- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Wide‐Bandgap Perovskite/Gallium Arsenide Tandem Solar Cells
摘要： Gallium arsenide (GaAs) photovoltaic (PV) cells have been widely investigated due to their merits such as thin-film feasibility, flexibility, and high efficiency. To further increase their performance, a wider bandgap PV structure such as indium gallium phosphide (InGaP) has been integrated in two-terminal (2T) tandem configuration. However, it increases the overall fabrication cost, complicated tunnel-junction diode connecting subcells are inevitable, and materials are limited by lattice matching. Here, high-efficiency and stable wide-bandgap perovskite PVs having comparable bandgap to InGaP (1.8–1.9 eV) are developed, which can be stable low-cost add-on layers to further enhance the performance of GaAs PVs as tandem configurations by showing an efficiency improvement from 21.68% to 24.27% (2T configuration) and 25.19% (4T configuration). This approach is also feasible for thin-film GaAs PV, essential to reduce its fabrication cost for commercialization, with performance increasing from 21.85% to 24.32% and superior flexibility (1000 times bending) in a tandem configuration. Additionally, potential routes to over 30% stable perovskite/GaAs tandems, comparable to InGaP/GaAs with lower cost, are considered. This work can be an initial step to reach the objective of improving the usability of GaAs PV technology with enhanced performance for applications for which lightness and flexibility are crucial, without a significant additional cost increase.
关键词： gallium arsenide,phase segregation,perovskite/GaAs tandem cells,thin-film flexible tandem cells,wide-bandgap perovskites
更新于2025-09-12 10:27:22
-
Elemental micro-segregation characteristic of fiber laser welded Hastelloy C-276 sheet
摘要： The elemental micro-segregation characteristic within the weld zone for ytterbium fiber laser welded Hastelloy C-276 sheet was investigated. The analysis of segregation ratio and equilibrium distribution coefficient of elements, determined through EDS data, indicate the reduction in micro-segregation of elements compared with the previous reported literatures for laser welded Hastelloy C-276. High melting efficiency of ytterbium fiber laser, reduction in the amount of linear heat input, and high cooling rate of the mushy zone lead to the reduction in micro-segregation. The melting efficiency of ytterbium fiber laser for welding of Hastelloy C-276 of 64% is higher than that (48%) of conventional welding methods. High melting efficiency leads to the reduction in the linear heat input required for welding. Hence, in the present investigation, the same was found to substantially reduce as compared to the previous reported literature. The cooling rate from liquidus temperature to solidus temperature at the weld centerline was found to be in the order of 103 °C/s. Cellular dendritic substructure that constituted for lower micro-segregation was formed at the weld centerline.
关键词： laser welding,Hastelloy C-276 alloy,fiber laser,micro-segregation
更新于2025-09-12 10:27:22
-
Improving fusion zone microstructure inhomogeneity in dissimilar-metal welding by laser welding with oscillation
摘要： Laser processing of welding with oscillation was adopted to weld dissimilar metals of Ni-Cr-Mo and Cu-Cr-Zr so as to prevent the generation of the macroscopic segregation. Analyses of morphology, element distribution and mechanical property were carried out to investigate the effect of oscillation on dissimilar-metal welding. The results indicated that with the application of oscillation of laser, the poor mixing zone and the partial melting strengthening phases were obviously reduced, and the distribution of main constituent elements was more uniform. Due to the better effect of solid solution strengthening, the maximum increment of the tensile strength and elongation could approximately be up to 20% and 45%, respectively.
