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Artificial skin that simultaneously mimics sensory feedback and mechanical properties of natural skin holds substantial promise for next-generation robotic and medical devices. However, achieving such a biomimetic system that can seamlessly integrate with the human body remains a challenge. Through rational design and engineering of material properties, device structures, and system architectures, we realized a monolithic soft prosthetic electronic skin (e-skin). It is capable of multimodal perception, neuromorphic pulse-train signal generation, and closed-loop actuation. With a trilayer, high-permittivity elastomeric dielectric, we achieved a low subthreshold swing comparable to that of polycrystalline silicon transistors, a low operation voltage, low power consumption, and medium-scale circuit integration complexity for stretchable organic devices. Our e-skin mimics the biological sensorimotor loop, whereby a solid-state synaptic transistor elicits stronger actuation when a stimulus of increasing pressure is applied.

'Smart' bandages based on multimodal wearable devices could enable real-time physiological monitoring and active intervention to promote healing of chronic wounds. However, there has been limited development in incorporation of both sensors and stimulators for the current smart bandage technologies. Additionally, while adhesive electrodes are essential for robust signal transduction, detachment of existing adhesive dressings can lead to secondary damage to delicate wound tissues without switchable adhesion. Here we overcome these issues by developing a flexible bioelectronic system consisting of wirelessly powered, closed-loop sensing and stimulation circuits with skin-interfacing hydrogel electrodes capable of on-demand adhesion and detachment. In mice, we demonstrate that our wound care system can continuously monitor skin impedance and temperature and deliver electrical stimulation in response to the wound environment. Across preclinical wound models, the treatment group healed ~25% more rapidly and with ~50% enhancement in dermal remodeling compared with control. Further, we observed activation of proregenerative genes in monocyte and macrophage cell populations, which may enhance tissue regeneration, neovascularization and dermal recovery.

Intrinsically stretchable bioelectronic devices based on soft and conducting organic materials have been regarded as the ideal interface for seamless and biocompatible integration with the human body. A remaining challenge is to combine high mechanical robustness with good electrical conduction, especially when patterned at small feature sizes. We develop a molecular engineering strategy based on a topological supramolecular network, which allows for the decoupling of competing effects from multiple molecular building blocks to meet complex requirements. We obtained simultaneously high conductivity and crack-onset strain in a physiological environment, with direct photopatternability down to the cellular scale. We further collected stable electromyography signals on soft and malleable octopus and performed localized neuromodulation down to single-nucleus precision for controlling organ-specific activities through the delicate brainstem.

This review was aimed to analyze existing polymer-based technologies for electrets used in memory devices and artificial synapses. We categorize five types of electrets and analyze their performance, characteristics, applicability, and limitations.

Intrinsically stretchable bioelectronic devices based on soft and conducting organic materials have been regarded as the ideal interface for seamless and biocompatible integration with the human body. However, the grand challenge remains for the conducting polymer to possess both high mechanical ductility and good electrical conduction at cellular level feature sizes. This longstanding material limitation in organic bioelectronics has impeded the full exploitation of its unique benefits. Here, we introduce a new molecular engineering strategy based on rationally designed topological supramolecular networks, which allows effective decoupling of competing effects from multiple molecular building blocks to meet complex requirements. We achieve two orders of magnitude improvement in the conductivity under 100% strain in physiological environment, along with the capability for direct photopatterning down to 2 μm. These unprecedented capabilities allow us to realize previously inaccessible bioelectronic applications including high-resolution monitoring of ‘soft and malleable’ creatures, e.g., octopus, and localized neuromodulation down to single nucleus precision for controlling organ-specific activities through delicate tissues, e.g., brainstem.

We report the effects of the composition on the stretchability and conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) polymer blends with soft polymers including poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA) and their application in pressure sensors. The composition–stretchability relationship was investigated with the stress–strain curves of the bulk films. Among these polymer blends, PAA-based blends outperformed in stretchability, attributed to the low glass transition temperature and ductile nature of PAA. And the composition–conductivity relationship was studied with conductive atomic force microscopy, Gaussian simulation and infrared spectroscopy. The PAA-based blends presented well-dispersed morphology for PEDOT and the strongest hydrogen bonding network between PAA and PEDOT:PSS was created through the blending, which gave rise to stable and high conductivity. Furthermore, the conductivity of the PEDOT:PSS/PAA blend at 20/80 wt ratio was largely increased (13 to 125 S cm−1) and stretchability (elongation at break) increased from 20 to 40% through methanol treatment. Finally, PAA-based blends treated with methanol were applied to the pressure sensor device, achieving a very high sensitivity of 39.90 kPa−1 at 20% tensile strain, a quick response time of around 49 ms, and a low detection limit of about 27.4 Pa. This study suggested a novel and facile approach to manipulate the structure and stretchability of the PEDOT:PSS polymer blending system for stretchable electronics.

