title: Carrier motion in as-spun and annealed P3HT:PCBM blends revealed by ultrafast optical electric field probing and Monte Carlo simulations.
abstract: Charge transport dynamics in solar cell devices based on as-spun and annealed P3HT:PCBM films are compared using ultrafast time-resolved optical probing of the electric field by means of field-induced second harmonic generation. The results show that charge carriers drift about twice as far during the first 3 ns after photogeneration in a device where the active layer has been thermally annealed. The carrier dynamics were modelled using Monte-Carlo simulations and good agreement between experimental and simulated drift dynamics was obtained using identical model parameters for both cells, but with different average PCBM and polymer domain sizes. The calculations suggest that small domain sizes in as-spun samples limit the carrier separation distance disabling their escape from geminate recombination.
authors.affiliation: Center for Physical Sciences and Technology, Savanoriu 231, LT-02300 Vilnius, Lithuania.
authors.forename: Vytautas
authors.initials: V
authors.lastname: Abramavičius
authors.forename: Dimali
authors.initials: D
authors.lastname: Amarasinghe Vithanage
authors.forename: Andrius
authors.initials: A
authors.lastname: Devižis
authors.forename: Yingyot
authors.initials: Y
authors.lastname: Infahsaeng
authors.forename: Annalisa
authors.initials: A
authors.lastname: Bruno
authors.forename: Samuel
authors.initials: S
authors.lastname: Foster
authors.forename: Panagiotis E
authors.initials: PE
authors.lastname: Keivanidis
authors.forename: Darius
authors.initials: D
authors.lastname: Abramavičius
authors.forename: Jenny
authors.initials: J
authors.lastname: Nelson
authors.forename: Arkady
authors.initials: A
authors.lastname: Yartsev
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström
authors.forename: Vidmantas
authors.initials: V
authors.lastname: Gulbinas