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Circularly polarized light (CPL)‐responsive artificial synaptic devices are of significant interest for advanced neuromorphic visual systems, as they enhance perceptual capabilities and enable the development of novel applications. Nevertheless, progress in this field is hindered by the lack of suitable CPL‐active organic semiconductor materials. In this study, environmentally friendly cellulose nanocrystals (CNCs) with a chiral helical structure as a dielectric layer to realize CPL‐resolved behaviors in organic synaptic transistors are utilized. The device exhibits a much stronger response to right‐handed CPL (RCPL) than to left‐handed CPL (LCPL) because the left‐handed helical structure of CNCs reflects LCPL while transmitting RCPL. By modulating electrical and CPL optical signals, the device successfully simulates multiple synaptic activities, including electrical synaptic plasticity, CPL‐dependent optical synaptic plasticity, and brain‐like learning and memory behavior controlled by photoelectric cooperative stimulation. Additionally, the device demonstrates applications in blue‐light‐induced visual fatigue simulation, CPL recognition, and optical wireless encrypted communication. Importantly, the sensitivity of the device to CPL is not constrained by the properties of organic semiconductor materials. These findings offer a promising strategy for the development of advanced artificial synaptic devices and CPL‐resolved neuromorphic visual systems. [ABSTRACT FROM AUTHOR]

The development of intrinsically stretchable polymer semiconductor holds substantial promise in the field of wearable electronics. However, charge transport mobility is typically compromised in existing stretchable semiconductors to achieve the desired stretchability. Herein, a novel "regional conjugation" strategy is proposed to design an intrinsically stretchable polymer semiconductor oligo‐diketopyrrolopyrrole‐thieno[3,2‐b]thiophene (DPPTT)–urethane, in which oligo‐DPPTT conjugated units and alkyl urethane nonconjugated units are introduced. The regional conjugation of oligo‐DPPTT in the polymer backbone endows DPPTT–urethane with good molecular packing, leading to a high mobility of up to 1.7 cm2 V−1 s−1. Additionally, incorporating alkyl urethane nonconjugated units in the backbone can reduce film crystallinity and chain aggregation, which contribute to the stretchability of the polymer thin film. Consequently, fully stretchable transistors retain carrier mobility even at 100% biaxial tensile strain. Furthermore, the fully stretchable organic field‐effect transistor arrays show remarkable charge transport reversibility and durability after 1000 stretch–release cycles at 25% strain. Additionally, the device exhibits extraordinary electrical stability in air atmosphere. Overall, these results indicate that the "regional conjugation" strategy provides an effective and promising methodology to design intrinsically stretchable and high‐performance polymer semiconductor that can advance the development of soft and wearable electronics. [ABSTRACT FROM AUTHOR]

Diketopyrrolopyrrole (DPP)‐based polymer semiconductors have drawn great attention in the field of organic electronics due to the planar structure, decent solubilizing capability, and high crystallinity. However, the electron‐deficient capacity of DPP derivatives are not strong enough, leading to relatively high‐lying lowest unoccupied molecular orbital (LUMO) energy levels of the corresponding polymers. As a result, n‐type and ambipolar DPP‐based polymers are rare and their electron mobilities also lag far behind the p‐type counterparts, which limits the development of important p‐n‐junction‐based electronic devices. Therefore, new design strategies have been proposed recent years to develop n‐type/ambipolar DPP‐based polymers with improved performances. In this view, these molecular design strategies are summarized, including copolymerization of DPP with different acceptors and weak donors, DPP flanked aromatic ring modification, DPP‐core ring expansion and DPP dimerization. The relationship between the chemical structures and organic thin‐film transistor performances is intensively discussed. Finally, a perspective on future trends in the molecular design of DPP‐based n‐type/ambipolar polymers is also proposed. [ABSTRACT FROM AUTHOR]

Abstract The development of intrinsically stretchable polymer semiconductor holds substantial promise in the field of wearable electronics. However, charge transport mobility is typically compromised in existing stretchable semiconductors to achieve the desired stretchability. Herein, a novel “regional conjugation” strategy is proposed to design an intrinsically stretchable polymer semiconductor oligo‐diketopyrrolopyrrole‐thieno[3,2‐b]thiophene (DPPTT)–urethane, in which oligo‐DPPTT conjugated units and alkyl urethane nonconjugated units are introduced. The regional conjugation of oligo‐DPPTT in the polymer backbone endows DPPTT–urethane with good molecular packing, leading to a high mobility of up to 1.7 cm2 V−1 s−1. Additionally, incorporating alkyl urethane nonconjugated units in the backbone can reduce film crystallinity and chain aggregation, which contribute to the stretchability of the polymer thin film. Consequently, fully stretchable transistors retain carrier mobility even at 100% biaxial tensile strain. Furthermore, the fully stretchable organic field‐effect transistor arrays show remarkable charge transport reversibility and durability after 1000 stretch–release cycles at 25% strain. Additionally, the device exhibits extraordinary electrical stability in air atmosphere. Overall, these results indicate that the “regional conjugation” strategy provides an effective and promising methodology to design intrinsically stretchable and high‐performance polymer semiconductor that can advance the development of soft and wearable electronics.

In this work, p‐type polymer semiconductor poly(2‐((3,6,7,10,11‐pentakis (hexyloxy) triphenylene‐2‐yl)oxy)ethyl methacrylate) (PMHT) is added into polyetherimide (PEI). Benefiting from the electrostatic interaction between strong electrophilic charged phenyls of the PEI matrix and strong electronegative benzophenanthrene unit of the PMHT filler, the physical cross‐linked networks are formed in polymer blends. Meanwhile, the lowest unoccupied molecular orbital level of PEI is close to the highest occupied molecular orbital level of PMHT, which is easy to establish electron–hole pair by Coulomb force. Thus, the carrier trap is constructed in the heterojunction region between PMHT filler and PEI matrix. Both physically cross‐linked networks and electron–hole pairs can promote breakdown strength (Eb) of PEI and decrease energy loss. Importantly, PMHT filler can improve the dielectric constant of PEI. As a result, 0.75 wt% PMHT/PEI delivers an ultrahigh discharge energy density (Ud) of 10.7 J cm−3 at an Eb of 680 MV m−1 and at room temperature, and maintains a charge and discharge efficiency of above 90%. In addition, a superior Ud of 5.1 and 3.3 J cm−3 is achieved at 150 and 200 °C, respectively. This paper creates a new perspective for preparing high‐properties polymer dielectrics by combining the advantages of cross‐linking and electron–hole pairs. [ABSTRACT FROM AUTHOR]

