Fig. 1. (Color online) Description of dopants and OSCs. The molecular structure of (a) dopant DPI-TPFB and (b) OSC PBBT-2T. The performance characterization of OFETs based on PBBT-2T, (c) transfer characteristics and (d) output characteristics.

Fig. 2. (Color online) Characterization of DPI-TPFB doping effect. (a) The UV−vis−NIR absorption spectra of doped PBBT-2T solutions at varying doping ratios (the molar ratio specifies the molar proportion of the dopant to the polymer monomer). (b) The polaron absorption peak intensities (at 1700 nm, i.e., 0.73 eV) of DPI-TPFB doped PBBT-2T solutions with increasing doping ratios. (c) The ESR spectra of DPI-TPFB doped PBBT-2T films. (d) The polaron generation efficiency of DPI-TPFB doped PBBT-2T films extracted from ESR spectra.

Fig. 3. (Color online) Characterize the properties of doped PBBT-2T films. (a) The Schematic diagram of the device structure used for measuring the electrical conductivity of doped films by the four-point probe method. (b) The electrical conductivity of PBBT-2T films dependent on doping ratios. (c) The work function of PBBT-2T films dependent on the doping ratios.

Fig. 4. (Color online) Characterize the morphology of PBBT-2T films. The AFM morphology of PBBT-2T films (the scanning range is 5 × 5 μm²). (a) pristine, (b) 10 mol%, (c) 30 mol%, (d) 50 mol%, (e) 70 mol%, and (f) 100 mol% DPI-TPFB-doped PBBT-2T films.

Fig. 5. (Color online) Assessing the broad doping applicability of DPI-TPFB in OSCs. (a) The molecular structure of P3HT and N2200. (b) The ESR spectra of pristine P3HT and doped P3HT films doped by DPI-TPFB. (c) The electrical conductivity of P3HT films dependent on doping ratios. (d) The ESR spectra of pristine N2200 and doped N2200 films doped by DPI-TPFB. The transfer characteristics of OFETs with BGBC structure (as shown in the illustration) in the saturation region, (e) pristine N2200 and (f) N2200 films doped with DPI-TPFB.

Fig. 6. (Color online) Characterization of thermoelectric performance of DPI-TPFB-doped PBBT-2T. (a) The schematic diagram of the structure of the thermoelectric device. (b) The thermoelectric potential difference of PBBT-2T films dependent on the temperature difference at different doping ratios. (c) The electrical conductivity, Seebeck coefficient, and power factor of DPI-TPFB-doped PBBT-2T films as a function of doping ratios. (d) The relationship between Seebeck coefficient and electrical conductivity for DPI-TPFB-doped PBBT-2T films.