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Thermoelectric (TE) materials are significant for sustainable development because they can be used to harvest waste heat into electricity. Organic TE materials have unique merits including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. But their TE properties particularly the Seebeck coefficient are notably lower than the inorganic counterparts. Here, a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) film is reported with a very high Seebeck coefficient and figure of merit (zT) at room temperature through secondary doping, dedoping engineering, and ionic energy filtering. The PEDOT:PSS films are successively treated with acid, base, and vitamin C that is a reductant, and then coated with 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIM:DCA) that is an ionic liquid. This can exhibit a record‐high Seebeck coefficient and power factor of 111 µV K−1 and 1285 µW m−1 K−2, respectively, and the corresponding zT value is 1.05. This is the highest zT value for polymers and polymer composites, and it is comparable to that of the best inorganic TE materials. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials have attracted significant attention because they can be used to directly harvest waste heat into electricity. Organic TE materials like poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have advantages including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. However, their TE properties are notably inferior to their inorganic counterparts. Here, PEDOT:PSS films with very high thermoelectric properties through the sequential treatments with H2SO4, water, and ethanol solution of tetrakis(dimethylamino)ethylene (TDAE) are reported for the first time. The PEDOT:PSS films can exhibit a Seebeck coefficient of 58.2 µV K−1 and electrical conductivity of 1552 S cm−1, and the corresponding power factor is 526 µW m−1 K−2. The water treatment prior to the TDAE solution treatment is crucial for the high TE properties of PEDOT:PSS films. Without the water treatment, the control PEDOT:PSS films exhibit a Seebeck coefficient of only 32.4 µV K−1 and electrical conductivity of 1124 S cm−1, and the corresponding power factor is only 118 µW m−1 K−2. The effect of the water treatment on the Seebeck coefficient is attributed to the swelling of PEDOT:PSS films, which facilitates the penetration of TDAE from solution into the polymer films and thus the reduction of PEDOT:PSS. [ABSTRACT FROM AUTHOR]

Stretchable, skin-interfaced, and wearable strain sensors have risen in recent years due to their wide-ranging potential applications in health-monitoring devices, human motion detection, and soft robots. High aspect ratio (AR) silver nanowires (AgNWs) have shown great potential in the flexible and stretchable strain sensors due to the high conductivity and flexibility of AgNW conductive networks. Hence, this work aims to fabricate highly stretchable, sensitive, and linear kirigami strain sensors with high AR AgNWs. The AgNW synthesis parameters and process windows have been identified by Taguchi's design of experiment and analysis. Long AgNWs with a high AR of 1556 have been grown at optimized synthesis parameters using the one-pot modified polyol method. Kirigami sensors were fabricated via full encapsulation of AgNWs with Ecoflex silicon rubber. Kirigami-patterned strain sensors with long AgNWs show high stretchability, moderate sensitivity, excellent linearity (R2 = 0.99) up to 70% strain and can promptly detect finger movement without obvious hysteresis. [ABSTRACT FROM AUTHOR]

Perovskite materials are promising candidates for efficient optoelectronic applications. However, the highly ionic nature of perovskite crystals would induce the defects formation within perovskite during device operation, which is detrimental to the device performance and long-term stability. Herein, a strategy to decrease the defects levels and prompt the extraction of detrapped chargers in perovskite films is realized by introducing an ultra-thin 2D WS 2 interlayer to guide van der Waal quasi-epitaxial perovskite growth. Various optoelectronic characterizations and DFT calculation clearly reveal that the 2D WS 2 inhibits the native defects formation and shallow the deep defects levels within perovskite. In addition, the 2D WS2 interlayer can promptly extract the detrapped charges to reduce the interfacial recombination. Consequently, the among-highest efficiency of 20.92% with significantly enhanced V oc and FF and decent moisture stability (90% over 20 days) is achieved for the inverted planar perovskite solar cell. This work enlightens the deep understanding of highly efficient and stable perovskite photovoltaic devices with the aid of 2D materials, which should contribute to the development of devices based on perovskite/2D heterojunction. Image 1 • 2D WS 2 /3D perovskite heterojunction is fabricated for 20.92% inverted planar perovskite solar cell. • 2D WS 2 can help the perovskite photovoltaic devices keep long-term stability. • 2D WS 2 can guide epitaxial growth of the perovskite to improve its crystallinity, crystal size and film uniformity. • 2D WS 2 can improve defects formation energy and shallow defects levels within perovskite. • 2D WS 2 possesses ultra-high hole mobility to extract the detrapped charges within perovskite. [ABSTRACT FROM AUTHOR]

It is of great significance to develop high‐performance thermoelectric (TE) materials, because they can be used to harvest waste heat into electricity and there is abundant waste heat on earth. The conventional TE materials are inorganic semimetals or semiconductors like Bi2Te3 and its derivatives. However, they have problems of high cost, scarce/toxic elements, high thermal conductivity, and poor mechanical flexibility. Organic TE materials emerged as the next‐generation TE materials because of their merits including solution processability, low cost, abundant element, low intrinsic thermal conductivity, and high mechanical flexibility. Organic TE materials are mainly conducting polymers because of their high conductivity. Both the conductivity and Seebeck coefficient depend on the doping level, and they are interdependent. Hence, the TE properties of polymers can be improved through doping/dedoping engineering. There are three types of doping forms, oxidative (or reductive) doping, protonic acid doping, and charge transfer doping. Accordingly, they can be dedoped by different approaches. In this article, we review the methods to dope and dedope p‐type and n‐type TE polymers and the combination of doping and dedoping to optimize their TE properties. Secondary doping is also covered, since it can significantly enhance the conductivity of some TE polymers. [ABSTRACT FROM AUTHOR]

