Cu2ZnSnS4纳米颗粒及其薄膜的制备与表征

采用热注入法,在油胺(OLA)中合成出Cu2ZnSnS4(CZTS)纳米颗粒,并在玻璃衬底上制备了薄膜,研究了不同合成温度对纳米颗粒生成的影响.通过X射线衍射仪、拉曼光谱仪、透射电子显微镜、扫描电子显微镜、紫外可见分光光度计对所得纳米晶材料的结构与成分、颗粒大小与形貌、光吸收谱进行了测试分析.研究结果表明:采用热注入法的最佳合成温度在260℃左右,该温度下生成的多晶CZTS纳米颗粒尺寸约10 nm,分散性良好,光学禁带宽度约1.5 eV.     

周期性前驱体的预硫化处理对Cu2ZnSnS4薄膜的影响EI北大核心CSCD

Cu2ZnSnS4薄膜具有组成元素来源丰富、吸收系数高等优点,是理想的薄膜太阳能电池吸收层材料。采用磁控溅射法沉积周期性金属叠层前驱体,再进行两步硫化处理制备出Cu2ZnSnS4薄膜,分析第一步硫化(即预硫化)对Cu2ZnSnS4薄膜特性的影响。结果表明,预硫化处理可促进前驱体的硫化反应。经过预硫化处理的Cu2ZnSnS4薄膜的结晶度优于未进行预硫化处理的Cu2ZnSnS4薄膜。当预硫化温度为350℃时,增加预硫化时间有利于硫化反应的进行,并抑制Sn元素损失,但过长的预硫化时间导致Cu2ZnSnS4薄膜中易出现二次相,影响薄膜的特性。预硫化温度350℃、预硫化时间10 min的Cu2ZnSnS4薄膜结晶度最优,薄膜组分具有贫Cu、富Zn特性,且薄膜表面无孔隙。     

A novel aqueous phase synthetic route for CuInSe2 nanocrystals

A novel aqueous phase synthetic route for CuInSe2 nanoparticles is presented. In our synthesis, the Se precursor used was Na2SeSO3 and CuI, while InCl3 were used as precursors for copper and indium, respectively. The reaction was performed in water under basic condition in the presence of thioglycolic acid (TGA). TGA has a crucial effect on the formation of CIS nanocrystals in aqueous media. With less amount of TGA compared to the optimum amount, only amorphous CIS was formed while larger amount caused the formation of Cu2-xSe crystals because TGA had a lower reactivity of In3+ to Se2- ion. The ratio of reagents used optimized the structure, while the composition and properties of the nanomaterials obtained were studied applying various techniques such as XRD, SEM, TEM, TG/DSC, and XPS.     

Cu_2ZnSnS_4薄膜的研究进展

Cu2ZnSnS4(CZTS)薄膜太阳能电池具有低成本、高效率、安全无毒等优点,是最具发展前景的太阳能电池之一,近几年来开始受到广泛关注。简要介绍了国内外几种制备Cu2ZnSnS4薄膜的方法,包括蒸发法、溅射法、脉冲激光沉积法、电化学沉积法、喷涂热解法、Sol-gel法、丝网印刷法,并阐述了这几种方法的优点及存在的问题,展望了今后CZTS薄膜的研究方向,认为通过溶剂热或热注入法制备出CZTS纳米晶体后,再通过丝网印刷法或旋涂等法制成CZTS薄膜能降低生产成本,在电池的工业化生产中具有很广阔的应用前景。     

Synthesis,characterization, and electrical property of CdTe/trioctylphosphine oxide core/shell nanowires

Thick trioctylphosphine oxide (TOPO) layers were controllably coated onto CdTe nanowires. The shell thicknesses were readily tuned by controlling the reaction temperatures in coordinating TOPO solvent or by varying amounts of TOPO in noncoordinating ODE solvent. The shells were coherent and rough if synthesized in the TOPO solvent, while the shells became very uniform and smooth if synthesized in the ODE solvent. The electrically insulating effects of TOPO shells were directly confirmed through nanodevice of individual core/shell nanowire (NW). The present scheme to overcoat TOPO around semiconductor NWs could, in principle, be exploited to be a general approach to encapsulate a variety of colloidal nanocrystals to form novel core–shell nanohybrids.     