Next-generation light-emitting displays on skin should be soft, stretchable and bright

Innocuous hydrogels with the characteristics of high conductivity, stretchability and air-stability have potential applications for emerging wearable and bio-related electronic devices. In this study, we develop a rapid and green method for stretchable supercapcitors using safer chemicals to produce hygroscopic conductive polymer hydrogels, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/poly(vinyl alcohol)/poly(methacrylic acid) (PEDOT:PSS/PVA/PMAA). The as-fabricated conductive polymer hydrogels show a high stretchability as well as a high conductivity (3.1 S cm−1) after absorbing water moisture as the plasticizer, which are used as current collectors and electrode materials to assemble the supercapacitor. By modulating the PEDOT: PSS composition in the hydrogel, the fabricated supercapacitor exhibits fascinating mechanical properties and excellent electrochemical characteristics. The supercapacitor has a maximum specific capacitance of 7.38 mF cm−2 at 10 mV/s, and shows 82% capacitance retention over 2000 charge-discharge electrochemical cycling testing at a current density of 10 mA cm−2. More importantly, the device could be stretched up to 100% strain without affecting the electrochemical performance and is well conserved after stretching 1000 times under 30% tensile strain.

We report the synthesis, morphology, and properties of intrinsically stretchable isoindigo–bithiophene conjugated copolymers (PII2T) by incorporating octyldecane (OD) and poly(acrylate amide) (PAAm) side chains. Stronger molecular aggregation and crystallinity could be observed from the AFM morphology and GIXD analysis due to the hydrogen bonding interaction between the PAAm side chains. Thus, it achieved excellent stretchability and superior charge carrier mobility compared to the parent PII2T polymer. PAAm side chains were controlled with 5 (PAAm5) and 10 (PAAm10) repeating units, and the PII2T backbones were designed using 0, 5 and 10% PAAm side chains (P1–P3). The experimental results showed that PII2T with 5–10% PAAm5 were beneficial for the improvement of crystallinity and stretchability. However, PII2T with 5% PAAm10 (P4) exhibited poor crystallinity and charge carrier mobility due to the bulkiness of the side chains that disturb the molecular stacking. PII2T with 5% of the PAAm5 side chains showed a higher hole mobility of 0.30 cm2 V−1 s−1. Also, the soft segment in the PAAm side chains provided an amorphous domain facilitating stable mechanical properties. For PII2T with 5% of the PAAm5 chains, the cracking onset strain, the crystallinity preservation, and the elastic modulus for the transferred thin film increased from 20 to 60%, 37 to 61%, and 0.89 to 0.75 GPa, respectively, compared with the parent PII2T polymer. The double printed polymer thin films under an 80% strain had a stable hole mobility of 0.06 cm2 V−1 s−1. The improved stretchability and charge carrier mobility were attributed to the intrinsic softness of the PAAm side chains and the hydrogen bonding interaction. It suggests that the incorporation of hydrogen-bonded PAAm side chains into the PII2T backbone provides great potential for flexible and wearable electronic applications.

We report the synthesis, morphology, and electronic properties of intrinsically stretchable AB-type, ABA-type, and BAB-type block copolymers (BCPs) of poly(3-hexylthiophene) (P3HT: A block) and elastic poly(octylene oxide) (POO: B block). By incorporating the soft coils, all BCP thin films exhibited clear self-assembled fibrillary nanostructures and largely improved stretchable mechanical properties within the films. The results from the absorption spectra and AFM images indicated that the self-assembled structures of the P3HT blocks in the block copolymers were related to the backbone sequences. Also, the phased-separated morphology of the AB-, ABA-, and BAB-block copolymers from GI-SAXS showed the average nanofibril d-spacing ranging from 17.9, 21.6, and 13.9 nm, respectively, which led to the same order on the formed nanofibril density. Among all the BCPs, only the ABA-type BCP thin film remains perfectly smooth and no wrinkle or crack is observed even up to the strain of 100%. These results indicate the significance of the conjugated/elastic block sequence for the morphology and physical properties of the prepared block copolymers. The resistive memory devices fabricated in the configuration of PDMS (substrates)/CNTs (bottom electrode)/BCP thin films (active layer)/Al (top electrode) exhibited non-volatile flash characteristics. In particles, the as-fabricated resistive memory device with the ABA-type BCP could endure up to 80% strain and an excellent ON/OFF current ratio was also achieved after 500 continuous stretching/releasing cycles under 50% strain. This work highlights the importance of molecular architectures on the conjugated/elastic ratios of BCPs for stretchable devices.

