- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Cation-Exchange-Derived InGaP Alloy Quantum Dots toward Blue Emissivity
摘要： In contrast to a substantial progress of heavy metal-free green and red emitters exclusively from indium phosphide (InP) quantum dots (QDs), the development of non-Cd blue QDs remains nearly unexplored. Synthesis of blue InP QDs with a bright, deep-blue emissivity is not likely viable, which is primarily associated with their intrinsic size limitation. To surmount this challenge, herein, the first synthesis of blue-emissive ternary InGaP QDs through In3+-to-Ga3+ cation exchange strategy is implemented. Pre-grown InP QDs turn out to be efficiently Ga-alloyed at a relatively low temperature of 280oC in the presence of Ga iodide (GaI3) and degree of Ga alloying is also found to be systematically adjustable by varying GaI3 amount. Such cation-exchanged InGaP cores are surface-passivated sequentially with ZnSeS inner and ZnS outer shell. As the amount of GaI3 added for cation exchange increases, the resulting double-shelled InGaP/ZnSeS/ZnS QDs produce consistent blue-shifts in photoluminescence (PL) from 475 to 465 nm, while maintaining high PL quantum yield in the range of 80?82%. Among a series of QD samples above 465 nm-emitting InGaP/ZnSeS/ZnS QDs are further employed as an emitting layer of all-solution-processed electroluminescent device. This unprecedented InGaP QD-based blue device generates maximum values of 1038 cd/m2 in luminance and 2.5% in external quantum efficiency.
关键词： InGaP alloy quantum dots,electroluminescent device,blue emissivity,cation exchange
更新于2025-09-19 17:13:59
-
Electronic doping-enabled transition from n- to p-type conductivity over Au@CdS core–shell nanocrystals toward unassisted photoelectrochemical water splitting
摘要： Here we show a novel strategy for tailoring the synergistic electrical properties of metal@semiconductor hybrid nanocrystals (HNCs) based on cation exchange-enabled electronic doping. As a demonstration, the conductive nature of Au@CdS core–shell HNCs was changed from n- to p-type by introducing Cu dopants into the CdS shell. The dependence of the conductivity type on the dopant concentration in the HNCs is disclosed by combined photoelectrochemical (PEC) studies. Moreover, a tandem PEC cell consisting of an undoped Au@CdS photoanode and a Cu-doped Au@CdS photocathode respectively modified with cocatalysts is fabricated, which displayed stable H2 and O2 evolution in unassisted PEC overall water splitting.
关键词： photoelectrochemical water splitting,electronic doping,cation exchange,metal@semiconductor hybrid nanocrystals
更新于2025-09-16 10:30:52
-
Kinetics of Cr <sup>3+</sup> to Cr <sup>4+</sup> ion valence transformations and intra-lattice cation exchange of Cr <sup>4+</sup> in Cr,Ca:YAG ceramics used as laser gain and passive Q-switching media
摘要： This paper focuses on the kinetics of Cr4+ formation in Cr,Ca:YAG ceramics prepared by solid-state reaction sintering. The kinetics of Cr4+ formation was studied by annealing of Cr,Ca:YAG ceramics in ambient air under different temperatures at different times, resulting in the transformation of Cr3+ to Cr4+. The activation energy (Ea) of Cr3+ oxidation determined by the Jander model was 2.7 ± 0.2 eV, which is in good correlation with the activation energy of innergrain oxygen diffusion in the YAG lattice. It is concluded that Cr3+ to Cr4+ transformation in YAG ceramics is limited by oxygen diffusion through the grain body. It was established that in Cr,Ca:YAG ceramics, the intralattice cation exchange, in which the Cr4+ ions exchange positions with the Al3+ ions, switching from “A” to “D” sites, is faster than Cr3+ to Cr4+ oxidation. In the temperature range of 900–1300 ○C, the reaction enthalpy of Al3+/Cr4+ ion exchange between octahedral “A” and tetrahedral “D” lattice sites is close to zero, and this exchange ratio is thermodynamically driven by entropy.