Low-temperature noninjection approach to homogeneously-alloyed PbSe(x)S(1-x) colloidal nanocrystals for photovoltaic applications

Homogeneously alloyed PbSe(x)S(1-x) nanocrystals (NCs) with their excitonic absorption peaks in wavelength shorter than 1200 nm were developed for photovoltaic (PV) applications. Schottky-type solar cells fabricated with our PbSe?.?S?.? NCs as their active materials reached a high power conversion efficiency (PCE) of 3.44%, with an open circuit voltage (V(oc)) of 0.49 V, short circuit photocurrent (J(sc)) of 13.09 mA/cm2, and fill factor (FF) of 0.54 under Air Mass 1.5 global (AM 1.5G) irradiation of 100 mW/cm2. The syntheses of the small-sized colloidal PbSe(x)S(1-x) NCs were carried out at low temperature (60 °C) with long growth periods (such as 45 min) via a one-pot noninjection-based approach in 1-octadecene (ODE), featuring high reaction yield, high product quality, and high synthetic reproducibility. This low-temperature approach employed Pb(oleate)? as a Pb precursor and air-stable low-cost thioacetamide (TAA) as a S source instead of air-sensitive high-cost bis(trimethylsilyl)sulfide ((TMS)?S), with n-tributylphosphine selenide (TBPSe) as a Se precursor instead of n-trioctylphosphine selenide (TOPSe). The reactivity difference of TOPSe made from commercial TOP 90% and TBPSe made from commercial TBP 97% and TBP 99% was addressed with in situ observation of the temporal evolution of NC absorption and with 31P nuclear magnetic resonance (NMR). Furthermore, the addition of a strong reducing/nucleation agent diphenylphosphine (DPP) promoted the reactivity of the Pb precursor through the formation of a Pb-P complex, which is much more reactive than Pb(oleate)?. Thus, the reactivity of TBPSe was increased more than that of TAA. The larger the DPP-to-Pb feed molar ratio, the more the Pb-P complex, the higher the Se amount in the resulting homogeneously alloyed PbSe(x)S(1-x) NCs. Therefore, the use of DPP allowed reactivity match of the Se and S precursors and led to sizable nucleation at low temperature so that long growth periods became feasible. The present study brings insight into the formation mechanism of monomers, nucleation/growth of colloidal composition-tunable NCs, and materials design and synthesis for next-generation low-cost and high-efficiency solar cells.     

Synthesis of Sb2E3 (E = S, Se) nanorods with a flat cross section by a rapid hot injection method

We report herein a simple colloidal synthesis route, i.e., rapid injection of E (E = S, Se) source into a hot solvent (1-octadecence, ODE) containing antimony precursor (antimony stearate), to grow Sb2E3 nanorods. The as-prepared nanorods were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). The mechanism for growth of Sb2E3 nanorods was also clarified from the view of crystal structure-directed growth. We believe that the method present here is a more straightforward and cost-effective route to prepare Sb2E3 nanocrystals with high quality.     

Catalytic solid-phase seeding of silicon nanowires by nickel nanocrystals in organic solvents

Colloidal nickel (Ni) nanocrystals were used to direct the synthesis of crystalline silicon (Si) nanowires in an organic solvent. The reaction temperatures ranged from 400 degrees C to 520 degrees C with pressures from 14.3 to 23.4 MPa, conditions that are well above the critical point of the solvent. The Ni nanocrystals play two roles in the synthesis: (1) Ni catalyzes the decomposition of the silicon precursors, i.e., arylsilanes, alkylsilanes, and trisilane, to silicon; (2) Ni nanocrystals induce silicon crystallization through the solid-phase alloying of Si in the Ni seeds. We call this nanowire growth mechanism supercritical fluid-solid-solid (SFSS) synthesis.     

