Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: Organic semiconductors
HL 50.8: Vortrag
Mittwoch, 13. März 2013, 11:30–11:45, H13
Spectroscopic investigation of air induced charge trapping in n-type polymer semiconductors — •Riccardo Di Pietro1, Tom B. Kehoe2, and Henning Sirringhaus2 — 1Institut für Physik und Astronomie, Universität Potsdam, Germany — 2Cavendish Laboratory, University of Cambridge, United Kingdom
We have performed an optical spectroscopy study of how the presence of oxygen and water affects the radical anion charge states in one of the most widely studied electron transporting conjugated polymers, poly{[N,N9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bisthiophene)} (P(NDI2OD-T2)). By combining the results obtained from Charge Accumulation Spectroscopy (CAS)[1], a technique which allows optical quantification of the concentration of charged species in the polymer film, with electrical characterization of P(NDI2OD-T2) organic field-effect transistors (OFETs) we have been able to study the mechanism for bias-stress degradation upon exposure to ambient atmosphere. Here we show that the stability of the polymer anion against water is limited by two competing reactions, one involving the well-known electrochemical oxidation of the polymer anion by water and the other involving a radical anion-catalyzed chemical reaction of the polymer with water leading to degradation of the polymer film.
[1] Di Pietro, R. and Sirringhaus, H. High Resolution Optical Spectroscopy of Air-Induced Electrical Instabilities in n-type Polymer Semiconductors. Adv. Mater. 24 (2012).