3,4‐Difluorothiophene‐substituted aryls, i.e., 1,4‐bis(3,4‐difluorothiophen‐2‐yl)‐benzene (Ph‐2FTh), 1,4‐bis(3,4‐difluorothiophen‐2‐yl)‐2,5‐difluorobenzene (2FPh‐2FTh), and 4,7‐bis(3,4‐difluorothiophen‐2‐yl)‐2,1,3‐benzothiadiazole (BTz‐2FTh), are synthesized as C─H monomers for the synthesis of conjugated polymers (CPs) via direct arylation polycondensation (DArP) with diketopyrrolopyrrole (DPP) and isoindigo (IID) derivatives as C─Br monomers. The Gibbs free energies of activation for direct arylation (ΔG298 K, kcal mol−1) for α─C─H bonds of thiophene moieties as calculated by density functional theory (DFT) are 14.3, 16.5, and 16.4 kcal mol−1 for Ph‐2FTh, 2FPh‐2FTh and BTz‐2FTh, respectively, meaning that inserting an electron‐deficient unit in 3,3′,4,4′‐tetrafluoro‐2,2′‐bithiophene (4FBT, ΔG298K: 14.6 kcal mol−1) may cause a reactivity decrease of the C─H monomers. Photophysical and semiconducting properties of the resulting six CPs (i.e., DPP‐Ph, DPP‐2FPh, DPP‐BTz, 2FIID‐Ph, 2FIID‐2FPh, and 2FIID‐BTz) are characterized in detail. DPP‐based CPs show ambipolar transport properties while IID‐based ones exhibited n‐type behavior owing to the deeper frontier molecular orbital energy levels of IID‐based CPs. With source/drain electrodes modified with polyethylenimine ethoxylated, n‐channel organic thin‐film transistors with maximum electron mobility of 0.40, 0.54, 0.29, 0.05, 0.16, and 0.01 cm2 V−1 s−1 for DPP‐Ph, DPP‐2FPh, DPP‐BTz, 2FIID‐Ph, 2FIID‐2FPh, and 2FIID‐BTz, respectively, are fabricated. DPP‐2FPh exhibits the best device performance due to the good film morphology and the highest intermolecular packing order. [ABSTRACT FROM AUTHOR]

Polymer semiconductors are prominent photocatalysts for H 2 O 2 photosynthesis thanks to their unparalleled structural and functional designability. This review comprehensively summarizes their molecular design strategies, recent progresses and underlying reaction mechanisms for stabilizing and promoting H 2 O 2 production. Perspectives on challenges and opportunities of future research are also provided. [Display omitted] Hydrogen peroxide (H 2 O 2) has attracted considerable attention as an environmentally friendly oxidant and a potential energy carrier. In comparison to the traditional anthraquinone method, photocatalytic H 2 O 2 synthesis from molecular oxygen and water offers an appealing route for sustainable and cost-effective H 2 O 2 synthesis. Recently, polymer semiconductors have emerged as a promising class of metal-free photocatalysts for H 2 O 2 production owing to their abundant building blocks and versatile synthetic methods. These distinctive features allow for the rational molecular design of organic semiconductors and the modulation of their photophysical and photocatalytic properties, making them ideal candidates for high-efficiency photocatalysis. Herein, we summarize the latest advances in the development of polymer semiconductors for photocatalytic H 2 O 2 production. This review starts with a brief introduction of the fundamental principles and reaction systems involved in photocatalytic H 2 O 2 production. Subsequently, the molecular design strategies of polymer photocatalysts are discussed in detail for enhancing charge separation and promoting surface catalytic reactions. At last, the existing challenges and possible opportunities in this field are presented. This review aims to provide detailed insights and guidelines for the rational design of innovative organic semiconductors for efficient photocatalytic H 2 O 2 production. [ABSTRACT FROM AUTHOR]

Polymer semiconductors (PSCs) are essential active materials in mechanically stretchable electronic devices. However, many exhibit low fracture strain due to their rigid chain conformation and the presence of large crystalline domains. Here, a PSC/elastomer blend, poly[((2,6‐bis(thiophen‐2‐yl)‐3,7‐bis(9‐octylnonadecyl)thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene)‐5,5′‐diyl)(2,5‐bis(8‐octyloctadecyl)‐3,6‐di(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4‐dione)‐5,5′‐diyl]] (P2TDPP2TFT4) and polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS) are systematically investigated. Specifically, the effects of molecular weight of both SEBS and P2TDPP2TFT4 on the resulting blend morphology, mechanical, and electrical properties are explored. In addition to commonly used techniques, atomic force microscopy‐based nanomechanical images are used to provide additional insights into the blend film morphology. Opposing trends in SEBS‐induced aggregation are observed for the different P2TDPP2TFT4 molecular weights upon increasing the SEBS molecular weight from 87 to 276 kDa. Furthermore, these trends are seen in device performance trends for both molecular weights of P2TDPP2TFT4. SEBS molecular weight also has a substantial influence on the mesoscale phase separation. Strain at fracture increases dramatically upon blending, reaching a maximum value of 640% ± 20% in the blended films measured with film‐on‐water method. These results highlight the importance of molecular weight for electronic devices. In addition, this study provides valuable insights into appropriate polymer selections for stretchable semiconducting thin films that simultaneously possess excellent mechanical and electrical properties. [ABSTRACT FROM AUTHOR]

Designing n‐type polymers with high electrical conductivity remains a major challenge for organic thermoelectrics (OTEs). Herein, by devising a novel selenophene‐based electron‐deficient building block, the pronounced advantages of selenium substitution in simultaneously enabling advanced n‐type polymers is demonstrated with high mobility (≈2 orders of magnitude higher versus their sulfur‐based analogues due to both intensified intra‐ and inter‐chain interactions) and much improved n‐doping efficiency (enabled by the largely lowered LUMO level with a ≈0.2 eV margin) of the resulting polymers. Via side chain optimization and donor engineering, the selenium‐substituted polymer, f‐BSeI2TEG‐FT, achieves a highest conductivity of 103.5 S cm−1 and power factor of 70.1 µW m−1 K−2, which are among the highest values reported in literature for n‐type polymers, and f‐BSeI2TEG‐FT greatly outperformed the sulfur‐based analogue polymer by 40% conductivity increase. These results demonstrate that selenium substitution is a very effective strategy for improving n‐type performance and provide important structure‐property correlations for developing high‐performing n‐type OTE materials. [ABSTRACT FROM AUTHOR]

