A series of thienoisoindigo (TIG)-based conjugated polymers (CPs) with high molecular weights are synthesized by direct arylation polycondensation (DArP) by using TIG derivatives as C-Br monomer and multi-halogenated thiophene derivatives, i.e., (E)-1,2-bis(3,4-difluorothien-2-yl)ethene (4FTVT), (E)-1,2-bis(3,4-dichlorothien-2-yl)ethene (4ClTVT), 3,3',4,4'-tetrafluoro-2,2'-bithiophene (4FBT), and 3,3',4,4'-tetrachloro-2,2'-bithiophene (4ClBT), as C-H monomers. Density functional theory (DFT) calculations reveal the high selectivity between alpha-C-H bonds in 4FTVT, 4ClTVT, 4FBT, and 4ClBT and beta-C-H bonds in TIG C-Br monomer. All four resulting CPs exhibit low optical bandgaps of ca. 1.20 eV and ambipolar transport characteristics with both electron and hole mobility above 0.1 cm(2) V-1 s(-1) as elaborated with organic thin-film transistors (OTFTs). The polymer TIG-4FTVT delivers the best device performance. With this polymer, n-channel OTFTs with electron mobility up to 1.67 cm(2) V-1 s(-1) and p-channel OTFTs with hole mobility up to 0.62 cm(2) V-1 s(-1) are fabricated by modifying source/drain electrodes with polyethylenimine ethoxylated (PEIE) and MoO3, respectively, to selectively inject electrons and holes.

This work demonstrates that the close π–π stacking distance is a more important factor to the electron mobility than crystallinity in near-amorphous polymer semiconductors.

Morphological and electrical control over conjugated polymers has a great potential for the fabrication of high-performance organic thin-film transistors (OTFTs). Herein, we employed a multifunctional polymeric additive, namely, PBTTT-b-HTPB, to optimize the molecular packing order of an isoindigo-based model polymer (IIDSiC8) and simultaneously regulate the minority carriers for boosted transport properties in OTFTs via facile solution processing. By detailed comparative study, we demonstrated that PBTTT-b-HTPB remarkably improved the crystallinity of IIDSiC8 by forming elongated fibers with higher molecular order in a thin film, which originated from the larger size ordered solution aggregates due to the presence of the insulating block. On the other hand, the p-type conjugated block of PBTTT worked as a hole trapping center, resulting in significantly increased electron density, reduced off-current, and optimal n-type performance. Benefiting from the collaborative morphological and electrical regulation, IIDSiC8/PBTTT-b-HTPB films displayed well-aligned ordered morphology and a high electron mobility up close to 7 cm2 V-1 s-1 together with an on/off ratio of 106 in bar-coated OTFTs. The high electron mobility is among the top performance values reported for isoindigo-based polymers. Our work has achieved simultaneous optimization of film microstructures and carrier transport characteristics of polymer semiconductors, providing opportunities for the production of OTFT devices with a superior performance.

Polythiophenes are the most appealing donor materials in organic solar cells (OSCs) due to their simple chemical structures. However, the top-performance polythiophenes are typically synthesized via Stille polycondensation, which is problematic due to significant toxicity and poor atom economy. By contrast, direct arylation polycondensation (DArP) is an eco-friendly, and atom-efficient alternative for synthesizing conjugated polymers, while the best efficiency for DArP-derived polythiophenes is below 12%. This study reports a series of polythiophene-based donors synthesized via DArP. Among these, PT4F-Th reaches a power conversion efficiency (PCE) of 16.4%, which not only matches the current record for polythiophene-based donor materials, but also marks the highest PCE achieved by DArP-derived donors to date. The superior performance of PT4F-Th is largely attributed to its optimal temperature-dependent aggregation behavior and moderate miscibility with acceptors, along with the highest crystallinity among the candidates, resulting in the most favorable blend film morphology. This study underscores the significant potential of DArP-derived polythiophenes in developing high-performance and eco-friendly OSCs. A series of polythiophene-based donors are synthesized using direct arylation polycondensation (DArP), highlighting PT4F-Th, which achieves an outstanding power conversion efficiency (PCE) of 16.4% in binary organic solar cells (OSCs). This efficiency sets a new record for DArP-derived donors. Blend film morphology is characterized by X-ray scattering and microscopy, emphasizing the synergistic effects of temperature-dependent aggregation behavior and miscibility. image