In this study, we first revealed green materials – poly-lysines (poly-L-lysine and poly-L-lysine blend poly-D-lysine) – as electron-extraction layers (EELs) in organic photovoltaics (OPVs). The distinct configurations of poly-lysine enantiomers were verified by conducting zeta potential analysis, and their work function (WF)-tuning capabilities for indium tin oxide (ITO) were affirmed by ultraviolet photoelectron spectroscopy (UPS). These two poly-lysine groups, with different arrangements of the amino groups that built up different surface dipoles on the ITO substrate, altered the surface energy and WF of ITO. Poly-L-lysine optimized the WF of ITO for efficient carrier transport in the OPV device, in the electron transporting layer-free OPV devices, and we observed a high power conversion efficiency (PCE) of 10.01% in the device configuration of ITO/interlayer/BHJ/MoO3/Ag. As the first examination of poly-lysine enantiomers for OPVs, we provided the WF-tuning functions – increasing polarity as an interfacial dipole is formed at the corresponding interface, and discovered a promising interfacial material possessing high efficiency and benefitting from a long-term stability to perform in a stable PCE with about 80% of its original PCE remaining after continuous heat and light treatment for 400 hours.

In this study, a series of alcohol-soluble cross-linked block copolymers (BCPs) consisting of poly(n-butyl acrylate) (poly(nBA)) and poly(N-vinyl-1,2,4-triazole) (poly(NVTri)) blocks with different individual functions and lengths are designed and developed. These presynthesized cross-linked BCPs (PBAn–Trim) were, for the first time, revealed to exhibit many advantages in serving as the electron-extraction layer (EEL) for organic photovoltaics (OPVs). The cross-linked BCPs possessed intense ionic functionality, showing well capability to form effective interfacial dipoles at the indium tin oxide interface to facilitate the charge extraction at the corresponding interface. Furthermore, it also consisted a core–shell structure, wherein the polar poly(NVTri) core was well protected by the poly(nBA) shell to endow improved robustness against solvent erosion and thermal/photo inputs. Consequently, the PBA70–Tri30 device yielded a decent power conversion efficiency of 8.03% with a Voc of 0.83 V, much exceeding ...

Photonic data storage has diverse optoelectronic applications such as optical sensing and recording, integrated image circuits, and multibit-storage flash memory. In this study, we employ conjugated/insulated polymer blends as the charge storage electret for photonic field-effect transistor memory devices by exploring the blend composition, energy level alignment, and morphology on the memory characteristics. The studied conjugated polymers included poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PF), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[{2,5-di(3',7'-dimethyloctyloxy)-1,4-phenylene-vinylene}-co-{3-(4'-(3″,7″-dimethyloctyloxy)phenyl)-1,4-phenylenevinylene}-co-{3-(3'-(3',7'-dimethyloctyloxy)phenyl)-1,4-phenylenevinylene}] (SY-PPV), and poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT), and the insulated polymers were polystyrene (PS) and poly(methyl methacrylate) (PMMA). The photonic memory device using the PF/PS blend electret exhibited a dynamic switching behavior with light-writing and voltage-erasing processes both within only 1 s, along with a high contrast on the current on/off ratio between "Photo-On" and "Electrical-OFF" over 106 and the decent retention time for more than 3 months. In addition, the multilevel memory behavior could be observed using different light sources of 405, 450, and 520 nm or energy intensity, which was supported by surface potential analysis. The characteristics were superior to those of the devices using PF/PMMA blend due to the higher charge storage behavior of PS supported by fluorescence analysis. The PF/PS blend film prepared from the chlorobenzene solvent exhibited mesh-like and aggregated PF domains in the PS matrix and enhanced the contact surface area between the semiconductor and blend electret, leading to a higher memory window. The photonic memory behavior was also observed in the blend electrets of PS with the low band gap polymer, MEH-PPV, SY-PPV, or F8BT, by changing the photoresponsive light sources. Our study demonstrated a new electret system to apply on the multilevel photonic memory devices.

