Publication date: 31st March 2013
Often the presence of electronic states within the band gap is claimed to be the origin of fast charge carrier trapping and electron-hole recombination in transition metal oxides. Prominent among these mid-gap states are the intersite and intrasite d-d transitions. We report transient optical spectroscopy of Co3O4 where these d-d transitions can be selectively excited and probed. The data suggests that excited electrons thermalize within a few picoseconds to the mid-gap, near infrared d-d states, while recovery due to hole capture takes place on the ~0.6 ns time scale. The dependence of the transient probe spectrum and kinetics on excitation density, pump wavelength, and across different morphologies of Co3O4 supports the primary conclusion; resonant two photon absorption just below the d-d transitions prevents the data from ruling out the possible contribution of lower energy states. How hole capture by such electron trap states could mediate charge flow during the water oxidation reaction on Co3O4 and materials with similar mid-gap states is discussed. Future experiments will elucidate the extent to which this type of carrier relaxation is generic to transition metal oxides.
M. Waegele, H. Doan, and T. Cuk. Implications of the mid-gap, d-manifold to photoexcited carrier dynamics in cobalt oxide. Submitted to Phys. Rev. B. 2013.
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.