Figure 3

Schematic overview of energy transfer from photoexcited excitons in silicon nanoparticles to absorbed oxygen molecules. Optical excitation (green arrows, ‘pump’) generates excitons confined in silicon nanoparticles that can recombine to emit photoluminescence (red arrows, ‘PL’) or can transfer energy to those absorbed oxygen molecules that are in the triplet ground state (black arrow, ‘energy transfer’). Excited oxygen molecules in the singlet state can return to their ground state (blue arrows, ‘relaxation’) via emission of luminescence and/or non-radiative relaxation processes.