Abstract Polymer semiconductors (PSCs) are essential active materials in mechanically stretchable electronic devices. However, many exhibit low fracture strain due to their rigid chain conformation and the presence of large crystalline domains. Here, a PSC/elastomer blend, poly[((2,6‐bis(thiophen‐2‐yl)‐3,7‐bis(9‐octylnonadecyl)thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene)‐5,5′‐diyl)(2,5‐bis(8‐octyloctadecyl)‐3,6‐di(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4‐dione)‐5,5′‐diyl]] (P2TDPP2TFT4) and polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS) are systematically investigated. Specifically, the effects of molecular weight of both SEBS and P2TDPP2TFT4 on the resulting blend morphology, mechanical, and electrical properties are explored. In addition to commonly used techniques, atomic force microscopy‐based nanomechanical images are used to provide additional insights into the blend film morphology. Opposing trends in SEBS‐induced aggregation are observed for the different P2TDPP2TFT4 molecular weights upon increasing the SEBS molecular weight from 87 to 276 kDa. Furthermore, these trends are seen in device performance trends for both molecular weights of P2TDPP2TFT4. SEBS molecular weight also has a substantial influence on the mesoscale phase separation. Strain at fracture increases dramatically upon blending, reaching a maximum value of 640% ± 20% in the blended films measured with film‐on‐water method. These results highlight the importance of molecular weight for electronic devices. In addition, this study provides valuable insights into appropriate polymer selections for stretchable semiconducting thin films that simultaneously possess excellent mechanical and electrical properties.

Abstract Inverted perovskite solar cells (PVSCs) have recently made exciting progress, showing high power conversion efficiencies (PCEs) of 25% in single-junction devices and 30.5% in silicon/perovskite tandem devices. The hole transporting material (HTM) in an inverted PVSC plays an important role in determining the device performance, since it not only extracts/transports holes but also affects the growth and crystallization of perovskite film. Currently, polymer and self-assembled monolayer (SAM) have been considered as two types of most promising HTM candidates for inverted PVSCs owing to their high PCEs, high stability and adaptability to large area devices. In this review, recent encouraging progress of high-performance polymer and SAM-based HTMs is systematically reviewed and summarized, including molecular design strategies and the correlation between molecular structure and device performance. We hope this review can inspire further innovative development of HTMs for wide applications in highly efficient and stable inverted PVSCs and the tandem devices. Graphical Abstract

Since the first report of diketopyrrolopyrrole (DPP)-based conjugated polymers for organic thin-film transistors (OTFTs), these polymers have attracted great attention as representative semiconductors in high-performance OTFTs. Through unremitting efforts in molecular-structure regulation and device optimization, significant mobilities exceeding 10 cm2·V−1·s−1 have been achieved in OTFTs, greatly promoting the applied development of organic circuits. In this review, we summarize our progress in molecular design, synthesis and solution-processing of DPP-based conjugated polymers for OTFT devices and circuits, focusing on the roles of design strategies, synthesis methods and processing techniques. Furthermore, the remaining issues and future outlook in the field are briefly discussed. [ABSTRACT FROM AUTHOR]

Stretchable polymer semiconductors are an essential component for skin‐inspired electronics. However, the lack of scalable patterning capability of stretchable polymer semiconductors limits the development of stretchable electronics. To address this issue, photo‐curable stretchable polymer blends consisting of a high‐mobility donor–acceptor conjugated polymer and an elastic rubber through thiol–ene chemistry are developed. The thiol–ene reaction can selectively cross‐link the rubber with alkene or vinyl groups without damaging the electronic properties of the conjugated polymer. The conjugated polymer chains embedded in the elastic polymer matrix induce a semi‐interpenetrating polymer network (SIPN). The thiol–ene‐cross‐linked network provides great solvent resistance and enhances stretchability for the embedded conjugated polymer. The well‐defined patterned film with a feature size of ≈10 µm can be obtained using UV light at 365 nm through conventional photolithography processes. Furthermore, the SIPN‐based transistors show increased mobilities from 0.61 to 1.18 cm2 V−1 s−1 when applying the strain from 0% to 100%. Moreover, the hole mobility can still maintain at 0.87 cm2 V−1 s−1 after 1000 strain‐and‐release cycles at the strain of 25%. This study sheds light on the molecular design of photo‐curable polymer semiconductors for the mass production of stretchable circuits. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) have attracted significant attention due to their unique ionic–electronic charge coupling, which holds promise for use in a variety of bioelectronics. However, the typical electronic components of OECTs, such as the rigid metal electrodes and aqueous electrolytes, have limited their application in solid‐state bioelectronics that requires design flexibility and a variety of form factors. Here, the fabrication of a solid‐state homojunction OECT consisting of a pristine polymer semiconductor channel, doped polymer semiconductor electrodes, and a solid electrolyte is demonstrated. This structure combines the photo‐crosslinking of all of the electronic OECT components with the selective doping of the polymer semiconductor. Three Lewis acids (gold (III) chloride (AuCl3), iron (III) chloride (FeCl3), and copper (II) chloride (CuCl2)) are utilized as dopants for the metallization of the polymer semiconductor. The AuCl3‐doped polymer semiconductor with an electrical conductivity of ≈100 S cm−1 is successfully employed as the source, drain, and gate electrodes for the OECT, which exhibited a high carrier mobility of 3.4 cm2 V−1 s−1 and excellent mechanical stability, with negligible degradation in device performance after 5000 cycles of folding at a radius of 0.1 mm. Homojunction OECTs are then successfully assembled to produce NOT, NAND, and NOR logic gates. [ABSTRACT FROM AUTHOR]

With the rise of skin-like electronics, devices are increasingly coming into close contact with the human body, creating a demand for polymer semiconductors (PSCs) that combine stretchability with reliable electrical performance. However, balancing mechanical robustness with high carrier mobility remains a challenge. To address this, tris(pentafluorophenyl)borane (BCF) for Lewis acid doping is proposed to improve charge mobility while enhancing stretchability by increasing structural disorder. Through systematic investigation, several key structural principles have been identified to maximize the effectiveness of BCF doping in stretchable PSCs. Notably, increasing the lamellar stacking distance and reducing crystallinity facilitate the incorporation of BCF into the alkyl side-chain regions, thereby enhancing both mobility and stretchability. Conversely, stronger Lewis base groups in the main chain negatively impact these improvements. These results demonstrate that with a small addition of BCF, a two-fold increase in carrier mobility is achieved while simultaneously enhancing the crack onset strain to 100%. Furthermore, doped PSCs exhibit stable mobility retention under repeated 30% strains over 1000 cycles. This method of decoupling carrier mobility from mechanical properties opens up new avenues in the search for high-mobility stretchable PSCs., (© 2024 Wiley‐VCH GmbH.)

