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The electrolysis of aromatic molecules is a useful method for the synthesis and deposition of conducting polymers. However, this method cannot be applied to diverse large‐area electronic devices because films grow vertically on the surface of an electrically connected working electrode. Herein, the remote‐controllable lateral electropolymerization of 3,4‐ethylenedioxythiophene using direct‐current voltage superimposed alternating‐current voltage (ADC)‐bipolar electrochemistry is reported. The use of shape‐designed dual bipolar electrodes and systematic optimization of the process parameters led to the fabrication of uniform poly(3,4‐ethylenedioxythiophene) (PEDOT) films on 2‐inch glass wafers and flexible plastic substrates. The oxidation levels and microstructures of ADC‐electropolymerized PEDOTs with various supporting electrolytes are investigated and correlated with their thermoelectric properties. A soft thermocouple and resistive‐type gas sensor based on an ADC‐electrodeposited PEDOT are demonstrated to monitor cerebral temperature in a brain replica and to sense nitrogen dioxide gas, respectively. [ABSTRACT FROM AUTHOR]

Due to their inherent flexibility, solution-processable conjugated polymers are increasingly being considered for the cost-effective production of thin-film semiconductor devices used in Internet of Everything (IoE) applications. With considerable improvements in charge carrier mobilities, the final challenge impeding the commercialization of conjugated polymers may be improving their environmental and electrical stabilities. Recent studies have improved the stability of computing devices (i.e., transistors) by eliminating interface traps and water molecules within conjugated polymers. However, the stability issue of Schottky diodes, which play a crucial role in configuring thin-film IoE devices used in wireless communication and energy harvesting, has been largely overlooked. This study reveals that aluminum, which is commonly used as a cathode metal in polymer Schottky diodes, creates a nonstoichiometric effect when deposited on conjugated polymers, thereby leading to the formation of charge traps over time, which reduces the rectification ratio of the Schottky diodes and induces a significant bias stress effect during operation. To address this issue, we introduce a zinc-oxide sacrificial interlayer between the conjugated polymer and cathode. This interlayer effectively eliminates the penetrated Al metal or ionized Al-induced nonstoichiometric effect without reducing the charge injection efficiency, achieving exceptional environmental and operational stability. The printed polymer Schottky diodes demonstrate consistent rectifying operation at 13.56 MHz for several months with negligible changes in electrical characteristics. [ABSTRACT FROM AUTHOR]

Rubbing‐induced alignment of conjugated polymers is systematically investigated in terms of intra‐ and inter‐molecular interaction. Various polymer films with a broad range of polymer chain rigidity are rubbed, and the degree of polymer chain alignment is quantitatively characterized. The rubbing technique effectively aligns crystalline domains in conjugated polymer films when the temperature approaches the critical rubbing temperature (Trc$T_{\mathrm{r}}^{\mathrm{c}}$), at which the rearrangement and the slip of polymer chains are possible. A polymer with significant intra‐/inter‐molecular interactions exhibits higher Trc$T_{\mathrm{r}}^{\mathrm{c}}$, though quantitative analysis reveals an intermediately aligned state at temperature Tr′ lower than Trc$T_{\mathrm{r}}^{\mathrm{c}}$. This state originates from polymer chain aggregation in an amorphous domain. The intermediately aligned state can be controlled by plasticizer, which enables low‐temperature alignment of high‐mobility polymer film by reducing Tr′ to near 100 °C, increases the crystallinity, and improves the alignment effect at this state comparable to that of the completely aligned state obtained at extremely high temperatures. [ABSTRACT FROM AUTHOR]

