Effective Negative Diffusion of Singlet Excitons in Organic Semiconductors
We have studied the diffusion of singlet and triplet excitons in tetracene crystals, a prototype singlet fission material, using ultrafast microscopy techniques. Upon laser excitation, triplets diffuse steadily while the singlet exciton distribution narrows, corresponding to an effective negative singlet diffusion. This counterintuitive result is explained by nonlinear triplet‒triplet annihilation. View the article in the Journal of Physical Chemistry Letters.