American Physical Society, Physical Review Letters, 17(109)
DOI: 10.1103/physrevlett.109.176601
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Tail states in organic semiconductors have a significant influence on device performances by acting as traps in charge transport. We present a study of the controlled passivation of acceptor tail states in fullerene C_{60} by the addition of electrons introduced by molecular n doping. Using ultralow doping, we are able to successively fill the traps with charges and examine the changes in conductivity, activation energy, mobility, and Fermi-level position. Passivation of the traps leads to an increase of the electron mobility in C_{60} by more than 3 orders of magnitude, to reach 0.21 cm^{2}/(V s).