In recent years, ionic liquid (IL)‐based solid polymer electrolytes (SPEs) have attracted much attention as conducting or capacitive materials for stretchable electronics. To fabricate fast and mechanically robust electronic devices, the high ionic conductivity and high elastic toughness of the SPE are essential. However, it has been challenging to achieve both high ionic conductivity and high elastic toughness simultaneously because high ionic conductivity generally requires low crystallinity of the polymer chains. Herein, a facile strategy for fabricating highly conductive, mechanically robust, and thermally stable SPE is demonstrated. A glass fiber mesh and La0.57Li0.29TiO3 particles as dual‐supporters are introduced, and 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) and bis(trifluoromethylsulfonyl)amine lithium salt (LiTFSI) (having the same anion) as the dual salt in the polymer electrolyte is introduced. Consequently, the SPE exhibits a superior ionic conductivity of 2.4 × 10−2 S cm−1 at room temperature and an outstanding elastic toughness of ≈170.3 kJ m−2. Finally, the dual‐salt/dual‐supporter SPE is successfully applied to high‐performance organic electrolyte‐gated transistors as gate dielectric materials and highly sensitive capacitive pressure sensors as force‐sensitive dielectric layers. [ABSTRACT FROM AUTHOR]

To impart high stretchability to semiconducting polymers, researchers have used a photocrosslinking approach based on the nitrene chemistry of an azide‐incorporated molecular additive. However, understanding of the molecular design of azide crosslinkers with respect to their effects on the electrical and mechanical properties of semiconducting polymer thin films is lacking. In this study, the effects of an azide photocrosslinker's molecular length and structure on the microstructural, electrical features, and stretchability of photocrosslinked conjugated polymer films is investigated. For a systematic comparison, a series of nitrene‐induced photocrosslinkers (n‐NIPSs) with different numbers of ethylene glycol repeating units (n = 1, 4, 8, 13) that bridge two tetrafluoro‐aryl azide end groups is synthesized. Two semicrystalline conjugated polymers and two nearly amorphous conjugated polymers are co‐processed with n‐NIPSs and crosslinked by brief exposure to UV light. It is found that, among the synthesized n‐NIPSs, the shortest one (1‐NIPS) is the most efficient in improving the stretchability of crosslinked indacenodithiophene‐benzothiadiazole films and that the improvement is achieved only with nearly amorphous polymers, not with semicrystalline conjugated polymers. On the basis of systematic studies, it is suggested that crosslinking density in amorphous regions is important in improving thin film stretchability. [ABSTRACT FROM AUTHOR]

Conducting polymers are of interest for a broad range of applications from bioelectronics to thermoelectrics. The factors that govern their complex charge transport physics include the structural disorder present in these highly doped polymer films and the Coulombic interactions between the electronic charge carriers and the dopant counterions. Previous studies have shown that at low doping levels carriers are strongly trapped in the vicinity of the counterions, while at high doping levels charge transport is not limited by Coulombic trapping, which manifests itself in the conductivity being independent of the size of the dopant counterion. Here a recently developed ion exchange doping method is used to investigate the ion size dependence of a semicrystalline polythiophene‐based model system across a wide range of conductivities. It is found that the regime in which the charge and thermoelectric transport is not or only weakly dependent on ion size, extends to surprisingly low conductivities. This surprising observation is explained by a heterogeneous doping that involves doping of the amorphous domains to high doping levels first before doping of the ordered, crystalline domains occurs. The study provides new insights into how the thermoelectric physics of conducting polymers evolves as a function of doping level. [ABSTRACT FROM AUTHOR]

The field of polymer‐based nanoscience has always been of significant interest in the search for polymer/carbon nanotube (CNT) nanocomposites with optimized material properties for new applications. Herein, it is demonstrated that data collected from the online literature can be used to develop an efficient deep learning model to design acrylonitrile–butadiene–styrene (ABS)/CNT binary composites. A dataset of 14 945 data points is constructed from 110 studies. The results demonstrate that compared with a vanilla deep regression model, the proposed model achieves a 26% lower average mean absolute error and an accuracy of 80.6%, which is 16.2% higher than the vanilla deep regression model in predicting the six electrical and mechanical properties of target ABS/CNT composites. In addition, a Monte Carlo simulation integrated with the developed deep neural network (DNN) model effectively screens input variables for users and thus appropriately guides them to manufacture a composite product with desired physical properties. [ABSTRACT FROM AUTHOR]