As a renewable and sustainable resource, solar energy exploited to conduct interfacial water evaporation has attracted considerable attention. However, conventional photo-thermal materials mainly focus on the issues of energy efficiency and multifunctionality, the lack of scalable, low-cost, flexible and washable features severely restrict the application from labs to industrialization. Significantly, owing to the low utilization of the spatial volume of the conventional two-dimensional (2D) evaporators, the development of editable and controllable 3D structures toward improved energy efficiency is highly desirable. Inspired by the traditional sewing clothes, herein, a functional photo-thermal fabrics with excellent scalable, washable and inexpensive features is designed to realize tunable and programmable 2D/3D structures, which enable the favorable in-plane and out-of-plane water extraction from liquid/solid medium. Since the polypyrrole (PPy) has favorable photo-thermal, stable features and strong interactions with the fibrous cotton, an in situ tunable oxypolymerization strategy was employed to construct PPy modified cotton fabric. The facile and robust approach enables the formation of a large-area PPy-modified cotton (PMC), which could function as a 2D generator for well-controlled in-plane water evaporation. Furthermore, the excellent sewable and editable features of the fabrics allow the programmable integration of these functional PMC building blocks into 3D system towards high-efficient out-of-plane solar vaporization. Specifically, the 3D design can adapt the photo-thermal fabrics to diverse environments with efficient purified water collection even from sand matrix. A functional photo-thermal fabric with favorable washable, sewable and programmable features is designed to realize tunable and programmable 2D/3D structures, which enable the favorable in-plane and out-of-plane water extraction from liquid/solid medium. In our system, a large-scale polypyrrole-modified cotton (PMC) was readily fabricated by a wet method of oxypolymerization, which was further cut and sewn to the pure cotton for a bilayer 3D building block. As a proof of concept, these as-prepared building blocks were orderly sewn together to realize an editable 3D PMC, enabling an enhanced energy efficiency. The programmable system has provided an alternative to achieve environmentally adaptable solar steam generation in a high-efficient, scalable and accessible way, implicating significant potentials in applications such as water distillation, sewage treatment and even extreme water extraction under some sand or marsh conditions. Image 1 • Robust, scalable and low-cost polypyrrole-modified cotton fabric with tunable microstructures. • The photo-thermal fabric presents good mechanical strength, washable/tailorable properties and programmable features. • The 2D photo-thermal fabric with well-controlled in-plane solar-to-thermal conversion can be further employed as building blocks to realize a well-designed 3D structure for enhanced out-of-plane water extraction in a confined system. • The 3D structure can demonstrate environmentally adaptable features, which can extract purified water from both liquid (e.g. seawater) and solid (e.g. sand) mediums in high efficiency. [ABSTRACT FROM AUTHOR]

Organic thermoelectric (TE) materials are regarded as the next‐generation TE materials because of their merits including low cost, high mechanical flexibility, and low intrinsic thermal conductivity. However, their Seebeck coefficient is usually quite low. Herein, a new strategy is demonstrated to greatly enhance the Seebeck coefficient of poly(3,4‐ethylenedioxy‐thiophene):poly(styrenesulfonate) (PEDOT:PSS), which is the most popular TE polymer, through polaron level splitting via π–π overlapping with nonpolar small aromatic molecules including anthracene, naphthalene, and pyrene. Although these aromatic molecules are neither oxidizing nor reducing agent, they can greatly enhance the Seebeck coefficient of PEDOT:PSS films pre‐treated with dimethyl sulfoxide, acid, or acid then base, while they do not lower the electrical conductivity too much. Through such a treatment with anthracene, the Seebeck coefficient can be up to 45.5 µV K−1, and the ZT value can be up to 0.27. The enhancement is ascribed to the splitting of the lower polaron energy level of PEDOT, which is induced by the π–π overlapping between the aromatic compounds and conjugated PEDOT. This can shift up the Fermi level, thereby enhancing the Seebeck coefficient. [ABSTRACT FROM AUTHOR]

It is of great significance to develop high‐performance n‐type ionic thermoelectric materials. Herein, the turnover from p‐ to n‐type and great improvement in the n‐type ionic Seebeck coefficient of ionogels through synergistic dopings of cations and anions, is reported. Doping with silver trifluoromethanesulfonate (AgOTf) can turn the ionic Seebeck coefficient of the ionogels consisting of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIM:BF4) from 5.52 to −26.4 mV K−1 under a relative humidity (RH) of 75%. The TE performances can be further improved through the combination with the anti‐solvent method, and the ZTi value can be up to 1.7 under 91% RH, the highest for n‐type ionogels. Such p‐ to n‐type turnover and great improvement in the n‐type ionic Seebeck coefficient can be attributed to synergistic doping by Ag+ and OTf−. Ag+ can form a complex with BMIM+, and OTf− can have strong Coulomb interaction to BMIM+. Both can retard the migration of the BMIM+ cations and thus increase the difference in the mobilities of BMIM+ and BF4−. This is the first time that synergistic dopings by both cations and anions for ionic TE materials has been observed. [ABSTRACT FROM AUTHOR]

