Controlled Ligand-Free Growth of Free-Standing CsPbBr Perovskite Nanowires.

Metal halide perovskite nanowires are widely studied due to their unique electronic and optical characteristics, making them promising for light emitting and detection applications. We developed a ligand-free method to grow vertically aligned free-standing CsPbBr nanowires from anodized aluminum oxide nanopore substrates. Here, we investigate the growth process using microscopy with ultraviolet and visible light excitation, revealing a highly dynamic process with pronounced fluorescence at locations where high-density free-standing nanowires could be found.

Cooling-Induced Order-Disorder Phase Transition in CsPbBr Nanocrystal Superlattices.

Perovskite nanocrystal superlattices are being actively studied after reports have emerged on collective excitonic properties at cryogenic temperatures, where energetic disorder is minimized due to the frozen lattice vibrations. However, an important issue related to structural disorder of superlattices at low temperatures has received little attention to date. In this work, it is shown that CsPbBr nanocrystal superlattices undergo a reversible order-disorder transition upon cooling to 90 K.

Evidence for capture of spin-labeled ibuprofen drug molecules by lipid rafts in model membranes.

Lipid rafts are lipid-cholesterol nanostructures thought to exist in cell membranes, which are characterized by higher ordering compared to their surroundings. Ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) have a high affinity for phospholipid membranes and can alter their structure and biological properties. Here we use electron paramagnetic resonance (EPR) in its pulsed electron spin echo (ESE) version to study spin-labeled ibuprofen (ibuprofen-SL) in a raft-mimicking bilayer, which consists of an equimolar mixture of the phospholipids dioleoyl-glycero-phosphocholine (DOPC) and dipalmitoyl-glycero-phosphocholine (DPPC), with cholesterol added in various proportions.

Fate of Optical Excitons in FAPbI Nanocube Superlattices.

Understanding the nature of the photoexcitation and ultrafast charge dynamics pathways in organic halide perovskite nanocubes and their aggregation into superlattices is key for potential applications as tunable light emitters, photon-harvesting materials, and light-amplification systems. In this work, we apply two-dimensional coherent electronic spectroscopy (2DES) to track in real time the formation of near-infrared optical excitons and their ultrafast relaxation in CH(NH)PbI nanocube superlattices. Our results unveil that the coherent ultrafast dynamics is limited by the combination of the inherent short exciton decay time (≃40 fs) and the dephasing due to the coupling with selective optical phonon modes at higher temperatures.

Programmable Carbon Nanotube Networks: Controlling Optical Properties Through Orientation and Interaction.

The lattice geometry of natural materials and the structural geometry of artificial materials are crucial factors determining their physical properties. Most materials have predetermined geometries that lead to fixed physical characteristics. Here, the demonstration of a carbon nanotube network serves as an example of a system with controllable orientation achieving on-demand optical properties.