Single crystal reflects the intrinsic physical properties of a material, and single crystals with high-crystalline quality are highly desired for the acquisition of high-performance devices. We found that large single crystals of perovskite CH3NH3PbI3(Cl) could be grown rapidly from chlorine-containing solutions. Within 5 days, CH3NH3PbI3(Cl) single crystal as large as 20 mm × 18 mm × 6 mm was harvested. As a most important index to evaluate the crystalline quality, the full width at half-maximum (fwhm) in the high-resolution X-ray rocking curve (HR-XRC) of as-grown CH3NH3PbI3(Cl) single crystal was measured as 20 arcsec, which is far superior to so far reported CH3NH3PbI3 single crystals (∼1338 arcsec). The unparalleled crystalline quality delivered a low trap-state density of down to 7.6 × 10(8) cm(-3), high carrier mobility of 167 ± 35 cm(2) V(-1) s(-1), and long transient photovoltaic carrier lifetime of 449 ± 76 μs. The improvement in the crystalline quality, together with the rapid growth rate and excellent carrier transport property, provides state-of-the-art single crystalline hybrid perovskite materials for high-performance optoelectronic devices.

With an increasing penetration of wind power in the modern electrical grid, the increasing replacement of large conventional synchronous generators by wind power plants will potentially result in deteriorated frequency regulation performance due to the reduced system inertia and primary frequency response. A series of challenging issues arise from the aspects of power system planning, operation, control and protection. Therefore, it is valuable to develop variable speed wind turbines (VSWTs) equipped with frequency regulation capabilities that allow them to effectively participate in addressing severe frequency contingencies. This paper provides a comprehensive survey on frequency regulation methods for VSWTs. It fully describes the concepts, principles and control strategies of prevailing frequency controls of VSWTs, including future development trends. It concludes with a performance comparison of frequency regulation by the four main types of wind power plants.

Artificial synapses/neurons based on electronic/ionic hybrid devices have attracted wide attention for brain-inspired neuromorphic systems since it is possible to overcome the von Neumann bottleneck of the neuromorphic computing paradigm. Here, we report a novel photoneuromorphic device based on printed photogating single-walled carbon nanotube (SWCNT) thin film transistors (TFTs) using lightly n-doped Si as the gate electrode. The drain currents of the printed SWCNT TFTs can gradually increase to over 3000 times of their starting value after being pulsed with light stimulation, and the electrical signals can maintain for over 10 min. These characteristics are similar to the learning and memory functions of brain-inspired neuromorphic systems. The working mechanism of the light-stimulated neuromorphic devices is investigated and described here in detail. Important synaptic characteristics, such as low-pass filtering characteristics and nonvolatile memory ability, are successfully emulated in the printed light-stimulated artificial synapses. It demonstrates that the printed SWCNT TFT photoneuromorphic devices can act as the nonvolatile memory units and perform photoneuromorphic computing, which exhibits potential for future neuromorphic system applications.

Electronic Supplementary Informa on (ESI) available: additional XRD spectra, polarization curves, Tafel plots and electrolyte resistance of catalysts prepared in this work, overall XPS spectra, nitrogen adsorption-desorption isotherm and EIS spectra of V-Co-Fe-343, List of relative parameters for oxygen evolution reaction. See Hydrogen (H2) generated from water splitting is deemed as the ideal replacement for conventional sources of energy. Catalysts play a valuable role in water splitting, especially the oxygen evolution reaction (OER). Here, we report a Fe-doped Co3V2O8 nanoparticle catalyst ( iron-rich V-Co-Fe), which possesses outstanding OER catalytic activity with ƞj = 10 mA cm -2 = 307 mV, and a low Tafel slope of 36 mV dec -1 , benefiting by large degree of amorphization, rich porous structure as well as high specific surface area (about 232.1 m 2 g -1 ). And, more remarkable, the catalytic performance of the V-Co-Fe catalyst is markedly superior to commercial ruthenium oxide. In addition, the durability of the V-Co-Fe catalyst is fine. The current density collapses by less than 3 percent at 1.55V vs. RHE after 11 h, in comparison with the initial value. Moreover, this work reveals that the V-Co-Fe catalyst displays an excellent performance in both OER catalytic activity and stability, which may have the potential to be the ideal substitute of noble metal-based catalysts for water splitting to obtain affordable clean energy.