Novel Polymer Nanowire Crystals of Diketopyrrolopyrrole‐Based Copolymer with Excellent Charge Transport Properties

Abstract

The first demonstration of polymer nanowire (PNW) crystals based on a diketopyrrolopyrrole-based copolymer (i.e., PDTTDPP), and their application to field-effect transistors (FETs) is reported. Remarkably, transmission electron microscopy and selected area electron diffraction analyses of the PNW reveal its single-crystalline (SC) nature. FETs fabricated of a SC PNW exhibit a maximal charge carrier mobility of ≈7.00 cm(2) V(-1) s(-1) , which is almost one order of magnitude higher than that of the thin-film transistors made of the same polymer (PDTTDPP).

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.…”

“…Due to the difficulty of unfolding chains to a totally extended conformation, there are few examples of preparing conjugated polymer single crystals under strict conditions like concise temperatures, extremely slow evaporation and/or specific substrates, etc. [73][74][75][76][77][78]. Thirdly, according to Einstein-Stokes Equation, D = K B T/6πηa, the diffusion coefficient (D) is inverse to the sizes of moving unit (a) in solutions.…”

Organic Semiconductor Single Crystals for Electronics and Photonics

“…In fact, the fabrication of highly ordered conjugated polymer solid structures is imperative for a fundamental understanding of charge‐transport and other physical properties of polymeric optoelectronics as well as for achieving intrinsically high charge‐carrier mobility and unique optical features for high‐performance polymeric electronic and photonic devices . Recent advances have shown the promise of achieving 1D single‐crystalline structures from some typical conjugated polymers, such as poly(3‐hexylthiophene) (P3HT), poly(paraphenylene ethynylene) (PPE) and donor–acceptor copolymers, through carefully optimizing the solution‐processing conditions. However, the crystals obtained from solutions of these crystalline conjugated polymers are relatively poor, which limits further investigation, for example, into their anisotropic properties .…”

High Aspect Ratio Conjugated Polymer Nanowires for High Performance Field-Effect Transistors and Phototransistors

“…34 However, this polymer showed a relatively poor ability to form NWs, which were limited to short lengths. Furthermore, the corresponding SC-PNW FET exhibited a lower charge carrier mobility than we expected.…”