Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: Organic semiconductors
HL 50.4: Vortrag
Mittwoch, 13. März 2013, 10:15–10:30, H13
Trap passivation in organic semiconductors using ultra-low molecular doping — •Selina Olthof1,2, Swagat Mohapatra3, Sanjeev Singh4, Stephen Barlow3, Shafigh Mehraeen3, Veaceslav Coropceanu3, Jean-Luc Brédas3, Seth Marder3, Bernard Kippelen4, and Antoine Kahn2 — 1Institut für Physikalische Chemie, Universität zu Köln, Germany — 2Department of Electrical Engineering, Princeton University, USA — 3Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Tech, Atlanta, USA — 4Center for Organic Photonics and Electronics and School of Electrical and Computer Engineering, Georgia Tech, Atlanta, USA
Trap states in the band gap of organic semiconductors play a detrimental role in the performance of devices. We use charge carriers released from ultra low amounts of a molecular n-dopant to gradually fill up and thereby passivate trap states in the matrix material C60. The changes in Fermi level position as well as charge carrier transport are investigated. Experiments and kinetic Monte Carlo simulations confirm a distinct change in electronic behavior for doping concentration below and above typical trap densities. After passivation, an increase in C60 electron mobility by more than three orders of magnitude is achieved. We show that in organic field effect transistors the device performance can be greatly improved by trap filling, with high current on/off ratios as long as the doping concentration is kept below the trap density of the matrix. Controlled ultra-low doping is shown to be an effective way to passivate unwanted traps in organic semiconductor films.