Manganese‐Doping‐Induced Quantum Confinement within Host Perovskite Nanocrystals through Ruddlesden–Popper Defects

The concept of doping Mn2+ ions into II–VI semiconductor nanocrystals (NCs) was recently extended to perovskite NCs. To date, most studies on Mn2+ doped NCs focus on enhancing the emission related to the Mn2+ dopant via an energy transfer mechanism. Herein, we found that the doping of Mn2+ ions into CsPbCl3 NCs not only results in a Mn2+‐related orange emission, but also strongly influences the excitonic properties of the host NCs. We observe for the first time that Mn2+ doping leads to the formation of Ruddlesden–Popper (R.P.) defects and thus induces quantum confinement within the host NCs. We find that a slight doping with Mn2+ ions improves the size distribution of the NCs, which results in a prominent excitonic peak. However, with increasing the Mn2+ concentration, the number of R.P. planes increases leading to smaller single‐crystal domains. The thus enhanced confinement and crystal inhomogeneity cause a gradual blue shift and broadening of the excitonic transition, respectively

Near-infrared Emitting CulnSe2/CulnS2 Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange

The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu+ extraction rate is coupled to the In3+ incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-extracting agent. In this way, Cu+ ions can be extracted by trioctylphosphine ligands only when the In–P bond is broken. This results in readily available In3+ ions at the same surface site from which the Cu+ is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible

Disconnecting Symmetry Breaking from Seeded Growth for the Reproducible Synthesis of High Quality Gold Nanorods

https://pubs.acs.org/doi/suppl/10.1021/acsnano.8b09658/suppl_file/nn8b09658_si_002.pdfOne of the major difficulties hindering the widespread application of colloidal anisotropic plasmonic nanoparticles is the limited robustness and reproducibility of multistep synthetic methods. We demonstrate herein that the reproducibility and reliability of colloidal gold nanorod (AuNR) synthesis can be greatly improved by disconnecting the symmetry-breaking event from the seeded growth process. We have used a modified silver-assisted seeded growth method in the presence of the surfactant hexadecyltrimethylammonium bromide and n-decanol as a co-surfactant to prepare small AuNRs in high yield, which were then used as seeds for the growth of high quality AuNR colloids. Whereas the use of n-decanol provides a more-rigid micellar system, the growth on anisotropic seeds avoids sources of irreproducibility during the symmetry breaking step, yielding uniform AuNR colloids with narrow plasmon bands, ranging from 600 to 1270 nm, and allowing the fine-tuning of the final dimensions. This method provides a robust route for the preparation of high quality AuNR colloids with tunable morphology, size, and optical response in a reproducible and scalable manner

Разработка системы измерения производительности реализаций blockchain

Долголев Филипп Петрович Разработка системы измерения производительности реализаций blockchain Старший преподаватель кафедры системного программирования Кириленко Яков Александрович При разработке приложений на основе технологии blockchain, из-за наличия множества различных реализаций, разработчики сталкиваются с проблемой выбора. Один из важных критериев при выборе - производительность. В процессе поиска системы, позволяющей измерить производительность различных реализаций blockchain, не обнаружены ни проприетарные системы, ни с открытым исходным кодом. В рамках этой работы рассматривается разработка модульной системы, решающей эту проблему. Использованных источников: 18 Долголев, Ф. П. Разработка системы измерения производительности реализаций blockchain: выпускная квалификационная работа: защищена 01.06.2017 / Долголев Филипп Петрович. – СПб., 2017. – 21 с. – Библиография: с. 20–21.Filipp Dolgolev Blockchain Implementations Benchmarking Tool senior lecturer, dept. of software engineering Iakov Kirilenko Mathematics & mechanics, software engineering department Since there are many different types of blockchain technologies, developers are faced with a dilemma of which technology to choose when developing applications for a particular use case. One of the most important criteria effecting the selection is performance. During our research, we were unable to source either proprietary, or open source solutions allowing to benchmark various blockchain technologies performances. In this context, we are considering the development of such a solution. Sources cited: 18 Dolgolev, F. Blockchain Implementations Benchmarking Tool: Graduation thesis: Defended 01.06.2017 / Filipp Dolgolev. – St. Petersburg., 2017. – 21 pp. – Bibliography: pp. 20–21

Thermal Stability of Gold/Palladium Octopods Studied in Situ in 3D: Understanding Design Rules for Thermally Stable Metal Nanoparticles

Multifunctional metal nanoparticles (NPs) such as anisotropic multimetallic NPs are crucial for boosting nanomaterial based applications. Advanced synthetic protocols exist to make a large variety of such nanostructures. However, a major limiting factor for the usability of them in real life applications is their stability. Here, we show that Au/Pd octopods, 8-branched nanocrystals with Oh symmetry, with only a low amount of Pd exhibited a high thermal stability and maintained strong plasmon resonances up to 600 C. Furthermore, we study the influence of the composition, morphology and environment on the thermal stability and define key parameters for the design of thermally stable multifunctional NPs

Thermal stability of gold/palladium octopods studied in situ in 3D : understanding design rules for thermally stable metal nanoparticles

Multifunctional metal nanoparticles (NPs) such as anisotropic multimetallic NPs are crucial for boosting nanomaterial-based applications. Advanced synthetic protocols exist to make a large variety of such nanostructures. However, a major limiting factor for the usability of them in real life applications is their stability. Here, we show that Au/Pd octopods, eight-branched nanocrystals with <i>O</i>_<i>h</i> symmetry, with only a low amount of Pd exhibited a high thermal stability and maintained strong plasmon resonances up to 600 °C. Furthermore, we study the influence of the composition, morphology, and environment on the thermal stability and define key parameters for the design of thermally stable multifunctional NPs