- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Highly Efficient Copper-Rich Chalcopyrite Solar Cells from DMF Molecular Solution
摘要： Theoretical calculation suggests Cu-rich chalcopyrite absorbers contain less defects and have potential to achieve better performance than Cu-poor absorbers. However, this has not been demonstrated due to the detrimental Cu2-xSe impurity remaining in the absorber. Here, we report highly efficient Cu-rich chalcopyrite solar cells by selenizing dimethylformamide molecular precursor solution processed precursor films under high Ar pressure. Characterizations using XRD, Raman, SEM, TEM, c-AFM, PL, and glow discharge optical emission spectroscopy (GDOES) show high pressure selenization enables high quality Cu-rich chalcopyrite absorber materials with stoichiometric composition, smooth surface, high conductivity, and Cu2-xSe free grain boundaries, leading to efficient CuIn(S,Se)2 and Cu(In,Ga)(S,Se)2 devices with power conversion efficiency of 14.5% and 15.2%, both are the best performing chalcopyrite solar cells from non-hydrazine solutions. Our results demonstrate high Ar pressure selenization is a new strategy to fabricate high quality Cu-rich absorber which has great potential to further improve chalcopyrite solar cell efficiency.
关键词： Cu-rich,chalcopyrite,selenization,CIGS,DMF,high pressure
更新于2025-09-12 10:27:22
-
Tunable self‐powered n‐SrTiO <sub/>3</sub> photodetectors based on varying CuS‐ZnS nanocomposite film (p‐CuZnS, p‐CuS, and n‐ZnS)
摘要： Dense Boron-doped diamond (BDD) composites were fabricated by high pressure and high-temperature sintering (HPHT) at 5 GPa and 1450 °C for 300 s in presence of Al, B and C as sintering additives. Phase compositions, microstructures, and electrochemical performances of sintered specimens were investigated by X-ray di?raction (XRD), scanning electron microscopy (SEM), and electrochemistry. Results suggested that Al3BC3 and Al4C were formed by in-situ reaction between sintering additives and diamond, which can promote densi?cation of BDD. In addition, BDD composites containing 10 wt% sintering additives exhibited the highest electrical resistivity (4.40 × 10?4 Ω m) and hole concentration (4.55 × 1025/m3). The working potential windows of BDD composite electrodes in 0.1 M H2SO4, 0.1 M Na2SO4 and 0.1 M NaOH electrolytes were estimated to 1.9 V, 2.9 V and 2.3 V, respectively. Electron transfer coe?cients of composite electrodes approached 0.5, con?rming good reversibility. Finally, methylene blue was completely degraded by BDD composite electrodes within 120 min using NaCl as supporting electrolyte.
关键词： High-pressure and high-temperature sintering,Boron-doped diamond,Electrochemical performances
更新于2025-09-11 14:15:04
-
OH planar laser-induced fluorescence measurement for H<sub>2</sub>/O<sub>2</sub> jet diffusion flames in rocket combustion condition up to 7.0 MPa
摘要： This study focuses on the application of OH planar laser-induced fluorescence (OH-PLIF) in high-pressure rocket combustion conditions, up to 7.0 MPa. The signal to noise ratio of PLIF degrades in high-pressure combustion owing to effects such as line broadening and interference from intense chemiluminescence. The OH(2,0) band excitation method was applied to obtain the OH(2,1) fluorescence emitted near 290 nm and filter out the intense OH(0,0) band chemiluminescence emitted near 308 nm. The gaseous H2/O2 (GH2/GO2) jet diffusion flame was formed using a recessed coaxial shear injector. The GH2/GO2 injection Reynolds number, Re (ReH2/ReO2 ≈ 2320/22800–4660/45600), was varied to examine the variation of the flame structure and reaction zone thickness under each pressure condition Pc, and Re injection condition. In addition, the variation of the experimentally derived full width at half maximum (FWHM) of the radial OH distribution, ?OH, with the Damk?ehler number, Da, was compared with that of the simulated FWHM of the OH mole fraction, ?OH-SIM. The OH distribution was clearly observed in the instantaneous PLIF image while eliminating the intense OH chemiluminescence even in the highest pressure condition of 7.0 MPa, which is a pressure higher than any of the previous OH-PLIF studies conducted on rocket combustion. The flame structure showed the typical characteristics of a turbulent jet diffusion flame and depended on Re rather than on the chamber pressure Pc. The variation of ?OH with Da corresponded qualitatively with ?OH-SIM and showed the characteristics of flame stretch in the vicinity of the injector.