关键词： intralattice cation exchange,Cr4+:YAG ceramics,solid-state reaction sintering,oxygen diffusion,Cr3+ oxidation
更新于2025-09-16 10:30:52
-
Pink all-inorganic halide perovskite nanocrystals with adjustable characteristics: Fully reversible cation exchange, improving the stability of dopant emission and light-emitting diode application
摘要： In this work, we proposed a straightforward and effective strategy for preparing pink all-inorganic halide perovskite nanocrystal (NC) phosphors for light-emitting diode (LED) application. The pink perovskite NCs with varying Mn contents could be easily and steadily obtained via postsynthetic ion exchange at room temperature. The dependence of the size and optical properties of pink NCs on dopant content was systematically investigated. The reversible anion exchange processes of pink perovskite NCs were conducted with halide salts containing or excluding Pb. The contrasting results suggested that the irreversibility of Mn-emission was mainly affected by the fully reversible cation exchange between Pb2+ and Mn2+. The pink NCs with better stability of dopant emission and high monodispersity were successfully developed by compounding with silica. A pink LED was further made by using the pink NCs/silica composites as pink phosphors on a 395 nm InGaN LED chip. This work provides a feasible strategy for the fabrication of pink LEDs, which may have great application prospects in the field of special lighting, like neon lights and plant growth lights.
关键词： light-emitting diodes,anion exchange,perovskite nanocrystals,stability,cation exchange
更新于2025-09-12 10:27:22
-
Cation exchange synthesis of CuIn <sub/>x</sub> Ga <sub/>1?x</sub> Se <sub/>2</sub> nanowires and their implementation in photovoltaic devices
摘要： CuInxGa1(cid:1)xSe2 (CIGS) nanowires were synthesized for the ?rst time through an in situ cation exchange reaction by using CuInSe2 (CIS) nanowires as a template material and Ga-OLA complexes as the Ga source. These CIGS nanowires maintain nearly the same morphology as CIS nanowires, and the Ga/In ratio can be controlled through adjusting the concentration of Ga-OLA complexes. The characteristics of adjustable band gap and highly e?ective light-absorbances have been achieved for these CIGS nanowires. The light-absorbing layer in photovoltaic devices (PVs) can be assembled by employing CIGS nanowires as a solar-energy material for enhancing the photovoltaic response. The highest power conversion e?ciency of solar thin ?lm semiconductors is more than 20%, achieved by the Cu(InxGa1(cid:1)x)Se2 (CIGS) thin-?lm solar cells. Therefore, these CIGS nanowires have a great potential to be utilized as light absorber materials for high e?ciency single nanowire solar cells and to generate bulk heterojunction devices.
关键词： CIGS nanowires,solar cells,photovoltaic devices,light absorber materials,cation exchange
更新于2025-09-12 10:27:22
-
Cation‐Exchange Synthesis of Highly Monodisperse PbS Quantum Dots from ZnS Nanorods for Efficient Infrared Solar Cells
摘要： Infrared solar cells that utilize low-bandgap colloidal quantum dots (QDs) are promising devices to enhance the utilization of solar energy by expanding the harvested photons of common photovoltaics into the infrared region. However, the present synthesis of PbS QDs cannot produce highly efficient infrared solar cells. Here, a general synthesis is developed for low-bandgap PbS QDs (0.65–1 eV) via cation exchange from ZnS nanorods (NRs). First, ZnS NRs are converted to superlattices with segregated PbS domains within each rod. Then, sulfur precursors are released via the dissolution of the ZnS NRs during the cation exchange, which promotes size focusing of PbS QDs. PbS QDs synthesized through this new method have the advantages of high monodispersity, ease-of-size control, in situ passivation of chloride, high stability, and a “clean” surface. Infrared solar cells based on these PbS QDs with different bandgaps are fabricated, using conventional ligand exchange and device structure. All of the devices produced in this manner show excellent performance, showcasing the high quality of the PbS QDs. The highest performance of infrared solar cells is achieved using ≈0.95 eV PbS QDs, exhibiting an efficiency of 10.0% under AM 1.5 solar illumination, a perovskite-filtered efficiency of 4.2%, and a silicon-filtered efficiency of 1.1%.