关键词： Segregation,Dissimilar-metal,Laser processing,Welding,Microstructure
更新于2025-09-12 10:27:22
-
Influence of Vanadium on the Microstructure of IN718 Alloy by Laser Cladding
摘要： A deleterious Laves phase forms in the solidi?ed structure of Inconel 718 (IN718) alloy during laser cladding. However, e?ective removal methods have not yet been identi?ed. In this study, we ?rst added the IN718 alloy cladding layers with a trace amount of vanadium (V, 0.066 wt.%). Then, we studied the solidi?cation structure of cladding layers using a confocal laser scanning microscope and scanning electron microscopy. The microstructure and Laves phase morphology were investigated. The distribution of niobium (Nb) was observed by experiment as well. We found that V is evenly distributed in dendrites and interdendritic zones. A more re?ned dendrite structure, reduced second dendrite arm spacing and lower volume fraction of Laves phase were observed in the solidi?cation structure. The results of linear energy-dispersive X-ray spectroscopy (EDS) indicate that the concentration of Nb decreases with an increasing of the distance from the Laves phase. The V-containing sample displayed a relatively slower decreasing tendency. The IN718 alloy sample was harder with the addition of V. In addition, the porosity of the sample decreased compared with the blank sample. The presented ?ndings outline a new method to inhibit the Nb segregation in IN718 alloy during laser cladding, providing reference signi?cance for improving the performance of IN718 alloy samples during actual processing.
关键词： laves phase,element segregation,vanadium,laser cladding,microstructure
更新于2025-09-11 14:15:04
-
Grain growth in strontium titanate in electric fields: the impact of space-charge on the grain-boundary mobility
摘要： The present study investigates grain growth in the perovskite oxide strontium titanate in an electric field. The seeded polycrystal technique was chosen as it provides a sensitive and controlled setup to evaluate the impact of different parameters on grain growth due to the well-defined driving force for grain growth. Current blocking electrodes were used to prevent Joule heating. The results show faster grain growth, and thus, higher grain-boundary mobility at the negative electrode. It is argued that the electric field causes point-defect redistribution, resulting in a higher oxygen vacancy concentration at the negative electrode. The local oxygen vacancy concentration is suggested to affect the space-charge potential at the grain-boundaries. A thermodynamic treatment of the grain-boundary potential at a grain-boundary without field shows that for a high oxygen vacancy concentration less space-charge and less accumulation of cationic defects to the boundary occurs. Therefore, at the negative electrode, a higher oxygen vacancy concentration results in less space-charge and less accumulation of cationic defects. The lower degree of defect accumulation requires less diffusion of segregated defects during grain-boundary migration, so that at the negative electrode faster grain growth is expected, as found in the experiments.
关键词： field assisted,segregation,defects,space-charge,grain-boundaries,grain growth
更新于2025-09-10 09:29:36
-
Comparison of ZnO buffer layers prepared by spin coating or RF magnetron sputtering for application in inverted organic solar cells
摘要： We compared the electrical, optical, structural, and morphological properties of radio-frequency (RF) magnetron-sputtered ZnO and solution-processed ZnO nanoparticle (NP) buffer layers on ITO cathodes for use in inverted polymer solar cells (IPSCs). Continuous sputtering resulted in integration of the ZnO buffer layer in the ITO cathodes, which were then used as transparent cathodes for IPSCs. Although the electrical, optical, and morphological properties as well as work function of RF-sputtered ZnO film were similar to those of solution-processed ZnO NP film, the power conversion efficiency (PCE) of IPSCs with an RF-sputtered ZnO buffer layer was much lower than that of IPSCs with a solution-processed ZnO NP buffer layer due to vertical phase segregation of the organic active layer. However, intentional bias sweeping of IPSCs with an RF-sputtered ZnO buffer layer improved performance due to diffusion of PC70BM through the PV-D4610 donor layer and formation of a suitable heterojunction structure. Based on transmission electron microscope examination and dark current-voltage curves, we suggest a possible mechanism to explain the difference in behavior of RF-sputtered ZnO and solution-processed ZnO NP buffer layers in IPSCs.
