Fig. 2: Exciton diffusion length measurements.

The dynamics of the singlet excitons measured with the 670 nm pump excitation at different densities in films of (a) BTP-eC9 (850 nm), (b) L8-BO-F (814 nm), (c) BTP-eC9:L8-BO-F (850 nm).The fluence-dependent singlet exciton decays are fitted to the exciton annihilation model (Eq. (1)).