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We present a comparative study of ultrafast photo-conversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photo-induced absorption in Tc and Pc crystals is activated and temperature-independent respectively, demonstrating dominant singlet-triplet exciton fission. In Pc films (as well as C$_{60}$-doped films) this decay channel is suppressed by electron trapping. These results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.
Engineering a low singlet-triplet energy gap ({Delta}EST) is necessary for efficient reverse intersystem crossing (rISC) in delayed fluorescence (DF) organic semiconductors, but results in a small radiative rate that limits performance in LEDs. Here,
We explore the possibility that hyperfine interaction causes the recently discovered organic magnetoresistance (OMAR) effect. Our study employs both experiment and theoretical modelling. An excitonic pair mechanism model based on hyperfine interactio
Different from traditional semiconductors, the organic semiconductors normally possess moderate many-body interactions with respect to charge, exciton, spin and phonons. In particular, the diagonal electron-phonon couplings give rise to the spatial l
We have experimentally tested the hypothesis of free charge carrier mediated spin-transport in the small molecule organic semiconductor Alq3 at room temperature. A spin current was pumped into this material by pulsed ferromagnetic resonance of an adj
We present neutron diffraction, magnetic susceptibility and specific heat data for a single-crystal sample of the cubic (Cu3Au structure) compound Pr3In. This compound is believed to have a singlet (Gamma1) groundstate and a low-lying triplet (Gamma4