sb2Se3,Lattice mismatch
更新于2025-09-23 15:19:57
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Organic heterostructures composed of one- and two-dimensional polymorphs for photonic applications
摘要： Organic heterostructures (OHSs) consist of organic micro/nanocrystals are of essential importance for the construction of integrated optoelectronics in the future. However, the scarcity of materials and the problem of phase separation still hinder the fine synthesis of OHSs. Herein, based on the α phase one-dimensional (1D) microrods and the β phase 2D microplates of one organic compound 3,3′-((1E,1′E)-anthracene-9,10-diylbis(ethane-2,1-diyl))dibenzonitril (m-B2BCB), we facilely synthesized the OHSs composed of these two polymorph phases, whose growth mechanism is attributed to the low lattice mismatch rate of 5.8% between (001) plane of α phase (trunk) and (010) crystal plane of β phase (branch). Significantly, the multiport in/output channels can be achieved in the OHSs, which demonstrates the structure-dependent optical signals with the different output channels in the OHSs. Therefore, our experiment exhibits the great prospect of polymorphism in OHSs, which could provide further applications on multifunctional organic integrated photonics circuits.
关键词： heterostructure,integrated optoelectronics,fine synthesis,lattice mismatch,polymorph
更新于2025-09-23 15:19:57
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Tailoring the solar-blind photoresponse characteristics of ?2-Ga2O3 epitaxial films through lattice mismatch and crystal orientation
摘要： Realizing manipulation of the photoelectric properties of wide bandgap semiconductors is a main challenge for succeeding next-generation functional optoelectronics. As an intriguing wide bandgap semiconductor, β-Ga2O3 (Eg ~ 4.9 eV) is emerging as a promising candidate for photodetectors operating in solar-blind region. Here, we show that by selecting substrates with different symmetries and lattice parameters [i.e. (100) MgO, (100) MgAl2O4 and (0001) α-Al2O3], epitaxial β-Ga2O3 films with (100)- or (2?01)-oriented could be fabricated. We found that the photoresponse characteristics are strongly correlated with the lattice mismatch and film orientation. In particular, (100)-oriented β-Ga2O3 film grown on MgO substrate with smaller lattice mismatch exhibited a 254 nm responsivity of 0.1 A·W-1 and detectivity of 4.3×1012 Jones, which are approximately an order of magnitude higher than that of the (2?01)-oriented β-Ga2O3 film. Our work may provide a strategy to develop further high performance solar-blind photodetectors.
关键词： β-Ga2O3,crystal orientation,epitaxial films,lattice mismatch,solar-blind photodetectors
更新于2025-09-19 17:13:59
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Enhanced thermal stability of electron transport layer-free perovskite solar cells via interface strain releasing
摘要： The thermal decomposition of perovskite films on ZnO surfaces is generally believed to originate from specific surface states of ZnO and the impact from the lattice mismatch between ZnO and perovskite films on this process has long been ignored. In this research, the role of lattice mismatch in the thermal degradation process of cesium-containing perovskite films on Al doped ZnO (AZO) is studied. A Ba(OH)2 buffer layer on the surface of AZO is employed to release the lattice mismatch and suppress the thermal degradation of perovskite films resulted from ZnO. Consequently, perovskite films with enhanced thermal stability and crystalline properties are obtained. Meanwhile, the Ba(OH)2 films efficiently passivate the surface trap states and reduce the vacuum level of the AZO surfaces. On this basis, electron transport layer-free perovskite solar cells yield the best efficiency of 18.18% and the thermal stability is obviously improved.
关键词： Lattice mismatch,Perovskite solar cell,Electron transport layer-free,Thermal stability
更新于2025-09-16 10:30:52
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Mixed FEM for quantum nanostructured solar cells
摘要： The gradient theory of piezoelectricity is developed for 3D analyses of QDs with the functionally graded lattice mismatch between the QD and the matrix. Governing equations in the gradient theory contain higher order derivatives than in conventional approaches. Then, it is needed to apply the C1-elements for approximation of primary ?elds in the FEM. The mixed FEM with the C0 continuous interpolation and collocation approach for kinematic constraints between strains and displacements is developed. The high-density arrays of quantum dots requires to consider various sizes for the representative volume element of the nanostructured solar cell created by the QD (InAs) and matrix (GaAs).
