DOI: https://doi.org/10.29363/nanoge.emlem.2023.031
Publication date: 18th August 2023
Among the transition metal oxides (TMOs), spinel Co3O4 has recently emerged as promising material for photovoltaic and photocatalytic applications. Spinel Co3O4 contains Co[3+] and Co[2+] centers respectively occupying octahedral and tetrahedral sites surrounded by O[2-] anions. The two nonequivalent Cobalt centers are characterized by paired and unpaired d-orbital electronic configurations, determining the presence of Mott-Hubbard and charge transfer gaps close in energy. Because of its complex physics involving the correlated interaction of multiple degrees of freedom, the investigation of its relaxation dynamics calls for experimental approaches able to disentangle electronic, spin and lattice photo-responses with ultrafast time resolution. With ultrafast X-ray emission spectroscopy (XES) at the FXE instrument of the European X-ray free electron laser (EXFEL), we studied the temporal evolution of metal-centered transient electronic configurations, which are degenerate in the optical domain. Specifically, we excited the ligand-to-metal charge transfer (LMCT) and metal-to-metal charge transfer (MMCT) transitions of Co3O4 by pumping a 27 nm thin film at 400 nm and 800 nm, respectively. Our results rule out a stepwise relaxation cascade from the highest LMCT to the lowest d-d gap through the intermediate MMCT state, presenting a radically different picture compared to previous time-resolved optical studies on Co3O4. These results establish correlative time-resolved X-ray emission and optical spectroscopy as a novel strategy for the investigation of condensed matter systems.
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.