Colloidal Quasi-2D Methylammonium Lead Bromide Perovskite Nanostructures with Tunable Shape and High Chemical Stability.

Control over the lateral dimensions of colloidal nanostructures is a complex task which requires a deep understanding of the formation mechanism and reactivity in the corresponding systems. As a result, it provides a well-founded insight to the physical and chemical properties of these materials. In this work, the preparation of quasi-2D methylammonium lead bromide nanostripes and discuss the influence of some specific parameters on the morphology and stability of this material is demonstrated.

Photoexcitation of PbS nanosheets leads to highly mobile charge carriers and stable excitons.

Solution-processable two-dimensional (2D) semiconductors with chemically tunable thickness and associated tunable band gaps are highly promising materials for ultrathin optoelectronics. Here, the properties of free charge carriers and excitons in 2D PbS nanosheets of different thickness are investigated by means of optical pump-terahertz probe spectroscopy. By analyzing the frequency-dependent THz response, a large quantum yield of excitons is found.

The influence of coarticulatory and phonemic relations on individual compensatory formant production.

Previous auditory perturbation studies have shown that speakers are able to simultaneously use multiple compensatory strategies to produce a certain acoustic target. In the case of formant perturbation, these findings were obtained examining the compensatory production for low vowels /ɛ/ and /æ/. This raises some controversy as more recent research suggests that the contribution of the somatosensory feedback to the production of vowels might differ across phonemes.

Micron-Size Two-Dimensional Methylammonium Lead Halide Perovskites.

Hybrid lead halide perovskites with 2D stacking structures have recently emerged as promising materials for optoelectronic applications. We report a method for growing 2D nanosheets of hybrid lead halide perovskites (I, Br and Cl), with tunable lateral sizes ranging from 0.05 to 8 μm and a structure consisting of n stacked monolayers separated by long alkylamines, tunable from bulk down to n = 1.

In-Plane Anisotropic Faceting of Ultralarge and Thin Single-Crystalline Colloidal SnS Nanosheets.

The colloidal synthesis of large, thin two-dimensional (2D) nanosheets is fascinating but challenging, since the growth along the lateral and vertical dimensions needs to be controlled independently. In-plane anisotropy in 2D nanosheets is attracting more attention as well. We present a new synthesis for large colloidal single-crystalline SnS nanosheets with the thicknesses down to 7 nm and lateral sizes up to 8 μm.

Colloidal lead iodide nanorings.

Colloidal chemistry of nanomaterials experienced a tremendous development in the last decades. In the course of the journey 0D nanoparticles, 1D nanowires, and 2D nanosheets have been synthesized. They have in common to possess a simple topology.

Copper sulfide nanosheets with shape-tunable plasmonic properties in the NIR region.

2D copper sulfide nanocrystals are promising building blocks of plasmonic materials in the near-infrared (NIR) spectral region. We demonstrate precise shape and size control (hexagonal/triangle) of colloidal plasmonic copper sulfide (covellite) nano-prisms simply by tuning the precursor concentration without the introduction of additional ligands. The ultra-thin 2D nanocrystals possess sizes between 13 and 100 nm and triangular or hexangular shapes.

Insights into the formation mechanism of two-dimensional lead halide nanostructures.

We present a colloidal synthesis strategy for lead halide nanosheets with a thickness of far below 100 nm. Due to the layered structure and the synthesis parameters the crystals of PbI are initially composed of many polytypes. We propose a mechanism which gives insight into the chemical process of the PbI formation.

New ways to synthesize lead sulfide nanosheets-substituted alkanes direct the growth of 2D nanostructures.

Two-dimensional colloidal nanosheets represent very attractive optoelectronic materials. They combine good lateral conductivity with solution-processability and geometry-tunable electronic properties. In the case of PbS nanosheets, so far synthesis has been driven by the addition of chloroalkanes as coligands.