In recent years, the exploitation of stretchable organic solar cell (OSC) has attracted significant research interests due to the rapid progress of wearable electronics. However, the development of a stretchable OSC is quite challenging since it has a strict requirement for the mechanical deformability and durability of each constituent layer in device. In this work, we successfully fabricated an efficient, stretchable inverted OSC by adopting a buckle-on-elastomer strategy, for which an ultrathin poly(ethylene naphthalate) (PEN) substrate coupled with a pre-strained (100%) 3M elastomeric tape was employed as the device substrate. Owing to the pre-strained status of the elastomer, the ensemble wrinkle will be formed in response to accommodate the strain once the pre-strain was released, which can afford the derived OSC with a much improved mechanically robustness and stretchability. As a result, we demonstrated that a pristine efficient (PCE: 5.61%) OSC using such buckling scaffold can remain its 74% efficiency under 30% compression and, more importantly, can still retain its 64.3% efficiency after 50-cycle compression-stretching testing from 0% to 30% compression. Besides, the effects of mechanical deformation and durability on the electrical performance are also investigated. This work proves that the buckle-on-elastomer strategy can be a good solution for realizing efficient OSCs with reasonably good mechanical durability, revealing great potential serving as an ultrathin and lightweight power source for wearable device applications.

In this work, a stretchable resistive memory device was demonstrated using a functional polyimide with intrinsic stretchability. A series of poly(siloxane-imide)s based on different dianhydrides (ODPA, BPDA, and PMDA) and diamines with different siloxane lengths (DMS-A12 (molecular weight = 900–1000) and DMS-A15 (molecular weight = 3000)) were synthesized for a systematic study. By incorporating the flexible siloxane chain into the polyimide's backbone, the overall solubility and stretchability of the derived polymers can be improved. The memory behavior of these poly(siloxane-imide)s was first examined in the conventional structure, and a stable WORM-type memory property was observed. It could have resulted from the formation of a conductive filament induced by charge transfer and accumulation. Among all the studied polymers, ODPA-A12 showed a Young's modulus (1.596 MPa) compatible with the crosslinked polydimethylsiloxane (PDMS) elastomer, revealing promising potential for stretchable device fabrication. Based on this advantage, a stretchable resistive memory device was realized using ODPA-A12 as the active layer with the employment of the cross-linked PDMS elastomer as the substrate and a carbon nanotube (CNT) as the electrode (PDMS/CNTs/PI/Al). The device not only showed stable WORM-type memory characteristics with a high On/Off ratio (>106) under up to 40% strain, but also possessed high mechanical endurance under 20% strain for 600 stretching cycles. Our results highlight the merits of siloxane-containing polymers for applications in stretchable electronic devices.

Harnessing biomass to fabricate electronic devices has lately drawn significant research attention because it not only represents a promising strategy for making materials but is also beneficial for the sustainable development of technologies. Numerous recent studies have demonstrated that green materials are promising candidates for synthesizing high-performance materials, such as biopolymers and hierarchical porous carbons. To catch up with this emerging tide, we have here compiled a comprehensive overview of state-of-the-art green materials, with a specific emphasis on recent progress in biodegradable polymeric materials and biomass-based carbon materials, together with their electronics and energy storage applications. Besides, we also assess the performance of end-of-life electronics recycling to highlight the merits of integrating green design with resource recovery.

Ternary organic photovoltaics (OPVs) have recently attracted intense research attention since they have been proven as an effective approach to enhance device performance. We herein describe a new strategy to realize high-performance ternary OPVs by using biaxially extended octithiophene (8T)-based wide-bandgap (Eg) conjugated polymers as the third photoactive component. Owing to the π–π transition of the biaxially extended conjugated side-chains, such polymers exhibit intense absorption in the near-ultraviolet region, in addition to the original intra-charge transfer (ICT) feature arising from the main backbone, revealing a new molecular design for wide-Eg polymers. By further tailoring the polymer backbone with p-type moieties such as thiophene (T) or thienothiphene (TT), two wide-Eg (∼2.0 eV) polymers, P8TT and P8TTT, with absorption wavelengths below 650 nm, were prepared, showing high complementary absorption to the spectra of both the state-of-the-art fullerene-(PTB7-Th:PC71BM) and non-fullerene-based (PBDB-T:ITIC) bulk-heterojunction (BHJ) systems. By providing suitable energy levels, P8TTT was demonstrated to enhance the power conversion efficiency (PCE) of its derived fullerene- and non-fullerene-based ternary blends by 7.58% and 6.60%, respectively, with only a small loading amount (10 wt%). This study manifests a new perspective in wide-Eg material design for realizing efficient ternary BHJ systems.

