Modelling Photoluminescence in Organic Systems: Exploring the impact of aggregation and mechanical effects on the molecular, electronic and optical properties

DIPC Seminars

Speaker

Josianne Owona
DIPC

When

2025/12/03
11:00

Place

DIPC Josebe Olarra Seminar Room

Host

Claire Tonnelé

Add to calendar

iCal

Kimika Teorikoa Seminar

Light-driven innovations play a key role in modern technology, from solar energy conversion in photovoltaic cells to stimuli-responsive wearables supporting diagnosis and treatment of diseases. These developments rely on the efficiency of a material’s photoluminescent response, for which organic compounds offer versatile candidates owning to their structural diversity, photophysical tunability, and responsiveness to external stimuli. Photoluminescence, a form of light emission principally initiated by photoexcitation, involves the promotion of an electron to an excited state followed by radiative relaxation. While the luminescent properties of individual organic molecules are now well described and controlled by molecular design, predicting and tuning emission in the solid-state remain challenging. In this regime, intermolecular interactions strongly influence the luminescent response. Aggregation can lead to electronic interaction between chromophores, affecting orbital overlap and energy level splitting, which may either enhance or quench emission depending on molecular disposition. Furthermore, mechanical stress can perturb molecular conformation, crystal packing, or charge distribution, thereby altering (non-)radiative transitions. Consequently, photoluminescence efficiency can be tuned through supramolecular organization or external stimuli. Despite their technological application potential, the complexity of photophysical phenomena in organic solids requires a deeper theoretical understanding to predict and control their properties. This thesis investigates the influence of molecular aggregation and mechanical effects on different photoluminescent phenomena (namely, fluorescence, phosphorescence and nonlinear optical response) of organic compounds using quantum chemical modelling. Density functional theory and its time-dependent extension were employed to provide a comprehensive mechanistic picture, often inacessible experimentally, of photophysical pathways, and to elucidate how structural, electronic and mechanical variations shape the photoluminescence behaviour.