Spin-Polarized Anthracene Triplet States Sensitized by Si QDs Revealed by Time-Resolved EPR Spectroscopy

However, the magnetic interactions that govern the generation and transfer of spin polarization in these systems are not well understood. Here, we report the first time-resolved electron paramagnetic resonance (EPR) study of triplet energy transfer (TET) in colloidal Si QDs conjugated with two anthracene-based organic molecules: 9-ethylanthracene and 9-vinylanthracene.

Triplet formation and spin dynamics monitored with time-resolved continuous-wave and pulsed EPR spectroscopy reveal Dexter-type TET from Si QDs to the anthracene moiety. Notably, the electron spin polarization of these conjugates displayed unusual fully emissive patterns, a surprising result that cannot be explained by the conventional spin-orbit or radical-pair mechanisms typically seen in purely organic donor–acceptor systems.