title: Characterization of local electrochemical doping of high performance conjugated polymer for photovoltaics using scanning droplet cell microscopy.
abstract: The electrochemical oxidation of a next generation low bandgap high performance photovoltaic material namely poly[4,8-bis-substituted-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-4-substituted-thieno[3,4-b] thiophene-2,6-diyl] (PBDTTT-c) thin film was investigated using a scanning droplet cell microscope. Cyclic voltammetry was used for the basic characterization of the oxidation/doping of PBDTTT-c. Application of the different final potentials during the electrochemical study provides a close look to the oxidation kinetics. The electrical properties of both doped and undoped PBDTTT-c were analyzed in situ by electrochemical impedance spectroscopy giving the possibility to correlate the changes in the doping level with the subsequent changes in the resistance and capacitance. As a result one oxidation peak was found during the cyclic voltammetry and in potentiostatic measurements. From Mott-Schottky analysis a donor concentration of 2.3 × 1020cm-3and a flat band potential of 1.00 V vs. SHE were found. The oxidation process resulted in an increase of the conductivity by two orders of magnitude reaching a maximum for the oxidized form of 1.4 S cm-1.
authors.affiliation: Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Austria.
authors.forename: Jacek
authors.initials: J
authors.lastname: Gasiorowski
authors.affiliation: Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz, Austria.
authors.forename: Andrei Ionut
authors.initials: AI
authors.lastname: Mardare
authors.affiliation: Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Austria.
authors.forename: Niyazi Serdar
authors.initials: NS
authors.lastname: Sariciftci
authors.affiliation: Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz, Austria.
authors.forename: Achim Walter
authors.initials: AW
authors.lastname: Hassel
keywords: Electrochemical doping; Organic semiconductors; Polymer thin films; Scanning droplet cell microscopy (SDCM)
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