We present a strategy for controlling the device performance of organic field effect transistor (OFET) memory devices by using a metallo-phthalocyanine (MPc)-cored star-shaped polystyrene as a charge storage material. MPc-cored four-armed star polymers (M = Cu or Zn) with polystyrene arms of three different number-average molecular weights were prepared by atom transfer radical polymerization and cyclization reactions with metal ions; the density of the MPc cores dispersed in the polymer matrix was dependent on the lengths of polymer arms. The charge carrier mobility of pentacene-based OFET memory devices containing the star polymer varied with the nature of the MPc-cored star polymer layer owing to the presence of the MPc core unit as well as the nanostructures of the polymer thin films. Application of an external gate bias to the OFET device caused significant reversible shifts in the threshold voltage, and the magnitude of the memory shifts was proportional to the weight percentage of MPc cores in the star polymer matrix. The memory device showed a high memory on/off current ratio (>105) and long retention characteristics (>105 s), permitting it to be characterized as a nonvolatile organic memory device; the retention time extended upon increasing the Mn of the star polymer. The MPc-cored star polymer is a promising material designed as a charge storage layer for controlling the performance of organic flash memory devices.

A stretchable and mechanical robust field-effect transistor is essential for soft wearable electronics. To realize stretchable transistors, elastic dielectrics with small current hysteresis, high elasticity, and high dielectric constants are the critical factor for low-voltage-driven devices. Here, we demonstrate the polar elastomer consisting of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP):poly(4-vinylphenol) (PVP). Owing to the high dielectric constant of PVDF-HFP, the device can be operated under less than 5 V and shows a linear-regime hole mobility as high as 0.199 cm2 V–1 s–1 without significant current hysteresis. Specifically, the PVDF-HFP:PVP blends induce the vertical phase separation and significantly reduce current leakage and reduce the crystallization of PVDF segments, which can contribute current hysteresis in the OFET characteristics. All-stretchable OFETs based on these PVDF-HFP:PVP dielectrics were fabricated. The device can still keep the hole mobility of approximately 0.1 cm...

We report the synthesis, morphology, and properties of poly(3-hexylthiophene)-block-poly(butyl acrylate) (P3HT-b-PBA) for stretchable electronics applications, which are consisted of semiconducting P3HT and low glass transistion temperature (Tg) PBA blocks. The P3HT-b-PBA thin films self-assembled into fibrillar-like nanostructures and maintained the edge-on oreientation even at a low P3HT composition, based on the results from atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD). By varying the P3HT/PBA ratio, the tensile modulus decreased as the block length of PBA increased, from 0.93 GPa for P3HT to 0.19 GPa for P3HT-b-PBA12k. The field effect transistor (FET) using P3HT-b-PBA as the active layer exhibited a high p-type mobility over 10–2 cm2 V–1 s–1, indicating its good charge transporting ability. Furthermore, the P3HT-b-PBA6k based FET under 100% strain had a high mobility of 2.5 × 10–2 cm2 V–1 s–1 with an on/off ratio of 7.2 × 106, and it maintained over 10–2 cm2 V–1 s–1 fo...

Carbohydrate-based block copolymers, such as maltoheptaose-block-polyisoprene (MHPI), were successfully employed as polyelectrolytes in a light-emitting electrochemical cell (LEC) to realize organic multi-state electrical memory. The observation of distinctive multi-state memristive behavior could be attributed to the controlled ion motion in MHPI and the electron capture capabilities introduced by its constituent hydroxyl groups. The newly developed sandwich-structured memory device is based on a LEC platform as the light-emitting electrochemical cell memory (LECM). Furthermore, the fabricated LECM exhibited excellent ternary-state memory behavior with high ON2/ON1/OFF current ratios of 106/105/1 as well as excellent stabilities for each respective state. The study not only illustrates the use of carbohydrate-based materials as promising electrolytes for LECM applications, but also provides a new horizon in the development of organic multi-state electrical memory devices.

