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Abstract Charge transport in electrostatically doped poly[benzimidazobenzophenanthroline]‐BBL thin films in a field‐effect transistor geometry were investigated in the temperature range 150 K < T < 370 K. At low temperatures activation and hopping transport mechanisms dominated, while phonon scattering dominated at high temperatures. The activation energies (E_A) were found to lie in the range 140 meV < E_A < 400 meV implying the existence of deep traps within the polymer bandgap of 1.8 eV. Two quasi‐linear dependencies ofE_Aon the gate voltage (V_g) were observed withE_Adecreasing asV_gincreased. An unexpected “metallic‐like” transport characteristic appeared forT > 335 K which depended onV_g. Enhanced electron delocalization combined with increased carrier density could be responsible for this “metallic‐like” behavior. Our results show that the existence of deep traps with multiple energy distributions, combined with increased carrier density led to the unusual temperature dependence of charge transport observed in BBL. 

Abstract A poly(triaryl amine) thin film field effect transistor was investigated in air with ionic liquid (IL) gating for the first time. The transistor retained a high‐on/off ratio of ~700 and mobility of ~10⁻²cm²/V‐s. When compared to a transistor based on the conducting polymer polyaniline under similar operating conditions, it was found to exhibit superior performance. Significantly low‐operating voltages (±1 V) enhances the possibility of its use in organic electronics. The device was successfully tested for binary operation, and we demonstrate its suitability for use in low‐power consumption electronic circuits. 

Charge transport in ferroelectric (FE) gated graphene far from the Dirac point (DP) was studied in the temperature range 300 K < T < 350 K. A non-monotonic/monotonic/non-monotonic behavior in the conductivity [σ(T)] was observed as one moved away from the DP. As the gate polarization increased, additional impurity charges were compensated, which reduced charge scattering. The uncompensated charges doped graphene and σ(T) switched to a monotonic increase with increasing T. However, far from the DP, the polarization reached saturation, which resulted in still lower impurity charge scattering. The carrier concentration increased, and a non-monotonic response in σ(T) reappeared, which was attributed to phonon scattering. A theoretical model is presented that combined impurity charge and phonon scattering conduction mechanisms. The top gate polarizable FE provided a novel approach to investigate charge transport in graphene via controlled compensation of impurity charges, and in the process revealed non-monotonic behavior in σ(T) not previously seen in SiO2 back gated graphene devices. 

Charge transport near the Dirac point (DP) was investigated in graphene using ferroelectric (FE) gating in the temperature range of 300 < T < 350 K. We observed that the conductivity (σ) near the DP had a positive temperature gradient that switched to a negative temperature gradient with increasing temperature. The switch to a negative temperature gradient shifted to higher temperatures and gradually weakened upon moving away from the DP. Impurity charge compensation via polarization of the FE together with a temperature-dependent graphene–impurity charge separation was proposed as being responsible for the non-monotonicity in σ(T). A self-consistent theory for graphene transport with impurity charge scattering and phonon scattering was used to analyze the results. Non-monotonic charge transport was also observed in the temperature dependence of the residual conductivity (σr). Theoretical analysis of both σ and σr revealed a temperature independent contribution of ∼1.16e2h that is probably inherent to pristine graphene. 

A diode is fabricated using poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT‐PSS) and n‐doped Si. Using an ionic liquid (IL) gel as the gate dielectric, the diode rectification ratio is tunable up to four orders of magnitude at very low operating voltages. Both p–n and Schottky type diodes are observed in the same device depending on the polarity of the gate voltage. IL‐gated electrostatic/electrochemical doping in PEDOT‐PSS is believed to be responsible for this switch. The turn‐on voltage in the first quadrant of the current–voltage (I–V) curve for the p–n diode is in the range 0.2–0.4 V. The Schottky diode operates in the third quadrant. This is the first report on a tunable diode using an IL to control its operation, and the low operating voltages make these diodes excellent candidates for use in reduced power consumption electronics.