One-pot synthesis of CuFeSe2 cuboid nanoparticles

Ternary semiconducting CuFeSe₂ nanocrystals of a particular shape and size were successfully synthesized using a cost-effective and simple one-pot chemical route. X-ray powder diffraction and field emission scanning electron microscopy results indicated that the as-synthesized CuFeSe₂ comprised cuboid nanoparticles with dimensions of 50–150 nm as well as a tetragonal phase. Elemental analysis yielded an atomic ratio of Cu:Fe:Se of 1:1.06:2.17. The synthesis temperature and the solvent octadecylamine were significant in determining the structural phases and morphologies of the final products. The optimal condition for synthesizing the tetragonal CuFeSe₂ phase with cuboid nanoparticles was a reaction temperature of 200 °C for 1 h in octadecylamine solvent. A possible mechanism of the formation of ternary CuFeSe₂ nanoparticles with controllable shapes is discussed.     

A synthetic route for metal–ceramic interpenetrating phase composites

A novel synthetic route for metal–ceramic interpenetrating phase composites (IPCs) is proposed. The method excludes infiltration operations and eliminates the problem of closed pores and low wettability between ceramic and metal phase. We suggest using two-stage processing including preparation of composite powder precursors by reaction in a metal matrix and subsequent compaction of as-synthesized nanostructured powders. The appropriate choice of compaction technique allows obtaining dense nanostructured bulk IPCs. Bulk interpenetrating phase TiB₂–Cu nanocomposites were fabricated by Spark Plasma Sintering (SPS) and shock wave compaction of powder precursors.     

(Ga₁-xZnx)(N₁-xOx) nanocrystals: visible absorbers with tunable composition and absorption spectra

Bulk oxy(nitride) (Ga(1-x)Zn(x))(N(1-x)O(x)) is a promising photocatalyst for water splitting under visible illumination. To realize its solar harvesting potential, it is desirable to minimize its band gap through synthetic control of the value of x. Furthermore, improved photochemical quantum yields may be achievable with nanocrystalline forms of this material. We report the synthesis, structural, and optical characterization of nanocrystals of (Ga(1-x)Zn(x))(N(1-x)O(x)) with the values of x tunable from 0.30 to 0.87. Band gaps decreased from 2.7 to 2.2 eV over this composition range, which corresponded to a 260% increase in the fraction of solar photons that could be absorbed by the material. We achieved nanoscale morphology and compositional control by employing mixtures of ZnGa(2)O(4) and ZnO nanocrystals as synthetic precursors that could be converted to (Ga(1-x)Zn(x))(N(1-x)O(x)) under NH(3). The high quality of the resulting nanocrystals is encouraging for achieving photochemical water-splitting rates that are competitive with internal carrier recombination pathways.     

Synthesis of noble metal/carbon nanotube composites in supercritical methanol

A simple and efficient route has been employed to deposit noble metal nanoparticles (Pt, Ru, Pt-Ru, Rh, Ru-Sn) onto carbon nanotubes (CNTs) in supercritical methanol solution. In this method, the inorganic metallic salts acted as metal precursors, and methanol as solvent as well as reductant for the precursors. The as-prepared nanocomposites were structurally and morphologically characterized by X-ray diffraction spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. It was demonstrated that the CNTs were decorated by crystalline metal nanoparticles with uniform sizes and a narrow particle size distribution. The size and loading content of the nanoparticles on CNTs could be tuned by manipulating reaction parameters. Furthermore, the formation mechanism of the composites was also discussed.     