Reservoir computing has attracted considerable attention due to its low training cost. However, existing neuromorphic hardware, focusing mainly on shallow-reservoir computing, faces challenges in providing adequate spatial and temporal scales characteristic for effective computing. Here, we report an ultra-short channel organic neuromorphic vertical transistor with distributed reservoir states. The carrier dynamics used to map signals are enriched by coupled multivariate physics mechanisms, while the vertical architecture employed greatly increases the feedback intensity of the device. Consequently, the device as a reservoir, effectively mapping sequential signals into distributed reservoir state space with 1152 reservoir states, and the range ratio of temporal and spatial characteristics can simultaneously reach 2640 and 650, respectively. The grouped-reservoir computing based on the device can simultaneously adapt to different spatiotemporal task, achieving recognition accuracy over 94% and prediction correlation over 95%. This work proposes a new strategy for developing high-performance reservoir computing networks.

Open-shell conjugated polymers with a high intrinsic conductivity and high-spin ground state hold considerable promise for applications in organic electronics and spintronics. Herein, two novel acceptor-acceptor (A–A) conjugated polymers based on a highly electron-deficient quinoidal benzodifurandione unit have been developed, namely DPP-BFDO-Th and DPP-BFDO. The incorporation of the quinoidal moiety into the polymers backbones enables deeply aligned lower-lying lowest unoccupied molecular orbital (LUMO) levels of below −4.0 eV. Notably, DPP-BFDO exhibits an exceptionally low LUMO (−4.63 eV) and a high-spin ground state characterized by strong diradical characters. Moreover, a self-doping through intermolecular charge-transfer is observed for DPP-BFDO, as evidenced by X-ray photoelectron spectroscopy (XPS) studies. The high carrier concentration in combination with a planar and linear conjugated backbone yields a remarkable electrical conductivity ( σ ) of 1.04 S cm −1 in the “undoped” native form, ranking among the highest values reported for n-type radical-based conjugated polymers. When employed as an n-type thermoelectric material, DPP-BFDO achieves a power factor of 12.59 μW m −1  K −2 . Furthermore, upon n-doping, the σ could be improved to 65.68 S cm −1 . This study underscores the great potential of electron-deficient quinoidal units in constructing dopant-free n-type conductive polymers with a high-spin ground state and exceptional intrinsic conductivity.

Photoelectric synaptic transistors integrate optical sensing and synaptic functions into a single device, which has significant advantages in neuromorphic computing for visual information, recognition, memory, and processing. However, the weight updating of existing photoelectric synapses is predominantly based on separate utilization of light and electrical stimuli to regulate synaptic excitation and inhibition. This approach significantly restricts the processing speed and application scenarios of devices. In this work, we propose bipolar synaptic organic/inorganic heterojunction transistor (BSOIHT) that can effectively simulate bidirectional (excitatory/inhibitory) synaptic behavior under light stimulation. Furthermore, by changing the position of electrode contacts and the metals of source and drain electrodes, carrier injection of the transistor is significantly improved with reduced synaptic event power consumption down to 2.4 fJ. Moreover, the BSOIHTs are adopted to build the neuromorphic vision system, which effectively facilitates image preprocessing and substantially enhances the recognition accuracy from 44.93% to 87.01%. This paper provides new avenues for the construction of energy-efficient artificial vision systems.

All-polymer photodetectors possess unique mechanical flexibility and are ideally suitable for the application in next-generation flexible, wearable short-wavelength infrared (SWIR, 1000–2700 nm) photodetectors. However, all-polymer photodetectors commonly suffer from low sensitivity, high noise, and low photoresponse speed in the SWIR region, which significantly diminish their application potential in wearable electronics. Herein, two polymer acceptors with absorption beyond 1000 nm, namely P4TOC-DCBT and P4TOC-DCBSe, were designed and synthesized. The two polymers possess rigid structure and good conformational stability, which is beneficial for reducing energetic disorder and suppressing dark current. Owing to the efficient charge generation and ultralow noise current, the P4TOC-DCBT-based all-polymer photodetector achieved a specific detectivity ( ) of over 10 12 Jones from 650 (visible) to 1070 nm (SWIR) under zero bias, with a response time of 1.36 μs. These are the best results for reported all-polymer SWIR photodetectors in photovoltaic mode. More significantly, the all-polymer blend films exhibit good mechanical durability, and hence the P4TOC-DCBT-based flexible all-polymer photodetectors show a small performance attenuation (<4 %) after 2000 cycles of bending to a 3 mm radius. The all-polymer flexible SWIR organic photodetectors are successfully applied in pulse signal detection, optical communication and image capture.