Organic thermoelectric (TE) materials are considered as the next‐generation TE materials owing to their merits including high mechanical flexibility, low cost, abundant elements, and nontoxicity. However, their Seebeck coefficient is lower than that of the inorganic counterparts by around one order of magnitude, and thus they have a lower dimensionless figure of merit (ZT) value. Herein, the significant enhancement in the Seebeck coefficient and thus the overall TE properties of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) that is the most popular TE polymer by adding a zwitterion like rhodamine 101 (R101), N‐dodecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propane‐sulfonate (DDMAP), or 1‐(N,N‐dimethylcarbamoyl)‐4‐(2‐sulfoethyl) pyridinium hydroxide (DMCSP) are reported. In particular, R101 can enhance the Seebeck coefficient of the acid‐then‐base‐treated PEDOT:PSS from 21.2 to 61.6 μV K−1. The PEDOT:PSS/R101 film can exhibit a power factor of 546 μW m−1 K−2 and a ZT of 0.46 that is the highest for pure organic solid films. The enhancement in the Seebeck coefficient is ascribed to the energy filtering induced by the dipole moment of zwitterion and the π–π overlapping between conjugated rhodamine 101 and PEDOT:PSS. To distinguish it from the conventional methods, this method is named as the molecular energy filtering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continuous power generation by ITECs is demonstrated. • Continuous ITECs can supply comparable or even higher specific average power than conventional intermittent ITECs. • An equivalent circuit is proposed for the ITECs. • Expressions are derived for the performance of ITECs. Ionic conductors emerged as the next-generation thermoelectric (TE) materials mainly due to their high thermopower, which is higher than that of the electronic conductors by 1–2 orders in magnitude. However, they cannot be directly used in TE generators (TEGs) because ions cannot transport across the electrodes into the external circuit. Instead, they can be used in ionic TE capacitors (ITECs) to harvest heat. Nevertheless, the ITECs reported in literatures are operated in an intermittent mode, and repeated connection and disconnection to the external load are required. These severely affect their application in practice. Here, we demonstrate the continuous operation of ITECs with the external load always connected. In addition, an equivalent circuit is proposed for the ITECs in the continuous mode, which can account for the TE parameters like the peak voltage and voltage decay time constant. The continuous ITEC can supply comparable power or even higher performance than the control intermittent ITEC, depending on the temperature variation. This work is significant for the practical application of ionic TE materials in heat conversion and the sustainable development of human society. [ABSTRACT FROM AUTHOR]

To efficiently harvest the abundant waste heat on earth is of great significance for sustainable development. Thermoelectric materials can be used to directly convert heat into electricity, and ionic thermoelectric materials like ionic liquids (ILs) are considered as the next‐generation thermoelectric materials. It is important to develop novel methods to improve the overall thermoelectric properties particularly the thermopower. Herein, the great enhancement in the thermopower of 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIM:DCA) is reported that is an IL by introducing zeolitic imidazolate framework (ZIF‐8) that is a metal‐organic framework (MOF) for the first time. The presence of 40 wt.% ZIF‐8 can greatly increase the ionic thermopower of EMIM:DCA from 8.8 to 31.9 mV K−1 at room temperature, and the ZIF‐8/EMIM:DCA mixture at the ZIF‐8 loading of 10 wt.% can exhibit a ZTi value of 3.1, notably higher than that (0.59) of neat EMIM:DCA. The enhancement in the thermopower is attributed to the increase in the difference of the mobilities of EMIM+ and DCA− by ZIF‐8. Because DCA− is smaller while EMIM+ is larger than the pore size of ZIF‐8, the DCA− transport is hindered by ZIF‐8, while EMIM+ can bypass ZIF‐8. [ABSTRACT FROM AUTHOR]

Intrinsically conducting polymers can have important application in biology because they can be conductive and have good biological compatibility. Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been the most popular conductive polymer in biological application due to its solution processability in water. PEDOT:PSS can be used as electrode materials or active materials of biological devices or circuits. It is important to study the effect of biomaterials on the structure and properties of PEDOT:PSS films. In this work, water-soluble vitamins that are biomaterials needed for organisms are used to treat PEDOT:PSS. They can significantly enhance the conductivity of PEDOT:PSS from 0.3 S cm −1 up to higher than 1000 S cm −1 . The conductivity enhancement depends on the structure of vitamins. The highest conductivity enhancement was observed for PEDOT:PSS treated with vitamin B3. The vitamin-induced changes in the structure and properties of PEDOT:PSS were studied by UV–Vis absorption spectroscopy, temperature-dependence of resistance measurements, atomic force microscopy and cyclic voltammetry. The characterizations indicate that vitamins can induce phase segregation between PEDOT and PSS and the conformational change of the PEDOT chains. These discoveries are important to understand the application of PEDOT:PSS in biology and the development of new biological application of PEDOT:PSS. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multifunctional MXene-coated textile was prepared by a facile dip-coating method. • Lightly cross-linked PDMS network endowed the textile stable adhesive properties. • The adhesive textile showed good electro-/photo-thermal conversion performance. • The smart textile showed good electromagnetic interference shielding properties. • The adhesive textile showed stable pressure-sensing response for motion detection. Adhesion between flexible devices and skin surface facilitates portability of devices and reliable signal acquisition from human body, which is essential for medical therapy devices or monitoring systems. Here, we utilize a simple, cost-effective, and scalable layer-by-layer dip-coating method to fabricate a skin-adhesive multifunctional textile-based device, consisting of three parts: low-cost and easily available airlaid paper (AP) substrate, conductive MXene sensitive layer, and adhesive polydimethylsiloxane (PDMS). The adhesive layer of lightly cross-linked PDMS enables the device to form conformal contact with skin even during human joint bending. The smart textile device exhibits excellent electro-thermal and photo-thermal conversion performance with good cycling stability and tunability. Furthermore, the textile electronics show good electromagnetic interference (EMI) shielding properties due to the good electrical conductivity, as well as sensitive and stable pressure sensing properties for human motion detection. Consequently, this efficient strategy provides a possible way to design multifunctional and wearable electronic textiles for medical applications. [ABSTRACT FROM AUTHOR]

