Dr. Mathieu G. Silly
Talk Title:
High resolution and time resolved soft X-ray photoemission spectroscopy for studying nanomaterials with application in photovoltaics
Speaker Biography:
Dr. Mathieu G. Silly is beamline Scientist at the TEMPO Beamline at the Synchrotron Soleil in France, since 2008. He is in charge with the development of pump probe experiment using high resolution photoemission spectroscopy to study transient phenomena in photoexcited materials. He was graduated from “Institut d’Optique Graduate School” (France) in 2000 and received his PhD Degree in surface science in 2004 from University of Paris XI (France). In 2005, he worked as a postdoc fellow at the ONERA on the optical properties of hBN wide band gap 2D semiconductor. He joined the synchrotron SOLEIL in 2006 to develop the time resolved photoemission spectroscopy on the TEMPO beamline. After being co beamline manager in 2017, he was appointed head of the LASER installation. His main research interests include the optical, electronic and chemical properties of 2D and nano materials. He is author/co-author of over 130 publications in refereed journals.
Talk Abstract:
Quantum dots (QDs) referring to semiconductor nanoparticules exhibit unique electronic and optical properties. Due to their small size, QDs optical and electronic properties differ from those of the bulk semiconductor. The Electronic properties as work function, band gap and doping of QDs can be tuned by changing the size and the composition of the nanoparticles. Colloidal QDs by ligand exchange offer very flexible media to tune the QDs electronic properties. These behaviors make QDs very efficient materials for application in many domains as bioimaging, solar cells, light emission diodes, LASER diodes, and transistors. Photovoltaics is one of the most active fields of research to meet future energy needs with greener energy. The main challenge remains increasing the photoconversion efficiency by engineering the QDs structure and electronic properties. High resolution photoemission spectroscopy (HRPES) as a chemical and surface sensitive technics is a very promising approach to associate the electronic to the chemical properties of QDs. Time resolved photoemission spectroscopy (TRPES), under pulsed laser excitation, permits to determine the charge carrier lifetime and to evidence interfacial charge transfer process at electrodes/QDs interfaces.
Through various examples measured in particular on TEMPO Beamline, we will show how HRPES and TRPES studies performed in Synchrotron is capable of meeting current and future challenges for photovoltaic nanomaterials.
Keywords:
Synchrotron, photoemission, nanoparticles, photovoltaic
