RESUMO
Perovskite nanocrystals have excellent optical properties but suffer from environmental instability and production up-scaling which limit their commercial application. Here, we report the gram-scale ultrasound-mediated synthesis of silane passivated CsPbBr3 nanocrystals using (3-aminopropyl) triethoxysilane (APTS) as the primary surface ligand surface. The surface engineering endowed the CsPbBr3@SiOR NCs with extended environmental stability, a narrow emission bandwidth and a high photoluminescence quantum yield (PLQY > 75%). Thanks to these excellent optical properties, high-efficiency lateral and vertical photodetectors were fabricated. In particular, the layered vertical photodiode composed of ITO/Ga2O3/CsPbBr3/Au exhibited a broadband photoresponse from 350-700 nm with a responsivity peaking at 44.5.1 A W-1 and specific detectivity above 1013 Jones when illuminated at 470 nm wavelength and biased at +5 V. These results correspond to the best-in-class performance perovskite nanocrystal PD and confirm the extraordinary potential of CsPbBr3@SiOR for the development of efficient optoelectronic devices.
RESUMO
Self-healing materials inspire the next generation of multifunctional wearables and Internet of Things appliances. They expand the realm of thin film fabrication, enabling seamless conformational coverage irrespective of the shape complexity and surface geometry for electronic skins, smart textiles, soft robotics, and energy storage devices. Within this context, the layer-by-layer (LbL) technique is versatile for homogeneously dispersing materials onto various matrices. Moreover, it provides molecular level thickness control and coverage on practically any surface, with poly(ethylenimine) (PEI) and poly(acrylic acid) (PAA) being the most used materials primarily employed in self-healing LbL structures operating at room temperature. However, achieving thin film composites displaying controlled conductivity and healing ability is still challenging under ambient conditions. Here, PEI and PAA are mixed with conductive fillers (gold nanorods, poly(3,4-ethylene dioxythiophene): polystyrenesulfonate (PEDOT:PSS), reduced graphene oxides, and multiwalled carbon nanotubes) in distinct LbL film architectures. Electrical (AC and DC), optical (Raman spectroscopy), and mechanical (nanoindentation) measurements are used for characterizing composite structures and properties. A delicate balance among electrical, mechanical, and structural characteristics must be accomplished for a controlled design of conductive self-healing composites. As a proof-of-concept, four LbL composites were chosen as sensing units in the first reported self-healing e-tongue. The sensor can easily distinguish basic tastes at low molar concentrations and differentiate trace levels of glucose in artificial sweat. The formed nanostructures enable smart coverages that have unique features for solving current technological challenges.
RESUMO
Heavy metals are toxic especially when they are introduced into the environment due to anthropogenic activities such as metallurgy, mining, and tanning. Removing these pollutants has become a worldwide concern since they cannot be degraded into nontoxic forms causing extended effects in the ecosystems. The use of an Aspergillus australensis was evaluated in order to remove Cu2+ from simulated wastewater. The fungus was isolated from river sludges contaminated with heavy metals and was first evaluated for the determination of Cu2+ tolerance levels. Microscopic fluorescence analysis was carried out to determine the effect of Cu2+ presence on the viability, cellular components, polyhydroxyalkanoates production, and oxidative stress of the fungus, as a response to the stress caused by exposure to metal. In order to achieve copper removal, the A. australensis biomass was produced using batch cultures, and the mycelium was immobilized on a textile media in order to compare the copper-removal efficiency of live or dead biomass. The optimal values of pH and temperature for biomass production were established by using a surface response analysis. Live immobilized biomass was capable of removing Cu2+ from 1.54 ± 0.19 to 2.66 ± 0.26 mg of copper/ g of dry biomass, while values of 1.93 ± 0.03 to 2.36 ± 0.29 mg of copper/g of dry biomass were observed when dead biomass was used. As was expected, copper removal using biomass varied depending on the pH and temperature used.