A phase transition self-healing strategy, involving crystallization and melting, is applied to high modulus hydrogel-mediated composites. There is a conflict between excellent self-healing performance and high modulus because the repairing heavily relies on the mobility of polymer chains. In contrast to dynamic interactions-based self-healing strategies, the melting and recrystallization of crystal lattices can achieve ideal self-healing ability without significant external energy consumption. [Display omitted] • Innovative self-healing strategy based on the melting and crystallization of crystal lattices, inspired by metal welding. • The phase change self-healing strategy overcomes the conflict between high modulus and satisfying self-healing capability of polymers. • The self-healing process is moderate, consuming less time and energy than the well-studied intrinsic self-healing mechanisms. • Benefited from the reversibility of melting and crystallization, the same damaged region could be repaired multiple times. The self-healing efficiencies of polymers are inversely proportional to their modulus, as the recovery of the polymer network heavily relies on the mobility of polymer chains. Therefore, reinvigorated by the metal welding, we have developed S-PAM-SA-x supercooling hydrogels, consisting of polyacrylamide hydrogel networks and inorganic CH 3 COONa·3H 2 O phase change materials. Subsequently, rigid self-healing H-PAM-SA-x composites were achieved via self-actuated crystallization-related phase change from the supersaturated hydrogels, resulting in a significant enhancement in mechanical properties. Notably, Young's modulus experienced an astonishing increase from 0.07 to 387.1 MPa. The H-PAM-SA-130 % composites demonstrated satisfactory self-healing performance based on the phase change of melting and crystallization, as the dominant mechanical carrier was found to be the crystal lattice rather than the PAM network. Leveraging the reversible nature of melting and crystallization, the same position can undergo multiple healing cycles without compromising self-healing efficiencies. Moreover, this distinctive dynamic phase change process significantly expands the range of functional applications, encompassing self-healing, adhesion, and patterns' replication among others. [ABSTRACT FROM AUTHOR]

Electromagnetic interference has surged due to the widespread use of electronic communication technologies in integrated electrical systems. Traditionally, inflexible electromagnetic shielding materials have numerous drawbacks, such as being very brittle, uncomfortable to wear, and inappropriate for use in flexible applications. This review explores the advances in flexible (particularly stretchable and compressible) electromagnetic functional materials-based elastomers and a selection of the remarkable supporting deformable polymer matrixes. Additionally, it provides a comprehensive overview of the appropriate delicate structure and the associated manufacturing progress. Furthermore, it comprehensively outlines inventive uses of flexible shields in the fields of energy, sensing, mechanics, and communication, which extend far beyond electromagnetic protection, as well as their present state of development and prospects. Among them, we provide the first well-rounded overview of reconfigurable shielding devices and propose reconfigurability factors (r) and sensitivity (S) to quantify reconfigurable performance as well. This study diverges from prior studies that mostly concentrated on fulfilling conventional specifications (e.g., thin, lightweight, broad, and strong), and may be characterized as the future age of intelligent, adaptable, integrated shields. [ABSTRACT FROM AUTHOR]

Although ionic thermoelectric (iTE) materials can have very high thermopower, it is of great significance to develop novel methods to further improve the ionic thermopower and figure of merit (ZTi). Here, significant improvement in the thermopower and thus the ZTi value of an ionogel by cationic doping, is reported. Doping sodium dicyanamide (Na:DCA) into the ionogels of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIM:DCA) that is an ionic liquid can greatly enhance the thermopower. This is attributed to the interactions between the doped Na+ cations and DCA– anions, thereby increasing the difference in the mobilities of EMIM+ cations and DCA– anions. Moreover, through the combination with the solid networks engineering by an anti‐solvent to PVDF‐HFP, the PVDF‐HFP/EMIM:DCA ionogel doped with 0.5 mol% Na+ with respect to EMIM+ exhibits an ionic thermopower of 43.8 ± 1.0 mV K–1, ionic conductivity of 19.4 ± 0.3 mS cm–1 and thermal conductivity of 0.183 W m–1 K–1 at the relative humidity of 85% and room temperature. The corresponding ZTi value thus reaches 6.1 ± 0.4, much higher than the previous ZTi records of iTE materials. These ionogels can be used in the iTE capacitors for the thermoelectric conversion. [ABSTRACT FROM AUTHOR]

With the rapid development of the Internet of Things, convenient and portable self-powered devices are in great need. Among all substitutes that could provide clean and sustainable power, the flexible perovskite solar cells (FPSCs) are the most attractive with the characteristics of flexibility, lightweight, high power conversion efficiency, and low cost. In this review, the recent advances of FPSCs are summarized, focusing on the materials' assessment of flexible and durable substrate, transparent electrode, low-temperature processed charge transporting layer, and mechanically robust perovskite film, with device design interspersed in each part. Finally, the challenges of FPSCs in terms of higher efficiency, higher flexibility, higher stability, and scalable fabrication are summarized. [ABSTRACT FROM AUTHOR]

Because stretchable strain sensors that have a resistance or capacitance sensitive to strain can sense skin deformation during physical movement, they have been extensively studied as wearable devices for healthcare monitoring. In principle, they can be used to monitor starch‐based food processing in real time, since starch‐based food can have remarkable volume change during processing. Monitoring starch‐based food processing in real time can help achieve high quality and high productivity while reducing energy consumption. Nevertheless, there is no such report in the literature. Here, a blend of starch and a biocompatible intrinsically conducting polymer, poly(3,4‐ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS), is reported as a stretchable strain sensor to monitor starch‐based food processing including fermentation, steaming, storage, and refreshing in a real‐time manner. The resistance of the blends increases during the food volume expansion mainly caused by the fermentation, steaming, and refreshing, and it decreases as a result of the food volume shrinkage during cooling or storage. The signals can be thus used to optimize the processing conditions and control the food quality. This technology can be easily combined with the Internet of Things. [ABSTRACT FROM AUTHOR]