Inverted perovskite solar cells (PVSCs) have recently made exciting progress, showing high power conversion efficiencies (PCEs) of 25% in single-junction devices and 30.5% in silicon/perovskite tandem devices. The hole transporting material (HTM) in an inverted PVSC plays an important role in determining the device performance, since it not only extracts/transports holes but also affects the growth and crystallization of perovskite film. Currently, polymer and self-assembled monolayer (SAM) have been considered as two types of most promising HTM candidates for inverted PVSCs owing to their high PCEs, high stability and adaptability to large area devices. In this review, recent encouraging progress of high-performance polymer and SAM-based HTMs is systematically reviewed and summarized, including molecular design strategies and the correlation between molecular structure and device performance. We hope this review can inspire further innovative development of HTMs for wide applications in highly efficient and stable inverted PVSCs and the tandem devices. [ABSTRACT FROM AUTHOR]

Understanding molecular design rules for stretchable polymer semiconductors is important for enabling next generation stretchable electronic circuits. To simultaneously improve both electrical properties and mechanical stretchability, a design strategy is reported in introducing conjugated rigid fused‐rings with bulky side groups in semiconducting polymers. In this work, the understanding of this design concept is improved by systematically investigating the effect of different types of bulky side groups asymmetrically substituted on conjugated polymer semiconductor backbones. Specifically, four types of side groups are investigated, including naphthalene (NaPh), biphenyl (PhPh), thienylphenyl (ThPh), and alkylphenyl (C4Ph), asymmetrically substituted on benzodithiophene units, namely asy‐BDT. With the four types of side groups installed on BDT‐containing conjugated polymers in an asymmetrical fashion, it is observed that they reduced the polymer chain aggregation and film crystallinity, hence improving the film stretchability. Furthermore, the fully conjugated polymer backbone allows maintenance of good charge carrier mobilities. Specifically, polymer PDPP‐C4Ph (with C4Ph side groups) shows the highest mobility in the fully stretchable transistor and maintained its mobility even after being subjected to hundreds of stretching‐releasing cycles at 25% strain. Overall, the results provide anunderstanding of the use of asymmetrically substituted fused‐ring conjugated polymer structures to tune mechanical and charge transport properties. [ABSTRACT FROM AUTHOR]

Cyano substitution is vital to the molecular design of polymer semiconductors toward highly efficient organic solar cells. However, how regioselectivity impacts relevant optoelectronic properties in cyano-substituted bithiophene systems remain poorly understood. Three regioisomeric cyano-functionalized dialkoxybithiophenes BTHH, BTHT, and BTTT with head-to-head, head-to-tail, and tail-to-tail linkage, respectively, were synthesized and characterized in this work. The resulting polymer semiconductors (PBDTBTs) based on these building blocks were prepared accordingly. The regiochemistry and property relationships of PBDTBTs were investigated in detail. The BTHH moiety has a higher torsional barrier than the analogs BTHT and BTTT, and the regiochemistry of dialkoxybithiophenes leads to fine modulation in the optoelectronic properties of these polymers, such as optical absorption, band gap, and energy levels of frontier molecular orbitals. Organic field-effect transistors based on PBDTBTHH had higher hole mobility (4.4 × 10−3 cm2/(V·s)) than those (ca. 10−4 cm2/(V·s)) of the other two polymer analogs. Significantly different short-circuit current densities and fill factors were obtained in polymer solar cells using PBDTBTs as the electron donors. Such difference was probed in greater detail by performing space-charge-limited current mobility, thin-film morphology, and transient photocurrent/photovoltage characterizations. The findings highlight that the BTHH unit is a promising building block for the construction of polymer donors for high-performance organic photovoltaic cells. [ABSTRACT FROM AUTHOR]

In the present study, the effects of chain length variation of Poly(3-hexyl) thiophene polymer, which is one of the appropriate alternatives of Spiro-O-MeTAD used as a hole transfer layer (HTL) in perovskitebased solar cells (PSC), on thin-film morphology and device performance were investigated. Furthermore, nanowires of long (UZ) and short-chain (KZ) P3HT were obtained in the solution phase and then comparative photovoltaic performance analyses were carried out by fabricating PSC devices. As a result, it was determined that the morphological changes resulting from the polymer chain length directly affect the charge transfer between the active layer and HTL. KZ-P3HT presented better performance than both standard P3HT (5.99) and UZ-P3HT (2.68) polymers with a power conversion efficiency (PCE) of 7.74%. It was demonstrated that the main reason for this is that the fringed structure, detected by AFM images, increases the contact ratio at the perovskite/HTM interface. In addition, thanks to the morphological improvements in nano-wire studies, it was observed that the photovoltaic performance of the PSC device containing UZ-P3HT increased by 5.51%. Contrary to UZ-P3HT, it was determined that after the conversion of KZ-P3HT to the nanowire, the fringed structure on the surface disappeared and therefore the efficiency decreased to 5.81%. [ABSTRACT FROM AUTHOR]

Understanding charge transport in π‐conjugated polymers is critical for the design of high‐mobility polymers. However, charge transport in donor–acceptor (D–A) type copolymers and the roles of D and A units are still unclear. Herein, the charge transport properties of three cyclopentadithiophene (CDT)‐based D–A type copolymers with CDT as a common donor and benzothiadiazole, fluoro‐2,1,3‐benzothiadiazole, or pyridyl‐2,1,3‐thiadiazole (PTz) as an acceptor are investigated. The best charge transport is found for CDT‐PTz showing 0.79 ± 0.01 cm2 V−1 s−1 hole mobility in field‐effect transistors, with the lowest energetic disorder by temperature‐dependent mobility measurements. Using various structural probes and density functional theory simulations, it is found that CDT‐PTz has the most rigid and planar backbone structure and the strongest intramolecular dipole moment thanks to the noncovalent N–S interactions and the strong electron‐withdrawing PTz acceptor unit. These structural properties lead to strong intermolecular interactions in CDT‐PTz, reducing its π–π stacking distance, producing strong aggregation even in hot dilute solutions. The enhanced mobility in CDT‐PTz is attributed to this high quality π–π stacking, driven by increased backbone rigidity and strong molecular dipoles. This work suggests that rigidifying the copolymer backbone with enhanced push–pull strength of the D–A units is a key requirement for high‐mobility D–A copolymers. [ABSTRACT FROM AUTHOR]

Doping polymer semiconductors is a central topic in plastic electronics and especially in the design of novel thermoelectric (TE) materials. In this contribution, it has been demonstrated that doping of oriented semicrystalline P3HT thin films with the dopant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate), known as magic blue (MB), helps reach charge conductivities of 3000 S cm−1 and TE power factors of 170 ± 30 μW mK−2 along the polymer chain direction. A combination of transmission electron microscopy, polarized optical absorption spectroscopy, Rutherford backscattering, and TE property measurements helps clarify the conditions necessary to achieve such high charge conductivities. A comparative study with different dopants demonstrates that the doping mechanism is intimately related to the semicrystalline structure of the polymer and whether crystalline, amorphous or both phases are doped. The highest charge mobilities are observed when the dopant MB is preferentially located in the amorphous phase of P3HT, leaving the structure of P3HT nanocrystals almost unaltered. In this case, the P3HT nanocrystals are doped from their interface with the surrounding amorphous phase. These results indicate that doping preferentially the amorphous phase of semicrystalline polymer semiconductors is an effective strategy to reduce polaron localization, enhance charge mobilities, and improve TE power factors. [ABSTRACT FROM AUTHOR]

