Nanoscale triplet exciton diffusion via imaging of up-conversion emission from single hybrid nanoparticles in molecular crystals.

Up-conversion materials composed of donor and acceptor molecules which convert low energy photons into higher energy ones by triplet-triplet annihilation can improve the sensitivity of photocatalysts or the efficiency of solar cells. The use of crystalline materials can lead to a decrease in the up-conversion threshold intensity due to increased diffusion length L