Search

Zn-metal batteries (ZnBs) are safe and sustainable because of their operability in aqueous electrolytes, abundance of Zn, and recyclability. However, the thermodynamic instability of Zn metal in aqueous electrolytes is a major bottleneck for its commercialization. As such, Zn deposition (Zn 2+ → Zn(s)) is continuously accompanied by the hydrogen evolution reaction (HER) (2H + → H 2 ) and dendritic growth that further accentuate the HER. Consequently, the local pH around the Zn electrode increases and promotes the formation of inactive and/or poorly conductive Zn passivation species (Zn + 2H 2 O → Zn(OH) 2 + H 2 ) on the Zn. This aggravates the consumption of Zn and electrolyte and degrades the performance of ZnB. To propel HER beyond its thermodynamic potential (0 V vs standard hydrogen electrode (SHE) at pH 0), the concept of water-in-salt-electrolyte (WISE) has been employed in ZnBs. Since the publication of the first article on WISE for ZnB in 2016, this research area has progressed continuously. Here, an overview and discussion on this promising research direction for accelerating the maturity of ZnBs is provided. The review briefly describes the current issues with conventional aqueous electrolyte in ZnBs, including a historic overview and basic understanding of WISE. Furthermore, the application scenarios of WISE in ZnBs are detailed, with the description of various key mechanisms (e.g., side reactions, Zn electrodeposition, anions or cations intercalation in metal oxide or graphite, and ion transport at low temperature)., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The emergence of artificial intelligence and the Internet of Things has led to a growing demand for wearable and maintenance-free power sources. The continual push toward lower operating voltages and power consumption in modern integrated circuits has made the development of devices powered by body heat finally feasible. In this context, thermoelectric (TE) materials have emerged as promising candidates for the effective conversion of body heat into electricity to power wearable devices without being limited by environmental conditions. Driven by rapid advances in processing technology and the performance of TE materials over the past two decades, wearable thermoelectric generators (WTEGs) have gradually become more flexible and stretchable so that they can be used on complex and dynamic surfaces. In this review, the functional materials, processing techniques, and strategies for the device design of different types of WTEGs are comprehensively covered. Wearable self-powered systems based on WTEGs are summarized, including multi-function TE modules, hybrid energy harvesting, and all-in-one energy devices. Challenges in organic TE materials, interfacial engineering, and assessments of device performance are discussed, and suggestions for future developments in the area are provided. This review will promote the rapid implementation of wearable TE materials and devices in self-powered electronic systems., (© 2021 Wiley-VCH GmbH.)

Low-cost, non-toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n-type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n-type organic thermoelectrics to date. An organic mixed ion-electron n-type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi-frozen ionic carriers yield a large ionic Seebeck coefficient of -3021 μV K -1 , while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm -1 at 60% relative humidity. The overall power factor is remarkably high (165 μW m -1 K -2 ), with a ZT = 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi-constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers., (© 2020 Wiley-VCH GmbH.)

