Evolution of the Seebeck p-n transition at 300 K. (a) Variations of the conductivity and Hall coefficients, and corresponding. (b) Seebeck and Nernst coefficients during the in-situ dedoping process of one a highly doped (100 mmol L⁻¹ FeCl₃) PDPP4T device. The dedoping was achieved by repeating a specific annealing process under vacuum (see MATERIALS AND METHODS section), and after each annealing process the device will cool down to 300 K to perform the conductivity, Hall, Seebeck, and Nernst effect measurements. The number of dedoping cycles represents the accumulated number of annealing process. (c) Revealed PDPP4T hole and electron partial thermopower evolution versus total thermopower during the entire dedoping process from n-type to p-type.