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Achieving both high redox activity and rapid ion transport is a critical and pervasive challenge in electrochemical energy storage applications. This challenge is significantly magnified when using large‐sized charge carriers, such as the sustainable ammonium ion (NH4+). A self‐assembled MXene/n‐type conjugated polyelectrolyte (CPE) superlattice‐like heterostructure that enables redox‐active, fast, and reversible ammonium storage is reported. The superlattice‐like structure persists as the CPE:MXene ratio increases, accompanied by a linear increase in the interlayer spacing of MXene flakes and a greater overlap of CPEs. Concurrently, the redox activity per unit of CPE unexpectedly intensifies, a phenomenon that can be explained by the enhanced de‐solvation of ammonium due to the increased volume of 3 Å‐sized pores, as indicated by molecular dynamic simulations. At the maximum CPE mass loading (MXene:CPE ratio = 2:1), the heterostructure demonstrates the strongest polymeric redox activity with a high ammonium storage capacity of 126.1 C g−1 and a superior rate capability at 10 A g−1. This work unveils an effective strategy for designing tunable superlattice‐like heterostructures to enhance redox activity and achieve rapid charge transfer for ions beyond lithium. [ABSTRACT FROM AUTHOR]

In this study, the synthesis and characterization of the fluorescent metal–organic framework (MOF)‐polymer composites is reported based on zirconium‐based MOFs (UiO‐66 and UiO‐66(OH)₂) and a conjugated polyelectrolyte, poly(phenylene ethynylene) carboxylate (PPE‐CO₂‐108). The defect‐rich nature of these Zr‐MOFs facilitates strong interactions between the polyelectrolyte's carboxylic acid moieties and the open metal sites on the Zr clusters within the MOF nanoparticles. The composites are prepared by a simple impregnation approach, where MOF nanocrystals suspended in HEPES buffer are added to the polymeric solution under sonication for 10 min. The obtained MOF composites (i.e., UiO‐66‐CPE and UiO‐66 (OH)2‐CPE) are characterized using powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer‐Emmett‐Teller (BET) surface area, zeta potential measurements, and UV–vis spectroscopy. The characterization confirmed the homogeneous distribution of the MOF nanocrystals on the polymer as seen in the SEM images, and the interaction with PPE‐CO₂‐108 is confirmed by the decrease in the surface areas from 1050 to 590 m2 g−1 for UiO‐66‐CPE and from 500 to 137 m2 g−1, for UiO‐66(OH)2‐CPE. Fluorescence microscopy revealed strong fluorescence in the microparticles, confirming robust polymer‐MOF interaction. The composites also exhibit improved photostability of the conjugated polyelectrolyte, suggesting their potential for applications in biomedical imaging and other areas requiring stable and bright fluorescent systems. [ABSTRACT FROM AUTHOR]

Organic mixed ionic‐electronic conductors with tunable doping, low threshold voltages, and air stability are crucial for bioelectronic applications. A homopolymer based on an alkoxy thiophene monomer and its copolymer with a thiophene carrying ethylene glycol side chains are synthesized and converted to self‐doped conjugated polyelectrolytes, P3HOTS‐TMA+, and P3HOTS‐TMA+‐co‐P3MEEET. The self‐doping occurs during the conversion to polyelectrolytes. Both polyelectrolytes show high electrical conductivity without any external dopants. UV–Vis–NIR spectroscopy and spectroelectrochemistry confirm excellent air stability of the doped state. In an organic electrochemical transistor (OECT), the P3HOTS‐TMA+ operates in depletion mode, while P3HOTS‐TMA+‐co‐P3MEEET exhibits accumulation mode of operation with low threshold voltage, both showing fast response times. On the other hand, the non‐doped homopolymer, P3MEEET, shows a high negative threshold voltage in accumulation mode. Thus, copolymerization with the self‐dopable monomer changes the mode of operation as well as the threshold voltage substantially. Ultraviolet photoelectron spectroscopy reveals a considerable reduction of the hole injection barrier for the self‐doped system P3HOTS‐TMA+. Mott‐Schottky analysis shows reduction in charge carrier concentration in the copolymer compared to the homopolymer. Thus, the copolymerization strategy with a self‐dopable monomer is an efficient tool for tuning the degree of doping leading to low threshold voltage in OECTs. [ABSTRACT FROM AUTHOR]

