RESUMEN
This work reports in situ (active) electrochemical control over the coupling strength between semiconducting nanoplatelets and a plasmonic cavity. We found that by applying a reductive bias to an Al nanoparticle lattice working electrode the number of CdSe nanoplatelet emitters that can couple to the cavity is decreased. Strong coupling can be reversibly recovered by discharging the lattice at oxidative potentials relative to the conduction band edge reduction potential of the emitters. By correlating the number of electrons added or removed with the measured coupling strength, we identified that loss and recovery of strong coupling are likely hindered by side processes that trap and/or inhibit electrons from populating the nanoplatelet conduction band. These findings demonstrate tunable, external control of strong coupling and offer prospects to tune selectivity in chemical reactions.
RESUMEN
Semiconductor nanocrystals (NCs) can function as efficient gain materials with chemical versatility because of their surface ligands. Because the properties of NCs in solution are sensitive to ligand-environment interactions, local chemical changes can result in changes in the optical response. However, amplification of the optical response is technically challenging because of colloidal instability at NC concentrations needed for sufficient gain to overcome losses. This paper demonstrates liquid lasing from plasmonic lattice cavities integrated with ligand-engineered CdZnS/ZnS NCs dispersed in toluene and water. By taking advantage of calcium ion-induced aggregation of NCs in aqueous solutions, we show how lasing threshold can be used as a transduction signal for ion detection. Our work highlights how NC solutions and plasmonic lattices with open cavity architectures can serve as a biosensing platform for lab-on-chip devices.
RESUMEN
With increasing applications for voltage-controlled magnetism, the need to more fully understand magnetoelectric coupling and strain transfer in nanostructured multiferroic composites has also increased. Here, multiferroic nanocomposites were synthesized using block copolymer templating to create mesoporous cobalt ferrite (CFO), followed by partly filling the pores with ferroelectric zirconium-substituted hafnia (HZO) using atomic layer deposition (ALD) to produce a porous multiferroic composite with enhanced mechanical flexibility. Upon electrical poling of the nanocomposite, we observed large changes in the magnetization. These changes partly relaxed upon removing the electric field, suggesting a strain-mediated mechanism. Both the anisotropic strain transfer from HZO to CFO and the strain relaxation after the field was removed were confirmed using high-resolution X-ray diffraction measurements collected during in-situ poling. The in-situ observation of both anisotropic strain transfer and large magnetization changes allows us to directly characterize the strong multiferroic coupling that can occur in flexible, nanostructured composites.
RESUMEN
Volumetric three-dimensional displays offer spatially accurate representations of images with a 360° view, but have been difficult to implement due to complex fabrication requirements. Herein, a chemically enabled volumetric 3D digital light photoactivatable dye display (3D Light PAD) is reported. The operating principle relies on photoactivatable dyes that become reversibly fluorescent upon illumination with ultraviolet light. Proper tuning of kinetics and emission wavelengths enables the generation of a spatial pattern of fluorescent emission at the intersection of two structured light beams. A first-generation 3D Light PAD was fabricated using the photoactivatable dye N-phenyl spirolactam rhodamine B, a commercial picoprojector, an ultraviolet projector and a custom quartz imaging chamber. The system displays a minimum voxel size of 0.68 mm3, 200 µm resolution and good stability over repeated 'on-off' cycles. A range of high-resolution 3D images and animations can be projected, setting the foundation for widely accessible volumetric 3D displays.
