Proceedings of September Meeting 2016 (NFM16)
Publication date: 14th June 2016
Ligand-induced shape-transformation of PbSe nanocrystals.
Nanocrystals of the lead chalcogenide family belong to the most investigated nanocrystals (NCs) due to their tuneable infrared absorption and emission, and their propensity to self-assemble in several types of nanocrystal solids. For instance, PbSe NCs can fuse together into ordered single crystalline structures, forming new two-dimensional materials [1][2]. Studies on the oriented attachment of these building blocks clarified that this fusion process almost exclusively occurs in the <100> crystallographic direction [3]. To understand this process in more detail, more knowledge about the available facets and general shape is essential. Besides the shape, also the facet termination and ligand distribution on each facet is crucial. We used FT-IR to measure the number of oleate ligands per nanocrystal. Since bound and unbound Pb(oleate)2 structures have distinct signatures it is possible to measure the attached and freely dispersed ligands. Due to the fast and dynamic nature of the ligand bounding, we could add extra ligands to a NCs dispersion. With this simple procedure, NCs with low and high ligand density can easily be created. Subsequently, an extended HAADF-STEM study has been performed on a both batches. By quantifying the scattering of each atomic column of a crystal viewed in a certain crystallographic direction, the number of Pb atoms per column can be quantified, which can be reconstructed into a 3D shape of PbSe NCs. This procedure is repeated for 10 particles where it became clear that the <111> crystal facets increase in size at the expense of the <100> and <110> facets with increasing ligand coverage. The increased density of oleate ligands on the NCs results in a remarkable transformation in shape: NCs with low ligand density possess a truncated cubic shape and the NCs with maximum ligand coverage a truncated octahedron. These results strongly suggest a preferential and almost exclusive binding of Pb-oleate moieties on the [111] facets [4].
References
[1] W. H. Evers, et al. Nano Lett., vol. 13, no. 6, pp. 2317–2323, 2013.
[2] E. Kalesaki, et al. Phys. Rev. X, vol. 4, pp. 1–12, 2014.
[3] M. P. Boneschanscher, et al. Science (80-. )., vol. 344, no. 6190, pp. 1377–1380, 2014.
[4] J.L Peters et al., in preparation.
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.