Self-assembled monolayer (SAM) hole transport layers are commonly used in state-of-the-art perovskite single-and multi-junction solar cells. Their precursor molecules are prone to aggregation. We report SAM-solution-pH-modulation that effectively suppresses aggregation, improving deposited film quality. We designed and synthesized a novel material, 6-aminohexylphosphonic acid hydrochloride (6AHPACl), to be added to the (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz) solution as part of a co-SAM strategy. Apart from the advantage of pH modulation, the inclusion of 6AHPACl improved SAM anchoring, SAM/perovskite interface energetics, and wettability of the overlaying perovskite layer and therefore its quality. This co-SAM strategy enabled demonstrations of a wide-band gap (1.67 eV) perovskite cell producing a champion efficiency of 22.8% and a 1 cm2 monolithic perovskite-silicon double junction cell producing a certified efficiency of 29.1%. An encapsulated device retained 95% of its efficiency after 1,010 thermal cycles (-40 degrees C to 85 degrees C). Another encapsulated double junction device surpassed the International Electrotechnical Commission (IEC) 61215 humidity freeze test.

The world's energy supply is undergoing a transformation, incorporating a diversity of sustainable technologies. Among these, hydrogen is attracting increasing attention as an energy carrier, produced either directly or via ammonia as a high‐energy density carrier. Central to both routes are electrocatalysts that can convert electrical power into chemical reactions (electrochemistry). To meet the demands of large area electrodes, there is growing interest in industrial coating processes, such as the combined approach of electrochemical etching followed by magnetron sputtering. In this study, titanium substrates are electrochemically etched to create nanoporous structures which are then coated with ultrathin films of catalytic materials (ruthenium and molybdenum) and finally overcoated with a hydrophobic plasma polymer nanolayer. This presents as an alternate pathway to produce scaled electrocatalysts for driving forward the next generation of electrochemical energy generation technologies.

Layered metal halide perovskites in the alternating cation interlayer (ACI) family typically exhibit small interlayer spacing, lowering exciton binding energy and promoting free carrier generation, favorable for photovoltaic devices. However, most reported ACI phase perovskites incorporate volatile methylammonium (MA) cations, susceptible to instability. Here, for wide-bandgap (> 2 eV) solar cells, we demonstrate ammonium-free-ACI perovskites with equimolar cesium and formamidinium in the A-site producing predominantly n = 2 ACI phase, which forms spontaneously after spin-coating. Further device optimization via Rb-substitution in the bulk and the insertion of piperazine-1,4-diium chloride (PDCl) and PCBM between the perovskite and electron-selective C-60 layer results in a power conversion efficiency (PCE) of 10.6%, which is to date the highest for n = 2 layered perovskite solar cells. The encapsulated cell retains 90% of initial PCE after 400 h of maximum power point tracking, outperforming reported perovskite solar cells of the same bandgap, highlighting the value of avoiding ammonium species and halide mixing.

PEDOT:Tosylate (PEDOT:Tos), a conducting polymer, has emerged as a versatile material, yet its potential for gas sensing remains unexplored. This study presents the first investigation of pristine PEDOT:Tos as a chemiresistive gas sensor for detecting methanol (MeOH), at room temperature. We demonstrate that pristine PEDOT:Tos can detect methanol down to 5 ppm. Furthermore, we examine the influence of a simple urea surface treatment, which significantly enhances the sensor's performance. The urea-modified sensor exhibits an ∼3.7 times increase in response to 100 ppm MeOH (from ∼6 to ∼22% relative resistance change) and achieves a calculated limit of detection of 1.19 ppm. While the treatment improves response magnitude, it also increases the response and recovery times to 17 min and 8 h, respectively, suggesting strong analyte interaction suitable for cumulative sensing applications, such as long-term environmental or agricultural monitoring. Complementary density functional theory calculations confirm a charge transfer mechanism underpinning the sensing response. This work establishes PEDOT:Tos as a promising and easily modifiable material for room-temperature gas sensing, paving the way for new applications in industrial safety and environmental science. Furthermore, the demonstrated ease of surface modification offers a pathway for tuning electrical properties, enabling broader applicability.

It is well established that plants need a range of soil nutrients to grow. In farming, these nutrients are generally added to the soil in the form of fertilizers. However, depending on the soil conditions (such as temperature, water content, pH, and soil type), nutrients may not be in the right form for plant uptake. Determining the availability of nutrients in the soil for plant growth is therefore critical for the yield and productivity of modern farming. A considerable amount of research and knowledge has been developed that shows the importance of the soil pH on the availability (or not) of nutrients. Furthermore, pH plays a crucial role in controlling the availability of potential toxic elements, such as aluminum and manganese. This review article discusses recent research aimed at real‐time and continuous soil pH measurement in‐situ. More specifically, it focuses on the development of polymer materials that will ultimately enable pH measurements for the specific application of in‐ground pH sensing. Given the breadth of the polymeric sensor research field, this review has a narrowed focus on optical and electrochemical transduction methods.

