Excitonoverdracht

Excitonoverdracht, also known as exciton transfer or exciton migration, is a fundamental photophysical process occurring in molecular systems and materials where energy is non-radiatively transferred from one excited molecule (an exciton) to another. This process typically happens when two chromophores are in close proximity and the electronic transition energy of the donor is resonant with that of the acceptor. The transfer of energy occurs without the physical movement of electrons themselves, hence it is a form of energy migration.

The mechanism of excitonoverdracht is most commonly described by the Förster resonance energy transfer (FRET) model for long-range transfer (typically 1-10 nm) and the Dexter electron exchange model for shorter-range transfer (less than 1 nm). FRET relies on dipole-dipole coupling and is sensitive to the distance and relative orientation of the donor and acceptor. Dexter transfer, on the other hand, requires orbital overlap between the donor and acceptor molecules and is a second-order process.

Excitonoverdracht plays a crucial role in a variety of natural and artificial systems. In photosynthesis, it is essential for efficiently channeling light energy absorbed by antenna pigments to the reaction centers. In organic light-emitting diodes (OLEDs) and other optoelectronic devices, excitonoverdracht is a key mechanism for energy transport and can influence device efficiency and color. Understanding and controlling excitonoverdracht is therefore important for designing efficient energy conversion and light-emitting technologies.