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A low-band gap semiconducting polymer with an acceptor-donor-acceptor architecture is newly designed and synthesized by incorporating a π-extended thiazole-vinylene-thiazole unit. The resulting thiazole-containing diketopyrrolopyrrole copolymer exhibits well-balanced ambipolar characteristics with hole mobility of up to 0.11 cm 2 V -1 s -1 and electron mobility of up to 0.30 cm 2 V -1 s -1 , which are suitable for applications in polymer electronics., (© 2021 Wiley-VCH GmbH.)

Research into printing techniques has received special attention for the commercialization of cost-efficient organic electronics. Here, we have developed a capillary pen printing technique to realize a large-area pattern array of organic transistors and systematically investigated self-organization behavior of printed soluble organic semiconductor ink. The capillary pen-printed deposits of organic semiconductor, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS_PEN), was well-optimized in terms of morphological and microstructural properties by using ink with mixed solvents of chlorobenzene (CB) and 1,2-dichlorobenzene (DCB). Especially, a 1:1 solvent ratio results in the best transistor performances. This result is attributed to the unique evaporation characteristics of the TIPS_PEN deposits where fast evaporation of CB induces a morphological evolution at the initial printed position, and the remaining DCB with slow evaporation rate offers a favorable crystal evolution at the pinned position. Finally, a large-area transistor array was facilely fabricated by drawing organic electrodes and active layers with a versatile capillary pen. Our approach provides an efficient printing technique for fabricating large-area arrays of organic electronics and further suggests a methodology to enhance their performances by microstructural control of the printed organic semiconducting deposits.

Application‐oriented patterned growth of organic semiconductor (OSC) thin films with single crystalline domains is crucial for fabricating sophisticated high‐performance organic‐electronic and optoelectronic devices; however, fabricating these patterned nanometer‐thick crystals in a simple, fast, and effective manner is a difficult task with a roll‐to‐roll printing process. Here, a simple bar‐coating approach to form an array of single‐crystal‐like OSC thin‐film patterns at a rate of a few millimeters per second is introduced. To this end, the processing parameters of a gap‐controlled bar‐coating method is optimized, including coating speed, crystal nucleation, and solution fluidics, which allow a high degree of morphological control of bar‐coated OSC films in an area of several centimeters. In particular, it is demonstrated that the solutal‐Marangoni flow induced by a suitable solvent additive can considerably improve molecular mass transport and induce favorable vertical phase separation. Thus, organic transistors based on the OSC patterns fabricated with the additive‐assisted bar coating show a field‐effect mobility of up to 20 cm2 V−1 s−1 and superior operational stability. The proposed bar coating method will facilitate an industry‐level application of organic electronics. [ABSTRACT FROM AUTHOR]

A polymer blend is an essential member of a class of materials analogous to metal alloys, in which two polymers are blended together to create a noble material with different physical properties. Not only the physicochemical properties of each polymer but also their relative interaction and miscibility are a key to eliciting novel materials properties. Here, we investigated the effects of blending a flexible coil-type insulating polymer on the charge transport characteristics of rigid planar semiconducting polymers. To this end, we systematically controlled the blending ratio of the commercial insulating polymer, polystyrene, and one of two different diketopyrrolopyrrole-based donor-acceptor alternating copolymers, and characterized the electrical, microstructural, and morphological properties of the semiconductor–insulator polymer blend films. We found that the electrical properties of the films are strongly correlated with the polymer blend ratio and the resulting films' vertical segregation and crystalline structures and that hole transport and electron transport alter differently with the polymer backbone structure and blend ratio. These results are expected to be greatly helpful in optimizing the semiconductor–insulator polymer ink formulations for potential use in printed electronics. [Display omitted] • A comparative study on charge transport and structural properties of polymer blends comprising a flexible coil-type insulating polymer and a rigid planar semiconducting copolymer. • The charge transport properties are strongly correlated with the polymer blend ratio, annealing temperature, and polymer backbone structure. • The change of hole and electron transport properties depends sensitively on the chemical structure of the semiconducting polymer and blend ratio. [ABSTRACT FROM AUTHOR]

Understanding the microstructuresof semiconducting polymers iscritical for improving the charge transport properties of polymerfield-effect transistors (PFETs). A series of diketopyrrolopyrrole-basedcopolymers designed by implementing the concept of intramolecularnoncovalent conformational locks through the functionalization ofpolymer backbones with fluorine atoms or methoxy groups were synthesizedand compared with their unfunctionalized analogue. In contrast tothe bimodal texture of the unfunctionalized polymer, the thin filmsof the polymer with fluorine atoms exhibit predominantly edge-on texturewith much improved crystalline ordering. The thin films of the polymermodified with methoxy groups have a principally face-on texture. Thesedramatic differences in thin-film texture can be correlated with thepolymers’ solubilities. Furthermore, the improved crystallineordering of these semiconductor polymers enables the fabrication ofhigh-performance PFETs: the hole mobility of the methoxy-modifiedpolymer is reduced by half with respect to that of the unmodifiedpolymer, whereas the hole mobility values of the fluorine-modifiedpolymer are up to ∼6 times higher, approximately 1.32 cm2V–1s–1, and exhibitpronounced thermal stability. These results provide new guidelinesfor the molecular design of semiconducting polymers with noncovalentconformational locks. [ABSTRACT FROM AUTHOR]

Bar coating, organic semiconductors, organic transistors, semiconductor blend, single crystal, solutal-Marangoni flow The use of an appropriate solvent additive enhances molecular mass transport and induces vertical phase separation between a small-molecule semiconductor and a polymeric semiconductor. Keywords: bar coating; organic semiconductors; organic transistors; semiconductor blend; single crystal; solutal-Marangoni flow EN bar coating organic semiconductors organic transistors semiconductor blend single crystal solutal-Marangoni flow 1 1 1 07/10/21 20210709 NES 210709 In article number 2100196, Boseok Kang, Kilwon Cho, and co-workers report a novel bar-coating approach using a solutal-Marangoni flow to form an array of single-crystal-like organic semiconductor thin-film patterns at a high rate in a consecutive manner. [Extracted from the article]