This entry contains the research data supporting the article "Non-equilibrium transport in polymer mixed ionic-electronic conductors at ultra-high charge densities". The repository version of the article is available at https://www.repository.cam.ac.uk/handle/1810/369592.

Included in the dataset are charge transport, spectroscopic, and theoretical characterisation of the polymers IDT-BT, DPP-BTz, and PBTTT.

This entry comprises a main zip file containing 15 files, each corresponding to a Figure or an Extended Data Figure in the article. The main zip file shall be decompressed to obtain access to the 15 underlying files. The data that is contained in each file is summarised below:

Figure 1.xlsx - OECT transfer curve of IDT-BT, temperature dependent of an IDT-BT OECT, and the corresponding Seebeck coefficient - conductivity plot. The data can be accessed in Microsoft Excel.

Figure 2.xlsx - double-gated transfer curves of IDT-BT at various doping states, and the 19F nuclear spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) vs temperature obtained from 19F NMR experiments of IDT-BT doped with TFSI. The data can be accessed in Microsoft Excel.

Figure 3.tgz - results of 2D Hubbard model calculations of doped IDT-BT. Upon decompressing the .tgz file, a MATLAB script "fig3_theory.m" is available which can be used to plot Figure 3 (as it appears in the article) from the underlying .dat files, which could also be found in the .tgz entry.

Figure 4.zip - charge modulation spectroscopy of doped IDT-BT. Upon decompressing the .zip file, a MATLAB script "Processing.m" is available which can be used to plot Figure 4 (as it appears in the article) from the underlying .csv files, which could also be found in the .zip entry.

Figure 5.xlsx - Seebeck measurements of double-gated IDT-BT transistors, with the corresponding double-gated transfer curve. The data can be accessed in Microsoft Excel.

Extended Data Figure 1 - S2p X-ray photoemission spectra of IDT-BT, DPP-BTz, and PBTTT as a function of doping level. Three .xlsx files have been uploaded (Extended Data Figure 1 - PBTTT.xlsx, Extended Data Figure 1 - DPPBTz.xlsx, and Extended Data Figure 1 - IDTBT.xlsx). The data can be accessed in Microsoft Excel.

Extended Data Figure 2.xlsx - Ultraviolet photoemission spectra of IDT-BT, DPP-BTz, and PBTTT as a function of doping level. The data can be accessed in Microsoft Excel.

Extended Data Figure 3.xlsx - cyclic voltammogram and the corresponding conductivity at various doping stages of PBTTT, DPP-BTz, and IDT-BT. The data can be accessed in Microsoft Excel.

Extended Data Figure 4.xlsx - UV-Vis-NIR and FTIR spectra of ion-gated IDT-BT. The data can be accessed in Microsoft Excel.

Extended Data Figure 5.xlsx - electron spin resonance spectroscopy of ion-gated IDT-BT, i.e. total paramagnetic susceptibility, Curie and Pauli components of paramagnetic susceptibility, and the associated device OECT transfer curve. The data can be accessed in Microsoft Excel.

Extended Data Figure 6.xlsx - OECT transfer curves of other polymer/ion combinations allowing access to Regime III. The data can be accessed in Microsoft Excel.

Extended Data Figure 7.xlsx - OECT transfer curve and temperature dependence of Seebeck coefficient of PBTTT and DPP-BTz. The data can be accessed in Microsoft Excel.

Extended Data Figure 8.zip - density functional theory band structure and density of states of PBTTT, DPP-BTz, and IDT-BT. Upon decompressing the .zip file, three folders are available corresponding to the three polymers. In each folder a MATLAB .m script can then be used to generate the figures in panels a, b, and c from the underlying .dat files, which have also been uploaded in the .zip entry.

Extended Data Figure 9.xlsx - field-effect mobilities extracted from the symmetric and anti-symmetric components of double-gated IDT-BT transfer curves. The data can be accessed in Microsoft Excel.

Extended Data Figure 10.xlsx - double-gated transfer curves of PBTTT and DPP-BTz, and the corresponding symmetric and anti-symmetric mobilities. The data can be accessed in Microsoft Excel.