关键词： PbS,quantum dots,nanorods,cation exchange,solar cells
更新于2025-09-11 14:15:04
-
Transformation of the Anion Sublattice in the Cation-Exchange Synthesis of Au <sub/>2</sub> S from Cu <sub/>2-x</sub> S Nanocrystals
摘要： Cation exchange is a versatile post-synthetic technique that has been exploited in the synthesis of metastable nanocrystals through preservation of the anion sublattice. Here we report on the mechanistic details of the synthesis of metastable Au2S via cation exchange with Cu2-xS nanocrystals. This conversion requires a transformation of the anion sublattice, from hcp in Cu2-xS to bcc Au2S accompanied by an expansion of the unit cell. The ligand environment plays a key role in the driving force of the reaction as the presence of oleylamine allows the conversion to proceed at room temperature while the addition of trioctylphosphine hinders the reaction. By employing transmission electron microscopy (TEM) on faceted nanocrystals and partial cation exchange of nanocrystals, it was demonstrated that the reaction proceeds in a highly directional manner through the pyramidal facets. Since cation exchange produces high quality nanocrystals as seen through XRD and TEM, UV-Vis and Raman spectroscopy were used to characterize the optoelectronic properties of the metastable Au2S nanocrsytals. A Tauc plot analysis revealed a band gap of 2.6 eV, while two intrinsic Raman modes were identified at 265 cm-1 and 329 cm-1. Density functional theory (DFT) calculations of structures, energy bands, optical spectra, and phonon spectra were performed and combined with the experimental data to provide additional insights into the characterization of Au2S nanocrystals.
关键词： XRD,Raman spectroscopy,UV-Vis,trioctylphosphine,nanocrystals,TEM,Cation exchange,DFT,Cu2-xS,anion sublattice transformation,Au2S,oleylamine
更新于2025-09-09 09:28:46
-
Structure-Selective Synthesis of Wurtzite and Zincblende ZnS, CdS, and CuInS <sub/>2</sub> Using Nanoparticle Cation Exchange Reactions
摘要： For polymorphic solid-state systems containing multiple distinct crystal structures of the same composition, identifying rational pathways to selectively target one particular structure is an important synthetic capability. Cation exchange reactions can transform a growing library of metal chalcogenide nanocrystals into different phases by replacing the cation sublattice, often while retaining morphology and crystal structure. However, only a few examples have been demonstrated where multiple distinct phases in a polymorphic system could be selectively accessed using nanocrystal cation exchange reactions. Here, we show that roxbyite (hexagonal) and digenite (cubic) Cu2?xS nanoparticles transform upon cation exchange with Cd2+, Zn2+, and In3+ to wurtzite (hexagonal) and zincblende (cubic) CdS, ZnS, and CuInS2, respectively. These products retain the anion and cation sublattice features programmed into the copper sulfide template, and each phase forms to the exclusion of other known crystal structures. These results significantly expand the scope of structure-selective cation exchange reactions in polymorphic systems.
关键词： zincblende,cation exchange reactions,wurtzite,ZnS,metal chalcogenide nanocrystals,CdS,polymorphic solid-state systems,CuInS2
更新于2025-09-04 15:30:14
-
Preparation of Nano-SiO2/Al2O3/ZnO-Blended PVDF Cation-Exchange Membranes with Improved Membrane Permselectivity and Oxidation Stability
摘要： Ion exchange membranes are used in practically every industry; however, most of them have defects such as low permeability and poor oxidation resistance. In this paper, cation-exchange membranes were prepared with poly (vinylidene fluoride) (PVDF) blended with nano-SiO2, nano-Al2O3 and nano-ZnO. Sulfonic acid groups were injected into the membrane prepared by styrene grafting and sulfonation. The methods used for characterizing the prepared membranes were Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and electrochemical measurements. Membrane performance, such as the ion exchange capacity (IEC), water uptake (WU), transport number, membrane permselectivity, membrane resistance, functional groups, and morphology were also evaluated. The hydrophilia, IEC, and permselectivity of cation-exchange membranes depended on the nanoparticle content of the membrane matrix. High transport property values were obtained, which increased with increasing nano-SiO2/Al2O3/ZnO weight fractions. Finally, the cation-exchange membranes prepared with 1.5% nano-SiO2, 2.0% nano-Al2O3 or 2.0% nano-ZnO all exhibited excellent membrane properties, including membrane permselectivity (PVDF/2% ZnO-g-PSSA membranes, 94.9%), IEC (PVDF/2% Al2O3-g-PSSA membranes, 2.735 mmol·g?1), and oxidation resistance (PVDF/1.5% SiO2-g-PSSA membranes, 2.33%). They can be used to separate applications in a variety of different areas, such as water treatment, electro-driven separation, heavy metal smelting, or other electrochemical processes.
关键词： cation-exchange membrane,nano-SiO2/Al2O3/ZnO,poly(vinylidene fluoride),membrane performance
更新于2025-09-04 15:30:14