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DTSTART:20250627T080000Z
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LOCATION:ICFO Auditorium
SUMMARY:ICFO | GIULIA LO GERFO MORGANTI
CLASS:PUBLIC
DESCRIPTION:The growing global energy demand\, coupled with the need to red
 uce CO2 emissions\, highlights the urgency of developing sustainable energ
 y solutions. Despite its vast potential\, solar energy remains underutiliz
 ed due to technological challenges. Most solar technologies&mdash\; includ
 ing photovoltaics (PV)\, concentrated solar power\, and artificial photosy
 nthesis&mdash\; depend on three core processes: light absorption\, energy 
 conversion\, and energy transport. Understanding how light is converted an
 d transmitted&mdash\; primarily via exciton diffusion&mdash\; in materials
  ranging from semiconductors to biomimetic and biological systems is essen
 tial for improving the performance of both optoelectronic devices and natu
 ral photosynthesis.\nThis thesis examines how dimensionality\, defects\, a
 nd molecular geometry affect exciton diffusion\, aiming to uncover structu
 re-function relationships that govern energy transport in energy-related m
 aterials. Using advanced spatiotemporal microscopy &mdash\; including Time
 -Correlated Single-Photon Counting Microscopy\, Transient Reflection Micro
 scopy\, and a novel technique developed by my group\, Structured Excitatio
 n Energy Transfer (StrEET) &mdash\; this research investigates exciton dif
 fusion in organic semiconductors\, 2D perovskites\, transition metal dicha
 lcogenides (TMDCs)\, and bio-inspired systems.\nKey findings show that dim
 ensionality critically influences exciton mobility. In Y6 organic films &m
 dash\; a leading non-fullerene acceptor for organic photovoltaics &mdash\;
  I performed the first direct measurements of exciton diffusion\, revealin
 g that confinement enhances mobility. Combined with morphological tuning v
 ia additives\, diffusion coefficients increase by over 50%. In 2D perovski
 tes\, increasing thickness boosts both diffusion and anisotropy\, yielding
  diffusion lengths well beyond those of conventional organic systems.\nTMD
 C studies reveal that\, beyond dimensionality\, defects and substrate inte
 ractions significantly affect exciton mobility. In suspended monolayers\, 
 multiple transport regimes &mdash\; rapid\, negative\, and slow diffusion 
 &mdash\; are observed\, each constrained by trap states and sensitive to s
 tructural and environmental changes.\nLastly\, this work explores how mole
 cular packing and geometry influence exciton transport in bio-inspired sys
 tems like porphyrin films and bacterial LH2 networks. Using the novel high
 ly sensitive StrEET technique\, I conducted the first direct measurements 
 of exciton transport in photosynthetic systems. Denser molecular packing e
 nhances diffusion while reducing exciton lifetimes\; the optimal diffusion
  length\, comparable to that of top organic semiconductors\, arises from a
  balance between these competing effects\, offering insights into the desi
 gn of artificial light-harvesting systems.\nOverall\, this research demons
 trates that excitonic transport can be engineered by tuning material prope
 rties such as dimensionality\, defect density\, and molecular organization
 . These findings provide guiding principles for developing more efficient 
 optoelectronic and bio-inspired energy technologies\, supporting the trans
 ition to sustainable energy solutions.\nFriday June 27\, 10:00 h. ICFO Aud
 itorium \nThesis Director: Prof. Dr. Niek Van Hulst
DTSTAMP:20260407T073600Z
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