Interfacial engineering has proven to be important in regulating the performance of optoelectronics. However, immobilized interlayer molecules may diffuse between adjacent layers in devices and induce an inferior electrical performance. In this study, the polyethylenimine ethoxylated (PEIE) modification layer at the source-drain contacts/semiconductor interface was cross-linked with siloxane cross-linking agents (SCAs) to enhance the performance of organic thin film transistors (OTFTs) based on diketopyrrolopyrrole-type conjugated polymer (P4FTVT-C32). Our results demonstrate that the improvement of device performance is closely related to the electron-donating ability and the surface energy-modifying capabilities of the functional group on SCAs. Tertiary amino group-containing (N,N-dimethylaminopropyl)trimethoxysilane (NTMS) is in favor of stronger electron-donating ability for higher carrier density and further reduced work function of Au contacts and moderate surface potential for large semiconductor crystalline domains. As a result, OTFTs modified by NTMS-cross-linked PEIE exhibited increased electron mobility to over 7 cm(2) V-1 s(-1) from similar to 3 cm(2) V-1 s(-1), together with increased on/off ratio by similar to 1 order of magnitude as compared to that modified by un-cross-linked PEIE. On the other hand, cross-linking of PEIE interlayer with alkyl-substituted SCA trimethoxy(octyl)silane (TOTS) led to the largest surface tension for largest crystalline domain size, highest alignment degree, and compact stacking of P4FTVT-C32 and thus increased the electron mobility over 5 cm(2) V-1 s(-1). The PEIE interlayer cross-linking strategy was also verified in isoindigo- and naphthalenediimide-based n-channel OTFTs in terms of enhanced electron mobility and on/off ratio. This work highlighted the potential of interlayer cross-linking strategy using functional cross-linkers in enhancing the performance of organic electronics.

The increasing amount of electronic exerts a profound impact on both the environment and human health. Looking forward, it is imperative to develop electronic products that can degrade under mind condition, which largely relies on the development of degradable organic semiconductors (OSCs). Yet, designing degradable OSCs with decent electrical properties is challenging. In this study, two degradable n-type OSCs based on a dynamic covalent CC bond formed via the Knoevenagel condensation reaction are reported. The cleavage of Knoevenagel formed CC bond through a retro-Knoevenagel process imparts the degradability of these two OSCs in the weak base, particularly in the human-friendly alpha-amino acid of lysine. Meanwhile, the CC bond formed by Knoevenagel reaction preserves optimal backbone planarity and good electron delocalization of the molecules. This, in turn, endows the OSCs with commendable electron transport performance, achieving an electron mobility of up to 0.57 cm(2) V-1 s(-1) in organic thin-film transistors. This work provides a new insight into the molecular design strategy for the development of OSCs with degradability and good electrical properties.

Doping is a crucial strategy for effectively modulating the charge transport properties of organic semiconductors and thus the performance of the resulting organic optoelectronic devices. In this study, we report an ammoniumyl radical cation oxidant, tris(4-bromophenyl)ammoniumyl hexachloroantimonate (magic blue, MB), for tuning the performance of diketopyrrolopyrrole polymer (TDPP-Se)-based organic thin-film transistors (OTFTs). In comparison to the classical dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), MB oxidizes TDPP-Se into nonradical bipolarons at a higher polaron yield of similar to 100% and lower energy levels to trap unwanted minority carriers. As a result, the MB-doped system overcomes the leveling up of off-current prevalently observed in doped OTFTs. In addition, MB is compatible with the host semiconductor and enhances the crystallization of the polymer, facilitating the formation of ordered films with a reduced trap density. Following optimization of the doping ratio, bar-coated OTFTs achieve a maximum mobility of 7.59 cm(2) V-1 s(-1), with the threshold voltage reduced to -2 V and without sacrificing the on/off ratio. These results demonstrate the potential of the strong radical oxidant for high polaron yield p-doping in organic optoelectronic devices.

High ambipolar mobility emissive conjugated polymers (HAME-CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade-off relationship between high ambipolar mobility and strong solid-state luminescence, the development of HAME-CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME-CPs are developed. A series of simple non-fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two-step microwave assisted C−H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid-state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10 −2  cm 2  V −1  s −1 , and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME-CPs by efficient synthesis and rational design.

