Ultralow Doping in Organic Semiconductors: Evidence of Trap Filling

Selina Olthof, Shafigh Mehraeen, Swagat K. Mohapatra, Stephen Barlow, Veaceslav Coropceanu, Jean-Luc Brédas, Seth R. Marder, and Antoine Kahn

Phys. Rev. Lett. 109, 176601 – Published 26 October 2012

Abstract

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 $0.21 {cm}^{2} / (V s)$ .

Received 19 May 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.176601

Authors & Affiliations

Selina Olthof^1,*, Shafigh Mehraeen², Swagat K. Mohapatra², Stephen Barlow², Veaceslav Coropceanu², Jean-Luc Brédas², Seth R. Marder², and Antoine Kahn^1,†

¹Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
²Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA