Organic Field‐Effect Transistors based on Highly Ordered Single Polymer Fibers

Abstract

Ultrahigh-mobility organic field-effect transistors (OFETs) based on a CDT-BTZ donor-acceptor copolymer are realized by reaching high molecular order and pronounced alignment in single fibers within a short OFET channel via solution processing. The macromolecules directionally self-assemble in a quasi crystal-like order in the fibers providing in this way an unhindered charge carrier pathway with mobilities as high as 5.5 cm(2) V(-1) s(-1).

Structure and Morphology Control in Thin Films of Conjugated Polymers for an Improved Charge Transport

“…These micro-sized crystals display diffraction dots in selected area electron diffraction (SAED) patterns, indicating the single crystal nature of them as the most thermodynamic stable state of chains proven also by the unchanged crystalline structures and morphology for crystals after thermal annealing [76]. With the perfect order in crystals and proper orientation of chains, the carrier mobilities in these crystals were very high [73,78,167,170] According to the discussions above, a scheme for optimizing the solution state is proposed as subsequent disentanglement, promotion of both coil-to-rod transition and rod-to-rod stacking following, and tuning the nucleation-growth process. Combining all these strategy into a systematic program for tuning ordered aggregation of conjugated polymers for charge transport in solution will be helpful for the straight processing of solution to prepare efficient film devices.…”

“…However, a too slow evaporation of solvent by drop-casting resulted in the fusing of fibrils again, indicating the nature of a favored kinetic equilibrium state for dispersed long fibrils (Figure 23c). Compared with the nanofibril morphology in nanoscale obtained by "slow" spin-coating, a much slower evaporation rate of solvent in a sealed room helps the formation of crystals with larger sizes in micro scale [73,74,78,[167][168][169][170]. Apart from extremely slow evaporation, factors such as the properties of substrate [167], temperature [73,167], solution concentration (<1.0 mg/mL) and solvent composition [74] are related to the formation of micro-sized crystals in films.…”

Solid-State Organization and Ambipolar Field-Effect Transistors of Benzothiadiazole-Cyclopentadithiophene Copolymer with Long Branched Alkyl Side Chains

“…This property can be realized by low-bandgap donor-acceptor copolymers, being also highly attractive for solar cells, due to their broad light absorption profiles, and have revealed high ambipolar mobilities over 1 cm²/Vs for both charge-carrier species [12]. In this context, benzothiadiazole-cyclopentadithiophene (CDT-BTZ) copolymers are one promising type of polymer leading to ultrahigh hole mobilities up to 5.5 cm²/Vs (in single-fiber FETs) when substituted with linear alkyl side chains and possessing higher molecular weight fractions [13,14]. It has to be noted that despite the relatively low bandgap of these derivatives of around 1.8 eV, only a unipolar hole transport was observed in standard device architectures (Au electrodes and hexamethyldisilazane (HMDS)-treated SiO 2 surface).…”

Unprecedented High Local Charge-carrier Mobility in P3HT Revealed by Direct and Alternating Current Methods

“…High charge-carrier mobilities of conjugated polymers have been demonstrated by using a direct current method represented by FET device characterization, 11 with observation of a pronounced dependence of the mobility not only on the choice of materials but also on the device structures, 12 surface modification, 13 and processing conditions.…”