Ionic thermoelectric materials attract widespread attention due to their large Seebeck coefficient compared with electronic thermoelectric counterparts whose main charge carriers are electrons or holes. The present work shows that the ion-polymer matrix interaction can alter the Seebeck coefficient to a great extent. To further shed light on the role of ions, seven water-soluble inorganic chlorides are utilized in this work, to highlight the influence of the cationic softness parameter on the Seebeck coefficient in a PEDOT:PSS ionic conductor. We notice that cations with a positive or a small negative softness parameter value exhibit a negative Seebeck coefficient, resulting from limited thermal diffusion of the cations that are strongly bound to PSS- anions. Conversely, cations with a sufficiently negative softness parameter exhibit fast thermal diffusion due to weak binding to PSS- and, thus, lead to a positive Seebeck coefficient. Based on the established relationship, robust thermoelectric materials with a tunable Seebeck coefficient ranging from –9.63 mV/K to +3.07 mV/K are demonstrated. Our work highlights the important role of ionic properties and provides a pathway for the rational selection of ions in ionic thermoelectrics. [ABSTRACT FROM AUTHOR]

Use of inorganic charge transport layer has demonstrated relatively stable perovskite solar cells (PSCs). NiOx is the most widely used inorganic hole transport layer in inverted PSCs and different techniques and doping in this layer have been reported to improve the performance of these devices. This manuscript describes the synthesis of NiOx thin film which act as hole transport layer on glass substrate at the initial stage and PSC devices were fabricated at the secondary stage. Effect of post deposition annealing temperature on the composition, tuning of the work function and aligning it with perovskite work function increase the hole transport efficiency and improve the open circuit voltage of devices from 0.96 to 1.08 V is reported. Ultraviolet photoelectron spectroscopy results were used to check the change in work function and X-ray photoelectron spectroscopy to probe the underlying reason for improvement of devices are also included. The charge transfer efficiency is checked by the results of time resolved photoluminescence spectra is also given. Devices with NiOx as hole transport layer and ZnSe as electron transport layer are also described and performance of devices is also included in this manuscript. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acetate salts with various cations are studied as the dopant of EMIM:Ac ionogels. • Cationic doping can notably enhance the thermopower of ionogels. • The thermopower enhancement depends on the cations and their doping level. • The thermopower enhancement is related to the interactions of the doping cations to acetate of the ionogels. • The doping ionogels can exhibit a thermopower of 37.3 mV K−1 and ZT i of 2.1, much higher than that of the pristine ionogels. Ionic thermoelectric (ITE) materials have been attracting more and more attention for heat harvesting mainly because of their high thermopower, which is higher than that of the electronic conductors by 2–3 orders in magnitude. Controlling the ion-ion interaction of ITE materials can increase the ionic thermopower. It is important to deeply understand the mechanism for the ionic thermopower enhancement by ionic doping. Here, acetate salts with various cations including lithium (Li+), sodium (Na+), potassium (K+), cesium (Cs+), ammonia (NH 4 +), and nickel (Ni2+) are studied as the dopant of the ionogels consisted of gelatin and 1-ethyl-3-methylimidazolium acetate (EMIM:Ac) that is an ionic liquid. All the dopants can increase the ionic thermopower at low doping level, and the increment is related to the lattice energy and melting point of the acetate salts. Among these acetate salts, Na+ doping can give rise to the highest enhancement in the thermoelectric properties of the ionogels. The ionogel doped with Na+ can exhibit a high ionic Seebeck coefficient of 37.3 mV K−1 and ionic conductivity of 12.3 mS cm−1 at room temperature under the relative humidity of 90 %. The corresponding ZT i value is 2.1. The ionic thermopower and the ZT i value are much higher than that of the pristine ionogel. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have attracted much attention due to their high power conversion efficiency (PCE) and low cost fabrication. Since the PCE is critically related to the perovskite crystal morphology and quality, controlling the perovskite crystal formation is becoming more important. In this work, we chose PDDA polyelectrolyte as the crystal capping agent to modulate the perovskite thin film formation. The PDDA capping agent significantly enhanced the short-circuit current ( J sc ) and fill factor (FF) of the corresponding PSCs, which produced an optimal PCE of 14.1% compared to 12.5% of control device without the modifying agent. The effect of PDDA agent is examined by various techniques. It was found that improved surface morphology, enhanced crystallinity, and decreased grain boundary related defects are contributed to the performance and stability enhancement. [ABSTRACT FROM AUTHOR]