关键词： ZnO nanoparticles,Vertical phase segregation,Microstructure,Sputtered ZnO,Inverted polymer solar cells,Buffer layer
更新于2025-09-10 09:29:36
-
Ge Complementary Tunneling Field-Effect Transistors Featuring Dopant Segregated NiGe Source/Drain
摘要： Ge complementary tunneling field-effect transistors (TFETs) are fabricated with the NiGe metal source/drain (S/D) structure. The dopant segregation method is employed to form the NiGe/Ge tunneling junctions of sufficiently high Schottky barrier heights. As a result, the Ge p- and n-TFETs exhibit decent electrical properties of large ON-state current and steep sub-threshold slope (?? factor). Especially, ??d of 0.2 ??A/??m is revealed at ??g ? ??th = ??d = ±0.5 V for Ge pTFETs, with the ?? factor of 28 mV/dec at 7 K.
关键词： ON-state current,NiGe metal source/drain,Ge complementary tunneling field-effect transistors,sub-threshold slope,Schottky barrier heights,dopant segregation
更新于2025-09-10 09:29:36
-
Electronic Traps and Phase Segregation in Lead Mixed-Halide Perovskite
摘要： An understanding of the factors driving halide segregation in lead mixed-halide perovskites is required for their implementation in tandem solar cells with existing silicon technology. Here we report that the halide segregation dynamics observed in the photoluminescence from CH3NH3Pb(Br0.5I0.5)3 is strongly influenced by the atmospheric environment, and that encapsulation of films with a layer of poly(methyl methacrylate) allows for halide segregation dynamics to be fully reversible and repeatable. We further establish an empirical model directly linking the amount of halide segregation observed in the photoluminescence to the fraction of charge-carriers recombining through trap-mediated channels, and the photon flux absorbed. From such quantitative analysis we show that under pulsed illumination, the frequency of the modulation alone has no influence on the segregation dynamics. Additionally, we extrapolate that working CH3NH3Pb(Br0.5I0.5)3 perovskite cells would require a reduction of the trap-related charge-carrier recombination rate to (cid:46) 105 s?1 in order for halide segregation to be sufficiently suppressed.
关键词： photoluminescence,lead mixed-halide perovskites,halide segregation,charge-carrier dynamics,trap-mediated recombination
更新于2025-09-09 09:28:46
-
Controlling the Phase Segregation in Mixed Halide Perovskite through Nanocrystal Size
摘要： Mixed halide perovskites are one of the promising candidates in developing solar cells and LEDs, among others applications due to their tunable optical properties. Nonetheless, photoinduced phase segregation, by forming segregated Br-rich and I-rich domains, limits the overall applicability. We tracked the phase segregation with increasing crystalline sizes of CsPbBr3-xIx and their photoluminescence under continuous-wave laser irradiation (405 nm, 10 mW cm-2), and observed the occurrence of the phase segregation from the threshold size of 46 ± 7 nm. This results have an outstanding agreement with the diffusion length (45.8 nm) calculated also experimentally from the emission lifetime, segregation rates. Furthermore, through Kelvin probe forced microscopy, we confirmed the correlation between the phase segregation and the reversible halide ion migration among grain center/boundaries. These results open a way to achieve segregation-free mixed halide perovskites and improve their performances in optoelectronic devices.
关键词： nanocrystal size,photoluminescence,phase segregation,Kelvin probe force microscopy,Mixed halide perovskites
更新于2025-09-09 09:28:46
-
Visualizing Phase Segregation in Mixed-Halide Perovskite Single Crystals
摘要： Mixed organolead halide perovskites (MOHPs), CH3NH3Pb(BrxI1?x)3, have been shown to undergo phase segregation into I-rich domains under illumination, presenting a major challenge to their development in photovoltaic and light-emitting devices. Recent work suggests phase segregated domains are localized at crystal boundaries, driving investigations into the role of edge structure and the growth of larger crystals with reduced surface area. Herein, a method for growing large (30×30×1 μm) monocrystalline MAPb(BrxI1?x)3 single crystals is presented. The direct visualization of the growth of nanocluster-like I-rich domains throughout the entire crystal revealed grain boundaries are not required for this transformation. Narrowband fluorescence imaging and time-resolved spectroscopy provided new insight into the nature of phase segregated domains and the collective impact on optoelectronic properties.
关键词： perovskite,photoluminescence,lifetime,phase segregation,single crystal
更新于2025-09-09 09:28:46