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Ion Exchange/Insertion Reactions for Fabrication of Efficient Methylammonium Tin Iodide Perovskite Solar Cells
摘要： The low toxicity, narrow bandgaps, and high charge-carrier mobilities make tin perovskites the most promising light absorbers for low-cost perovskite solar cells (PSCs). However, the development of the Sn-based PSCs is seriously hampered by the critical issues of poor stability and low power conversion efficiency (PCE) due to the facile oxidation of Sn2+ to Sn4+ and poor film formability of the perovskite films. Herein, a synthetic strategy is developed for the fabrication of methylammonium tin iodide (MASnI3) film via ion exchange/insertion reactions between solid-state SnF2 and gaseous methylammonium iodide. In this way, the nucleation and crystallization of MASnI3 can be well controlled, and a highly uniform pinhole-free MASnI3 perovskite film is obtained. More importantly, the detrimental oxidation can be effectively suppressed in the resulting MASnI3 film due to the presence of a large amount of remaining SnF2. This high-quality perovskite film enables the realization of a PCE of 7.78%, which is among the highest values reported for the MASnI3-based solar cells. Moreover, the MASnI3 solar cells exhibit high reproducibility and good stability. This method provides new opportunities for the fabrication of low-cost and lead-free tin-based halide perovskite solar cells.
关键词： ion exchange/insertion reaction,solar cells,crystal growth,lead-free perovskites
更新于2025-09-23 15:19:57
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Non-isothermal <i>?2</i> grain growth behaviour of pure titanium under laser quenching
摘要： The primary understanding of laser-induced non-isothermal prior β grain growth behaviour of titanium alloys is given by adopting laser quenching on pure titanium. Results indicate that the prior β grains grow obviously within the limited laser interaction time. By establishing a finite element model combined with numerical approximations, the growth activation energy of prior β grain under laser-induced non-isothermal condition is determined as 44.4 kJ/mol, which is comparable to that under isothermal conditions. Grain boundary migration behaviour of pure titanium under laser-induced non-isothermal conditions is the same as that under isothermal conditions, but the prior β grain growth kinetics is largely accelerated due to the high heat input from the laser beam.
关键词： non-isothermal,Laser processing,pure titanium,crystal growth
更新于2025-09-23 15:19:57
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Effect of relative humidity during the preparation of perovskite solar cells: Performance and stability
摘要： Humidity is one of the main environmental factors that limits performance and stability of perovskite solar cells (PSC); it plays a critical role during the preparation of the perovskite film, influencing the crystal growth. In this work, it is investigated the effect of the relative humidity (RH) and type of atmosphere (nitrogen vs air) used during the deposition of both perovskite layer and hole extraction layer (HEL). While humidity and oxygen seem not to affect the HEL deposition step, the perovskite layer is notoriously influenced by the RH and by the presence of oxygen during its deposition. Until 10% of RH, the performance of devices prepared with a triple-cation perovskite layer deposited under a nitrogen environment was mostly unaffected, whilst for devices deposited in air that limit is lower. On the other hand, for high RH values (above 30%), devices prepared with a triple-cation perovskite layer deposited under N2 presented slightly better stability over time than the ones prepared under air. The best-performing device was prepared with a triple-cation perovskite layer deposited under dry air, presenting a power conversion efficiency of 16.7%. These results are of critical value when designing a plant for fabricating PSC showing that the perovskite layer may be deposited under a simple dry air atmosphere (RH < 1%).
关键词： Stability,Perovskite solar cells,Relative humidity effect,Crystal growth,Energy conversion
更新于2025-09-23 15:19:57
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Linear-nonlinear optical, dielectric and surface microscopic investigation of KH2PO4 crystal to uncover the decisive impact of dopant glycine
摘要： Present investigation has been started to perform the comparative study of pure and glycine doped KH2PO4 (KDP) single crystals grown by most commercial slow solvent evaporation technique. The grown crystals were subjected to single crystal X-ray diffraction analysis to determine their structural parameters. The linear optical studies of pure and glycine doped KDP crystal have been undertaken within 200 nm to 1100 nm wavelength range by means of UV-Vis studies. The enhancement in second harmonic generation (SHG) ef?ciency of glycine doped KDP crystal has been determined using a standard Kurtz-Perry powder test. The dielectric measurements have been carried out to explore the impact of glycine dopant on dielectric constant and dielectric loss of KDP crystal. The surface growth habitat and etch pit density of glycine doped KDP crystal have been evaluated using the results of microscopic etching studies. In light of obtained results the suitability of glycine doped KDP crystal for device applications has been discussed.
关键词： optical studies,etching studies,crystal growth,dielectric studies,nonlinear optical materials
更新于2025-09-23 15:19:57
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Pushing Boundaries: High Pressure, Supercritical Optical Floating Zone Materials Discovery
摘要： In this perspective review, we provide the rationale for utilizing supercritical fluids for solid state materials discovery in the context of recent advances in the field of high pressure synthesis. We discuss the importance of the transition from gas-like to solvent-like environments in which materials synthesis and crystallization is occurring, the appropriate conceptual frameworks for its impact on synthesis and directional solidification, and dispel popular myths. We provide an overview of materials that have been grown in single crystal form by the high pressure optical floating zone technique, report the first successful stable molten zone in an optical furnace at P = 300 bar, and show viability of the traveling solvent method even with high fluid pressures. Further, we report on some unexpected observations found in the highly dynamic synthesis environment of supercritical fluids, enabled by the ability to observe, in real time, materials behavior. Finally, we offer a perspective on the scientific domains opened by these new capabilities.