Doping polymer semiconductors is a central topic in plastic electronics and especially in the design of novel thermoelectric (TE) materials. In this contribution, it has been demonstrated that doping of oriented semicrystalline P3HT thin films with the dopant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate), known as magic blue (MB), helps reach charge conductivities of 3000 S cm−1 and TE power factors of 170 ± 30 μW mK−2 along the polymer chain direction. A combination of transmission electron microscopy, polarized optical absorption spectroscopy, Rutherford backscattering, and TE property measurements helps clarify the conditions necessary to achieve such high charge conductivities. A comparative study with different dopants demonstrates that the doping mechanism is intimately related to the semicrystalline structure of the polymer and whether crystalline, amorphous or both phases are doped. The highest charge mobilities are observed when the dopant MB is preferentially located in the amorphous phase of P3HT, leaving the structure of P3HT nanocrystals almost unaltered. In this case, the P3HT nanocrystals are doped from their interface with the surrounding amorphous phase. These results indicate that doping preferentially the amorphous phase of semicrystalline polymer semiconductors is an effective strategy to reduce polaron localization, enhance charge mobilities, and improve TE power factors. [ABSTRACT FROM AUTHOR]

Intrinsically stretchable semiconductors will facilitate the realization of seamlessly integrated stretchable electronics. However, to date demonstrations of intrinsically stretchable semiconductors have been limited. In this study, a new approach to achieve intrinsically stretchable semiconductors is introduced by blending a rigid high-performance donor-acceptor polymer semiconductor poly[4(4,4dihexadecyl4Hcyclopenta [1,2b:5,4b' ] dithiopen2yl) alt [1,2,5] thiadiazolo [3,4c] pyridine] (PCDTPT) with a ductile polymer semiconductor poly(3hexylthiophene) (P3HT). Under large tensile strains of up to 75%, the polymers are shown to orient in the direction of strain, and when the strain is reduced, the polymers reversibly deform. During cyclic strain, the local packing order of the polymers is shown to be remarkably stable. The saturated field effect charge mobility is shown to be consistently above 0.04 cm2 V-1s-1 for up to 100 strain cycles with strain ranging from 10% to 75% when the film is printed onto a rigid test bed. At the 75% strain state, the charge mobility is consistently above 0.15 cm2 V-1s-1. Ultimately, the polymer blend process introduced here results in an excellent combination of device performance and stretchability providing an effective approach to achieve intrinsically stretchable semiconductors.

Photo-patterning of polymer semiconductors using photo-crosslinkers has shown potential for organic circuit fabrication via solution processing techniques. However, the performance of patterning, including resolution (R), UV light exposure dose, sensitivity (S), and contrast (γ), remains unsatisfactory. In this study, a novel conjugated polymer based photo-crosslinker (PN3, Figure 1a) is reported for the first time, which entails phenyl-substituted azide groups in its side chains. Due to the potential π-π interactions between the conjugated backbone of PN3 and those of polymer semiconductors, PN3 exhibits superior miscibility with polymer semiconductors compared to the commonly used small molecule photo-crosslinker 4Bx (Figure 1a). Consequently, photo-patterning of polymer semiconductors with PN3 demonstrates improved performance with much lower UV light exposure dose, higher S and higher γ compared to 4Bx. By utilizing electron beam lithography, patterned arrays of polymer semiconductors with resolutions down to 500 nm and clearer edges are successfully fabricated using PN3. Furthermore, patterned arrays of PDPP4T, the p-type semiconductor (Figure 1b), after being doped, can function as source-drain electrodes for fabricating field-effect transistors (FETs) with comparable charge mobility and significantly lower sub-threshold swing value compared to those with gold electrodes., (© 2024 Wiley‐VCH GmbH.)

The thermomechanical behavior of polymer semiconductors plays an important role in the processing, morphology, and stability of organic electronic devices. However, donor–acceptor‐based copolymers exhibit complex thermal relaxation behavior that is not well understood. This study uses dynamic mechanical analysis (DMA) to probe thermal relaxations of a systematic set of polymers based around the benzodithiophene (BDT) moiety. The loss tangent curves are resolved by fitting Gaussian functions to assign and distinguish different relaxations. Three prominent transitions are observed that correspond to: i) localized relaxations driven primarily by the side chains (γ), ii) relaxations along the polymer backbone (β), and iii) relaxations associated with aggregates (α). The side chains are found to play a clear role in dictating Tγ, and that mixing the side chain chemistry of the monomer to include alkyl and oligo(ethylene glycol) moieties results in splitting the γ ‐relaxation. The β relaxations are shown to be associated with backbone elements along with the monomer. In addition, through processing, it is shown that the α‐relaxation is due to aggregate formation. Finally, it is demonstrated that the thermal relaxation behavior correlates well with the stress–strain behavior of the polymers, including hysteresis and permanent set in cyclically stretched films. [ABSTRACT FROM AUTHOR]

Semiconducting π‐conjugated polymers are the most promising candidates for flexible electronics owing to their facile processability and mechanical robustness; however, achieving steep and stable switching operations in polymer thin‐film transistors (TFTs) remains a serious challenge. Herein, it is shown that whole optimizations for eliminating interfacial carrier traps throughout the conductive path are necessary in achieving TFTs showing both exceptionally sharp switching and bias‐stress‐free characteristics. Inverted‐coplanar‐type TFTs composed of a highly lyophobic amorphous perfluoropolymer gate–dielectric interfaced with a push‐coated semiconducting polymer layer are manufactured. The use of the dielectric allows the establishment of bias‐stress‐free characteristics with minimized contact resistance. Additionally, fairly sharp on/off switching TFTs with the smallest normalized subthreshold swing can be obtained by utilizing a particular donor–acceptor copolymer that involves a self‐passivation mechanism working to achieve a trap‐minimized interface. These findings have opened a way for low‐power and robust device operations in polymer‐based flexible electronics. [ABSTRACT FROM AUTHOR]