Size-tunable near-infrared PbS nanoparticles synthesized from lead carboxylate and sulfur with oleylamine as stabilizer

High quality PbS nanocrystals are synthesized reproducibly through lead stearate and sulfur stabilized by oleylamine in a non-coordinating solvent. The morphology, crystalline form and phase composition of PbS nanocrystals are examined by transmission electron microscopy (TEM), high-resolution TEM, x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). The as-synthesized PbS nanocrystals have strong absorption and photoluminescence emissions in the near-infrared region. The size of PbS nanocrystals from 5 to 13?nm can be adjusted through the optimization of the synthesis conditions. The smaller PbS nanoparticles are obtained at the lower reaction temperature, lower precursor concentration, larger oleylamine quantity and larger lead precursor/sulfur ratio. The basic oleylamine enhances the reactivity of both lead stearate precursor and sulfur precursor in the reaction.     

A simple route to synthesize size-controlled Ag(2)S core-shell nanocrystals, and their self-assembly

Silver sulfide (Ag(2)S) nanocrystals were successfully synthesized by the thermal treatment of the single source precursors, silver dialkyldithiophosphates (Ag[S(2)P(OC(n)H(2n+1))(2)]), under mild reaction conditions. The size of Ag(2)S nanocrystals with regular shape can be controlled in the range of tens of nanometers by adjusting critical parameters, such as the carbon number of the substitute alkyl, the solvent and the reaction temperature. Electron diffraction and x-ray powder diffraction confirmed the orthorhombic phase of the Ag(2)S nanocrystals. The as-prepared Ag(2)S nanocrystals have an inorganic-organic core-shell structure, in which Ag(2)S nanocrystals are the inorganic core and the organic modifiers, consisting of oleylamine and dialkyldithiophosphate, are the shell. The organic modifiers were anchored to the surface of Ag(2)S nanocores by their active groups of?-NH(2) and?-SPS-?, respectively, and their direct-alkyl chains spread to the outside. So, these as-prepared Ag(2)S nanocrystals can self-assemble to form orderly two-dimensional arrays easily, and they disperse in some non-polar solvents stably.     

Ultra-large-scale syntheses of monodisperse nanocrystals

The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technological applications. The synthesis of monodisperse nanocrystals (size variation <5%) is of key importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the colour sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals, and monodisperse magnetic nanocrystals are critical for the next-generation multi-terabit magnetic storage media. For these monodisperse nanocrystals to be used, an economical mass-production method needs to be developed. Unfortunately, however, in most syntheses reported so far, only sub-gram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe (refs 10,11) and Au (refs 12,13) have been produced using colloidal chemical synthetic procedures. In addition, monodisperse magnetic nanocrystals such as Fe (refs 14,15), Co (refs 16-18), gamma-Fe(2)O(3) (refs 19,20), and Fe(3)O(4) (refs 21,22) have been synthesized by using various synthetic methods. Here, we report on the ultra-large-scale synthesis of monodisperse nanocrystals using inexpensive and non-toxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size-sorting process. Moreover, the particle size could be controlled simply by varying the experimental conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.     

2D molecular precursor for a one-pot synthesis of semiconducting metal sulphide nanocrystals

2D molecular materials, namely, metal alkyl thiolates, have been used as a single-source precursor for the synthesis of semiconducting metal sulphide nanocrystals (NCs) by thermal decomposition. These 2D molecular precursors have all the ingredients required for metal sulphide synthesis (metal source, sulphur source and protecting ligand). In this study, we demonstrate a simple and general ‘solvothermal decomposition’ approach for the synthesis of high-quality \(\hbox {Cu}_{2}\hbox {S}\), PbS, CdS, MnS and ZnS NCs. The size of the NC can also be controlled by changing the decomposition temperature. Furthermore, the optical properties of the NCs have also been studied.     

Synthesis of single crystal metal sulfide nanowires and nanowire arrays by chemical precipitation in templates

Single crystal metal sulfide nanowires and nanowire arrays were synthesized by chemical precipitation reaction in the channels of anodic aluminum oxide templates under ambient conditions with simple inorganic salts as precursors. Aligned metal sulfide arrays were achieved by dissolving the template. This template-directed synthesis yielded well-defined nanowires of varied lengths and diameters for almost all precursors. The crystal quality of metal sulfide nanowires was concentration-dependent, high single crystal nanowires were achieved at low concentrations.     