Artificial photonic synapses offer an efficient solution for overcoming the von Neumann bottleneck in data storage and processing, providing advantages over electrical synapses by eliminating the bandwidth-connection-density tradeoff and exhibiting low power consumption. Perovskite quantum dots (QDs) have garnered significant attention in artificial photonic synapses due to their facile synthesis and favorable optoelectronic properties. However, challenges such as limited carrier mobility and nonlinearity impede their performance in neuromorphic applications. In this study, CsPbBr3-attached MXene nanostructures (CsPbBr3-MXene), in-situ growth of CsPbBr3 QDs on MXene nanosheets, were proposed as the light-absorbing layer of a synaptic phototransistor. The heterostructure formed by CsPbBr3 and MXene enhances photocurrent generation. Comparative analyses between CsPbBr3-MXene synapse transistor and that containing only CsPbBr3 revealed a 24.6

Organic photoelectric neuromorphic devices that mimic the brain are widely explored for advanced perceptual computing. However, current individual neuromorphic synaptic devices mainly focus on utilizing linear models to process optoelectronic signals, which means that there is a lack of effective response to nonlinear structural information from the real world, severely limiting the computational efficiency and adaptability of networks to static and dynamic information. Here, a feedforward photoadaptive organic neuromorphic transistor with mixed-weight plasticity is reported. By introducing the potential of the space charge to couple gate potential, photoexcitation, and photoinhibition occur successively in the channel under the interference of constant light intensity, which enables the device to transform from a linear model to a nonlinear model. As a result, the device exhibits a dynamic range of over 100 dB, exceeding the currently reported similar neuromorphic synaptic devices. Further, the device achieves adaptive tone mapping within 5 s for static information and achieves over 90% robustness recognition accuracy for dynamic information. Therefore, this work provides a new strategy for developing advanced neuromorphic devices and has great potential in the fields of intelligent driving and brain-like computing. This work proposes a feedforward adaptive organic neuromorphic transistor with mixed-weight plasticity (MP-ONH) that transitions from linear mode to nonlinear mode based on light intensity. It achieves a dynamic range of 100 dB for light intensity, surpassing current similar synaptic devices. It also enables adaptive tone mapping in 5 s for static information and achieves over 90% accuracy in robust recognition of dynamic information.image

The large-scale fabrication and patterning of artificial perceptual systems are vital for the development of bionic systems. Traditional patterning processes are often constrained by the use of mask versions, which are not only expensive but also challenging to produce on a large scale. Inkjet printing technology with maskless patterning capability is well suited for current demands for large-scale preparation and patterning. However, the application of printing techniques is typically confined to the production of simple devices or the preparation of patterned active layers within more complex devices. In this study, we successfully fabricated fully inkjet-printed indium gallium zinc oxide (IGZO) memristor arrays to mimic artificial nociceptor (pain receptors). By integrating a layer of silver into the all metal-oxide indium tin oxide (ITO)/IGZO/ITO memristor, we achieved stable threshold switching characteristics, a large current switching ratio of 105, excellent switching durability of 104 cycles scans, and excellent spatial uniformity. We investigated the Ag-based conductive filament conduction mode and mimic LIF characteristics (leaky, integrate and fire), demonstrating the potential of the memristor as an artificial neuron. Lastly, we successfully implemented artificial nociceptor, including “threshold fire”, “relaxation”, “non-adaptation”, and “sensitization”, leveraging the stable threshold switching properties of the device. Our work demonstrates the significant potential of inkjet printing technology in the realization of bionic systems.

Crystalline and soluble 1D linear conjugated polymers (LCPs) have garnered considerable interest as cost-effective and efficient metal-free electrocatalysts for the oxygen reduction reaction (ORR) due to their high exposure of catalytic sites and ease of processing. However, difficulties remain in achieving excellent ORR performance for 1D LCPs by conventional molecular design. Herein, it is demonstrated the utilization of quinoidal units as a promising strategy to develop 1D LCPs for ORR. The incorporation of quinoidal unit not only results in polymers with strong inter- and intra-molecular interactions and low-lying LUMO (lowest unoccupied molecular orbital) energy levels, but also provides polymers with good crystallinity and commendable charge carrier mobilities. The electronic properties of these polymers are fine-tuned through the introduction of additional heteroatoms and/or substituents in the monomers and comonomers to understand and optimize their ORR catalytic activity. Evaluation of their catalytic performances reveals a remarkable half-wave potential and limiting current density of up to 0.74 V (vs reversible hydrogen electrod) and 7.50 mA cm-2, respectively. Notably, these performances are achieved without the addition of carbon nanomaterials as support. This study offers a new insight into the design of highly efficient metal-free organic electrocatalysts. 1D linear conjugated polymers containing a quinoidal unit are synthesized as the metal-free electrocatalysts for oxygen reduction reaction. These polymers show good film-forming properties, well-ordered structures, and excellent charge transport abilities. As a result, they exhibit high oxygen reduction reaction catalytic activities without the need for carbon nanomaterials as support. image