关键词： Jet diffusion flame,High-pressure combustion,Laser-induced fluorescence,Chemiluminescence,OH(2,0) band excitation
更新于2025-09-11 14:15:04
-
Effect of High Pressure in the Luminescence of Pr <sup>3+</sup> Doped Ge <sub/>2</sub> O- PbO Glass Containing Au Nanoparticles
摘要： In this paper it was investigated the combined effect of gold nanoparticles and high-pressure densification on the luminescence of Pr3+ doped heavy metal GeO2-PbO photonic glass. Localized states related to ion-trapped exciton defects, S1 and S2, were observed at 342 and 412 nm before densification. After densification under 7.7 GPa the structure of the glass host changed irreversibly, as indicated by the infrared spectrum, refractive index and density measurements. TEM analyses indicated that the high-pressure densification induced the formation of clusters of gold nanoparticles. The modifications observed in the absorption and luminescence spectra of Pr3+ ions in the VIS-NIR range were associated to the changes in the local field surrounding the Pr3+ ions in the host glass induced by high-pressure. For excitation at 445 nm (luminescence from 3P2) and 593 nm (luminescence from 1D2), the combined effect of densification and gold nanoparticles induced an increase in the emission band at 1050 cm-1. For excitation at 488 nm (luminescence from 3P0), the combined effect resulted in a strong decrease in the emission intensities in the VIS, revealing the emergence of non-radiative processes in resonance with 3P0 state. The observed behavior was probably due to energy transfer, ion trapped exciton defects and cross-relaxation processes among the Pr3+ ions and gold nanoparticles.
关键词： cross-relaxation processes,gold nanoparticles,Pr3+ doped,high-pressure densification,energy transfer,GeO2-PbO glass,luminescence
更新于2025-09-11 14:15:04
-
Comparison of HPHT and LPHT annealing of Ib synthetic diamond
摘要： Defect transformations in type Ib synthetic diamond annealed at a temperature of 1870 °C under stabilizing pressure (HPHT annealing) and in hydrogen atmosphere at normal pressure (LPHT annealing) are compared. Spectroscopic data obtained on the samples before and after annealing prove that the processes of nitrogen aggregation and formation of nitrogen-nickel complexes are similar in both cases. Essential differences between HPHT and LPHT annealing are stronger graphitization at macroscopic imperfections and enhanced lattice distortions around point defects in the latter case. The lattice distortion around point defects is revealed as a considerable broadening of zero-phonon lines of "soft" (vacancy-related) optical centers. It was found that LPHT annealing may enhance overall intensity of luminescence of HPHT-grown synthetic diamonds.
关键词： nitrogen aggregation,graphitization,low pressure high temperature annealing,synthetic type Ib diamond,spectral broadening,high pressure high temperature annealing
更新于2025-09-10 09:29:36
-
Spectroscopic properties and martensitic phase transition of Y4Al2O9:Ce single crystals under high pressure
摘要： High pressure studies of monoclinic yttrium aluminum oxide single crystals (Y4Al2O9 -YAM) doped with Ce3+ ions grown by micro-pulling-down method are reported. The results of absorption measurements in the mid-infrared prove the existence of four different sites in which Ce3+ ions substitute Y ions, in accordance with the crystallographic structure of YAM. The lowest 5d level of Ce3+ is located very close to the bottom of the conduction band for two of four Ce3+ related centers at ambient pressure, which results in strong temperature quenching of their luminescence. Two other Ce3+ centers do not emit at ambient pressure since their 5d levels are resonant with the conduction band. Application of high pressure above 11 GPa restores their luminescence. Consequences of such energy structure of various Ce3+ sites in YAM for the Dorenbos theory are discussed. The bandgap energy of YAM is found to be 5.93 eV, which is the smallest out of the three yttrium aluminum oxides. High-pressure synchrotron angle dispersive x-ray diffraction and Raman scattering measurements identify a phase transition occurring at pressures between 8 and 11 GPa, which has martensitic character. The second phase transition to another structure (likely with hexagonal symmetry) occurs at a pressure around 16 GPa.
关键词： high pressure,phase transition,X-ray diffraction,luminescence,single crystal
更新于2025-09-10 09:29:36
-
Two-dimensional Dy doped MoS2 ferromagnetic sheets
摘要： Magnetic two-dimensional materials have attracted immense consideration as spintronic devices. However, design and synthesis of the magnetic two-dimensional MoS2 crystals with more controllable electronic structure and better conductivity are still great challenges. Here, we make a breakthrough to synthesize the MoS2:Dy sheets with robust adjustable room-temperature ferromagnetic properties by a gas-liquid chemical deposition method. The as-synthesized samples are characterized by XRD, Raman, TEM, HRTEM and XPS. Furthermore, the magnetic properties of the samples are also investigated by VSM and Squid. The maximum observed saturation magnetization is 0.023 emu/g. The origin of ferromagnetism in the samples is investigated by using the ?rst-principles calculations based on the density functional theory. The ferromagnetism is mainly related to the exchange interactions among the S 3p, Mo 4d and Dy 5d orbits. The results indicate that the transformation of the localized charges can e?ectively engineer and manipulate the magnetic properties of 2D materials, making MoS2 a potential candidate for spintronics and electronic applications and providing a new perspective on other 2D layered materials in spintronics application.