AbstractStretchable conducting films are a prime necessity for future stretchable and wearable electronics. In this work, highly conducting poly(3,4 ethylenedioxythiophene):Tosylate (PEDOT:Tos) films are deposited on extremely stretchable styrene‐ethylene‐butylene‐styrene (SEBS) substrates via vapor phase polymerization (VPP) and their inherent properties are systematically studied. The charge transport and electrical properties of VPP PEDOT:Tos stretchable films are measured from room temperature down to the low temperature of 5 K. Interestingly, the mechanical properties of the stretchable substrate lead to buckling of the PEDOT:Tos that affect the electrical conductivity but not the charge carrier mobility, optical, and structural properties. The VPP PEDOT:Tos on the stretchable SEBS substrate show a semiconducting behavior as electrical resistance is enhanced upon cooling from room temperature to 5 K. Such kind of stretchable conducting films can be used for stretchable transistors, wearable sensing, energy storage, and electrochromic applications.

With the widespread use of batteries, their increased performance is of growing in importance. One avenue for this is the enhancement of ion diffusion, particularly for solid-state electrolytes, for different ions such as lithium (Li+) and magnesium (Mg2+). Unraveling the origin of better cation diffusion in confined ionic liquids (ILs) in a polymer matrix (ionogels) is compared to that of the IL itself. Ionic conductivity measured by electrochemical impedance spectroscopy for ionogels (7.0 mS cm(-1) at 30 degrees C) is very close to the conductivity of the non-confined IL (8.9 mS cm(-1) at 30 degrees C), that is, 1-ethyl-3-methyimidazolium bis(trifluorosulfonyl)imide (EMIM TFSI). An even better ionic conductivity is observed for confined EMIM TFSI with high concentrations (1 m) of lithium or magnesium salt added. The improved macroscopic transport properties can be explained by the higher self-diffusion of each ion at the liquid-to-solid interface induced by the confinement in a poly-vinylidenedifluoride (PVDF) polymer matrix. Upon confinement, the strong breaking down of ion aggregates enables a better diffusion, especially for TFSI anion and strongly polarizing cations (e.g., Li+, Mg2+.). The coordination number of these cations in the liquid phase confirmed that Li+ and Mg2+ interact with the polymer matrix. Moreover, it is a major result that the activation energy for diffusion is lowered.

Cesium-lead-bromide (CsPbBr3) has shown promise in thin film photovoltaics due to its desirable energy band gap, charge mobility and chemical and thermal stability. The low solubility of its single crystal in organic solvents has driven development of the two-step spin-coating technique. In this work, precursor solutions of different PbBr2 and CsBr concentrations were spin-coated and investigated via Photoelectron Spectroscopy. The properties of the CsxPbyBrz film in cross-section demonstrate this method leads to varying stoichiometries, work functions and band gaps through the thickness. This anisotropy of the perovskite thickness has ramifications for design of photovoltaic devices.

Nanoporous materials have gained prominence across multiple domains, including catalysis, optics, energy conversion, and sensing, due to their uniquely large surface areas and tunable pore sizes that enhance reactivity, selectivity, and electronic properties. Electrodes comprising solid nanoporous materials are conventionally prepared via a multistep process typically requiring the dispersion of nanosized materials and the incorporation of noncatalytic additives, such as binder and conductive carbons, which hinder their scalability and overall performance. Here, we present an innovative approach to fabricate binder-free nanoporous Pt-based electrocatalysts for the hydrogen evolution reaction by combining electrochemical etching with magnetron sputtering. Direct sputtering of platinum onto an electrochemically etched titanium substrate yields a nanoporous electrode exhibiting a remarkable electrocatalytic performance. The Pt-coated nanoporous electrode demonstrates superior kinetics, low overpotential, and improved charge-transfer impedance in hydrogen evolution reactions. This technique offers a scalable and versatile means of creating nanoporous electrocatalyst materials, allowing for the design of tailored catalyst materials for use in sustainable energy conversion technologies. The integration of metal surface nanoengineering and magnetron sputtering provides a promising pathway for customized catalyst development, advancing cleaner energy conversion processes such as direct CO2 and N-2 reduction for fuel and ammonia production.

