Hard coatings from metal boride nanocrystals ink

The invention relates to an ink composition for depositing a coating on a substrate, comprising a colloidal dispersion of metal boride nanocrystals (NCs) in a liquid medium, wherein said metal boride NCs are selected from metal hexaborides (MB6) and metal diborides (MB2), and wherein said metal boride NCs are at least partly coated with a dispersing aid, wherein said dispersing aid is a ligand comprising a boron-binding moiety and wherein said metal boride NCs are present in said ink composition in a concentration of at least 10 mg/mL

Nanoimprinted distributed feedback lasers of solution processed hybrid perovskites

Hybrid perovskite materials have considerable potential for light emitting devices such as LEDs and lasers. We combine solution processed CH3NH3PbI3 perovskite with UV nanoimprinted polymer gratings to fabricate distributed feedback (DFB) lasers. The lead acetate deposition route is shown to be an effective method for fabricating low-loss waveguides (loss coefficient ~6 cm-1) and highly compatible with the polymer grating substrates. The nanoimprinted perovskite exhibited single-mode band-edge lasing, confirmed by angle-dependent transmission measurements. Depending on the excitation pulse duration the lasing threshold shows a value of 110 μJ/cm2 under nanosecond pumping and 4 μJ/cm2 under femtosecond pumping. We demonstrate further that this laser has excellent stability with a lifetime of 10*8 pulses

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 PbI2 are initially composed of many polytypes. We propose a mechanism which gives insight into the chemical process of the PbI2 formation. Further, we found that the crystal structure changes with increasing reaction temperature or by performing the synthesis for longer time periods changing for the final 2H structure. In addition, we demonstrate a route to prepare nanosheets of lead bromide as well as lead chloride in a similar way. Lead halides can be used as a detector material for high-energy photons including gamma and X-rays

Air-Stable Thin Films of Tin Halide Perovskite Nanocrystals by Polymers and Al₂O₃ Encapsulation

Tin halide perovskites are promising for optoelectronics, although their sensitivity to ambient conditions due to Sn(II) oxidation presents a challenge. Encapsulation techniques can mitigate degradation and facilitate advanced studies of the intrinsic properties. To study and improve the ambient stability of CsSnBr3 and CsSnI3 nanocrystal (NC) thin films, we explored various encapsulation methods: organic, inorganic, and hybrid. We employed three methods for organic encapsulation: co-deposition with NCs, co-deposition with an additional top layer, and in situ polymerization with NCs. We synthesized thin layers of alumina by using atomic layer deposition for inorganic encapsulation. While individual methods offered marginal improvements, the hybrid approach provided the best results. By employing a hybrid heterostructured thin-film strategy, with the NC layer covered by a thin layer of poly(methyl methacrylate) followed by a 40 nm alumina layer, the stability in air was improved from a few seconds to a record period of 15 days, a crucial advancement for the further exploration of tin halide perovskites.</p

Luminescent crystals and manufacturing thereof

The present invention relates to the field of luminescent crystals (LCs), and more specifically to Quantum Dots (QDs) of formula A1aM2bXc, wherein the substituents are as defined in the specification. The invention provides methods of manufacturing such luminescent crystals, particularly by dispersing suitable starting materials in the presence of a liquid and by the aid of milling balls; to compositions comprising luminescent crystals and to electronic devices, decorative coatings; and to components comprising luminescent crystals.</p

Solid polymer composition

The present invention relates in a first aspect to a solid polymer component comprising luminescent crystals of 3-500 nm size, surfactant and a hardened/cured polymer. In a second aspect of the invention, a luminescent component comprises a first element comprising the solid polymer component according to the first aspect and an encapsulation enclosing the first element. In a third aspect of the invention, a luminescent component comprises a first film comprising the solid polymer composition of the first aspect. A fourth aspect of the invention relates to a light emitting device comprising the luminescent component according to the second or third aspect of the invention and a light source.</p

Opto-electronics of PbS quantum dot and narrow bandgap polymer blends

Here we report on the interaction between the narrow bandgap polymer [2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and lead sulphide (PbS) colloidal quantum dots (CQDs) upon photoexcitation. We show that the presence of both materials in a blend leads to a significant reduction of photoluminescence (PL) lifetime of the polymer. This observation is attributed, supported by transient absorption (TA) data, to an efficient electron transfer towards the QDs for excitons generated on the polymer. Furthermore, the ligand capping the QD surface exhibits a great impact on the dynamics of the PL, with the long-chain oleic acid (OA) largely suppressing any kind of interaction. By means of external quantum efficiency (EQE) measurements we find evidence that both components give rise to a contribution to the photocurrent, making this an interesting blend for future applications in hybrid organic-inorganic solar cells.</p

Blade-coated perovskite nanoplatelet polymer composites for sky-blue light-emitting diodes

Colloidal perovskite nanoplatelets (NPLs) have shown promise in tackling blue light-emitting diode challenges based on their tunable band gap and high photoluminescence efficiencies. However, high quality and large area dense NPL films have been proven to be very hard to prepare because of their chemical and physical fragility during the liquid phase deposition. Herein, we report a perovskite-polymer composite film deposition strategy with fine morphology engineering obtained using the blade coating method. The effects of the polymer type, solution concentration, compounding ratio and film thickness on the film quality are systematically investigated. We found that a relatively high-concentration suspension with an optimized NPL to polymer ratio of 1 : 2 is crucial for the suppression of phase separation and arriving at a uniform film. Finally, sky-blue NPL-based perovskite light-emitting diodes were fabricated by blade coating showing an EQE of 0.12%</p