The field-independent early-time drift velocity of carriers in polydiacetylenes: solitary-wave acoustic polaron or dispersive trap-limited transport in 1D?

Current controversy concerning the nature of the motion of charge carriers in polydiacetylene single crystals is examined. New results using picosecond time-resolved photocurrents are able to distinguish whether the observed saturated drift velocity is due to the motion of a solitary-wave acoustic polaron or a carrier moving in a distribution of traps and barriers, and indicate the former case. The relevance of the Onsager geminate recombination theory in these materials is also demonstrated unequivocally.