Planar perovskite solar cells (PSCs) with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) have attracted much interest because they can be fabricated by low temperature process and exhibit high power conversion efficiency (PCE). The PCE is strongly dependent on the interface properties between the PCBM layer and cathode. In this work, solution-processable material, rhodamine 101, was used as the interfacial layer between the PCBM layer and Ag cathode. These interfacial materials significantly increase the fill factor so as to the PCE of the PSCs. The optimal power conversion efficiencies are 13.2% (CH 3 NH 3 PbI 3 ) and 14.8% (CH 3 NH 3 PbI 3−x Cl x ) for the devices with rhodamine 101 as the electron collection interlayer, saliently higher than that (8.5% and 12.0%) of control devices without an electron-collection interlayer. The effect of the interfacial material is carefully examined by time-resolved photoluminance spectroscopy (TR-PL), ultraviolet photoelectron spectroscopy (UPS), and kelvin probe force microscopy (KPFM) techniques. Decreased work-function and energy barrier, enhanced electron extraction and prolonged free carrier lifetime all contributed to the photovoltaic performance improvement. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been widely used as the hole transport material in optoelectronic devices. To avoid the cross talk among different crossbars, PEDOT:PSS with low conductivity is required. It thus has a high loading of the non-conductive PSSH. The PSSH-to-PEDOT weight ratio is 6 for Clevios P VP Al 4083 that is the most popular polymer as the hole transport layer. However, the acidic PSSH brings severe problems to the device stability and performance. Here, PEDOT:PSS solutions with low acidity can be prepared through a facile treatment of PEDOT:PSS solution by probe ultrasonication. Two grades of PEDOT:PSS, Clevios PH1000 and Clevios P, with a PSSH-to-PEDOT weight ratio of 2.5 were treated by probe ultrasonication. The ultrasonication can lower the viscosity and the colloidal sizes of PEDOT:PSS solutions and conductivity of PEDOT:PSS films. The pH value of probe-ultrasonicated Clevios P was 2.12, higher than that (1.77) of pristine Clevios P VP Al 4083. The ultrasonication-treated PEDOT:PSS solutions were used as hole transport layer in polymer solar cells and perovskite solar cells. The photovoltaic performances of these solar cells are comparable to that of control devices employing Clevios P VP Al 4083 PEDOT:PSS as the hole transport layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hybrid device made of both electronic and ionic materials. • Harvest heat from both temperature gradient and temperature fluctuation. • Both materials contribute to heat harvesting. • Heat harvesting depends on the temperature fluctuation. Thermoelectric materials based on the Seebeck effect can harvest heat only from temperature gradient, while waste heat can induce both temperature gradient and temperature fluctuation. Here, we demonstrate the high performance in heat-to-electricity harvesting by integrating the thin film of an inorganic thermoelectric material, Bi 0.4 Sb 1.6 Te 3 , with an ionogel that has a high ionic thermovoltage due to the Soret effect. The hybrid inorganic-ionic thermoelectric converter composed of a Bi 0.4 Sb 1.6 Te 3 layer and an ionogel layer can generate power from both the temperature gradient via the Seebeck effect of Bi 0.4 Sb 1.6 Te 3 and the temperature fluctuation via the Soret effect of the ionogel. The overall performance of devices is related to the properties of the two layers, the interface between them, and the temperature gradient and fluctuation. Because of the additional heat harvesting from temperature fluctuation, this hybrid device can exhibit much higher performance in heat harvesting than the control thermoelectric generator (TEG) with the Bi 0.4 Sb 1.6 Te 3 layer alone, depending on the temperature fluctuation and humidity. The power performance of the hybrid converters can be higher than the TEG film by about 1/3 under temperature fluctuation at the relative humidity of 90%. [ABSTRACT FROM AUTHOR]

• A carbon nanoparticles-embedded paper-based analytical device (CNP-PAD) is developed to quantify hemoglobin concentration. • The fabrication technique combined the CNP synthesis and embedment processes into a facile single-step procedure. • CNP-PAD uses cellulosic paper as the sole fabrication material. • Synthesized CNP was comprehensively characterized to ascertain its optical property and chemical compositions. • CNP-PAD's applicability as a biosensor to detect the alterations in hemoglobin (Hb) concentration was demonstrated. The embedment of carbon nanoparticles (CNPs) on paper-based analytical devices (PADs) possesses great potential as a biosensing platform owing to the synergistic combination of their respective advantageous properties. However, their applicability in actual biomedical scenarios is undermined by their cumbersome fabrication process. Here, we present a CNP-embedded PAD (CNP-PAD) that is fabricated through a one-step laser engraving method. We demonstrate the ultra-fast in situ synthesis (< 20 s) of CNPs (diameter = 23 ± 9 nm) with cellulose paper by simple laser engraving. The CNP-PAD was characterized and optimized for hemoglobin measurements. Validation results obtained with human blood samples demonstrated a high degree of agreement (Pearson correlation coefficient = 0.97) with the standard laboratory measurement approach (cyanmethemoglobin method). This work creates a nexus between the fields of CNP and PAD, presenting advantages that highlight its suitability for accessible anemia diagnostics, particularly in resource-limited environments. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials/devices that can directly convert thermal energy into electricity provide a promising solution for sustainable energy development. As the flexible power supplies are urgently required for miniaturized and portable electronics, the development of flexible TE (FTE) devices, which have widespread application in the fields of power generation, flexible electronics, and wearable devices, has gained widespread attention. Over the past decades, research has largely focused on enhancing the ZT values of FTE materials and developing high-efficiency FTE generators (FTEGs). However, it is noted that in the past five years, research into FTE technologies is no longer confined to the electronic FTE materials and FTEGs. Many novel FTE applications, including self-powered multifunctional FTE sensors, ionic TE devices based on the Soret effect, multi-technology integrated TE devices, and even evaporation-driven quasi-TE nanogenerators, are emerging and demonstrate great practical significance. In this paper, recent advances achieved in wide FTE-related technologies are reviewed from the view of materials to devices. The specific structural designs and working principles of the FTE devices, the properties of the materials involved, the manufacturing strategies for device assembly, and their real functioning performances are comprehensively addressed with a few representative examples. Finally, several conclusions and future prospects for the development of FTE materials and devices are also provided. This review features a comprehensive understanding of the development roadmap for FTEs, which will help to guide future studies on flexible thermal energy harvesting/sensing applications and self-powered wearable electronics. • Recent progress on novel FTE-related/integrated applications besides FTE generators. • Identification of structure and working principle for each type of FTE application. • Structure-property relation of FTE materials and performance of FTE devices. • State-of-the-art strategies to achieve flexibility in FTE devices. • Prospects for FTEs in terms of materials, fabrication, performance, and diversity. [ABSTRACT FROM AUTHOR]

Thermogalvanic cells with organic redox couple (OTGCs) have received significant attention for low-grade heat harvesting due to their high thermopower, versatile molecular design, and tailorable physiochemical properties. However, their thermogalvanic conversion power output is largely hindered by slow kinetic rate, which limits practical applications. In this work, we demonstrate a high-performance liquid quinone/hydroquinone (Q/HQ) based OTGC by synergistic coupling redox reaction and thermogalvanic corrosion. By adding hydrochloric acid (HCl) into electrolyte solution, HCl not only boosts intrinsic redox kinetic rate of Q/HQ, but also induces rapid thermogalvanic corrosion of the copper electrode. Notably, these two processes reinforce each other kinetically. Consequently, the Q/HQ-based OTGC exhibits a rapid kinetic rate alongside an increased thermopower, leading to a significantly enhanced power output density. As a result, the Q/HQ-based OTGC achieves an enhanced effective conductivity σ eff of 4.22 S m -1 and a record high normalized power density P max (ΔT) -2 of 108.7 μW m -2  K -2 . This strategy provides a feasible and effective method for development of high-performance OTGCs., (© 2024 Wiley-VCH GmbH.)

