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High C-rate capability at 10C is a key performance indicator for the commercialization of the next-generation high-charging lithium microbattery. However, silicon (Si) anode satisfying the prerequisite high specific capacity suffers from poor electron/ionic conductivity, seriously limiting the 10C rate capability. Accordingly, we propose the strategy of inserting highly conductive silver nanoparticles (AgNPs) as an interlayer between two RF-sputtered amorphous Si thin films to form an Si/Ag/Si multilayered anode, with the density and spatial distribution of the AgNPs well-controlled by thermal evaporation. This strategy is exclusively beneficial to scale up film thickness for higher capacity. Without AgNPs, the 10C rate performance of the double-layer Si (D_Si) is worse than the single layer (S_Si) in the same total thickness, suggesting the adverse effect of the interface. However, this situation is progressively improved with the AgNPs density incorporated at the interface, where the densest AgNPs anode (D_SiAg3) demonstrated a noticeable improvement reaching 1250 mAh/g at 10 C with a 46% capacity retention rate. By scaling up to triple layers, T_SiAg3 performed the superior 10C rate capability to T_Si, testifying to the scalable potential of the unique design for boosting high-power batteries. Finally, with electrochemical impedance spectroscopy results, a possible mechanism to explain the enhancement in rate capability is subject to where Li-ion diffusion is accelerated by the charge-induced electric field condensing around the AgNPs. This design for a multilayered nanocomposite can contribute to the design and fabrication of high-charging batteries and battery-on-chip.

We report on a high-brightness ultraviolet (UV) nanoscale light source. The light emission diodes are constructed with graphene/ZnO nanowire/p-GaN vertical junctions, which exhibit strong UV electroluminescence (EL) emissions centered at a wavelength of 397 nm at one end of the ZnO nanowire. Compared to the horizontal heterojunction, the vertical junction based on the ZnO nanowire increases the interface area of the heterojunction along with a high-quality interface, thus making the device robust under a large excitation current. In this structure, transparent flexible graphene is used as the top electrode, which can effectively improve performance by increasing the carrier injection area. Moreover, by analyzing the relationship between the integrated light intensity and applied bias, a superlinear dependency with a slope of 3.99 is observed, which means high electrical-to-optical conversion efficiency. Three electron-hole irradiation recombination processes are distinguished according to the EL emission spectra., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Since the invention of triboelectric nanogenerators (TENGs), their output performance has been improved through various approaches such as material surface modification, device structure optimization, and so on, but rarely through the development of new friction materials. In this work, a magnetron sputtered Mg x Zn 1- x O film is developed as a viable friction material that rubs against polydimethylsiloxane in a TENG. The work function, measured by Kelvin probe microscopy, of the Mg x Zn 1- x O films can be effectively tuned by varying Mg composition, x, and exposed surface facets, which are shown to dominate the charge-transfer behavior. In addition, film thickness also plays an important role, affecting the output performance. The output voltage and total charge of a TENG with a Mg x Zn 1- x O film are demonstrated to be tremendously enhanced by 55 and 90 times, respectively, compared to that of a TENG with a ZnO film. Even more intriguingly, the tribo-output polarity can be reversed by adjusting the relative work function through varying the preferred growth orientation of the Mg x Zn 1- x O film, for a given value of Mg content.

Ultrathin three-dimensional topological insulator films are promising for use in field effect devices. (Bi 1-x Sb x ) 2 Se 3 ultrathin films were fabricated on SrTiO 3 substrate, where large resistance changes of ∼25 000% could be achieved using the back gate voltage. We suggest that the large ON/OFF ratio was caused by the combined effect of Sb-doping and the reduction of film thickness down to the ultrathin regime. The crossover of different quantum transport under an electric field may form the basis for topological insulators (TI)-based spin transistors with large ON/OFF ratios in the future.

We studied the dependence of the output of the piezoelectric nanogenerator (NG) on the inclining orientation of the ZnO nanowire arrays (NWAs). The oblique-aligned NWAs were grown by combing a modified oblique-angle sputtering technique for preparing the seed layer and hydrothermal growth. The piezoelectric output of the NWAs was studied by scanning the tip of an atomic force microscope along four different directions in reference to the inclining direction of the NWs. The statistical outputs were analyzed in reference to the theoretically calculated piezopotential distribution in the NWs. Our study provides in-depth understanding about the performance of NGs., (© 2011 American Chemical Society)

A multi-source/component spray coating process to fabricate the photoactive layers in polymer solar cells is demonstrated. Well-defined domains consisting of polymer:fullerene heterojunctions are constructed in ambient conditions using an alternating spray deposition method. This approach preserves the integrity of the layer morphology while forming an interpenetrating donor (D)/acceptor (A) network to facilitate charge transport. The formation of multi-component films without the prerequisite of a common solvent overcomes the limitations in conventional solution processes for polymer solar cells and enables us to process a wide spectrum of materials. Polymer solar cells based on poly(3-hexylthiophene):[6,6]-phenyl C(61) butyric acid methyl ester spray-coated using this alternating deposition method deliver a power conversion efficiency of 2.8%, which is comparable to their blend solution counterparts. More importantly, this approach offers the versatility to independently select the optimal solvents for the donor and acceptor materials that will deliver well-ordered nanodomains. This method also allows the direct stacking of multiple photoactive polymers with controllable absorption in a tandem structure even without an interconnecting junction layer. The introduction of multiple photoactive materials through multisource/component spray coating offers structural flexibility and tenability of the photoresponse for future polymer solar cell applications.

Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.