- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Consecutive Interfacial Transformation of Cesium Lead Halide Nanocubes to Ultrathin Nanowires with Improved Stability
摘要： Although all-inorganic CsPbX3 (X=Cl, Br, I) nanocrystals (NCs) have been considered as a promising material for photoelectronic devices, their applications are still limited because of their poor stability and the lack of in-depth understanding. Here, we demonstrate a post-treatment method for the preparation of ultrathin CsPbX3 nanowires (NWs) by treating CsPbBr3 nanocubes with thiourea solution. A systematic study showed a consecutively interfacial transformation process, in which CsPbBr3 nanocubes were first converted to Cs4PbBr6 NCs in the presence of thiourea, followed by a further transformation to CsPbBr3 NCs through an interfacial CsX-stripping process. To reduce the surface energy, an oriented attachment process has been realized and CsPbBr3 NCs aggregated to form ultrathin NWs. The ultrathin CsPbBr3 NWs exhibited high photoluminescence quantum yield (PLQY, up to 60%) and high resistance to water treatment, which can be attributed to the surface passivation by thiourea. In addition to thiourea, cysteine and thioacetamide that contain thiol group can also be used to trigger this transformation. This work can not only offer a facile method for the synthesis of efficient and stable ultrathin CsPbBr3 NWs, but also help to reveal the in-depth mechanisms which may be very useful in the field of metal halide perovskite NCs.
关键词： ultrathin nanowires,oriented attachment,Cs4PbBr6,CsPbBr3,thiourea
更新于2025-09-23 15:23:52
-
Microstructure characteristics of non-monodisperse quantum dots: On the potential of transmission electron microscopy combined with X-ray diffraction
摘要： Although the concept of quantum confinement was introduced more than thirty years ago, a wide application of the quantum dots is still limited by the fact that monodisperse quantum dots with controlled optoelectronic properties are typically synthesized on a relatively small scale. Larger scale synthesis techniques are usually not able to produce monodisperse nanoparticles yet. In this contribution, we illustrate the capability of the combination of transmission electron microscopy and X-ray diffraction to reveal detailed and scale-bridging information about the complex microstructure of non-monodisperse quantum dots, which is the first step towards a further upscalling of the techniques for production of quantum dots with controlled properties. As a model system, CdSe quantum dots synthesized using an automated robotic hot-injection method at different temperatures were chosen. The combined microstructure analytics revealed the size and shape of the CdSe nanocrystals and the kind, density and arrangement of planar defects. The role of the planar defects in the particle coarsening by oriented attachment and the effect of the planar fault arrangement on the phase constitution, on the crystallographic coherence of the counterparts and on the optoelectronic properties are discussed.
关键词： microstructure,optoelectronic properties,planar defects,transmission electron microscopy,X-ray diffraction,quantum dots,oriented attachment,CdSe
更新于2025-09-23 15:21:01
-
Synthesis of Highly-Oriented Black CsPbI <sub/>3</sub> Microstructures for High-Performance Solar Cells
摘要： Synthesis of a thin layer of perovskite with less pinholes and defects is vital for the construction of a high-performance perovskite solar cell (PSC). We report on an oriented attachment strategy to fabricate a black phase CsPbI3 highly-oriented quasi-single-crystalline microstructures film for constructing a mesoporous PSC device with enhanced power conversion efficiency, from 13.4% to 16.0%. The theoretical calculations and detailed in/ex situ characterizations demonstrate that the oriented attachment is driven by the predominant adsorption of dimethyl sulfoxide (DMSO) on the {212} facets of the yellow phase δ-CsPbI3 crystals which initially form a relatively oriented structure followed by phase transition to α-CsPbI3 crystals and merging into large highly-oriented quasi-single-crystalline microstructures film with {200} planes exposed under annealing. Our work demonstrates that the oriented attachment strategy enables the formation of highly-oriented quasi-single-crystalline perovskite microstructures films which are essential for realizing high-efficiency and stable thin film PSCs.
关键词： oriented attachment,DMSO,CsPbI3,perovskite solar cells,high-performance
更新于2025-09-23 15:21:01
-
Microwave-Assisted Synthesis and Assembly of Hyperbranched supra Quantum Dot CdE (E = S, Se, Te) Nanocrystals
摘要： Dichalcogenides are alternatives for synthesis of nano metalchalcogenides which provides a variety of precursors with different reactivities. Using disulfide, diselenide and ditelluride and their mixtures, metalchalcogenide nanocrystals (NCs) in which structures vary from spherical NCs with diameters of ~4 nm to large, hyperbranched NCs with diameters approaching 200 nm are synthesized. Study of the effects of the reaction temperature, concentration and ratio of reactants shows that hyperbranched supra quantum dots (HSQDs) form in three steps: nucleation, aggregation and kinetically-controlled growth. By tuning the concentration of precursors and reaction temperature, both aggregation and growth can be modulated and tetrapod NCs with arms of tunable length and thickness can be prepared. The more reactive precursor forms small NCs which work as a platform for formation of the arms from the less reactive precursor, providing controlled growth on the more reactive facets. By controlling the precursor ratio, the composition of the HSQDs can be controlled.
关键词： dichalcogenides,Microwave synthesis,asymmetric nanocrystals,oriented attachment
更新于2025-09-11 14:15:04
-
[SpringerBriefs in Materials] Anisotropic Metal Chalcogenide Nanomaterials (Synthesis, Assembly, and Applications) || Synthesis and Assembly
摘要： The synthetic protocol for anisotropic MC nanocrystals has been developed based on accumulation of a largely empirical recipe, followed by inductive conclusion. Afterwards, the initial parameters are optimized to obtain the targeted nanostructures. The systematic synthetic effort is repeated and devised to inter-relate each parameter with a rational design of novel and complex MC through nanostructures. Normally, thermodynamically-controlled growth reflects the inherent symmetry of the crystal structure, hence 3D nanocrystals are readily obtained. Synthesis of nanocrystals that do not have any preferential growth direction requires purposeful shape-guiding. Reduction of the surface energy of a certain facet is a powerful way to obtain anisotropic MCs, which can be achieved by selectively attaching organic surfactants or using the organic templates as the shape-determining reactor. The MC nanocrystals can then be merged to form 1D or 2D nanostructures. Such oriented attachment can be tailored by engineering the interaction between the nanocrystals. Chemical transformation of pre-existing anisotropic nanocrystals into others has recently received a lot of interest because it allows preparation of nanocrystals that are chemically different but have the same shape and dimensions.
关键词： anisotropic MC nanocrystals,oriented attachment,shape-guiding,chemical transformation,synthetic protocol
更新于2025-09-04 15:30:14