Conjugated polymers, which exhibit electrical and optical properties owing to the presence of conjugated π bonds along the polymer backbone, are semiconducting materials of utmost interest. However, their immiscibility in water imposes restrictions on their usage; they are typically processed using toxic and environmentally harmful organic solvents. To address these issues, research has focused on converting conjugated polymers into nanoparticle dispersions in water or alcohols. This strategy not only avoids toxic solvent usage but also enhances application utility. In this article, to provide a comprehensive understanding of conjugated polymer nanoparticles, we introduce two principal approaches for classifying nanoparticle formation strategies and their corresponding experimental methods: with respect to the particle formation mechanisms and their preparation methods; we will discuss six such methods. Then, we review three different applications of the conjugated polymer nanoparticles in the fields of electronics, energy, and bioimaging, associating their requirements for attaining superior device performance with the characteristics of each method, and accordingly discuss methodological perspectives for each application. [ABSTRACT FROM AUTHOR]

Heavy heteroatom substitution of the backbone is an effective strategy to improve molecular packing and charge delocalization in polymer semiconductors. Such a backbone modification also facilitates oxidative doping as a result of reduced ionization potential (IP). Here, the effect of single‐atom selenium substitution on doping and charge transport properties of a class of polythiophene copolymers is explored. The room temperature (RT) conductivities of the doped polymers are significantly enhanced by the selenium substitution for both molecular doping and ion exchange doping. The enhanced conduction is rationalized by the better crystallinity of the selenium‐containing system, which can be reinforced by a chain‐extended ribbon‐phase morphology induced by thermal annealing, which is robust toward doping. The resulting increase in the charge delocalization of the doped selenium‐containing system is evidenced by temperature‐dependent conductivities. In ion exchange doped films the maximum conductivity of ≈700 S cm−1 and a high thermoelectric (TE) power factor (PF) of 46.5 μW m−1 K−2 is achieved for the doped selenophene polymer and signatures of a metal‐insulator (M–I) transition are observed that are characteristics for heterogeneous conduction systems. The results show that single‐atom selenium substitution is an effective molecular design approach for improving the charge transport and TE properties of conjugated polymers. [ABSTRACT FROM AUTHOR]

The development of conjugated polymers with structures that are suitable for efficient molecular doping and charge transport is a key challenge in the construction of high‐performance conjugated polymer‐based thermoelectric devices. In this study, three novel conjugated polymers based on dithienopyrrole (DTP) are synthesized and their thermoelectric properties are compared. When doped with p‐dopant, a donor–acceptor type copolymer, DPP‐MeDTP, exhibits higher electrical conductivity and thermoelectric power factor compared to the other donor–donor type copolymers. The high electrical conductivity of DPP‐MeDTP compared to the other polymers originates from the high degree of backbone planarity and molecular order, which contributes to its high charge carrier mobility. In addition, the highly crystalline structure of DPP‐MeDTP is well maintained upon doping, while the crystalline order of the other polymers decreases significantly upon doping. The findings of this work not only provide insights into the design of DTP‐based conjugated polymers for thermoelectric use but also demonstrate the significance of a high degree of molecular order and structural robustness upon doping to achieve high thermoelectric performance. [ABSTRACT FROM AUTHOR]

Solution‐processable donor–acceptor‐type conjugated copolymers are considered one of the most promising alternatives to inorganic semiconductors. The introduction of strong electron‐withdrawing groups in the acceptor units of the copolymers has been shown to favor fast charge transport; however, the correlation among the halogen‐substituted molecular structure, solid‐state packing, and charge transport properties is unclear. In this study, new chlorine‐atom‐substituted donor–acceptor copolymers comprising chlorobenzo[c]‐[1,2,5]thiadiazole and 4,4‐dihexadecyl‐4H‐cyclopenta[1,2‐b:5,4‐b′]dithiophene are synthesized and their physicochemical properties are compared with those of their unsubstituted or nitrogen‐incorporated backbone analogs. In addition, the regioregularity of the synthesized copolymers is controlled to investigate the effects of regiochemistry on the polymer backbone alignment using the nanogroove method. The results demonstrate that different degrees of regioregularity in the main chains induce a substantially dissimilar effect of the nanogroove and capillary force on the orientation of the polymer backbone, long‐range crystalline order, and charge transport properties of the conjugated polymers. [ABSTRACT FROM AUTHOR]

