Hongling Lv

Controlled growth and photoconductive properties of hexagonal SnS2 nanoflakes with mesa-shaped atomic steps

We demonstrated the controlled growth of two-dimensional (2D) hexagonal tin disulfide (SnS2) nanoflakes with stacked monolayer atomic steps. The morphology was similar to flat-topped and step-sided mesa plateaus or step pyramids. The SnS2 nanoflakes were grown on mica substrates via an atmospheric-pressure chemical vapor deposition process using tin monosulfide and sulfur powder as precursors. Atomic force microscopy (AFM), electron microscopy, and Raman characterizations were performed to investigate the structural features, and a sequential layer-wise epitaxial growth mechanism was revealed. In addition, systematic Raman characterizations were performed on individual SnS2 nanoflakes with a wide range of thicknesses (1–100 nm), indicating that the A1g peak intensity and Raman shifts were closely related to the thickness of the SnS2 nanoflakes. Moreover, photoconductive AFM was performed on the monolayer-stepped SnS2 nanoflakes, revealing that the flat surface and the edges of the SnS2 atomic steps had different electrical conductive properties and photoconductive behaviors. This is ascribed to the dangling bonds and defects at the atomic step edges, which caused a height difference of the Schottky barriers formed at the interfaces between the PtIr-coated AFM tip and the step edges or the flat surface of the SnS2 nanoflakes. The 2D SnS2 crystals with regular monolayer atomic steps and fast photoresponsivity are promising for novel applications in photodetectors and integrated optoelectronic circuits.

Correction to “All-Inorganic Perovskite Solar Cells”

Figure 3. (a) J−V plot of CsPbBr3/carbon-based all-inorganic PSCs. The inset shows the corresponding photovoltaic parameters. (b) Statistical histogram of the PCEs of 40 individual CsPbBr3/ carbon-based all-inorganic PSCs. (c) Normalized PCEs of CsPbBr3/ carbon-based all-inorganic PSCs and MAPbI3/carbon-based and MAPbI3/spiro-MeOTAD-based hybrid PSCs as a function of storage time in humid air (90−95% RH, 25 °C) without encapsulation. (d) Normalized PCEs of CsPbBr3/carbon-based all-inorganic PSCs and MAPbI3/carbon-based hybrid PSCs as a function of time heated at high temperature (100 °C) in a high-humidity ambient environment (90−95% RH, 25 °C) without encapsulation. (e) Normalized PCEs of CsPbBr3/carbon-based all-inorganic PSCs vs storage time during temperature cycles (between −22 and 100 °C) in a high-humidity ambient environment (90−95% RH, 25 °C) without encapsulation. Figure 4. (a) J−V plots of an all-inorganic PSC with a large active area of 1.0 cm measured in the forward and reverse scanning modes. (b) IPCE spectrum and integrated current density of the PSC in (a). Addition/Correction

High-Performance Li–Se Batteries Enabled by Selenium Storage in Bottom-Up Synthesized Nitrogen-Doped Carbon Scaffolds

Selenium (Se) has great promise to serve as cathode material for rechargeable batteries because of its good conductivity and high theoretical volumetric energy density comparable to sulfur. Herein, we report the preparation of mesoporous nitrogen-doped carbon scaffolds (NCSs) to restrain selenium for advanced lithium-selenium (Li-Se) batteries. The NCSs synthesized by a bottom-up solution-phase method have graphene-like laminar structure and well-distributed mesopores. The unique architecture of NCSs can severe as conductive framework for encapsulating selenium and polyselenides, and provide sufficient pathways to facilitate ion transport. Furthermore, the laminar and porous NCSs can effectively buffer the volume variation during charge/discharge processes. The integrated composite of Se-NCSs has a high Se content and can ensure the complete electrochemical reactions of Se and Li species. When used for Li-Se batteries, the cathodes based on Se-NCSs exhibit high capacity, remarkable cyclability, and excellent rate performance.