Publication date: 28th August 2024
To make better electronic and light-based devices using advanced materials, we need to understand how their structure affects their properties. Hybrid organic/inorganic perovskites are promising new materials, which are both soft and ionic, i.e. atoms can wiggle around their equilibrium positions and they are highly charged1. Transitions of electrons to different bands will distort the crystal lattice, and it will do so along specific vibrational coordinates. While there is consensus that electron-phonon interactions in these materials are crucial in determining their optoelectronic properties, i.e. EPC limits the maximum charge-carrier mobility2, it has been extremely challenging to obtain direct- and mode specific information on these interactions.
The big question is: which vibrational modes are coupled how strong to which electrons? And how do we measure this?
Here, we will dive into the world of (multidimensional) THz spectroscopy to answer the above questions. I will highlight our recently developed 2D-electron-phonon-coupling spectroscopy (2D-EPC), which can extract direct information on mode-specific electron-phonon interactions. We benchmarked this technique on prototypical methylammonium lead iodide, and show there is distinct behavior of the coupling of electrons between two different vibrational modes. Temperature dependent experiments allow us to follow the EPC over the tetragonal-to-orthorhombic phase transition, and polarization dependence allows us to study mode-specific and direction-dependent dispersion of this coupling3.
We also varied the A-site cation in three prototypical ‘black-phase’ perovskites: methylammonium (MA) lead iodide, formamidinium (FA) lead iodide and Cesium lead iodide, and demonstrate differences in the coupling between vibrational modes of the inorganic lattice and electrons with different energies.
V.K.S. and F.P. acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG) through the Collaborative Research Center TRR 288 (project number 422213477, project B09). H.K. and S.Q. thank the DFG for financial support through the Collaborative Research Center TRR 288 (project number 422213477, project B07). J.J.G. gratefully acknowledges support through an Alexander von Humboldt fellowship. This work was also supported by the National Research Foundation (NRF) of Korea (grant number 2021R1A6A1A10042944).
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.