Fig. 3: Doping level and temperature dependence of ALNE in PBTTT films, as well as ALNE in different polymers and comparison to other materials.

a PBTTT thermopower \(S\) and Nernst coefficients \(\nu\) versus different FeCl₃ doping concentration. b Doping concentration dependent PBTTT electrical conductivity \(\sigma\) and Hall mobility \({\mu }_{{{\rm{H}}}}\). c In-situ measured temperature \(T\) dependence of \(S\) and \(\nu\) in one 100 mmol L⁻¹ FeCl₃-doped PBTTT device. d Corresponding temperature dependence of \(\sigma\) and \({\mu }_{{{\rm{H}}}}\) of (c), which are normalized to their values at 300 K. The error bars in \({\mu }_{{{\rm{H}}}}\), \(S\) and \(\nu\) were determined from the uncertainty in the extraction of the electromotive force and represent one standard deviation. The error bars in \(\sigma\) were determined from the uncertainty in the film thickness measurements and represent one standard deviation. e Plot of Nernst coefficients \(\nu\) versus \({\mu }_{{{\rm{H}}}}T/{T}_{{{\rm{F}}}}\) for different polymers, bismuth, and graphene measured in this work at 300 K and various other materials reported in literature. \({T}_{{{\rm{F}}}}\) is the material Fermi temperature. The dashed black line represents the theoretical relationship predicted in the framework of FL theory. The presented polymer data points are located at the top-left area, denoted by various solid symbols with different colors, and largely deviate from the FL line, while the bismuth and graphene data points are denoted as brown solid diamonds and qualitatively follow the FL line. The \(\nu\), \({\mu }_{{{\rm{H}}}}\), and \({T}_{{{\rm{F}}}}\) of IEX-doped PBTTT were measured independently at the University of Cambridge (blue-green solid diamond), while the measurements of FeCl₃-doped PBTTT and other materials were performed at ICCAS. The direction of the orange arrow indicates the increasing FeCl₃ doping concentration of PBTTT. The green data points represent materials with the Nernst effect reported near or at room temperature. The Nernst effect of materials represented by purple points and WS₂ are reported at low temperatures. The detail information of \(\nu\), \({\mu }_{{{\rm{H}}}}\), \(T,\) and \({T}_{{{\rm{F}}}}\) for the data points shown are summarized in Supplementary Table 3. Source data are provided as a Source Data file.