Flexible and air‐stable phototransistors are highly demanded for wearable near‐infrared (NIR) image sensors. However, advanced NIR sensors via low‐cost, solution‐based processes remained a challenge. Herein, high‐performance inorganic–organic hybrid phototransistors are achieved based on solution processed n‐type metal oxide/polymer semiconductor heterostructures of In2O3/poly{5,5′‐bis[3,5‐bis(thienyl)phenyl]‐2,2′‐bithiophene‐3‐ethylesterthiophene]} (PTPBT‐ET). The In2O3/PTPBT‐ET hybrid phototransistor combines the advantages of both fast electron transport in In2O3 and high photoresponse in PTPBT‐ET, showing high saturation mobility of 7.1 cm2 V−1 s−1 and large current on/off ratio of >107. As a result, the phototransistor exhibits high performance towards NIR light sensing with a responsivity of 200 A W−1, a specific detectivity of 1.2 × 1013 Jones, and fast photoresponse with rise/fall time of 5/120 ms. Remarkably, the hybrid phototransistor, without any passivation, demonstrates excellent electrical stability without performance degradation even after 160 days in air. A 10 × 10 phototransistor array is also enabled by virtue of the high device uniformity. Lastly, flexible In2O3/PTPBT‐ET phototransistor on polyimide substrate is attained, exhibiting outstanding mechanical flexibility up to 1000 bending/releasing cycles at a bending radius of 5 mm. These achievements pave the way for constructing air‐stable hybrid phototransistors for flexible NIR image sensor applications. [ABSTRACT FROM AUTHOR]

The stable multibit storage operation of solution‐processed organic nonvolatile memories (ONVMs) based on ferroelectric field‐effect transistors (FeFETs) for high density data storage devices are demonstrated. The proposed multibit ONVM structure consists of a p‐type polymer semiconductor sandwiched between poly(vinylidene fluoride‐trifluoroethylene) [P(VDF‐TrFE)] layers serving as ferroelectric gate insulators to form a dual gate ferroelectric–ferroelectric memory transistor (DG Fe‐FeMT). With the extra memory space created by the spatially separated ferroelectrics, a 2‐bit memory representation ("11", "10", "01" and "00") with clear memory margins is achieved due to the bistability of each P(VDF‐TrFE) and the high performance of the polymer semiconductor. The distinct four‐level reading of memory output currents (IM,OUTs) results from the independent programming voltages of the dual gates. An excellent distinct six‐level IM,OUTs are also achieved in DG Fe‐FeMT using the intermediate programming voltages. Finally, the possibility of 3−bit, or 8 memory states, are demonstrated by optimizing the bistability and intermediate polarization states of the ferroelectrics without increasing the device area horizontally. The DG Fe‐FeMT has a great potential for cost−effective flexible nonvolatile multibit data storage devices due to its solution‐process and low annealing temperatures. [ABSTRACT FROM AUTHOR]

Poly(3-hexylthiophene) (P3HT) thin films, obtained by normal spin-coating and solvent vapor assisted spin-coating (SVASP) before and after thermal annealing (TA), and the corresponding devices were prepared to unravel the microstructure-property relationship, which is of great importance for the development of organic electronics. When SVASP-TA films were used as the active layers of the organic field-effect transistors, a hole mobility up to 0.38 cm2·V−1·s−1 was achieved. This mobility was one of the highest values and one order of magnitude higher than that of the normal spin-coating films based transistors. The relationship between the microstructure and the device performance was fully investigated by UV-Vis absorption spectra, grazing incident X-ray diffraction (GIXD), and atomic force microscopy (AFM). The impressive mobility was attributed to the high crystallinity and ordered molecule packing, which stem from the synergistic effects of SVASP and thermal annealing. [ABSTRACT FROM AUTHOR]

The synthesis and experimental/theoretical characterization of a new series of electron‐transporting copolymers based on the naphthalene bis(4,8‐diamino‐1,5‐dicarboxyl)amide (NBA) building block are reported. Comonomers are designed to test the emergent effects of manipulating backbone torsional characteristics, and density functional theory (DFT) analysis reveals the key role of backbone conformation in optimizing electronic delocalization and transport. The NBA copolymer conformational and electronic properties are characterized using a broad array of molecular/macromolecular, thermal, optical, electrochemical, and charge transport techniques. All NBA copolymers exhibit strongly aggregated morphologies with significant nanoscale order. Copolymer charge transport properties are investigated in thin‐film transistors and exhibit excellent electron mobilities ranging from 0.4 to 4.5 cm2 V−1 s−1. Importantly, the electron transport efficiency correlates with the film mesoscale order, which emerges from comonomer‐dependent backbone planarity and extension. These results illuminate the key NBA building block structure–morphology–bulk property design relationships essential for processable, electronics‐applicable high‐performance polymeric semiconductors. [ABSTRACT FROM AUTHOR]

Polymer semiconductors hold tremendous potential for applications in flexible devices, which is however hindered by the fact that they are usually processed by halogenated solvents rather than environmentally more friendly solvents. An effective strategy to boost the solubility of high-performance polymer semiconductors in nonhalogenated solvents such as tetrahydrofuran (THF) by appending hydroxyl groups in the side chains is herein presented. The results show that hydroxyl groups, which can be easily incorporated into the side chains, can significantly improve the solubility of typical p- and n-types as well as ambipolar polymer semiconductors in THF. Meanwhile, the thin films of these polymer semiconductors from the respective THF solutions show high charge mobilities. With THF as the processing and developing solvents these polymer semiconductors with hydroxyl groups in the side chains can be well photopatterned in the presence of the photo-crosslinker, and the charge mobilities of the patterned thin films are mostly maintained by comparing with those of the respective pristine thin films. Notably, THF is successfully utilized as the processing and developing solvent to achieve high-density photopatterning with ≈82 000 device arrays cm -2 for polymer semiconductors in which hydroxyl groups are appended in the side chains., (© 2024 Wiley‐VCH GmbH.)

Photomultiplication‐type organic photodiodes (PM‐OPDs) rely on acceptor molecules for both charge separation and efficient gain generation. Herein, a new non‐fullerene acceptor is designed and synthesized by introducing thienylenevinylene (TV) groups into the conventional 2,2ʹ‐[[6,6,12,12‐tetrakis(4‐hexylphenyl)‐6,12‐dihydrodithieno[2,3‐d:2ʹ,3ʹ‐dʹ]‐s‐indaceno[1,2‐b:5,6‐bʹ]dithiophene‐2,8‐diyl]bis[methylidyne(3‐oxo‐1H‐indene‐2,1(3H)‐diylidene)]]bis[propanedinitrile] (ITIC) structure. The resulting TV‐ITIC acceptor possesses not only extended π‐conjugation length, which leads to lower energy bandgap as well as deeper lowest unoccupied molecular orbital (LUMO) level, but also enhanced hydrophobic characteristics, owing to the increased volumetric portion of the aliphatic chain, which improves the miscibility with the donor polymer semiconductor, poly(3‐hexylthiophene‐2,5‐diyl) (P3HT). Moreover, pristine TV‐ITIC films consist of intrinsically well‐ordered anisotropic crystallites, which are confirmed by 2D grazing incidence X‐ray diffraction (2D‐GIXD) analysis. All of these photophysical properties are beneficial for efficient exciton separation, electron trapping, and charge injection abilities of PM‐OPDs compared to those obtained with conventional ITIC. Because of such synergetic contributions of TV‐ITIC to the photomultiplication mechanism, the resulting optimized PM‐OPD exhibits a high external quantum efficiency (>74,000%) and a large specific detectivity (>1012 Jones). [ABSTRACT FROM AUTHOR]