Monitoring the gastric digestive function is important for the diagnosis of gastric disorders and drug development. However, there is no report on the in situ and real-time monitoring of digestive functions. Herein, we report a flexible fully organic sensor to effectively monitor protein digestion in situ in a simulated gastric environment for the first time. The sensors are made of a blend of gluten that is a protein and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) that is a conducting polymer. During the protein digestion, the breakdown of the polypeptides increases the level of separation among the PEDOT chains, thereby increasing the resistance. The resistance variation is sensitive to various conditions, including the concentration of pepsin that is the enzyme for protein digestion, temperature, pH value, and digestive drugs. Hence, these sensors can provide real-time information about the digestion and efficacy of digestive drugs. In addition, the signals can be collected via a convenient wireless communication manner.

High mechanical ductility and high mechanical strength are important for materials including polymers. Current methods to increase the ductility of polymers such as plasticization always cause a remarkable drop in the ultimate tensile strength. There is no report on the ductilization of polymers that can notably increase the elongation at break while not lowering the ultimate tensile strength. Here, we report the salt-induced ductilization of an intrinsically conducting polymer, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). Treating highly conductive PEDOT:PSS with a salt such as sodium perchlorate can enhance its elongation at break from 8.5 to 53.2%, whereas it hardly affects the tensile strength. Moreover, the resistance of the ductilized PEDOT:PSS films is insensitive to the tensile strain before fracture and slightly increases by only ~6% during the cyclic tensile testing with the strain up to 30%. These effects are ascribed to the decrease in the Coulomb attraction between PEDOT + and PSS - by the salt ions.

Cations and anions can accumulate at the two ends of an ionic conductor under temperature gradient, which is the so-called Soret effect. This can generate a voltage between the two electrodes, and the thermopower can be higher than that of the electronic conductors because of the Seebeck effect by 1-2 orders in magnitude. The thermoelectric properties of ionic conductors depend on the ionic thermopower, ionic conductivity, and thermal conductivity. Compared with other ionic conductors, like liquid electrolytes and hydrogels, ionogels made of an ionic liquid and a gelator can have the advantages of high thermopower and high stability. Great progress was recently made to improve the ionic conductivity and/or ionic thermopower of ionogels. They can be used in ionic thermoelectric capacitors (ITECs) to harvest heat. In addition, they can be integrated with electronic thermoelectric materials to harvest heat from both temperature gradient and temperature fluctuation, which can be caused by waste heat.

Dry epidermal electrodes that can always form conformal contact with skin can be used for continuous long-term biopotential monitoring, which can provide vital information for disease diagnosis and rehabilitation. But, this application has been limited by the poor contact of dry electrodes on wet skin. Herein, we report a biocompatible fully organic dry electrode that can form conformal contact with both dry and wet skin even during physical movement. The dry electrodes are prepared by drop casting an aqueous solution consisting of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), poly(vinyl alcohol) (PVA), tannic acid (TA), and ethylene glycol (EG). The electrodes can exhibit a conductivity of 122 S cm -1 and a mechanical stretchability of 54%. Moreover, they are self-adhesive to not only dry skin but also wet skin. As a result, they can exhibit a lower contact impedance to skin than commercial Ag/AgCl gel electrodes on both dry and sweat skins. They can be used as dry epidermal electrodes to accurately detect biopotential signals including electrocardiogram (ECG) and electromyogram (EMG) on both dry and wet skins for the users at rest or during physical movement. This is the first time to demonstrate dry epidermal electrodes self-adhesive to wet skin for accurate biopotential detection.

Tunable lens technology inspired by the human eye has opened a new paradigm of smart optical devices for a variety of applications due to unique characteristics such as lightweight, low cost, and facile fabrication over conventional lens assemblies. The fast-growing demands for tunable optical lenses in consumer electronics, medical diagnostics, and optical communications require the lens to have a large focal length modulation range and high compactness. Herein, for the first time, an all-solid tunable soft lens driven by highly transparent dielectric elastomer actuators (DEAs) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and waterborne polyurethane (PEDOT:PSS/WPU) transparent electrodes is developed. The deformation of the tunable soft lens is achieved by the actuation of DEAs, mimicking the change of the surface profile of the human eye to achieve remarkable focal length variations. Upon electrical activation, this tunable soft lens can vary its original focal length by 209%, which is one of the highest among current tunable soft lenses and far beyond that of the human eye. This study demonstrates that transparent DEAs are capable of achieving focus-variation functions, and potentially useful in artificial robotic vision, visual prostheses, and adjustable glasses, which will induce significant effects on the future development of tunable optics.

Ionic thermoelectric (i-TE) material with mobile ions as charge carriers has the potential to generate large thermal voltages at low operating temperatures. This study highlights the role of ions in i-TE hydrogels employing a poly(vinyl alcohol) (PVA) polymer matrix and a number of ion providers, e.g., KOH, KNO 3 , KCl, KBr, NaI, KI, and CsI. The relationship between the intrinsic physical parameters of the ion and the thermoelectric performance is established, indicating the ability to influence the hydrogen bond by the ion is a crucial factor. Among these i-TE hydrogels, the PVA/CsI hydrogel exhibits the largest ionic Seebeck coefficient, reaching 52.9 mV K -1 , which is the largest of all i-TE materials reported to date. In addition, our work demonstrates the influence of ions on polymer configuration and provides an avenue for ion selection in the Soret effect in ionic thermoelectrics.

