RESUMO
Large size of capacitors is the main hurdle in miniaturization of current electronic devices. Herein, a scalable solution-based layer-by-layer engineering of metallic and high-κ dielectric nanosheets into multilayer nanosheet capacitors (MNCs) with overall thickness of ≈20 nm is presented. The MNCs are built through neat tiling of 2D metallic Ru0.95 O2 0.2- and high-κ dielectric Ca2 NaNb4 O13 - nanosheets via the Langmuir-Blodgett (LB) approach at room temperature which is verified by cross-sectional high-resolution transmission electron microscopy (HRTEM). The resultant MNCs demonstrate a high capacitance of 40-52 µF cm-2 and low leakage currents down to 10-5 -10-6 A cm-2 . Such MNCs also possess complimentary in situ robust dielectric properties under high-temperature measurements up to 250 °C. Based on capacitance normalized by the thickness, the developed MNC outperforms state-of-the-art multilayer ceramic capacitors (MLCC, ≈22 µF cm-2 /5 × 104 nm) present in the market. The strategy is effective due to the advantages of facile, economical, and ambient temperature solution assembly.
RESUMO
Cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite quantum dots (QDs) have been intriguing optoelectronic materials for applications in various devices owing to their superior electronic and optical properties. However, poor resistance to humidity and light irradiation impedes their promotion. Herein, bulk perovskite-type layered CsCa2Ta3O10 is exfoliated into two-dimensional (2D) negatively charged Ca2Ta3O10- (CTO) nanosheets as seeds to in situ synthesize and composite CsPbBr3. The as-synthesized CsPbBr3/CTO nanocomposites possess improved green emission with apparently prolonged decay time with reference to bare CsPbBr3 QDs. The decay time can retrieve to a normal state when the nanocomposites are treated with some water. It is found that the CTO acts as a defect to trap the bound exciton of the loaded CsPbBr3. Protons from water can preferably replace Cs+ at the interface of the nanocomposites, resulting in the separation of the nanosheets and CsPbBr3 and retrieving the decay time. X-ray photoelectron spectroscopy results also indicate the strong interaction between CsPbBr3 and CTO with reference to the physical mixing sample of bare CsPbBr3 QDs and CTO nanosheets. The decoration of ultrathin 2D charge-bearing oxide nanosheets on the QDs benefits significant improvements in humidity resistance and photostability performance in light-emitting diode devices. This research offers a distinct strategy to modify the surface of perovskite QDs.