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 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 cm2 V−1 s−1 and electron mobility of up to 0.30 cm2 V−1 s−1, which are suitable for applications in polymer electronics. [ABSTRACT FROM AUTHOR]

In this progress report, recent advances in the development of organic transistors with superior bias stress stability and in the understanding of the charge traps that degrade device performance under prolonged bias stress are reviewed, with a particular focus on materials science and engineering methods. The phenomenological aspects of bias stress effects and the experimental methods for investigating charge traps are described. The recent progress in the bias stress stability of organic transistors is discussed in terms of those components that are the main focus of attempts to improve bias stress stability, i.e., organic semiconductor layers, gate dielectrics, and source/drain contacts. A brief summary of this progress is presented and the outlook for future research in this field is assessed. This report aims to summarize recent progress in this field and to provide some guidelines for studying bias stress–induced charge‐trapping phenomena. [ABSTRACT FROM AUTHOR]

Two acceptor–donor–acceptor small molecules based on a fused ring indacenodithieno[3,2-b]thiophene (IDTT) as a donor, and hemi-isoindigo units, methyleneoxindole (IDTT-MI) and thienylmethyleneoxindole (IDTT-T-MI) as acceptors were synthesized and characterized for application in solution-processed organic field-effect transistors. The incorporation of a thiophene bridge which extended the conjugation of the backbone maintained highly co-planar structures, and also endowed the small molecule with ordered crystalline structures and interconnected morphology. Consequently, IDTT-T-MI-based organic field-effect transistors exhibited a highest hole mobility of 0.80 cm2 V−1 s−1, which was the highest mobility for solution-processed hemi-isoindigo-based organic semiconductor materials. [ABSTRACT FROM AUTHOR]

We developed a patternable synthesis method of wafer-scale NbS2, which can be applied for the fabrication of source and drain electrodes of p- and n-type organic field-effect transistors (OFETs) and logic gates. NbS2 film with high uniformity was synthesized directly on a 2-in Si wafer. NbS2 patterns of various sizes and shapes were readily synthesized onto an entire wafer. OFETs with NbS2 electrodes exhibited superior performances to those with conventional metal electrodes. The superior performance of the former OFETs was primarily a result of the enhanced crystallinity of the organic semiconductor layer deposited onto the NbS2 electrode surface. Furthermore, organic complementary circuits such as NOT, NAND, and NOR gates were successfully assembled using the resulting OFETs as a proof of applicability of these devices to complex logic circuits. [ABSTRACT FROM AUTHOR]

A series of donor–acceptor (D–A) type polymers based on a thieno[3,2-b]thiophene isoindigo (TTID) acceptor and five different donors was synthesized to investigate the versatility of the TTID acceptor moiety. To enhance intermolecular interactions, the branching site of the branched alkyl side chains was adjusted far from the polymer backbone. All of these polymers have planar backbone structures and exhibit highly ordered crystallinity. The TTID acceptor unit contains bulky electron-rich thieno[3,2-b]thiophene (TT), so the electronic structure and electrical properties of the TTID-based polymers are sensitive to the length of the donor units. The polymers conjugated with short donors exhibit effective D–A push–pull interactions and therefore have efficient intramolecular charge transfer characteristics. In particular, the polymer that was copolymerized with the short thiophene donor exhibits the highest hole mobility (0.54 cm2 V−1 s−1) of the TTID-based polymers, because it has a desirable crystalline structure and a smooth thin film morphology as well as efficient D–A interactions. Copolymerization with the longer donors containing vinylene linkages results in larger band gaps and moderate device performance (0.04 cm2 V−1 s−1), which probably result because the D–A interactions of the resulting polymers are weaker than those in the polymers produced by copolymerization of TTID with short donors. [ABSTRACT FROM AUTHOR]