Monitoring surgical wounds post-operatively is necessary to prevent infection, dehiscence and other complications. However, the monitoring of deep surgical sites is typically limited to indirect observations or to costly radiological investigations that often fail to detect complications before they become severe. Bioelectronic sensors could provide accurate and continuous monitoring from within the body, but the form factors of existing devices are not amenable to integration with sensitive wound tissues and to wireless data transmission. Here we show that multifilament surgical sutures functionalized with a conductive polymer and incorporating pledgets with capacitive sensors operated via radiofrequency identification can be used to monitor physicochemical states of deep surgical sites. We show in live pigs that the sutures can monitor wound integrity, gastric leakage and tissue micromotions, and in rodents that the healing outcomes are equivalent to those of medical-grade sutures. Battery-free wirelessly operated bioelectronic sutures may facilitate post-surgical monitoring in a wide range of interventions., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Safer human-robot interactions mandate the adoption of proprioceptive actuation. Strain sensors can detect the deformation of tools and devices in unstructured and capricious environments. However, such sensor integration in surgical/clinical settings is challenging due to confined spaces, structural complexity, and performance losses of tools and devices. Herein, we report a highly stretchable skin-like strain sensor based on a silver nanowire (AgNW) layer and hydrogel substrate. Our facile fabrication method utilizes thermal annealing to modulate the gauge factor (GF) by forming multidimensional wrinkles and a layered conductive network. The developed AgNW-hydrogel (AGel) sensors sustain and exhibit a strain-sensitive profile (max. GF = ∼70) with high stretchability (200%). Due to its conformability, the sensor demonstrates efficacy in integration and motion monitoring with minimal mechanical constraints. We provide contextual cognizance of tooltip during a transoral procedure by incorporating AGel sensors and showing the fabrication methodology's versatility by developing a hybrid self-sensing actuator with real-time performance feedback.

Conductive stretchable hydrogels and ionogels consisting of ionic liquids can have interesting application as wearable strain and pressure sensors and bioelectrodes due to their soft nature and high conductivity. However, hydrogels have a severe stability problem because of water evaporation, whereas ionogels are not biocompatible or even toxic. Here, we demonstrate self-adhesive, stretchable, nonvolatile, and biocompatible eutectogels that can always form conformal contact to skin even during body movement along with their application as wearable strain and pressure sensors and biopotential electrodes for precise health monitoring. The eutectogels consist of a deep eutectic solvent that has high conductivity, waterborne polyurethane that is an elastomer, and tannic acid that is an adhesive. They can have an elongation at a break of 178%, ionic conductivity of 0.22 mS/cm, and adhesion force of 12.5 N/m to skin. They can be used as conformal strain sensors to accurately monitor joint movement and breath. They can be even used as pressure sensors with a piezoresistive sensitivity of 284.4 kPa -1 to precisely detect subtle physical movements like arterial pulses, which can provide vital cardiovascular information. Moreover, the eutectogels can be used as nonvolatile conformal electrodes to monitor epidermal physiological signals, such as electrocardiogram (ECG) and electromyogram (EMG).

Various in situ synthesis methods have been developed for the polymerization of 3,4-ethylenedioxythiophene monomers, such as electropolymerization, oxidative chemical vapor deposition, and vapor phase polymerization. Meeting industrial requirements through these techniques has, however, proven challenging. Here, we introduce an alternative method to fabricate highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) films in situ by solution means. The process involves sequential deposition of oxidants (V 2 O 5 in this case) and monomers. Excess reactants and by-products can be completely removed from the PEDOT film by MeOH rinsing. The obtained PEDOT films possess good crystallinity and high doping level, with carrier concentration three orders of magnitude higher than that of the commercial product (PH1000, Heraeus GmbH). The electrical conductivity of the as-cast PEDOT film reaches up to 1,420 S/cm. In addition, this method is fully compatible with large-scale printing techniques. These PEDOT conducting films enable the realization of flexible touch sensors, which demonstrate superior flexibility and sensitivity., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Multifunctional films can have important applications. Transparent and flexible films with high conductivity and magnetic properties can be used in many areas, such as electromagnetic interference (EMI) shielding, magnetic switching, microwave absorption, and also biotechnology. Herein, novel highly conductive and superparamagnetic thin films with excellent transparency and flexibility have been demonstrated. The films were formed from a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS; Clevios PH1000) aqueous solution added with iron oxide (Fe 3 O 4 ) nanoparticles that have a size of ∼20 nm by spin-coating. The PEDOT:PSS/Fe 3 O 4 films have a high conductivity of 1080 S/cm through treatment with methylammonium iodide in an organic solvent. The high-conductivity PEDOT:PSS/Fe 3 O 4 films can also have a saturation magnetization of 25.5 emu/g and an EMI shielding effectiveness of more than 40 dB in the 8-12.5 GHz (X band) frequency range. The PEDOT:PSS/Fe 3 O 4 films have additional advantages, like excellent transparency, good mechanical flexibility, low cost, and light weight. In addition, we fabricate flexible PEDOT:PSS/Fe 3 O 4 silk threads with a high magnetism and conductivity.

A nonvolatile plastic digital memory device based on nanofibers of the conjugated polymer polyaniline decorated with gold nanoparticles is reported. The device has a simple structure consisting of the plastic composite film sandwiched between two electrodes. An external bias is used to program the ON and OFF states of the device that are separated by a 3-orders-of-magnitude difference in conductivity. ON-OFF switching times of less than 25 ns are observed by electrical pulse measurements. The devices possess prolonged retention times of several days after they have been programmed. Write-read-erase cycles are also demonstrated. The switching mechanism is attributed to an electric-field-induced charge transfer from the polyaniline nanofibers to the gold nanoparticles. The active polymer layer is created by growing nanometer size gold particles within 30-nm-diameter polyaniline nanofibers using a redox reaction with chloroauric acid. This device combines two exciting research areas--nanoparticles and conducting polymers--to form a novel materials system with unique functionality.