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Large area and highly aligned polymer semiconductor sub-microwires were fabricated using the coaxial focused electrohydrodynamic jet printing technology. As indicated by the results, the sub-microwire arrays have smooth morphology, well reproducibility and controllable with a width of ~110 nm. Analysis shows that the molecular chains inside the sub-microwires mainly exhibited edge-on arrangement and the π-stacking direction (010) of the majority of crystals is parallel to the long axis of the sub-microwires. Sub-microwires based organic field effect transistors showed high mobility with an average of 1.9 cm2 V−1 s−1, approximately 5 times higher than that of thin film based organic field effect transistors. In addition, the number of sub-microwires can be conveniently controlled by the printing technique, which can subsequently concisely control the performance of organic field effect transistors. This work demonstrates that sub-microwires fabricated by the coaxial focused electrohydrodynamic jet printing technology create an alternative path for the applications of high-performance organic flexible device. Here, the authors fabricate large area and highly aligned polymer semiconductor sub-microwires arrays via coaxial focused electrohydrodynamic jet printing technology, achieving high on/off ratio and average mobility that is 5x higher than that of thin film based organic field effect transistors. [ABSTRACT FROM AUTHOR]

Ambipolar polymer semiconductors are potentially serviceable for logic circuits, light-emitting field-effect transistors (LFETs) and polymer solar cells (PSCs). Although several high-performance ambipolar polymers have been developed, their optoelectronic devices are generally processed from toxic chlorinated solvents. To achieve the commercial applications of organic FETs (OFETs), the polymers should be processed from nonchlorinated solvents, instead of chlorinated solvents. However, most conjugated polymers show poor solubility in nonchlorinated solvents. It is of great importance to develop ambipolar polymers that can be processed from nonchlorinated solvents. Here, we develop a nonchlorinated solvent processed polymer named poly[7-fluoro-N, N′-di(4-decyltetradecyl)-7′-azaisoindigo-6′,6″-(thieno[3,2-b]thiophene-2,5-diyl)-7‴-fluoro-N″, N‴-di(4-decyltetradecyl)-7″-azaisoindigo-6,6‴-([2,2″-bithiophene]-5,5″-diyl)] (PITTI-BT) by designing a monomer with a large molar mass. The polymer displays good solubility in p-xylene (PX). Well-aligned films of PITTI-BT are achieved by an off-center spin-coating (SC) method. Based on the high-quality films, the OFETs fabricated from PX solution achieve record ambipolar performance with hole and electron mobilities of 3.06 and 2.81 cm2 V−1 s−1, respectively. The combination of nonchlorinated solvents and good alignment process offers an effective and eco-friendly approach to obtain high-performance ambipolar transistors. [ABSTRACT FROM AUTHOR]

Benzopyrazinoisoindigo, a pigment reported 40 years ago, should be a good candidate for n-type semiconductors if the reported structure is correct. Reinvestigation of this molecule revealed that it is actually (4 H,4′ H)-benzopyrazinoisoindigo, which could be considered as the reduced form of benzopyrazinoisoindigo, and hence, it is a good candidate for p-type semiconductors. The route toward the synthesis of this molecule was optimized, and a mechanism was accordingly proposed. A field-effect transistor based on this material showed a hole mobility up to 2.5 × 10-2 cm2 V-1 s-1. [ABSTRACT FROM AUTHOR]

Abstract Organic field-effect transistors (OFETs) have received significant interest due to potential applications from low-cost active circuit to wearable health care devices. Organic semiconductors as one of the key components in OFETs have drawn great attentions during last decades. Among them, antiaromatic and quinoidal materials have become the most intensively studied semiconductors. Therefore, this review describes the chemical structures and efficiency characteristics of π-conjugated materials through antiaromaticity and quinoid strategy for OFETs. In addition, rational designs and synthetic methods for these materials will be summarized, and a practical guideline for accelerating the development of high-performance semiconducting materials and devices will be provided. [ABSTRACT FROM AUTHOR]

Ambipolar field-effect transistors based on polymer semiconductors facilitate the convenient fabrication of low-power complementary organic circuits. However, the species of ambipolar polymer semiconductors are limited; the design and synthesis strategies are scarce. This work demonstrated that bisthiophene-fused diketopyrrolopyrrole (DPPFu) was a wonderful building unit for ambipolar polymer semiconductors. Ambipolar polymer semiconductors could be obtained by copolymerizing DPPFu with both electron-deficient comonomers and electron-rich comonomers. P(DPPFu-T), P(DPPFu-TT) and P(DPPFu-BT) were synthesized by copolymerizing DPPFu with thiophene, thienothiophene and benzothiadiazole, respectively. The structural variation of comonomers allowed for a systematic study on the relationship between comonomer structure, frontier orbital energy level, orbital delocalization index, molecular packing, film morphology and the corresponding charge transport properties. Thienothiophene endowed P(DPPFu-TT) with maximum orientation of edge-on packing. The considerable delocalization extent of the lowest unoccupied molecular orbitals (LUMOs) for P(DPPFu-T) and P(DPPFu-TT) resulted in pronounced electron transport property. P(DPPFu-TT) displayed the best charge transport property with hole mobility up to about 0.1 cm2V−1s−1 and electron mobility of 7.5 × 10−2 cm2V−1s−1. P(DPPFu-BT) showed ideally balanced charge carrier mobilities for both holes and electrons of 1.6 × 10−2 cm2V−1s−1 and 1.7 × 10−2 cm2V−1s−1, respectively. Ion/Ioff ratios of all the ambipolar polymers were above 103. The ambipolarity of polymer semiconductors was related to not only push-pull electronic characteristics of comonomers, but also the planarity of polymer backbones and delocalization extent of frontier orbitals. Overall, this study provides valuable insights into the design and synthesis of ambipolar polymer semiconductors, which is crucial for the advancement of low-power complementary organic circuits. All the polymer semiconductors exhibited prominent ambipolar charge transport property. P(DPPFu-TT) displayed the best charge transport property and P(DPPFu-BT) showed ideally balanced charge carrier mobilities for both holes and electrons. Relationships between comonomer structure, frontier orbital energy level, orbital delocalization index, molecular packing, film morphology and the corresponding charge transport properties were investigated systematically. [Display omitted] • A series of ambipolar polymer semiconductors based on DPPFu were designed and successfully synthesized. • DFT calculations were employed to predict the physical characteristics of the ambipolar polymer semiconductors • Relationships between molecular packing, film morphology and charge transport properties were investigated systematically. • The hole and electron mobility of P(DPPFu-TT) were found to reach approximately 0.1 and 7.5×10-2 cm2V–1s–1, respectively. [ABSTRACT FROM AUTHOR]

Two structural isomers of six-fused-ring sulfur-containing molecules were synthesized as active materials for p-type organic field-effect transistors, and their optical and electrochemical properties were characterized. Field-effect transistors based on these compounds were fabricated to investigate the relationships between structures and semiconductor properties. [ABSTRACT FROM AUTHOR]