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Characterization of local electrochemical doping of high performance conjugated polymer for photovoltaics using scanning droplet cell microscopy.

Gasiorowski J, Mardare AI, Sariciftci NS, Hassel AW - Electrochim. Acta (2013)

Bottom Line: As a result one oxidation peak was found during the cyclic voltammetry and in potentiostatic measurements.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).

View Article: PubMed Central - PubMed

Affiliation: Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Austria.

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 × 10(20) cm(-3) and 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).

No MeSH data available.


Cyclic voltammetry as a function of the maximum achievable potential measured during oxidation of PBDTTT-c polymer.
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fig0010: Cyclic voltammetry as a function of the maximum achievable potential measured during oxidation of PBDTTT-c polymer.

Mentions: The electrochemical oxidation of PBDTTT-c was studied in a series of cyclic voltammograms measured with increased achievable final potential and the results are presented in Fig. 2. During the experiment, the maximum potential was increased from 0 V vs. SHE in steps of 0.05 V up to 1.50 V vs. SHE in order to probe the effect of doping of the polymer. For each measurement, two consecutive cycles were performed for probing the reproducibility of the oxidation process. As it can be observed, above 0.95 V vs. SHE an increase in the current, due to the beginning of the electrochemical oxidation process, was detected. This increase is fully reversible and is followed by a reduction process. The minimum of this reduction process is found at 1.15 V vs. SHE. Since the polymer was developed to serve as a donor in organic photovoltaic devices, the reversibility of the electrochemical oxidation process suggests a possible hole transporting property of this material. Further increasing the potential above 0.95 V vs. SHE, an almost linear increase in the maximum measured current is noticeable up to 1.4 V vs. SHE. Above this potential, a sudden decrease of the maximum current achieved due to the degradation process is observed. This process is related to the dissolution of the oxidized PBDTTT-c layer in PC as well as to a possible incipient degradation of the electrolyte or substrate. Additionally, above 1.3 V vs. SHE a strong difference between the first and the second scan is found. This difference increases with the increase in the applied potential. This behaviour, suggesting an irreversibility of the oxidation process, may be due to the degradation of the PBDTTT-c which starts to be dominant at high potentials. At the same time, the reduction process changes due to the same reason. A decrease in the peak minimum followed by a broadening of this peak is noticeable. This can be attributed to a degradation of the polymer layer. Interestingly, for this type of polymer no distinct oxidation peak was observed, but rather a continuous current increase until the maximum potential is reached.


Characterization of local electrochemical doping of high performance conjugated polymer for photovoltaics using scanning droplet cell microscopy.

Gasiorowski J, Mardare AI, Sariciftci NS, Hassel AW - Electrochim. Acta (2013)

Cyclic voltammetry as a function of the maximum achievable potential measured during oxidation of PBDTTT-c polymer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376049&req=5

fig0010: Cyclic voltammetry as a function of the maximum achievable potential measured during oxidation of PBDTTT-c polymer.
Mentions: The electrochemical oxidation of PBDTTT-c was studied in a series of cyclic voltammograms measured with increased achievable final potential and the results are presented in Fig. 2. During the experiment, the maximum potential was increased from 0 V vs. SHE in steps of 0.05 V up to 1.50 V vs. SHE in order to probe the effect of doping of the polymer. For each measurement, two consecutive cycles were performed for probing the reproducibility of the oxidation process. As it can be observed, above 0.95 V vs. SHE an increase in the current, due to the beginning of the electrochemical oxidation process, was detected. This increase is fully reversible and is followed by a reduction process. The minimum of this reduction process is found at 1.15 V vs. SHE. Since the polymer was developed to serve as a donor in organic photovoltaic devices, the reversibility of the electrochemical oxidation process suggests a possible hole transporting property of this material. Further increasing the potential above 0.95 V vs. SHE, an almost linear increase in the maximum measured current is noticeable up to 1.4 V vs. SHE. Above this potential, a sudden decrease of the maximum current achieved due to the degradation process is observed. This process is related to the dissolution of the oxidized PBDTTT-c layer in PC as well as to a possible incipient degradation of the electrolyte or substrate. Additionally, above 1.3 V vs. SHE a strong difference between the first and the second scan is found. This difference increases with the increase in the applied potential. This behaviour, suggesting an irreversibility of the oxidation process, may be due to the degradation of the PBDTTT-c which starts to be dominant at high potentials. At the same time, the reduction process changes due to the same reason. A decrease in the peak minimum followed by a broadening of this peak is noticeable. This can be attributed to a degradation of the polymer layer. Interestingly, for this type of polymer no distinct oxidation peak was observed, but rather a continuous current increase until the maximum potential is reached.

Bottom Line: As a result one oxidation peak was found during the cyclic voltammetry and in potentiostatic measurements.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).

View Article: PubMed Central - PubMed

Affiliation: Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Austria.

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 × 10(20) cm(-3) and 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).

No MeSH data available.