Interpreting the Hall effect of highly doped conducting polymers

Accurate determination of carrier density and mobility is fundamental to understanding the transport physics of conducting polymers and optimizing their performance. However, Hall effect measurements, widely used for determining carrier concentrations in other materials, have been of limited use for conducting polymers. Applying the conventional Hall coefficient expression ( R H = [ n H q ] − 1 ) consistently yields unphysically high carrier densities in heavily doped polymers. Here, we resolve this problem using a quasi–one-dimensional (Q1D) tight-binding model of the band structure of uniaxially aligned polymer films to analyze the p-type to n-type transition in the Hall effect observed upon increased doping. Our Q1D framework achieves excellent agreement between Hall-derived carrier densities and other independent measurements over a wide doping range. Our findings indicate that the transport physics of aligned polymers is governed by the topology of a single Q1D band within a simple band-filling framework and establish Hall measurements as a powerful tool for studying their charge transport physics.