[staff-physics-and-astronomy-HL-UHD-UD] Seminar Giulia Lo Gerfo

[Beta NAT Secretariaat]

Title: Excitons in motion: linking structure and transport in sustainable energy materials
Abstract: "As the global demand for sustainable energy grows, understanding how light-driven energy is transported in materials becomes increasingly important. This talk will explore how exciton diffusion — central to processes like photovoltaics and photosynthesis — is influenced by material properties such as dimensionality, defects, and molecular geometry. Using spatiotemporal microscopy techniques, I will investigate exciton dynamics in diverse systems, from organic semiconductors and 2D perovskites to TMDCs and bio-inspired assemblies. Key findings reveal that structural factors significantly enhance or hinder exciton mobility: reduced dimensionality improves diffusion in molecular films used in organic photovoltaics, while defects and environmental interactions shape multiple transport regimes in TMDCs.
A central focus of the talk will be the influence of molecular packing density in bio-inspired systems. Using StrEET, a novel technique developed in 2024 in our group — capable of measurements at fluences 10,000 times lower than previous methods and at illumination levels below natural sunlight — we achieved the first direct measurement of exciton diffusion in these systems. I will introduce a study on LH2 from Purple Bacteria and porphyrins as a model for BChl-c from Green Sulfur Bacteria. In both cases, increasing molecular packing density enhances the diffusion coefficient while shortening the exciton lifetime. The optimal diffusion length emerges from a delicate balance between these competing effects, offering guiding principles for designing artificial light-harvesting systems inspired by natural processes and advancing our understanding of nature itself."


When: Thursday 8th May, 1 pm
where:   Spectrum 5, on the 2nd floor of the VO Building (de Boelelaan 1100)
Speaker: Giulia Lo Gerfo ICFO, Barcelona, Spain

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