Poly­(3,4-ethylenedioxythiophene) (PEDOT) is certainly the most known and most used conductive polymer because it is commercially available and shows great potential for organic electronic, photovoltaic, and thermoelectric applications. Studies dedicated to PEDOT films have led to high conductivity enhancements. However, an exhaustive understanding of the mechanisms governing such enhancement is still lacking, hindered by the semicrystalline nature of the material itself. In this article, we report the development of highly conductive PEDOT films by controlling the crystallization of the PEDOT chains and by a subsequent dopant engineering approach using iron­(III) trifluoromethanesulfonate as oxidant, N-methyl pyrrolidone as polymerization rate controller and sulfuric acid as dopant. XRD, HRTEM, Synchrotron GIWAXS analyses and conductivity measurements down to 3 K allowed us to unravel the organization, doping, and transport mechanism of these highly conductive PEDOT materials. N-methyl pyrrolidone promotes bigger crystallites and structure enhancement during polymerization, whereas sulfuric acid treatment allows the replacement of triflate anions by hydrogenosulfate and increases the charge carrier concentration. We finally propose a charge transport model that fully corroborates our experimental observations. These polymers exhibit conductivities up to 5400 S cm–1 and thus show great promise for room temperature thermoelectric applications or ITO alternative for transparent electrodes.

Controlled substitutional doping of two-dimensional transition-metal dichalcogenides (TMDs) is of fundamental importance for their applications in electronics and optoelectronics. However, achieving p-type conductivity in MoS2 and WS2 is challenging because of their natural tendency to form n-type vacancy defects. Here, we report versatile growth of p-type monolayer WS2 by liquid-phase mixing of a host tungsten source and niobium dopant. We show that crystallites of WS2 with different concentrations of substitutionally doped Nb up to 1014 cm–2 can be grown by reacting solution-deposited precursor film with sulfur vapor at 850 °C, reflecting the good miscibility of the precursors in the liquid phase. Atomic-resolution characterization with aberration-corrected scanning transmission electron microscopy reveals that the Nb concentration along the outer edge region of the flakes increases consistently with the molar concentration of Nb in the precursor solution. We further demonstrate that ambipolar field-effect transistors can be fabricated based on Nb-doped monolayer WS2.