In this study, a series of alcohol-soluble cross-linked block copolymers (BCPs) consisting of poly( n-butyl acrylate) (poly( nBA)) and poly( N-vinyl-1,2,4-triazole) (poly(NVTri)) blocks with different individual functions and lengths are designed and developed. These presynthesized cross-linked BCPs (PBA

Over the past decades, the demand for organic memory has rapidly increased due to the development of flexible electronics. In this article, state-of-the-art nanostructured materials-based organic memory is reviewed, including nanoparticles, carbon nanotubes, graphene and nanowires. The operation mechanism and the impact of nanostructured materials on the electrical performance are discussed. Moreover, proposed charge-trapping mechanisms using nano-materials are reviewed to provide fundamental understanding as well as further performance improvement.

Biocompatible deoxyribonucleic acid (DNA), with high mechanical strength, was employed as the substrate for a Ag nanowire (Ag NW) pattern and then used to fabricate flexible resistor-type memory devices. The memory exhibited typical write-once-read-many (WORM)-type memory features with a high ON/OFF ratio (104), long-term retention ability (104 s) and excellent mechanical endurance.

A molecular nano-floating gate (NFG) of pentacene-based transistor memory devices is developed using conjugated polymer nanoparticles (CPN) as the discrete trapping sites embedded in an insulating polymer, poly (methacrylic acid) (PMAA). The nanoparticles of polyfluorene (PF) and poly(fluorene-alt-benzo[2,1,3]thiadiazole (PFBT) with average diameters of around 50–70 nm are used as charge-trapping sites, while hydrophilic PMAA serves as a matrix and a tunneling layer. By inserting PF nanoparticles as the floating gate, the transistor memory device reveals a controllable threshold voltage shift, indicating effectively electron-trapping by the PF CPN. The electron-storage capability can be further improved using the PFBT-based NFG since their lower unoccupied molecular orbital level is beneficial for stabilization of the trapped charges, leading a large memory window (35 V), retention time longer than 104 s with a high ON/OFF ratio of >104. In addition, the memory device performance using conjugated polymer nanoparticle NFG is much higher than that of the corresponding polymer blend thin films of PF/polystyrene. It suggests that the discrete polymer nanoparticles can be effectively covered by the tunneling layer, PMAA, to achieve the superior memory characteristics.

We fabricated dual functional electrospun (ES) nanofibers by a coaxial electrospinning technique for enhancing the organic photovoltaic (OPV) device efficiency. The nanofibers contained poly[2,7-(9,9-dihexylfluorene)-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT) nanoparticles as the luminescent solar concentrator (LSC) and Ag nanoparticles for the surface plasmon resonance (SPR) effect. Aligned- and crossed-fiber architecture patterns were fabricated to compare the effects of the architecture on the OPV efficiency. The plasmonic-enhanced LSC ES nanofibers with crosslinked poly(methacrylic acid) could be directly integrated into the conventional OPV configuration without sacrificing the coverage area of the active layer. In addition, the in situ reduction of Ag nanoparticles simultaneously enhanced the exciton generation of PFBT and the active materials with the SPR effect. The dual functional ES nanofibers with a crossed-pattern embedded into OPV devices provided significant light harvesting through down conversion and enhanced exciton generation. They led to PCE values of 4.11 and 7.12% for P3HT (poly(3-hexylthiophene)) : PC61BM ([6,6]-phenyl C61-butyric acid methyl ester) and PTB7 (polythieno[3,4-b]-thiophene-co-benzodithiophene) : PC71BM ([6,6]-phenyl C71-butyric acid methyl ester) ([6,6]-phenyl) photovoltaic cells, respectively, which are 18% enhancements compared to their parent devices. This interface-modification approach using plasmonic-enhanced LSC ES nanofibers provides a new approach for enhancing the OPV device performance.