关键词： Gradient theory,High-density arrays of quantum dots,Mixed FEM,Functionally graded lattice mismatch
更新于2025-09-16 10:30:52
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Epitaxy || Epitaxy and Device Properties of InGaAs Photodetectors with Relatively High Lattice Mismatch
摘要： In this chapter, our works on the developments of wavelength-extended InGaAs photodetectors with cutoff wavelength >1.7 μm are reviewed. Various InGaAs/InAlAs p-i-n heterojunction structures have been grown on InP and GaAs substrates by gas source molecular beam epitaxy, some details on the InGaAs photodetector structures and the techniques of metamorphic buffer layer such as linearly, step, and one-step continuously InAlAs graded buffer, and dislocation restraint methods of compositional overshoot and digital alloy are introduced. The material characteristics and device properties were evaluated by atomic force microscopy, high-resolution X-ray diffraction and reciprocal space mapping, cross-sectional transmission electron microscopy, and current-voltage measurements, etc. The results provide clues to the development of metamorphic device structures on lattice-mismatched material systems.
关键词： photodetector,X-ray diffraction,InGaAs,metamorphic,atomic force microscopy,photoluminescence,lattice mismatch
更新于2025-09-11 14:15:04
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Nanowires for energy: A review
摘要： Semiconductor nanowires (NWs) represent a new class of materials and a shift from conventional two-dimensional bulk thin films to three-dimensional devices. Unlike thin film technology, lattice mismatch strain in NWs can be relaxed elastically at the NW free surface without dislocations. This capability can be used to grow unique heterostructures and to grow III-V NWs directly on inexpensive substrates, such as Si, rather than lattice-matched but more expensive III-V substrates. This capability, along with other unique properties (quantum confinement and light trapping), makes NWs of great interest for next generation optoelectronic devices with improved performance, new functionalities, and reduced cost. One of the many applications of NWs includes energy conversion. This review will outline applications of NWs in photovoltaics, thermoelectrics, and betavoltaics (direct conversion of solar, thermal, and nuclear energy, respectively, into electrical energy) with an emphasis on III-V materials. By transitioning away from bulk semiconductor thin films or wafers, high efficiency photovoltaic cells comprised of III-V NWs grown on Si would improve performance and take advantage of cheaper materials, larger wafer sizes, and improved economies of scale associated with the mature Si industry. The thermoelectric effect enables a conversion of heat into electrical power via the Seebeck effect. NWs present an opportunity to increase the figure of merit (ZT) of thermoelectric devices by decreasing the thermal conductivity (j) due to surface phonon backscattering from the NW surface boundaries. Quantum confinement in sufficiently thin NWs can also increase the Seebeck coefficient by modification of the electronic density of states. Prospects for III-V NWs in thermoelectric devices, including solar thermoelectric generators, are discussed. Finally, betavoltaics refers to the direct generation of electrical power in a semiconductor from a radioactive source. This betavoltaic process is similar to photovoltaics in which photon energy is converted to electrical energy. In betavoltaics, however, energetic electrons (beta particles) are used instead of photons to create electron-hole pairs in the semiconductor by impact ionization. NWs offer the opportunity for improved beta capture efficiency by almost completely surrounding the radioisotope with semiconductor material. Improving the efficiency is important in betavoltaic design because of the high cost of materials and manufacturing, regulatory restrictions on the amount of radioactive material used, and the enabling of new applications with higher power requirements.
关键词： photovoltaics,light trapping,nanowires,quantum confinement,thermoelectrics,lattice mismatch,betavoltaics,III-V materials,semiconductor,energy conversion
更新于2025-09-09 09:28:46