The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

Cesium lead halide (CsPbX 3 , X = Cl, Br, I) nanocrystals (NCs) offer exceptional optical properties for several potential applications but their implementation is hindered by a low chemical and structural stability and limited processability. In the present work, we developed a new method to efficiently coat CsPbX 3 NCs, which resulted in their increased chemical and optical stability as well as processability. The method is based on the incorporation of poly(maleic anhydride-alt-1-octadecene) (PMA) into the synthesis of the perovskite NCs. The presence of PMA in the ligand shell stabilizes the NCs by tightening the ligand binding, limiting in this way the NC surface interaction with the surrounding media. We further show that these NCs can be embedded in self-standing silicone/glass plates as down-conversion filters for the fabrication of monochromatic green and white light emitting diodes (LEDs) with narrow bandwidths and appealing color characteristics.

3D crystals assembled entirely from DNA provide a route to design materials on a molecular level and to arrange guest particles in predefined lattices. This requires design schemes that provide high rigidity and sufficiently large open guest space. A DNA-origami-based "tensegrity triangle" structure that assembles into a 3D rhombohedral crystalline lattice with an open structure in which 90% of the volume is empty space is presented here. Site-specific placement of gold nanoparticles within the lattice demonstrates that these crystals are spacious enough to efficiently host 20 nm particles in a cavity size of 1.83 × 10 nm , which would also suffice to accommodate ribosome-sized macromolecules. The accurate assembly of the DNA origami lattice itself, as well as the precise incorporation of gold particles, is validated by electron microscopy and small-angle X-ray scattering experiments. The results show that it is possible to create DNA building blocks that assemble into lattices with customized geometry. Site-specific hosting of nano objects in the optically transparent DNA lattice sets the stage for metamaterial and structural biology applications.

Understanding the interactions between photoexcited charge carriers (electrons and holes) with lattice vibrations (phonons) in quantum confined semiconductor nanocrystals (NCs) is of fundamental interest and a prerequisite for their use in fabricating high-performance optoelectronic devices. Such interactions have a significant impact on their optoelectronic properties including their charge carrier mobility and photoluminescence. Here, we investigate these interactions in cesium lead halide (CsPbX 3 , where X is Cl, Br or I) NC perovskites. We show that a wide broadening of the excitonic linewidth in these NCs arises from strong exciton-phonon coupling, which is substantially dominated by longitudinal optical phonons via the Fröhlich interaction. Unlike the behavior of conventional semiconductors these NCs display a general red-shift of their emission energy peak with reducing temperature. Interestingly, the CsPbCl 3 NCs also display an initial blue-shift and undergo at structural phase transition at ~175 K to 200 K. The anomalous red-shift observed is modeled and analyzed using a Bose-Einstein two-oscillator model to interpret the interaction of excitons with acoustic and optical phonons which induce a renormalization of the bandgap. The net renormalization due to zero point motion (T= 0 K) was found to be ~41.6 meV and ~94.9 meV for CsPbBr 3 and CsPbI 3 NCs respectively.

Improving the stability of DNAo rigami structures with respect to thermal, chemical, and mechanical demands will be essential to fully explore the real-life applicability of DNAn anotechnology.H ere we present as trategy to increase the mechanical resilience of individual DNAo rigami objects and 3D DNAorigami crystals in solution as well as in the dry state.Byencapsulating DNAorigami in aprotective silica shell using sol-gel chemistry,all the objects maintain their structural integrity.T his allowed for ad etailed structural analysis of the crystals in ad ry state,t hereby revealing their true 3D shape without lattice deformation and drying-induced collapse. Analysis by energy-dispersive X-ray spectroscopys howed au niform silica coating whose thickness could be controlled through the precursor concentrations and reaction time.T his strategy thus facilitates shape-controlled bottom-up synthesis of designable biomimetic silica structures through transcription from DNAo rigami.