关键词： High pressure,2D materials,MoS2,First principles calculations,Ferromagnetism,Dy doping
更新于2025-09-10 09:29:36
-
High-Pressure Synthesis, Crystal Structure, Chemical Bonding, and Ferroelectricity of LiNbO <sub/>3</sub> -Type LiSbO <sub/>3</sub>
摘要： A polar LiNbO3 (LN)-type oxide LiSbO3 was synthesized by a high-temperature heat treatment under a pressure of 7.7 GPa and found to exhibit ferroelectricity. The crystal structural re?nement using the data of synchrotron powder X-ray di?raction and neutron di?raction and the electronic structure calculation of LN-type LiSbO3 suggest a covalent-bonding character between Sb and O. When comparing the distortion of BO6 in LN-type ABO3, the distortions of SbO6 in LiSbO3 and SnO6 in ZnSnO3, which included a B cation with a d10 electronic con?guration, were smaller than those of BO6 in LN-type oxides having the second-order Jahn?Teller active B cation, e.g., LiNbO3 and ZnTiO3. The temperature dependence of the lattice parameters, second harmonic generation, dielectric permittivity, and di?erential scanning calorimetry made it clear that a second-order ferroelectric?paraelectric phase transition occurs at a Curie temperature of Tc = 605 ± 10 K in LN-type LiSbO3. Further, ?rst-principles density functional theory calculation suggested that perovskite-type LiSbO3 is less stable than LN-type LiSbO3 under even high pressure, and the ambient phase of LiSbO3 directly transforms to LN-type LiSbO3 under high pressure. The phase stability of LN-type LiSbO3 and the polar and ferroelectric properties are rationalized by the covalent bonding of Sb?O and the relatively weak Coulomb repulsion between Li+ and Sb5+.
关键词： high-pressure synthesis,LiNbO3-type oxide,covalent bonding,ferroelectricity,second-order Jahn?Teller effect,LiSbO3
更新于2025-09-10 09:29:36
-
Novel bimetallic MOF phosphors with an imidazolium cation: structure, phonons, high- pressure phase transitions and optical response
摘要： We report the synthesis, crystal structure, phonons and luminescence properties of three novel heterometallic metal organic frameworks (MOFs) with perovskite-like topology of the following formulas: [C3H5N2]Na0.5Cr0.5(HCOO)3 (ImNaCr), [C3H5N2]Na0.5Al0.5(HCOO)3 (ImNaAl) and [C3H5N2]Na0.5Al0.475Cr0.025(HCOO)3 (ImNaAlCr with 5 mol% of Cr3+). ImNaCr crystallizes in a monoclinic system (P2/n space group) with one imidazolium cation (Im+) in an asymmetric unit forming six N–H?O and four C–H?O hydrogen bonds. In contrast to other known heterometallic MOFs, the complete substitution of Cr3+ ions with smaller Al3+ ions leads to a change of the crystal symmetry. ImNaAl adopts a monoclinic P21/n space group with two distinct Im+ cations and di?erent H-bonding patterns. The DSC measurements and XRD single-crystal studies show that the studied crystals do not undergo structural phase transitions in the 80–400 K range. The high-pressure Raman studies of ImNaCr reveal the presence of two reversible structural instabilities, ?rst in the 0.4–1.1 GPa range and second near 4 GPa. The ?rst pressure-induced phase transition involves weak distortion of the metal-formate framework, while the second one is associated with partial and reversible amorphization of the sample. We discuss the stability of heterometallic formate MOFs depending on their building blocks. The luminescence measurements show that both the fully concentrated crystal (ImNaCr) and the diluted one (ImNaAlCr) exhibit a Cr3+-based emission characteristic of intermediate ligand ?eld strength. We also show that the spectroscopic properties of heterometallic MOFs depend strongly on the templated cation, i.e. the decreasing size of the organic cation leads to an increase in the crystal ?eld.
关键词： high-pressure phase transitions,phonons,optical response,structure,imidazolium cation,bimetallic MOF phosphors
更新于2025-09-10 09:29:36
-
Growth of Structurally Perfect Diamond Single Crystals at High Pressures and Temperatures. Review
摘要： The investigations performed at high pressures and high temperatures (HTHP crystallization) have permitted clarifying the mechanism of phase transformations and carbon transport in solvent metals for diamond growth and elaborating methods for growing large-size structurally perfect diamond single crystals of types Ib, IIa, and IIb. The findings have provided the basis for the process of production of diamonds for applications in electronics, laser technology, precision machining operations, well drilling tools. The use of a large-volume six-punch high pressure apparatus makes it possible to grow diamond single crystals with a higher efficiency. It is estimated that this apparatus is capable of producing annually at least 1 mln carats of structurally perfect crystals of required types for various applications.
关键词： diamond single crystals,growth systems,temperature gradient method,high pressure apparatus
更新于2025-09-10 09:29:36