RESUMEN
Novel Ag-based thin film solar cells have attracted extensive attention in recent years in the photovoltaic (PV) field due to their outstanding properties like a high light absorption coefficient, low toxicity, abundance, and an appropriate band gap. The emerging Ag-based thin film materials such as Ag2S, AgBiS2, Ag3CuS2, AgInS2, AgBiSe2, Ag2ZnSnS4, Ag(In1-x,Gax)Se2, AgaBibIc, Cs2AgBiBr6, and Cu2AgBiI6 are becoming ideal materials for light absorbing layers in the new generation of PV devices. Although the efficiency of ATFSCs has improved significantly in recent years, it is much lower than those of other PV devices. The relatively low efficiency of ATFSCs is mainly caused by structural defects such as poor crystallinity, voids, and instability which occur during the preparation of light absorbing layers. This paper defines the concept and classification of Ag-based materials and introduces in detail a thin film preparation method by overcoming structural defects. Finally, the vision of achieving high-efficiency ATFSCs by improving structural defects is proposed.
RESUMEN
To safely and reliably use aluminum nitride (AlN) helices in the fabrication of novel micro/nanodevices, it is very important to know their mechanical properties. Herein, we investigate the mechanical properties of individual AlN helices using an in situ tensile-bending test. Tensile tests reveal that an AlN helix has an average ε of â¼4.7 ± 0.8% elastic deformation before a typical brittle fracture occurs. The bending test shows a two-step mechanical feature-linear-elastic followed by an elastic-plastic process-with an average ε bent of â¼54.5 ± 0.6%. Our results provide direct cognition about the mechanical properties of AlN helices and their benefit to the design of AlN-based flexible micro/nanodevices.
RESUMEN
A new sesquiterpene coumarin, bungeanin A (1), together with four known sesquiterpene coumarins, were isolated from the whole plants of Ferula bungeana Kitagawa. The structure of bungeanin A was elucidated by analysis of its spectroscopic data, including UV, IR, HR-ESI-MS, and extensive 1D and 2D NMR spectroscopy.
RESUMEN
Objective: To establish a high-performance liquid chromatographic method (HPLC) for the simultaneous determination of 16 compounds from Artemisia ordosica. Methods: HPLC was used to analyze 16 quality indicators of A. ordosica. The HPLC conditions were as follows: Agilent Eclipse Plus C18 column (250 mm × 4.6 mm, 5 µm) with acetonitrile (A)-water (B) as mobile phase, gradient elution: 0-10 min, 75%-65% B; 10-30 min, 65%-35% B; and finally 30-40 min, 35%-15% B. The flow rate was 1.0 mL/min, the column temperature was 40 °C, the injection volume was 10 µL, and monitored by absorbance at 285 nm for compounds 1-10, 12 and 225 nm for compounds 11, 13-16. Results: Under the selected experimental chromatographic conditions, compounds 1-16 showed good linearity (r > 0.9993) in a wide concentration range. Their average recoveries were 99.50%, 95.38%, 97.75%, 96.00%, 98.20%, 97.50%, 95.50%, 99.33%, 96.75%, 96.50%, 98.50%, 97.83%, 99.20%, 95.33%, 97.33% and 96.30%, respectively, and the RSD were 1.99%, 1.81%, 1.63%, 1.98%, 1.67%, 1.92%, 1.74%, 1.67%, 1.90%, 1.72%, 1.88%, 1.83%, 1.79%, 1.76%, 1.81% and 1.96%, respectively. Conclusion: Based on the results of the HPLC analysis, it was concluded that p-hydroxycinnamic acid (1), O-hydroxycinnamic acid (2), coniferyl alcohol (5), 5,4'-dihydroxy-7,3'-dimethoxyflavanone (8), 5,4'-dihydroxy-7-methoxyflavanone (9), 5-hydroxy-7,4'-dimethoxyflavanone (12), dehydrofalcarindiol (13), arteordoyn A (14), dehydrofalcarinol (15) and capillarin (16) are best suited for the role of quality indicators of A. ordosica grown in different ecological environments.
RESUMEN
A main concern of the promising DMF-based Cu2 ZnSn(Sx ,Se1- x )4 (CZTSSe) solar cells lies in the absence of a large-grain spanning structure, which is a key factor for high open-circuit voltage (Voc ) and power conversion efficiency (PCE). A new strategy to achieve CZTSSe large-grain spanning monolayer is proposed, by taking advantage of the synergistic optimization with a Cu2+ plus Sn2+ redox system and pre-annealing temperatures. A series of structural, morphological, electrical, and photoelectric characterizations are employed to study the effects of the pre-annealing temperatures on absorber qualities, and an optimized temperature of 430 â is determined. The growth mechanism of the large-grain spanning monolayer and the effect of redox reaction rate are carefully investigated. Three types of absorber growth mechanisms and a concept of critical temperature are proposed. The devices based on this large-grain spanning monolayer suppress the recombination of carriers at crystal boundaries and interfaces. The champion device exhibits a high Voc (>500 mV) and PCE of 11.76%, which are both the maximum values among DMF-based solar cells at the current stage.
RESUMEN
By understanding the growth mechanism of nanomaterials, the morphological features of nanostructures can be rationally controlled, thereby achieving the desired physical properties for specific applications. Herein, the growth habits of aluminum nitride (AlN) nanostructures and single crystals synthesized by an ultrahigh-temperature, catalyst-free, physical vapor transport process were investigated by transmission electron microscopy. The detailed structural characterizations strongly suggested that the growth of AlN nanostructures including AlN nanowires and nanohelixes follow a sequential and periodic rotation in the growth direction, which is independent of the size and shape of the material. Based on these experimental observations, an helical growth mechanism that may originate from the coeffect of the polar-surface and dislocation-driven growth is proposed, which offers a new insight into the related growth kinetics of low-dimensional AlN structures and will enable the rational design and synthesis of novel AlN nanostructures. Further, with the increase of temperature, the growth process of AlN grains followed the helical growth model.