Materials for energy harvesting: We aim at advancing the state-of-knowledge of polycrystalline materials for solar cells by probing light-matter interactions at the nanoscale. The performance of most materials for high-efficiency and low-cost photovoltaics (PV) is currently limited by their mesoscale behavior. Thus, to probe the local electrical and optical response of promising materials for PV we develop and realize innovative scanning probe microscopy methods based on nanospectroscopy. Our measurements provide a tomography of charge carrier generation, recombination and collection. We are (i) establishing the relationship between the physical behavior of these materials at relevant length scales and their structural/chemical properties, and (ii) elucidating the origin of the low open-circuit voltage in polycrystalline solar cells. Our functional imaging platform, with unprecedented spatial resolution, will enable the design of game-changing PV devices. For that, we are currently investigating both inorganic materials (CdTe, CIGS and polycrystalline III-V), and halide perovskites.
Materials for energy storage: To date, new rechargeable and safe batteries are urgently being developed to address the energy and power demands of our society, ranging from mobile communication to electric and hybrid vehicles. Nevertheless, the further development of safe, high performance all-solid-state-batteries requires the understanding and control of the relevant chemical reactions taking place during cycling. We use correlative microscopy to resolve the formation of solid-electrolyte interphases in energy storage devices with highly Li-ion conductive electrolytes, where we perform in operando experiments to probe lithiation/delithiation.
Optical Materials: The objective of this research is to develop a new class of materials with tunable optical response, for applications ranging from metamaterials to catalysis. The modulation of the dielectric function of metallic structures can enable the unprecedented control of the surface plasmon propagation in thin-films and the plasmon resonances in nanostructures. However, the fixed optical properties of metals severely constraint their use in photonic devices that operate at optical frequencies. To overcome the limitations imposed by the pre-defined dielectric function of metals we develop alloys formed by Ag, Au, Cu and Al to access materials with tunable optical responses, not found in nature. We combined simulations/calculations and experiments to design, fabricate and characterize the optical properties of alloyed thin films and nanostructures. The development of these optical materials has a potentially transformative effect on future nanophotonic devices by the complete control of their dielectric function and, therefore, superior optical performance.
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