Conjugated polymers (CPs) have been developed quickly as an emerging functional material with applications in optical and electronic devices, owing to their highly electron‐delocalized backbones and versatile side groups for facile processibility, high mechanical strength, and environmental stability. CPs exhibit multistimuli responsive behavior and fluorescence quenching properties by incorporating azobenzene functionality into their molecular structures. Over the past few decades, significant progress has been made in developing functional azobenzene‐based conjugated polymers (azo‐CPs), utilizing diverse molecular design strategies and synthetic pathways. This article comprehensively reviews the rapidly evolving research field of azo‐CPs, focusing on the structural characteristics and synthesis methods of general azo‐CPs, as well as the applications of charged azo‐CPs, specifically azobenzene‐based conjugated polyelectrolytes (azo‐CPEs). Based on their molecular structures, azo‐CPs can be broadly categorized into three primary types: linear CPs with azobenzene incorporated into the side chain, linear CPs with azobenzene integrated into the main chain, and branched CPs containing azobenzene moieties. These systems are promising for biomedical applications in biosensing, bioimaging, targeted protein degradation, and cellular apoptosis. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) have gained considerable attention due to their potential applications in emerging biosensor platforms. The use of conjugated polyelectrolytes (CPEs) as active materials in OECTs is particularly advantageous owing to their functional, water‐processable, and biocompatible nature, as well as their tunable electronic and ionic transport properties. However, there exists a lack of systematic studies of the structure‐property relationships of these materials with respect to OECT performance. This study shows how by tuning the molecular weight of self‐doped CPE (CPE‐K) it is possible to fabricate OECTs with a µC* value of 14.7 F cm−1 V−1 s−1, one order of magnitude higher than previously reported CPE‐based devices. Furthermore, OECTs with a transconductance of 120 mS are demonstrated via device engineering. While CPE‐K batches with different molecular weights show good doping behavior and high volumetric capacitance, as confirmed by spectroelectrochemistry and electrochemical impedance spectroscopy, the medium molecular weight possesses the highest carrier mobility of ≈0.1 cm2 V−1 s−1 leading to the highest transconductance. The enhanced charge transport is due to a favorable charge percolation pathway, as revealed by the combination of X‐ray analysis and conductive atomic force microscope. These insights provide guidelines for further improving the performance of CPE‐based OECTs. [ABSTRACT FROM AUTHOR]

Polythiophene‐based conjugated polyelectrolytes (CPE) are attracting increasing attention as sensor or interface materials in chemistry and biology. While cationic polythiophenes are better understood, limited structural information is available on their anionic counterparts. Limited access to well‐defined polymers has made the study of structure‐property relationships difficult and clear correlations have remained elusive. By combining controlled Kumada catalyst transfer polymerization with a polymer‐analog substitution, regioregular and narrowly distributed poly(6‐(thiophen‐3‐yl)hexane‐1‐sulfonate)s (PTHS) with tailored chain length are prepared. Analysis of their aqueous solution structures by small‐angle neutron scattering (SANS) revealed a cylindrical conformation for all polymers tested, with a length close to the contour length of the polymer chains, while the estimated radii remain too small (<1.5 nm) for extensive π‐stacking of the chains. The latter is particularly interesting as the longest polymer exhibits a concentration‐independent structured absorption typical of crystalline polythiophenes. Increasing the ionic strength of the solution diminishes these features as the Coulomb repulsion between the charged repeat units is shielded, allowing the polymer to adopt a more coiled conformation. The extended π‐conjugation, therefore, appears to be a key parameter for these unique optical features, which are not present in the corresponding cationic polythiophenes. [ABSTRACT FROM AUTHOR]

For an ideal electron interlayer, both electron injection and hole‐blocking properties are important to achieve better polymer light‐emitting devices (PLEDs) performance. Conjugated polyelectrolytes (CPEs) are applied widely in PLEDs to enhance charge injection. Understanding the role of backbone structures and energetic matching between the CPEs and emitters can benefit charge injection and balance. Herein, a postpolymerization approach to introduce varying amounts of alkyl sulfonate groups onto the backbone of a copolymer of 5‐fluoro‐2,1,3‐benzothiadiazole and 9,9′‐dioctylfluorene is utilized. This study finds that device performance is dependent on the percentage of sulfonate groups incorporated, with the optimal copolymer (CPE‐50%) maintaining efficient ohmic electron injection and gaining enhanced hole‐blocking properties, thereby achieving the most balanced hole/electron current. Therefore, the PLED with CPE‐50% interlayer exhibits the highest efficiency (20.3 cd A−1, 20.2 lm W−1) and the fastest response time (4.3 µs), which is the highest efficiency among conventional thin (70 nm) F8BT PLEDs with CPEs. These results highlight the importance of balanced charge carrier density in CPEs and highlight that postpolymerization modification is a useful method for fine‐tuning ionic content. [ABSTRACT FROM AUTHOR]

