absorption or emission of circularly polarized light is referred to as circular dichroism (CD) or circularly polarized luminescence (CPL), and leads to many practical technologies such as 3D displays, spintronics, quantum computing, drug screening, anti-counterfeiting, and photoelectric devices. [1][2][3][4][5][6] However, realizing such technologies requires the development of sources of circularly polarized light. Conventionally this involves filtering unpolarized light using an optical polarizer, the drawbacks of which include both decrease in intensity and need for additional optical elements. Current methods seek to circumvent these issues by producing direct sources of CPL, leading to device miniaturization, lower production costs, lower energy consumption, and faster data processing rates. [7] Small organic chiral fluorophores can be used for this purpose, but typically suffer from weak CPL with luminescence dissymmetry values on the order of g lum = 10 −4 to g lum = 10 −2 . [8,9] Additionally, many of these organic molecules show optical activity in the UV-range, whereas applications often require emission in the visible spectrum. One of the solutions is to couple chiral organic molecules with semiconductor nanocrystals (NCs), consequently achieving direct CPL in the visible spectrum. [10] Doing so, it is possible to achieve much stronger chiroptical signals. [11,12] Ligand-induced chirality has been shown to induce optical activity in semiconductor nanocrystals. [13] This involves the incorporation of chiral ligands either directly in the synthesis of colloidal nanocrystals, or through post-synthetic surface treatment. [14] This can result in new optical activity at the characteristic wavelengths corresponding to excitonic transitions of the NC, and both circular dichroism and circularly polarized luminescence can be observed. [15] However, materials showing CPL are less common than those exhibiting CD. [16] Furthermore, to produce high-performance CPL emitters through ligandinduced chirality requires both a chiral molecule compatible with the NC surface, and a NC with superior optoelectronic properties including narrow emission line width, high photoluminescence quantum yield, and a wide range of color tunability.Hybrid organic-inorganic perovskite nanocrystals meet these optoelectronic prerequisites, making them ideal candidates for Chiral halide perovskite nanocrystals have many applications in nextgeneration optoelectronic devices due to their interaction with polarized light. Through careful selection of chiral organic surface ligands, control over the circular dichroism (CD) and circularly polarized luminescence (CPL) of these materials can be achieved. However, while recent developments of CD-active perovskites have seen significant advances, effective CPL remains a challenge. Here, colloidal perovskite nanoplatelets are synthesized exhibiting room temperature CPL with dissymmetry factors up to g lum = 4.3 × 10 −3 and g abs = 8.4 × 10 −3 . Methylammonium lead bromide nanoplatelets are synthesized ...

We report the synthesis of ultrathin indium sulfide In 2 S 3 nanoribbons which display a giant aspect ratio using a simple and fast solvothermal method. They have a sub-nanometer thickness controlled at the atomic level, a width of (8.7 ± 0.1) nm, and a length which can reach several micrometers. We determine the atomic composition of the inorganic core by Rutherford backscattering spectrometry and measure by X-ray photoelectron spectrometry an oleylamine surface coverage of 2.3 ligands per nm 2 . X-ray diffraction experiments and simulations as well as high-resolution dark-field STEM point toward a P3̅ m1 trigonal crystallographic structure (γ phase). Transport measurements show that the nanoribbons display a n-type semiconductor unipolar behavior. Their lateral dimensions can be tuned by the reaction time, temperature, and by the amount of water present in the reaction medium: anhydrous synthesis conditions lead to hexagonal nanoplates, whereas the controlled addition of water induces a symmetry break yielding long rectangular nanoribbons. Depending on the dispersion solvent, these long ribbon-like nanoparticles can form either well-dispersed colloids or bundles in which they stack face-to-face. Their large aspect ratio induces the formation of gels at volume fractions as low as 1.3 × 10 −4 making them supergelators. The kinetics of gelation is strongly accelerated by an increase in the relative humidity of the ambient atmosphere.

A novel nanoparticle‐polymer composite is proposed, named inverse nanocomposites in this work. First, a rigid percolating scaffold of nanoparticles is formed, which is filled with a matrix and then polymerized. Targeted for use in thin‐film applications, these mesoporous nanoparticle scaffolds are prepared by combining the sol–gel chemistry of functionalized silanes with nanoparticles in dispersions. The nanoparticle coatings have high porosity, low density, good adhesion to the substrate, and interesting non‐classical properties, such as absorbency of highly viscous fluids. The porosity, which can be adjusted by changing the composition and preparation parameters, reaches 75%. The porous scaffold can be infiltrated with various fluids, including acrylic and epoxy monomers and even highly viscous pressure‐sensitive adhesives. If the monomers are polymerized after imbibition, the inverse nanocomposite is formed, consisting of a percolating particle network surrounded by a polymeric binder. Hence, the morphology comprises an interpenetrating system of two co‐continuous phases and not merely particles dispersed in a polymeric phase, as is typical for conventionally prepared nanocomposites.