1,721,454 research outputs found
Crystal Structure, Morphology, and Surface Termination of Cyan-Emissive, Six-Monolayers-Thick CsPbBr3 Nanoplatelets from X-ray Total Scattering
No full textHighly anisotropic colloidal CsPbBr3 nanoplatelets (NPLs) represent an appealing class of colloidal quantum wells with enhanced light emissivity. Strong quantum confinement imposed by the small platelet thickness and atomic flatness gives rise to enhanced oscillator strength, higher exciton binding energy, and narrow emission linewidth. While discrete thicknesses manifest themselves in discrete bandgap energies, fine-tuning of the emission energy can be achieved by compositional modulations. Here we address one of the most debated aspects of perovskite nanoplatelets: their crystal structure. Starting with the direct imaging by high-resolution electron microscopy (providing a clue on the pseudocubic faceting of the NPLs), we focus the study on X-ray total scattering techniques, based on the Debye scattering equation (DSE) approach, to obtain better atomistic insight. The nanoplatelets are six-monolayers thick and exhibit an orthorhombic structure. A thorough structure-morphology characterization unveils a specific orientation of the axial and equatorial bromides of the PbBr6 octahedra versus the NPLs thickness; we found that {010} and {101} planes of the orthorhombic CsPbBr3 lattice (Pnma space group) correspond to the six facets of the NPL, with basal planes being of {101} type. The NPLs undergo a lattice relaxation in comparison to cuboidal CsPbBr3 NCs; the major deformation is observed in the axial direction, which suggests a structural origin of the higher compliance along the b axis. The DSE-based analysis also supports a CsBr surface termination model, with half Cs sites and a half (or slightly more) Br sites vacant
Monodisperse Formamidinium Lead Bromide Nanocrystals with Bright and Stable Green Photoluminescence
No full textBright green emitters with adjustable photoluminescence (PL) maxima in the range of 530-535 nm and full-width at half-maxima (FWHM) of 25 nm are particularly desirable for applications in television displays and related technologies. Towards this goal, we have developed a facile synthesis of highly monodisperse, cubic-shaped formamidinium lead bromide nanocrystals (FAPbBr3 NCs) with perovskite crystal structure, tunable PL in the range of 470-540 nm by adjusting the nanocrystal size (5-12 nm), high quantum yield (QY) of up to 85% and PL FWHM of 22 nm. High QYs are also retained in films of FAPbBr3 NCs. In addition, these films exhibit low thresholds of 142 μJ cm-2 for amplified spontaneous emission
Нові органічні ліганди для стабілізації перовськітних квантових точок
No full textВ даній роботі було отримано 4 сполуки (додецилгуанідиніум бромід, стеарилгуанідиніум бромід, олеїлгуанідиніум бромід та 2- октилдодецилгуанідиніум бромід) з високими виходами.Кафедра супрамолекулярної хіміїНавчально-науковий інститут високих технологій Київського національного університету імені Тараса Шевченк
Ionic-electronic halide perovskite memdiodes enabling neuromorphic computing with a second-order complexity
Full text linkISSN:2375-254
Lead-Free Low-Dimensional Main Group Metal Halides: New Self-Trapped Excitonic Emitters and Their Applications
No full text
Silicon-based anode materials and conducting nano frameworks for rechargeable lithium batteries
No full textNanoprinted Quantum DOT/Graphene Infrared Photodetectors, and their Temperature-Dependent Mechanism of Charge Carrier Transfer
No full textChemical and electrochemical reactions of the 2-dimensional materials boron nitride and reduced graphene oxide
No full textNovel synthesis routes to colloidal nanocrystals of semiconductive metal pnictides and metal halides
No full text- …