Skin sampling is a diagnostic procedure based on the analysis of extracted skin tissues and/or the observation of biomarkers in bodily fluids. Sampling using microneedles (MNs) that minimize invasiveness is gaining attention over conventional biopsy/blood lancet. In this study, new MNs for electrochemically assisted skin sampling are reported, specifically tailored for combined skin tissue biopsy and interstitial fluid (ISF) extraction. To overcome risks associated with using metal MNs, a highly electroactive, mechanically flexible, and biocompatible organic conducting polymer (CP) coated onto plastic is chosen as an alternative. Two different variants of doped poly(3,4-ethylenedioxythiophene) are coated on polymethyl methacrylate and used in combination as a MN pair with subsequent testing via a variety of electrochemical techniques to (i) give real-time information of the MN penetration depth into the skin, and (ii) yield new information on various salts present in the ISF. The MN skin sampler shows the ability to extract ions from the hydrated excised skin as a step towards in vivo ISF extraction. The presence of ions was analyzed using X-ray photoelectron spectroscopy. This added chemical information in conjunction with the existing biomarker analysis increases opportunity for disease/condition detection. For example, in the case of psoriasis, information about salt in the skin is invaluable in combination with pathogenic gene expression for diagnosis.

The conducting polymer poly(3,4-ethylenedioxythiophene) (known as PEDOT) is routinely fabricated into doped thin films for investigation of its inherent properties as well as for a range of applications. Fabrication of PEDOT is often achieved via oxidative polymerisation, where the conducting polymer is polymerised and doped (oxidised) to yield a conductive polymer thin film. The oxidiser and the polymerisation temperature are two parameters that may influence the properties and performance of the resultant PEDOT thin film. In this study, the role of temperature for the chemical polymerisation of PEDOT using the oxidiser iron tosylate is investigated from a computational and experimental viewpoint. While computations of the doping energetics suggest increasing doping with increasing temperature, x-ray photoelectron spectroscopy of fabricated PEDOT thin films indicate doping is much more complicated. With the aid of computations of the spatial distribution functions for tosylate in PEDOT, experiments indicate that two different populations of tosylate anions exist in the PEDOT matrix. Their relative populations change as a function of the polymerisation temperature. Therefore, polymerisation temperature plays a critical role in tailoring the properties of PEDOT in pursuit of being fit-for-purpose for the desired application.

Recently, transdermal monitoring and drug delivery have gained much interest, owing to the introduction of the minimally invasive microneedle (MN) device. The advancement of electroactive MNs electrically assisted in the capture of biomarkers or the triggering of drug release. Recent works have combined conducting polymers (CPs) onto MNs owing to the soft nature of the polymers and their tunable ionic and electronic conductivity. Though CPs are reported to work safely in the body, their biocompatibility in the skin has been insufficiently investigated. Furthermore, during electrical biasing of CPs, they undergo reduction or oxidation, which in practical terms leads to release/exchange of ions, which could pose biological risks. This work investigates the viability and proliferation of skin cells upon exposure to an electrochemically biased MN pair comprising two differently doped poly(3,4-ethylenedioxy-thiophene) (PEDOT) polymers that have been designed for skin sampling use. The impact of biasing on human keratinocytes and dermal fibroblasts was determined at different initial cell seeding densities and incubation periods. Indirect testing was employed, whereby the culture media was first exposed to PEDOTs prior to the addition of this extract to cells. In all conditions, both unbiased and biased PEDOT extracts showed no cytotoxicity, but the viability and proliferation of cells cultured at a low cell seeding density were lower than those of the control after 48 h of incubation.

Now in their 5th decade of research and development, conducting polymers represent an interesting class of materials to underpin new wearable or conformable electronic devices. Of particular interest over the years has been poly(3,4-ethylenedioxythiophene), commonly known as PEDOT, owing to its ease of fabrication and relative stability under typical ambient conditions. Understanding PEDOT from a variety of fundamental and applied perspectives is important for how it can be enhanced, modified, functionalised, and/or processed for use in commercial products. This feature article highlights the contribution of the research team at the University of South Australia led by Professor Evans, and their collaborators, putting their work into the broader context of conducting polymer research and application. This review focuses on the vapour synthesis of PEDOT doped with the tosylate anion, the benefits of controlling its morphology/structure during synthesis, and its application as an active material interacting with secondary anions in sensors, energy devices and drug delivery.

The use of PEDOT in aqueous applications relies on nanoscale understanding and/or nanoengineered structures and properties. This enables their use in water-based settings such as within the human body or buried in agricultural soils.