We report high performance pentacene based organic field-effect transistor (OFET) memory devices using the electrets of conjugated rod-coil block copolymers, poly[2,7-(9,9-dihexylfluorene)]-block-poly(stearyl acrylate) (PF-b-PSA) and their nanocomposites with single-wall carbon nanotubes (SWCNT). The self-assembled PF-b-PSA electret, with the PF nanorods covered by the crystalline PSA block, exhibited a distinct hole-trapping capability due to the high electrical field generated in the confined dimension of the nanorods. Thus, it could effectively reduce the current leakage and stabilize data retention with a large memory window (35.8 V) and a high ON/OFF ratio over 104 s. Furthermore, the memory window of the device was further improved to 49.2 V by wrapping well-dispersed single-wall carbon nanotubes (SWCNT) in PF-b-PSA. The bundles of PF nanorods along the SWCNT effectively capture electrons and maintain retention characteristics similar to that of the PF-b-PSA device. This study demonstrated that the self-assembled conjugated rod-coil block copolymers and their nanocomposites could act as charge-storage electrets for high performance OFET memory devices through the precise morphology control.

This work introduces the preparation of zeolite-filled porous mixed matrix membranes (MMMs) and discusses their potential use for air separation. Porous polysulfone (PSF) matrix membranes were prepared using the nonsolvent-induced phase separation process. Scanning electron microscope and gas permeation experiments suggested the presence of closed pores in the porous matrix membranes. Furthermore, porous MMMs containing zeolite 4A particles as filler were prepared and characterized. The permeation properties of porous MMMs were highly dependent on the zeolite content. The introduction of zeolite particles distorted the closed pores in the PSF matrix and formed nonselective voids which resulted in very high oxygen flux but low O2/N2 selectivity. The annealing technique for modifying the nonselective pores present in the polymer–zeolite interface is also described in this study. The resulting annealed porous MMMs had the ability to separate O2 from N2 more effectively than traditional dense MMMs.

Donor-acceptor crosslinked poly[poly(ethylene glycol) methyl ether-methacrylate]-block-poly[1,1'-bis(2-ethylpentyl)-6-methyl-6'-(5-methyl-3-vinylthiophen-2-yl)-[3,3'-biindoline]-2,2'-dione] (poly(PEGMA)m -b-poly(VTIID)n ) nanoparticles with various vinylthiophene donor/isoindigo acceptor ratios are synthesized successfully. The prepared nanoparticles have uniform sizes and well-defined core-shell nanostructures. The intramolecular charge transfer is effectively enhanced due to the incorporation of acceptor groups after the crosslinking reaction. A transistor memory device is assembled using the synthesized polymer and has nonvolatile flash-type memory and amphiphilic trapping behavior. The optimized devices exhibit a significant memory window of approximately 38 V, a retention ability of over 104 s, and an endurance of at least 100 cycles. This study examines multiple applications of crosslinked core-shell nanoparticles, which demonstrates their promise as charge-storage dielectric materials for use in organic memory devices.

In this study, an easy to fabricate and low-cost, resistive-type CO"2 gas sensor made of poly(3,4-ethylenedioxythiophene) (PEDOT) and branched polyethylenimine (BPEI) layers was fabricated on an interdigitated electrode. The PEDOT film was made by in situ polymerization and the BPEI layer was subsequently drop-coated on top of the PEDOT film. Upon exposure to 1000ppm CO"2 at 95% relatively humidity (RH) of the BPEI-PEDOT composite sensor, the synergistic effect of BPEI on CO"2 sensing was subsequently investigated. The sensors showed no response (i.e. % of conductivity increase) if the sensor film was only made of a PEDOT layer without any BPEI. However, the response increased significantly to a value of 3.25% upon the addition of a layer of BPEI. The sensors also showed no obvious decay in the sensing response during repeated usages, providing the reusability of the technique for CO"2 detection. As for sensor's selectivity, the sensors showed higher response for CO"2 than for O"2. Originally, the sensor showed a long recovery time of nearly 1h. However, the long recovery time can be significantly shortened to approximately 10min by heating the sensors at higher temperature for CO"2 desorption. Thus, this easy and inexpensive fabrication process demonstrated that the sensor might have characteristics sufficient for real-world CO"2 detection.