The effect of addition of J-aggregates of polymethine dye into the hole-transport layer of an organic light-emitting diode (OLED) on its characteristics and operational stability was studied. Water-soluble PEDOT:PSS (poly(3,4-ethylenedioxythiophene)) and the interpolymer complex of polyaniline and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAn-PAMPSA) were used as the matrices of polymer nanocomposites. The highest efficiency characteristics of the OLEDs with the considered structure were achieved using PAn-PAMPSA at a particular component ratio in the interpolymer complex. Additives of J‑aggregates did not significantly affect the efficiency characteristics of the OLEDs; however, an increase in the operational stability of devices was recorded. [ABSTRACT FROM AUTHOR]

Introducing solubilizing α‐branched alkyl chains on a poly(diketopyrrolopyrrole‐alt‐terthiophene) results in a dramatic change of the structural, optical, and electronic properties compared to the isomeric polymer carrying β‐branched alkyl side chains. When branched at the α‐position the alkyl substituent creates a steric hindrance that reduces the tendency of the polymer to π–π stack and endows the material with a much higher solubility in common organic solvents. The wider π–π stacking and reduced tendency to crystallize, evidenced from grazing‐incidence wide‐angle X‐ray scattering, result in a wider optical band gap in the solid state. In solar cells with a fullerene acceptor, the α‐branched isomer affords a higher open‐circuit voltage, but an overall lower power conversion efficiency as a result of a too well‐mixed nanomorphology. Due its reduced π–π stacking, the α‐branched isomer fluoresces and affords near‐infrared light‐emitting diodes emitting at 820 nm. [ABSTRACT FROM AUTHOR]

A straightforward synthesis is reported for four structurally simple donor–acceptor conjugated polymers based on an alkylated difluorobenzotriazole and either unsubstituted bithiophene (T2) or thienylvinylthiophene (TVT) co‐monomers. Two solubilizing sidechains are investigated in which the position of the branching point is moved away from the conjugated backbone. Optoelectronic measurements and density functional theory calculations show very similar energetic properties between the polymers, with a slightly narrower bandgap for the vinylene incorporating TVT polymers as a result of extended conjugation. Transistor measurements demonstrate that the simplest polymer, containing a readily available 2‐decyltetradecyl sidechain with a T2 co‐monomer, exhibits the best device performance, with an average saturated mobility of 0.2 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Numerous strategies are developed to impart stretchability to polymer semiconductors. Although these methods improve the ductility, mobility, and stability of such stretchable semiconductors, they nonetheless still need further improvement. Here, it is shown that 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) is an effective molecular additive to tune the properties of a diketopyrrolopyrrole‐based (DPP‐based) semiconductor. Specifically, the addition of F4‐TCNQ is observed to improve the ductility of the semiconductor by altering the polymer's microstructures and dynamic motions. As a p‐type dopant additive, F4‐TCNQ can also effectively enhance the mobility and stability of the semiconductor through changing the host polymer's packing structures and charge trap passivation. Upon fabricating fully stretchable transistors with F4‐TCNQ‐DPP blended semiconductor films, it is observed that the resulting stretchable transistors possess one of the highest initial mobility of 1.03 cm2 V−1 s−1. The fabricated transistors also exhibit higher stability (both bias and environmental) and mobility retention under repeated strain, compared to those without F4‐TCNQ additive. These findings offer a new direction of research on stretchable semiconductors to facilitate future practical applications. [ABSTRACT FROM AUTHOR]

Thanks to recent progress in terms of materials properties, polymer field-effect transistors (FETs) operating in the MHz range can be achieved. However, further development toward challenging frequency ranges, for a field accustomed to slow electronic devices, has to be addressed with suitable device design and measurements methodologies. In this letter, we report n-type FETs based on a solution-processed polymer semiconductor where the critical features have been realized by a large-area compatible direct-writing technique, allowing to obtain a maximum frequency of transition of 19 MHz, as measured by means of Scattering Parameters (S-Parameters). This is the first report of solution-processed organic FETs characterized with S-Parameters. [ABSTRACT FROM AUTHOR]

Multifunctional semiconductors integrating unique optical, electrical, mechanical, and chemical characteristics are critical to advanced and emerging manufacturing technologies. However, due to the trade-off challenges in design principles, fabrication difficulty, defects in existing materials, etc., realizing multiple functions through multistage manufacturing is quite taxing. Here, an effective molecular design strategy is established to prepare a class of multifunctional integrated polymer semiconductors. The pyridal[1,2,3]triazole-thiophene co-structured tetrapolymers with full-backbone coplanarity and considerable inter/intramolecular noncovalent interactions facilitate short-range order and excellent (re)organization capability of polymer chains, providing stress-dissipation sites in the film state. The regioregular multicomponent conjugated backbones contribute to dense packing, excellent crystallinity, high crack onset strain over 100%, efficient carrier transport with mobilities exceeding 1 cm 2  V -1  s -1 , and controllable near-infrared luminescence. Furthermore, a homologous blending strategy is proposed to further enhance the color-tunable luminescent properties of polymers while effectively retaining mechanical and electrical properties. The blended system exhibits excellent field-effect mobility (µ) and quantum yield (Φ), reaching a record Φ · µ of 0.43 cm 2  V -1  s -1 . Overall, the proposed strategy facilitates a rational design of regioregular semicrystalline intrinsically stretchable polymers with high mobility and color-tunable intense luminescence, providing unique possibilities for the development of multifunctional integrated semiconductors in organic optoelectronics., (© 2023 Wiley-VCH GmbH.)