Vibration-assisted grinding is one of the most promising technologies for manufacturing optical components due to its efficiency and quality advantages. However, the damage and crack propagation mechanisms of materials in vibration-assisted grinding are not well understood. In order to elucidate the mechanism of abrasive scratching during vibration-assisted grinding, a kinematic model of vibration scratching was developed. The influence of process parameters on the evolution of vibration scratches to indentation or straight scratches is revealed by displacement metrics and velocity metrics. Indentation, scratch and vibration scratch experiments were performed on quartz glass, and the results showed that the vibration scratch cracks are a combination of indentation cracks and scratch cracks. Vibration scratch cracks change from indentation cracks to scratch cracks as the indenter moves from the entrance to the exit of the workpiece or as the vibration frequency changes from high to low. A vertical vibration scratch stress field model is established for the first time, which reveals that the maximum principal stress and tensile stress distribution is the fundamental cause for inducing the transformation of the vibration scratch cracking system. This model provides a theoretical basis for understanding of the mechanism of material damage and crack propagation during vibration-assisted grinding.

Developing n-doped conjugated polymers (CPs) with good air stability remains a significant obstacle to the advancement of organic thermoelectrics. In this study, three CPs (designated PmQ2F, PsQ4F, and PsQ6F) containing an oxindole-terminated quinoidal unit are synthesized. To obtain an isomeric purity quinoidal unit and tune the LUMO (lowest unoccupied molecular orbital) energies of the CPs, fluoride (F) atoms on the monomers are strategically installed. Compared to a polymer with isomeric quinoidal units (PmQ2F), polymers with an isomerically pure quinoidal unit (PsQ4F and PsQ6F) exhibited higher electron mobilities owing to their more-ordered molecular packing structures. After n-doping, PsQ4F and PsQ6F show higher electrical conductivities than PmQ2F. Moreover, the former demonstrated excellent air stability for over 2 months, which can be attributed to the synergistic effects of the quinoidal structure and the reduced LUMO energy. The work offers a novel molecular design strategy that can be expected to advance the development of n-type CPs for air-stable organic thermoelectrics. n-Type conjugated polymers are synthesized using an oxindole-terminated quinoidal unit. The exclusion of isomers within the quinoidal unit has a beneficial impact on the molecular packing, thereby significantly enhancing electron transport performance. After n-doping, the polymers show good air stability for over two months, owing to the synergistic effects of the quinoidal structure and the reduced LUMO energies. image

Selective doping of a single conjugated polymer (CP) to obtain p ‐type and n ‐type conductive materials would be highly attractive for organic thermoelectric applications, because it will greatly reduce the time and costs of synthesizing different types of CPs. However, this strategy has rarely been investigated. In this study, two CPs are synthesized, designated PTQDPP‐T and PTQDPP‐2FT, based on a newly developed quinoidal unit with thienoisatin as the termini and a thiophene‐flanked diketopyrrolopyrrole (ThDPP) unit as the quinoidal core. The electron‐rich thiophene rings in thienoisatin and the electron delocalization induced by thienoisatin resulted in polymers with high‐lying highest occupied molecular orbital, and the electron‐deficient nature of ThDPP unit and its quinoidal backbone endowed the polymers with low‐lying lowest unoccupied molecular orbitals. As a result, both polymers can be p ‐type and n ‐type doped. Because of its high mobility, doped PTQDPP‐2FT performed better in organic thermoelectric devices than the doped PTQDPP‐T. After being doped with FeCl 3 and N‐DMBI, PTQDPP‐2FT showed p ‐type and n ‐type power factors of 278.2 and 2.37 µW m −1 K −2 , respectively. These are the best for bipolar ( p ‐type and n ‐type) performances that obtained by selective doping of a single polymer.

The spacer length effect of seven poly(DPP-alt-terthiophene)s with tributylsilylalkyl side chains was systematically studied, and the polymer SiC6 exhibited the best device performance with a reliable hole mobility up to 2.69 cm2 V−1 s−1 from o-xylene.