Nano-floating gate memory devices (NFGM) using metal nanoparticles (NPs) covered with an insulating polymer have been considered as a promising electronic device for the next-generation nonvolatile organic memory applications NPs. However, the transparency of the device with metal NPs is restricted to 60~70% due to the light absorption in the visible region caused by the surface plasmon resonance effects of metal NPs. To address this issue, we demonstrate a novel NFGM using the blends of hole-trapping poly (9-(4-vinylphenyl) carbazole) (PVPK) and electron-trapping ZnO NPs as the charge storage element. The memory devices exhibited a remarkably programmable memory window up to 60 V during the program/erase operations, which was attributed to the trapping/detrapping of charge carriers in ZnO NPs/PVPK composite. Furthermore, the devices showed the long-term retention time (>105 s) and WRER test (>200 cycles), indicating excellent electrical reliability and stability. Additionally, the fabricated transistor memory devices exhibited a relatively high transparency of 90% at the wavelength of 500 nm based on the spray-coated PEDOT:PSS as electrode, suggesting high potential for transparent organic electronic memory devices.

Exploiting biomass has raised great interest as an alternative to the fossil resources for environmental protection. In this respect, polyethylene furanoate (PEF), one of the bio-based polyesters, thus reveals a great potential to replace the commonly used polyethylene terephthalate (PET) on account of its better mechanical, gas barrier, and thermal properties. Herein, a bio-based, flexible, conductive film is successfully developed by coupling a PEF plastic substrate with silver nanowires (Ag NWs). Besides the appealing advantage of renewable biomass, PEF also exhibits a good transparency around 90% in the visible wavelength range, and its constituent polar furan moiety is revealed to enable an intense interaction with Ag NWs to largely enhance the adhesion of Ag NWs grown above, as exemplified by the superior bending and peeling durability than the currently prevailing PET substrate. Finally, the efficiency of conductive PEF/Ag NWs film in fabricating efficient flexible organic thin-film transistor and organic photovoltaic (OPV) is demonstrated. The OPV device achieves a power conversion efficiency of 6.7%, which is superior to the device based on ITO/PEN device, manifesting the promising merit of the bio-based PEF for flexible electronic applications.

Stretchable apparatus have drawn increasing attention nowadays, especially in the applications of sensors, monitors, and optoelectronic devices.1-3 Thus far, the development of stretchable Li-ion battery is impeded by the lack of flexible electrodes associated with proper interconnecting structures for high utilization of active materials.4 As inspired by nature, a common biomaterial, shrimp shells (SSs)5, attracted our attention for fabricating an efficient, stretchable Li-ion batteries as considering its advantages, including i) the C-O, C-N and N-H stretches contained in the protein and chitin (poly-b(1/4)-N-acetyl-D-glucosamine) are beneficial for excellent electrochemical performance; ii) the constituent inorganic calcium carbonate acts as an in-situ template for the porous configuration (Fig. a); iii) The as-designed substrate could not only possess continuous electric conductivity when stretching but also accommodate a high active material loading. In this work, we successfully demonstrated a flexible, stretchable supercapacitor by using a hybrid electrode, wherein the as-prepared SSs carbon is interpenetrated into a polydimethylsiloxane (PDMS)-supported substrate. In this regard, the open network of pores was filled by the SSs carbon to provide high conductivity and stretchability. Besides, SWCNT was further sprayed onto this porous substrate to form a 3D interconnected porous structure as shown in Fig. b. Finally, by using a bifunctional polymeric electrolyte (BMITFSI-P(EO)20-LiTFSI, serving as separator and solid electrolyte with a high ionic conductivity of 1.6×10-4 S cm-1 to assemble the battery, the as-fabricated stretchable porous electrode can deliver a high energy density of 44.1 Wh kg-1 under 20% applied tensile strain. In addition, the capacitance retention shows 90% after bending from 0o to 180o. This study would pay the way for the future development of wearable supercapacitors, Li-ion batteries and beyond. W. Liu, M. S. Song, B. Kong and Y. Cui, Advanced Materials, 2016. D. J. Lipomi, M. Vosgueritchian, B. C. K. Tee, S. L. Hellstrom, J. A. Lee, C. H. Fox and Z. Bao, Nat Nano, 2011, 6, 788-792. Y. Huang, M. Zhong, F. Shi, X. Liu, Z. Tang, Y. Wang, Y. Huang, H. Hou, X. Xie and C. Zhi, Angewandte Chemie (International ed. in English), 2017, 56, 9141. W. Liu, Z. Chen, G. Zhou, Y. Sun, H. R. Lee, C. Liu, H. Yao, Z. Bao and Y. Cui, Advanced Materials, 2016, 28, 3578-3583. N. Yan and X. Chen, Nature, 2015, 524, 155-158. Figure 1