Electronic Structure of the Positive Radical of C-13-Labeled Poly(3-Octylthienylene Vinylene) Polymer

Abstract

Poly(3-octylthienylene vinylene) (O-PTV) has a great potential as low-bandgap p-type semiconductor for photovoltaic applications. Here, the positive radical state (positive polaron) is induced chemically in the O-PTV polymer in which the vinylene sites are selectively C-13-labeled. Using multi-frequency continuous wave and pulsed electron paramagnetic resonance, the g tensor and maximum H-1 and C-13 hyperfine couplings are determined. A comparative density functional theory (DFT) analysis of PTV-like oligomers is performed. The experimental parameters suggest a larger localization of the positive polaron than follows from the DFT analysis. The counter anion may play a crucial role in localizing the polaron.