Abstract Organic electrochemical transistors (OECTs) are thin-film transistors that have shown great promise in a range of applications including biosensing, logic circuits, and neuromorphic engineering. The device physics of OECTs are determined by the interaction between ionic and electronic charge carriers. This interaction sets OECTs apart from conventional transistor technologies and has necessitated the development of device models for the unique behavior of OECTs. In this Review, we discuss existing models for OECTs and provide a framework for understanding these models. Moreover, we show how the insight from these models inform device optimization. Finally, we discuss details of OECT operation that are not well-understood and that provide exciting opportunities for future research. Graphical abstract Image Highlights • Review article on device physics of organic electrochemical transistors. • Geometry scaling for response time and transconductance. • Understanding ionic/electronic mixed conduction. • Design strategies for mitigation of parasitic resistance. • Density of states influence on charge transport. [ABSTRACT FROM AUTHOR]

Abstract: A new asymmetric furan and thieno[3,2‐b]thiophene flanked diketopyrrolopyrrole (TTFDPP) building block for conjugated polymers is designed and used to generate a donor–acceptor semiconducting polymer, poly[3‐(furan‐2‐yl)‐2,5‐bis(2‐octyldodecyl)‐6‐(thieno[3,2‐b]thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐alt‐thieno[3,2‐b]thiophene] (abbreviated to PTTFDPP‐TT), consisting of TTFDPP unit copolymerized with thieno[3,2‐b]thiophene comonomer (TT), which is further synthesized. Results demonstrate that PTTFDPP‐TT‐based thin‐film transistors in a bottom‐gate bottom‐contact device configuration exhibit typical hole‐transporting property, with weak temperature dependence for charge carrier mobility from room temperature to 200 °C. In addition, the good solubility of PTTFDPP‐TT due to the incorporation of a polar furan unit and an asymmetric conjugated structure makes it able to be solution processed with a less toxic nonchlorinated solvent such as toluene, demonstrating comparable performance with that prepared from chlorinated solution. These results suggest PTTFDPP‐TT as a promising organic semiconductor candidate for annealing‐free, environmentally benign, and less energy‐consuming applications in large‐area flexible organic electronic devices. [ABSTRACT FROM AUTHOR]

Abstract We report on controllable ambipolar charge transport in polymeric semiconductors by the incorporation of viologen-based molecular additives. The viologen dopants selectively contribute to an increase in the charge carrier density of the electrons while enhancing the fibril-like crystalline thin-film morphology of the polymers to provide favourable charge transport in staggered-structure organic field-effect transistors. A well-balanced ambipolar behaviour is obtained at the optimised viologen concentration in donor-acceptor conjugated polymers by conversely modulating the p - and n -channel carrier mobilities within a given active layer. Complementary-like inverter circuits are demonstrated through the application of a simple blanket coating of a viologen-doped ambipolar semiconductor, which exhibits high ideal voltage switching at around half of the applied bias, a high gain of more than 50, and sufficient noise immunity to enable various applications for printed electronics and optoelectronics. Graphical abstract Controllable ambipolar charge transport in ambipolar polymer semiconductors by the incorporation of benzyl viologen-based molecular additives for applications to complementary-like solution-processed electronic circuits. Image 1 Highlights • Controllable ambipolar charge transport in ambipolar polymer semiconductors. • Selective contribution to an increase in the electron carrier density. • Enhancement of the fibril-like crystalline thin-film morphology. • A well-balanced ambipolar behaviour at the optimised viologen doping concentration. • CMOS-like inverters by a simple blanket coating of N-doped ambipolar semiconductor. [ABSTRACT FROM AUTHOR]

ABSTRACT: Herein, we report the synthesis, characterization, and field‐effect properties of two cross‐conjugated dithienylmethanone (DMO)‐based alternating polymers, namely, PDMO‐S and PDMO‐Se. Both polymers possess high thermal stability, good solubility, and broad absorption spectra. Their electrochemical properties were investigated using cyclic voltammetry, indicating that PDMO‐Se has higher HOMO/LUMO energy levels of −5.49/−3.49 eV than −5.57/−3.58 eV of PDMO‐S. The two polymers exhibited promising charge transport properties with the highest hole mobility of 0.12 cm2 V−1 s−1 for PDMO‐S and 0.025 cm2 V−1 s−1 for PDMO‐Se. AFM and 2D‐GIXRD analyses demonstrated that the PDMO‐S formed lamellar, edge‐on packing thin film with close π‐π stacking. These findings suggest that cross‐conjugated polymers might be potential semiconducting materials for low‐cost and flexible organic electronics. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1012–1019 [ABSTRACT FROM AUTHOR]

Bi-thieno[3,4]pyrrole-4,6-dione (bi-TPD) based copolymers containing 1,2-bis(2-thienyl)ethene ( P1 ) and 1,2-diphenylethene ( P2 ) units are synthesized and characterized. Their physicochemical and electrical properties as well as molecular packing structures in thin films have been fully investigated. P1 has higher HOMO energy levels and smaller bandgap than P2 , which is attributed to the stronger electron-donating ability of 1,2-bis(2-thienyl)ethene unit. Both polymers form continuous films and adopt face-on and edge-on co-orientation in the aggregation states. The crystallinity of P1 film is higher than that of P2 film. The optimal field-effect mobility is 0.74 cm 2 V −1 s −1 for P1 films and 0.32 cm 2 V −1 s −1 for P2 films. These results demonstrated the merits of 1, 2-bis(2-thienyl)ethene unit and the potential applications of bi-TPD based polymers in high performance polymer transistors. [ABSTRACT FROM AUTHOR]

Abstract: Conjugated polymers have evolved significantly in the past decade and have proven to be more than poorly conducting plastics. Instead, improved understanding has resulted in respectable charge‐carrier mobilities and power‐conversion efficiencies achieved by various donor‐acceptor‐type semiconducting polymers. However, their advantages in mechanical flexibility and deformability seem to have conflicting molecular design requirements from those for high charge‐carrier transporting properties. It is therefore a challenge to enhance the mechanical compliance of semiconducting polymers suitable for stretchable device applications. This progress report starts with a brief introduction to fracture mechanics and mechanical characterization techniques for thin polymer films, in order to consider the limitations and rationalization of current definition and parameters for stretchability. It then surveys different strategies that can be applied to improve the mechanical robustness and stretchability of polymer semiconductors, in particular focusing on molecular design aspects such as molecular weight and regioregularity, structural modifications in the polymer backbone and side chain, and postpolymerization modifications including blending and cross‐linking. Finally, directions for future development of next‐generation stretchable conjugated polymers are indicated. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, we report the synthesis, characterization, and application of two regioirregular naphthalenediimide (NDI)-based alternating conjugated polymers, namely P1 and P2, in which nitrile-substituted moiety, 2,3-bis(thiophen-2-yl)acrylonitrile and NDI moiety act as donor and acceptor unit, respectively. The two regioirregular polymers possess low-lying LUMO energy levels of −3.92 eV for P1 and −3.96 eV for P2. Both polymers possess typical dual-band UV−Vis−NIR absorption profiles of NDI-based polymers, and show broadened and red-shifted absorption spectra in the solid state compared with those in solutions. Field-effect transistor devices with top-gate bottom-contact configuration were used to evaluate the polymers' semiconducting properties. The two polymers exhibited promising and air-stable ambipolar charge transport characteristics. Thin film microstructure investigations (AFM and 2D-GIXRD) suggest both polymers formed continuous and smooth thin films, and adopted predominantly face-on molecular packing in the solid state. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3627-3635 [ABSTRACT FROM AUTHOR]