Proceedings of nanoGe September Meeting 2015 (NFM15)
Publication date: 8th June 2015
Understanding spin relaxation mechanisms is important to design spin preserving environments for future spin-based devices for information storage. Colloidal NCs, due to their high versatility regarding synthesis and processing as well as due to their unique and widely tunable optical properties are suitable candidates for such applications. Thus, comprehensive knowledge about the linkage between NC size, shape and material properties and exciton spin dynamics is highly desirable. We report on how spin dynamics between the dark exciton ground states split by the magnetic field are affected by the size and shape of the CdS shell. Interestingly we find, that the core/shell interface strongly affects the spin relaxation rate, whereas the shell shape and size have only slight impact. These results highlight the crucial role of the core/shell interface for the optical properties of NCs, especially for the relaxation and recombination dynamics of dark excitons. We also study the impact of the shell shape on magnetic field induced PL circular polarization. Our results indicate, that the saturation level of the Degree of Circular Polarization (DCP) in NCs depends on the aspect ratio of the shell. We elaborate a theoretical approach for analyzing and predicting polarization properties of NCs in the presence of an external magnetic field, which includes a dielectric enhancement effect resulting from an anisotropic shell as well as phonon-mediated coupling of the dark exciton ground state to bright exciton states with radiative transitions parallel and perpendicular to the hexagonal axis. Besides explaining the discrepancy existing in literature regarding DCP values [1-4], our model suggests, that, at low temperatures and in the presence of magnetic fields the PL can be polarized perpendicular to the hexagonal axis in contrast to what has been observed at room temperature [5]. This striking result highlights a new mechanism in the radiative recombination of the dark exciton.
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.