Standing Tall: surface decoupling of fluorophores through 3D molecular constructs
Modern technologies, from solar cells to optical sensors, depend on ultra-thin layers that can conduct or emit light. Traditionally, these layers are made using top-down lithography, a precise but expensive and energy-intensive process. In her thesis, Melina Vavali explores a greener, bottom-up alternative: using molecules that naturally organise themselves into ordered structures.
Vavali focuses on graphene, a single-atom thick form of carbon famous for its strength and conductivity. However, when light-emitting molecules (fluorophores) are placed directly on graphene, their glow disappears because of strong electronic interactions. To prevent this “quenching”, Vavali introduces specially designed three-dimensional molecular architectures that lift the light-emitting parts away from the graphene surface, electronically isolating them while keeping their structure stable.
These molecular assemblies are built like miniature scaffolds, combining three components: a pedestal (porphyrin or phthalocyanine), a fluorescent molecule, and a linker that connects the two. By fine-tuning these building blocks, the spacing and orientation of the light emitters can be precisely controlled.
Using advanced microscopy and spectroscopy techniques, Vavali demonstrated that this bottom-up design successfully preserves fluorescence – an important step toward fabricating more efficient, flexible, and eco-friendly photonic and optoelectronic devices.