Precursor reactivity differentiation for single-step preparation of Ag<Subscript>2</Subscript>Se@Ag<Subscript>2</Subscript>S core–shell nanocrystals with distinct absorption and emission properties enabling sensitive near-infrared photodetection

To obtain dual active near-infrared (NIR) nanomaterial with strong absorption and emission properties, we report herein a novel precursor reactivity differentiation strategy, i.e., utilizing 1-octadecene (ODE)–Se having the ability to react with Ag salts much stronger and faster than ODE–thiourea, for single-step preparation of Ag₂Se@Ag₂S nanocrystals (NCs). With this strategy, we were able to synthesize high-quality Ag₂Se@Ag₂S NCs with both excellent NIR absorption and emission properties. Particularly, these nanocrystals possess a rather strong and sharp excitonic absorption peak with a full width at half maximum less than 70 nm and a maximum fluorescence quantum yield as high as 24.3%. Their appealing optical properties and structural features were founded to be highly dependent on the Se to S precursor ratio in the reaction solutions, owing to such a ratio exerting a direct influence on the core sizes and shell thicknesses of the as-formed NCs. Taking advantage of their remarkable NIR absorption properties, self-powered photoelectrochemical-type photodetectors based on the as-prepared Ag₂Se@Ag₂S NCs were successfully fabricated, which demonstrate a much better response performance and photostability in comparison with those based on Ag₂Se NCs.     

Photoelectrochemical characterization of nanocrystalline thin-film Cu₂ZnSnS₄ photocathodes

Cu?ZnSnS? (CZTS) nanocrystals, synthesized by a hot injection solution method, have been fabricated into thin films by dip-casting onto fluorine doped tin oxide (FTO) substrates. The photoresponse of the CZTS nanocrystal films was evaluated using absorbance measurements along with photoelectrochemical methods in aqueous electrolytes. Photoelectrochemical characterization revealed a p-type photoresponse when the films were illuminated in an aqueous Eu(3+) redox electrolyte. The effects of CZTS stoichiometry, film thickness, and low-temperature annealing on the photocurrents from front and back illumination suggest that the minority carrier diffusion and recombination at the back contact (via reaction of photogenerated holes with Eu(2+) produced from photoreduction by minority carriers) are the main loss mechanisms in the cell. Low-temperature annealing resulted in significant increases in the photocurrents for films made from both Zn-rich and stoichiometric CZTS nanocrystals.     

Lattice Mismatch–Induced Formation of Copper Nanoplates with Embedded Ultrasmall Platinum or Palladium Cores for Tunable Optical Properties

Although noble metal nanocrystals have been studied extensively in the past decades, the shape-controlled synthesis of non-noble metal nanocrystals has remained challenging with limited success, which is a grand obstacle to their wide applications. Herein, a novel lattice mismatch–involved shape-control mechanism of Cu nanocrystals in a seed-mediated synthesis is reported, which can produce Cu nanoplates in high yield with tailored sizes (28–130 nm), holding great potential in optical and catalytic applications. The lattice mismatch between Cu and the seed is found effective in inducing crystallographic defects for symmetry breaking toward anisotropic nanocrystals. While a too-large lattice mismatch (11.7% for Au seeds) leads to multiple twin defects to form quasi-spherical Cu nanocrystals, an appropriately large lattice mismatch (7.7% for Pt and 6.9% for Pd seeds) successfully induces planar defects for the formation of Cu nanoplates. The size of the Cu nanoplates is customizable by controlling the concentration of the seeds, leading to tunable optical properties. A prototype of a colorimetric indicator with Cu nanoplates, potentially applicable to the safety control of foods and drugs is demonstrated. This mechanism paves a new way for the shape-controlled synthesis of Cu and other metal nanocrystals for a broad range of applications.