关键词： Single crystal growth,Materials discovery,Optical floating zone,High pressure synthesis,Supercritical fluids
更新于2025-09-23 15:19:57
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Two Novel Heteropolyniobates Using TeO <sub/>3</sub><sup>2–</sup> as Template and Linker
摘要： By adopting di?erent crystal growth methods, two novel organic?inorganic hybrids, [{Cu(phen)}6(H2O)(Te5Nb15.5Cu0.5O57)]3.5? and its dimer, have been successfully synthesized. These are fabricated by simple compound reactions and directed by the tellurite anions, which act as heteroanion templates and linkers, as well as a pendant ligand. The compounds were characterized by IR spectra, UV/vis, thermogravimetric analysis, and single crystal X-ray di?raction. Furthermore, the solution behavior was also investigated.
关键词： organic?inorganic hybrids,polyoxoniobate clusters,crystal growth methods,tellurite anions,heteropolyniobates
更新于2025-09-23 15:19:57
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Facile Synthesis and Characterization of Uniform PbS Nanorods
摘要： This work reports a facile solution route for the synthesis of uniform PbS nanorods in high yield by the reaction of lead acetate trihydrate (Pb(CH3COO)2·3H2O) and thioacetamide (TAA) with the assistance of surfactant cetyltrimethylammonium bromide (CTAB). The morphology, structure and optical properties of the products were characterized by means of X-ray powder diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis-NIR absorption spectroscopy and photoluminescence (PL) spectroscopy. It was found that the nanorods have a diameter of 36 nm and a length of 110 nm and show good UV-Vis-NIR absorption and PL emission properties. Moreover, a possible growth mechanism of formation PbS nanorods was proposed.
关键词： Chemical Synthesis,Crystal Growth,PbS Nanorods,Nanostructured Materials
更新于2025-09-19 17:15:36
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Growth, Thermal and Spectroscopic Studies of Bis-thiourea Nickel Barium Chloride Single Crystals
摘要： Bis-thiourea nickel barium chloride was synthesized and crystals were grown by slow aqueous solvent evaporation technique. The powder XRD analysis of grown crystal was suggested to have orthorhombic crystal structure. The unit cell parameters of grown crystal as: a = 9.70 ?, b = 10.68 ? and c = 17.95 ?. The contents of nickel and barium in the grown crystals was analyzed using EDAX. The presence of various functional groups was confirmed by FTIR spectroscopy studies. From the UV-visible spectrum, the material has about 90 % optical transparency in the entire visible region. From the thermogravimetric analysis, it was found that the crystals remained stable up to 170 oC. The endothermic reactions were identified from the differential thermal analysis.
关键词： Crystal growth,Slow evaporation technique,Bis-thiourea nickel barium chloride,Powder X-ray diffraction
更新于2025-09-19 17:15:36
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New Understanding of Crystal Control and Facet Selectivity of Titanium Dioxide Ruling Photocatalytic Performance
摘要： Engineering crystals of titanium dioxide (TiO2) to expose with the most reactive facet has been proved to significantly improve the photocatalytic performance. While most of TiO2 with facets reported in the past were in a particle form, herein we directly grow TiO2 with arbitrarily tunable facets onto the transparent conductive substrate. This could reduce interparticle boundaries, and thus suppress charge recombination and facilitate more efficient charge transport compared to particle-assembled films. Combined systematic experimental and theoretical (Density Function Theory, DFT) studies reveal that fluoride ions (F-) and protons (H+) could play a synergistic role in controlling TiO2 crystals in the way that F- ions change the crystal phase of TiO2 to anatase with low-indexed facets, while H+ ions increase of {001}/{101} ratio. Moreover, the reductive and oxidative sites of facets are clearly elucidated by a selective photodeposition of noble metal and metal oxide. Different photocatalytic tests manifested that {001} facet, which is conventionally believed as the highest reactive facet, does not always show highest performance. On the other hand, the facets reactivity appeared to depend on the types of reactions (reduction or oxidation) and the co-existing synergy of facets. These findings would clarify the ambiguous understanding about the true factors controlling facets, the true order of reactivity of each facet that has still been controversial, and pave a way to improve both efficiency and selectivity of TiO2 in a wide variety of photocatalytic applications in the future.
关键词： Facet Control,CO2 Photoreduction,TiO2,Crystal Growth,PEC Water Splitting
更新于2025-09-19 17:15:36
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Composition, structure and morphology of ZnOa??Co3O4 ceramic targets in the process of pulsed laser thin film deposition
摘要： This paper presents the results of the study of the composition, structure and morphology of ZnO–Co3O4 ceramic targets before and after laser ablation by the KrF excimer laser. X-ray diffraction analysis showed that the composition of the targets changes under the thermal effects of laser radiation: a new phase of CoO of the cubic structure is formed (a = 4.25 ?). The radial distribution of elements in the ZnO–Co3O4 targets after ablation by the KrF excimer laser was discovered for the first time. The atomic concentration of cobalt in the center was determined to be several times higher than its concentration at the edge of the targets. This can be explained by the thermal model of laser-semiconductor interaction. The morphology of the targets surface after the laser ablation was discovered to undergo significant changes. Pulsed nanosecond laser radiation induces the formation of center-oriented cone-shaped structures and micro-whiskers on the target surface. It was determined that the higher is the concentration of doping impurities in the target, the greater is the number of structures observed on the surface. The formation of “cones” and microwhiskers is explained by the generalized growth model of the vapor–liquid–crystal mechanism.
关键词： A1. Growth models,A2. Bulk crystal growth,A1. Characterization,A3. Physical vapor deposition processes,B2. Semiconducting II-VI materials,A1. Crystal structure
更新于2025-09-19 17:13:59