Reversible oxygen doping of conjugated polymer and its dedoping studied by Mott–Schottky analysis

• Annealing is effective way to control the doping level of conjugated polymer.
• Annealing in air leads to irreversible qualitative changes in the polymer sample.
• Dedoping dynamics is biexponential with two different timescales.
• Self-doping velocity depends on light intensity.

One of the important factors influencing on organic solar cells efficiency is doping of the polymer by atmospheric oxygen. It is known already that the doping may be partially reversed by annealing of the device, but the phenomenon is not well-studied yet. In this paper we studied processes of doping and dedoping of conjugated polymers, using well-known poly(3 hexylthiophene) (P3HT) and derivative of novel low-bandgap polymer poly(3,4-ethylenedioxyselenophene) (PEDOS-C12), by impedance spectroscopy.Possibility of dedoping under annealing was examined for both of the polymers. Influence of annealing atmosphere and sample preparation conditions on dedoping process were studied along with dynamics of self-doping and dedoping processes and influence of light on self-doping dynamics. Dedoping dynamics in inert atmosphere turn out to be biexponential.

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