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Incorporating active materials into metamaterials is expected to yield exciting advancements in the unprecedented versatility of dynamically controlling optical properties, which sheds new light on the future optoelectronics. The exploration of emerging semiconductors into terahertz (THz) meta‐atoms potentially allows achieving ultrafast nanodevices driven by various applications, such as biomedical sensing/imaging, ultrawide‐band communications and security scanners. However, ultrafast optical switching of THz radiation is currently limited to a single level of tuning speed, which is a main hurdle to achieve multifunctionalities. Here, a hybrid metadevice which can realize the pump‐wavelength controlled ultrafast switching response by the functionalization of double photoactive layers is demonstrated experimentally. A whole cycle of electromagnetically induced transparency switching with a half‐recovery state changes from 0.78 ns to 8.8 ps as pump wavelength varies from near infrared to near ultraviolet regions. The observed pump‐color selective switching speed changing from nanosecond scale to picosecond scale is ascribed to the wavelength‐dependent penetration length of Ge and the contrasting defect states between noncrystalline Ge and epitaxial Si layers. It is believed that the schemes regarding pump‐color controllable ultrafast switching behavior introduced here can inspire more innovations across the field of ultrafast photonics and can boost the reconfigurable metamaterial applications., All‐optical terahertz modulators with pump‐color selective ultrafast switching speed are realized by combining double layers of semiconductors with electromagnetically induced transparency meta‐atoms. The transmission/group delay of terahertz wave is modulated at contrasting switching speeds from sub‐nanoseconds to picoseconds when pumped by the near‐infrared and near‐ultraviolet beams. This work opens up new avenues for manipulating the dynamics of ultrafast metaphotonic devices.

This report presents an efficient synthesis of D6 -clenproperol and D6 -cimaterol with 99.5% and 99.7% isotopic abundance in acceptable yields and excellent chemical purities with deuterium isopropylamine as labelled precursor. Their structures and the isotope-abundance were confirmed by proton nuclear magnetic resonance and liquid chromatography-mass spectrometry.

Three stable and simple synthetic routes of labeled D9 -Mabuterol, D9 -Bambuterol, and D9 -Cimbuterol were described with 98.5%, 99.7%, and 98.4% isotopic abundance and good purity. These structures and isotope-abundance were confirmed according to 1 H NMR and liquid chromatography-tandem mass spectrometry.

Two new D-A type polymers PBDSe-DPP and PBDSe-ID were synthesized to explore new ideal semiconducting polymers, by conjugating acceptor unit diketopyrrolopyrrole/isoindigo to a donor unit benzo[1,2-b:4,5-b′]diselenophene, which is designed by substituting the sulfur atom with a selenium atom in the benzo[1,2-b:4,5-b′]dithiophene. The thermal, optical, electrochemical, photoelectric and photovoltaic properties of the two polymers were studied systematically. Relatively high open circuit voltage (0.7 and 0.75 V) and fill factor (>65%) were demonstrated for both polymers. Huge increase (by 64% and 120%) of the short circuit current density was achieved for both polymer based devices by using additive compared to the corresponding reference without additive, resulting in decent power conversion efficiency of 3.7% and 2.5% respectively with only simple optimizing consideration. We believe this class of BDSe polymer possesses a good potential to be alternatives of active material for photovoltaic applications.

Using first-principles calculations, we investigate the mechanical and electronic properties of phosphorene nanosheets under tensile strains. It is found that phosphorene possesses a prominent anisotropic elasticity with the large anisotropic factor of 15.5. Along the armchair direction, the phosphorene sheet exhibits a high tensile ductility, characterized by a large elastic strain limit of 0.31. While in the zigzag direction, the critical strain of phosphorene is dictated by the phonon instability and the in-plane soft mode occurs beyond the 0.22 strain. Under uniaxial strains, the band gaps of phosphorene can be modulated continuously, whose band features are also altered accordingly. A Dirac-like band structure appears in phosphorene under adequate strains along the zigzag direction. More interestingly, these Dirac cones of phosphorene display evident anisotropy, which have high Fermi velocities up to (6 - 7) x 10(5) m/s along the armchair direction but drop to zero along the zigzag direction. With such a characteristic, the strained phosphorene sheet acts as an intriguing one-dimensional metal, which enables the system many potential applications in power-efficient and ultrafast nanodevices. ((c) 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)