The coupling between charge accumulation in a conjugated polymer and the ionic charge compensation, provided from an electrolyte, defines the mode of operation in a vast array of different organic electrochemical devices. The most explored mixed organic ion-electron conductor, serving as the active electrode in these devices, is poly(3,4-ethyelenedioxythiophene) doped with polystyrelensulfonate (PEDOT:PSS). In this progress report, scientists of the Laboratory of Organic Electronics at Linköping University review some of the achievements derived over the last two decades in the field of organic electrochemical devices, in particular including PEDOT:PSS as the active material. The recently established understanding of the volumetric capacitance and the mixed ion-electron charge transport properties of PEDOT are described along with examples of various devices and phenomena utilizing this ion-electron coupling, such as the organic electrochemical transistor, ionic-electronic thermodiffusion, electrochromic devices, surface switches, and more. One of the pioneers in this exciting research field is Prof. Olle Inganäs and the authors of this progress report wish to celebrate and acknowledge all the fantastic achievements and inspiration accomplished by Prof. Inganäs all since 1981., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of a novel naphthalenediimide (NDI)-bithiazole (Tz2)-based polymer [P(NDI2OD-Tz2)] is reported, and structural, thin-film morphological, as well as charge transport and thermoelectric properties are compared to the parent and widely investigated NDI-bithiophene (T2) polymer [P(NDI2OD-T2)]. Since the steric repulsions in Tz2 are far lower than in T2, P(NDI2OD-Tz2) exhibits a more planar and rigid backbone, enhancing π-π chain stacking and intermolecular interactions. In addition, the electron-deficient nature of Tz2 enhances the polymer electron affinity, thus reducing the polymer donor-acceptor character. When n-doped with amines, P(NDI2OD-Tz2) achieves electrical conductivity (≈0.1 S cm -1 ) and a power factor (1.5 µW m -1 K -2 ) far greater than those of P(NDI2OD-T2) (0.003 S cm -1 and 0.012 µW m -1 K -2 , respectively). These results demonstrate that planarized NDI-based polymers with reduced donor-acceptor character can achieve substantial electrical conductivity and thermoelectric response., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Organic electrochemical transistors (OECTs) have been the subject of intense research in recent years. To date, however, most of the reported OECTs rely entirely on p-type (hole transport) operation, while electron transporting (n-type) OECTs are rare. The combination of efficient and stable p-type and n-type OECTs would allow for the development of complementary circuits, dramatically advancing the sophistication of OECT-based technologies. Poor stability in air and aqueous electrolyte media, low electron mobility, and/or a lack of electrochemical reversibility, of available high-electron affinity conjugated polymers, has made the development of n-type OECTs troublesome. Here, it is shown that ladder-type polymers such as poly(benzimidazobenzophenanthroline) (BBL) can successfully work as stable and efficient n-channel material for OECTs. These devices can be easily fabricated by means of facile spray-coating techniques. BBL-based OECTs show high transconductance (up to 9.7 mS) and excellent stability in ambient and aqueous media. It is demonstrated that BBL-based n-type OECTs can be successfully integrated with p-type OECTs to form electrochemical complementary inverters. The latter show high gains and large worst-case noise margin at a supply voltage below 0.6 V., (© 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ladder-type "torsion-free" conducting polymers (e.g., polybenzimidazobenzophenanthroline (BBL)) can outperform "structurally distorted" donor-acceptor polymers (e.g., P(NDI2OD-T2)), in terms of conductivity and thermoelectric power factor. The polaron delocalization length is larger in BBL than in P(NDI2OD-T2), resulting in a higher measured polaron mobility. Structure-function relationships are drawn, setting material-design guidelines for the next generation of conducting thermoelectric polymers., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Conducting polymers with bipolar membranes (a complementary stack of selective membranes) may be used to rectify current. Integrating a bipolar membrane into a polymer electrochromic display obviates the need for an addressing backplane while increasing the device's bistability. Such devices can be made from solution-processable materials., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Suspended microdevices are employed to measure the in-plane electrical conductivity, thermal conductivity, and Seebeck coefficient of suspended poly(3,4-ethylenedioxythiophene) (PEDOT) thin films. The measured thermal conductivity is higher than previously reported for PEDOT and generally increases with the electrical conductivity. The increase exceeds that predicted by the Wiedemann-Franz law for metals and can be explained by significant electronic thermal transport in PEDOT., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ambipolar polymeric field-effect transistors can be programmed into a p- or n-type mode by using the remanent polarization of a ferroelectric gate insulator. Due to the remanent polarity, the device architecture is suited as a building block in complementary logic circuits and in CMOS-compatible memory cells for non-destructive read-out operations., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Volatile impurities contained in polyethyleneimine (PEI), and identified as ethyleneimine dimers and trimers, are reported. These N-based molecules show a strong reducing character, as demonstrated by the change in electrical conductivity of organic (semi)conductors exposed to the PEI vapor. The results prove that electron transfer rather than a dipole effect at the electrode interface is the origin of the work-function modification by the PEI-based layers., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)