Conducting polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) are widely researched for application in electronic devices. Researcher's look to exploit the ability of these polymers to conduct electrical charge. To induce conductivity, the polymers are doped with counterions; for PEDOT, this is typically done with poly(styrenesulfonate) or tosylate (Tos). The Tos anions inserted within the PEDOT nanostructure stabilize positive defects (holes) on the polymer's conjugated backbone, which, in turn, facilitates electrical conduction. In this study, we use X-ray photoelectron spectroscopy to investigate the Tos doping of PEDOT within the outermost region (<15 nm) of electrochemically oxidized or reduced PEDOT:Tos nanoscale films. Computation of the predicted density of states from density functional theory studies is also conducted to aid in interpreting the ultraviolet photoelectron spectroscopy spectra. We observe that the doping of PEDOT:Tos is more complex than first thought, likely involving the nonionic triblock copolymer used during PEDOT's oxidative polymerization. This hypothesis is corroborated by time-of-flight secondary-ion mass spectrometry measurements on the outer 2 nm of the oxidized and reduced PEDOT:Tos. The observation of complex and heightened doping near the surface opens opportunities for the deliberate surface engineering of PEDOT:Tos nanofilms in polymer electronic applications such as electrochemical transistors and electrical connections.

This paper seeks to analyze and understand the dynamics between charitable donations and income inequality in the United States. Through the theoretical lens of financialization and income inequality, we analyze data from the Panel Survey of Income Dynamics. We utilize probabilistic regression models to find and compare the impact of demographics on the likelihood of an American household donating to charity. Our results show that age, sex, and income have positive impacts on donation likelihoods, while non-white racial groups can be seen having a lower probability of donation. Analyzing household data from lower-income groups allows for a recognizing of the impacts that income inequality has on philanthropy from a donor side population that has scarcely been looked at before.

Conducting polymers are promising candidates for wearable devices due to mechanical flexibility combined with electroactivity. While electrochemical measurements have been adopted as a central transduction method in many on-skin sensors, less studied is the stability of the active materials (in particular poly3,4-ethylenedioxythiophene, PEDOT) in such systems, particularly for "on-skin" applications. In this study, several different variants of doped PEDOT are fabricated and characterized in terms of their (electrical, physical, and chemical) stability in biological fluid. PEDOT doped with tosylate (TOS) or polystyrenesulfonate (PSS) are selected as prototypical forms of conducting polymers. These are compared with a new variant of PEDOT co-doped with both TOS and PSS. Artificial interstitial fluid (aISF) loaded with 1% wt/vol bovine serum albumin is adopted as the testing medium to demonstrate the stability in dermal applications (i.e., conducting polymer microneedles or coatings on microneedles). A range of techniques such as cyclic voltammetry and electrochemical impedance spectroscopy are used to qualify and quantify the stability of the doped conducting polymers. Furthermore, this study is extended by using human skin lysate in the aISF to demonstrate proof-of-concept for stable use of PEDOT in wearable "on-skin" electronics.

ABSTRACT The biocompatibility of conducting polymer has seen remarkable advancement in numerous biomedical applications. The tuneable electrical property expressed by doping and de‐doping of the polymer has contributed to electrical controlled film in terms of volume and conductivity. Also, higher sensitivity specially for ionic molecules brings forward new prospective in bio/sensing. Meanwhile, wearable devices for healthcare monitoring are becoming more prominent due to remote, real‐time and continuous monitoring. The flexible and stretchable property of organic electronic, in this paper represented by conducting polymer, as compared to rigid, conventional conductor unleashes high potential of conducting polymer as platform for wearable sensing device. In this review, properties of conducting polymers adopted in wearable devices focusing on on‐skin sensing are elaborated. The contribution of conducting polymers in various sensing targets, mainly categorized by chemical, tactile and electrophysiological is discussed, followed by types of the wearable sensors. Overall, our aim was to lay broader understanding of incorporation of the polymer within wearable sensing devices.

Conducting polymers are an interesting class of materials that can be tuned to have a range of properties through counterion doping. For most conducting polymers, the insertion of anions (the doping process) leads to the formation of carbocations (positive charge carriers) along the conjugated polymer backbone. In this research, we report on a scenario that arises where certain (commonly used) anions in water induce oxygenation of the conducting polymers heteroatom. This is in contrast to the widely reported doping process, and the recently reported hydrolysis of conducting polymers. We observe that the transition between these different conducting polymer-interactions/reactions is well described by the concept of structure-making and structure-breaking anions. Poly(3,4-propylenedioxy thiophene dimethyl) (PProDOT-Me-2), polypyrrole (PPy), and poly(3,4-ethylenedioxy thiophene) (PEDOT) thin films are exposed to a range of anions in water. Both PProDOT-Me-2 and PPy are susceptible to oxygenation, while in contrast PEDOT is doped, when exposed to structure-breaking anions. All the polymers show hydrolysis for structure-making anions. The knowledge of the interaction and/or reaction of conducting polymers with anions in water is not only critical to their application in devices for aqueous environments (i.e., sensing), but also for their processing and fabrication using water.