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Feburary 27, 2019
A self-powered high-performance photodetector based on MoS2/GaAs heterojunction with a high polarization sensitivity. ( Journal of Materials Chemistry C )
The rich variety and unique optoelectrical properties of two-dimensional (2D) layered nanomaterials allow researchers to design various photodetectors working at different wavelengths. In this study, a self-powered broadband photodetector was fabricated by constructing a heterojunction from a 2D MoS2 film and bulk GaAs. The MoS2/GaAs heterojunction photodetector demonstrated a wide response spectrum from deep ultraviolet (DUV) to near-infrared (NIR) with a high responsivity of 35.2 mA W−1, a high specific detectivity of 1.96 × 1013 Jones and a fast response speed of 3.4/15.6 μs at zero bias. Further investigation reveals that the MoS2/GaAs heterojunction photodetector shows high polarization sensitivity to a polarized optical signal with a peak-to-valley ratio of 4.8. Such high-performance and high polarization sensitivity of the MoS2/GaAs heterojunction photodetector indicate that it has great potential for photodetection in a complex environment.
February 13, 2019
Fully sp2-carbon conjugated two-dimensional covalent organic frameworks as artificial photosystem I with unprecedented efficiency. ( Angewandte Chemie )
The synthesis of fully conjugated sp2‐carbon covalent organic frameworks (COF) is extremely challenging given the difficulty of the formation of very stable carbon‐carbon double bonds (‐C=C‐). Here, we report the successful preparation of a 2D COF (TP‐COF) based on triazine as central planar units bridged by sp2‐carbon linkers through the ‐C=C‐ condensation reaction. High‐resolution‐transmission electron microscopy (HRTEM) clearly confirmed the tessellated hexagonal pore structure with a pore center‐to‐center distance of 2 nm. Powder X‐ray diffraction (PXRD) together with structural simulations revealed an AA stacking mode of the obtained layered structure. TP‐COF turned out to be an excellent semiconductor material with a LUMO energy of −3.23 eV and a band gap of 2.36 eV. Excitingly, this novel sp2‐carbon conjugated TP‐COF exhibited unprecedented coenzyme regeneration efficiency and can significantly boost the coenzyme‐assisted synthesis of l‐glutamate to a record‐breaking 97 % yield within 12 minutes.