The use of conjugated polyelectrolytes (CPEs) as interfacial layers (ILs) to increase the efficiency of organic light‐emitting diodes (OLEDs), organic solar cells (OSCs), and organic transistors is a well‐established strategy. Here, the rational process is reported that led to develop the bifunctional poly[(2,7‐(9,9'‐bis(6'‐diethoxylphosphorylhexyl)‐fluorene)‐alt‐(2,7‐(9,9′‐bis(6″‐trimethylammonium bromide)hexyl)‐fluorene)] (PF‐NBr‐EP). PF‐NBr‐EP is successfully incorporated as a cathode IL (CIL) in diverse electronic and optoelectronic devices. The properties of two fluorene‐based CPEs containing, respectively, phosphonate (EP) and ammonium (NBr) moieties used as building blocks for the synthesis of the PF‐NBr‐EP copolymer and their mixtures are investigated to evaluate the combined effect of the two moieties and therefore to gain insight into the behavior of PF‐NBr‐EP chemical structure in the devices. Additionally, the performance of OLEDs and OSCs is analyzed based on established active layers, incorporating all these neat and mixed CILs. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) is a critical component in achieving high device performance and stability in organic solar cells. Conjugated polyelectrolytes (CPEs) have become an attractive alternative due to film‐forming properties and ease of preparation. However, p‐type CPEs generally exhibit poor charge mobility and conductivity, incorporation of electron‐withdrawing units forming alternated D‐A conjugated backbone can make up for these deficiencies. Herein, the ratio of electron withdrawing moieties are further increased and two poly(A1‐alt‐A2) typed PIIDNDI‐Br and PDPPNDI‐Br based on the combination of naphthalene diimide (NDI) with isoindigo (IID) or diketopyrrolopyrrole (DPP) via direct arylation polycondensation are synthesized. These CPEs possess excellent alcohol solubility, a suitable lowest unocuppied molecular orbital energy level, and work function tunability. Surprisingly, the incorporation of IID and DPP units generate distinct self‐doping behaviors, which are confirmed by UV–vis absorption and ESR spectra. However, no matter doped or undoped, both CPEs present better charge‐transporting properties and conductivity when utilized as ETLs. The PIIDNDI‐Br and PDPPNDI‐Br display good universal compatibility with the blend of PM6:Y6 and PM6:L8‐BO, and PCEs of 18.32% and 18.36% are obtained, respectively, which also present excellent storage stability. In short, the combination of two different acceptors demonstrates an efficient strategy to design highly efficient ETLs for high performance photovoltaic devices. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems hold the promise of enabling sustainable microbial‐mediated energy interconversion between electrical and chemical energy. Herein, it is demonstrated how a single conjugated polymer can be used to enhance bidirectional extracellular electron transfer through forming self‐assembled coatings on individual cells. Specifically, the n‐type conjugated polyelectrolyte p(cNDI‐gT2) exhibits a reduction potential window between −0.1 and −0.8 V (vs Ag/AgCl), thereby driving thermodynamically favored electron transfer in both directions across the abiotic‐biotic interface that involves the outer membrane cytochromes and flavins of Shewanella oneidensis MR‐1. Electrochemical tests show that injection from an external electrode into Shewanella oneidensis MR‐1 is enabled at negative potentials (−0.6 V), while electron extraction is possible at positive potentials (0.2 V). Relative to controls, the biohybrid shows a sixfold increase in biocurrent generation and a 35‐fold increase in current uptake for the bioelectrosynthesis of succinate from fumarate. This demonstrated abiotic‐biotic synergy provides new strategies for designing multifunctional biohybrids. [ABSTRACT FROM AUTHOR]

Abstract Bioelectrochemical systems hold the promise of enabling sustainable microbial‐mediated energy interconversion between electrical and chemical energy. Herein, it is demonstrated how a single conjugated polymer can be used to enhance bidirectional extracellular electron transfer through forming self‐assembled coatings on individual cells. Specifically, the n‐type conjugated polyelectrolyte p(cNDI‐gT2) exhibits a reduction potential window between −0.1 and −0.8 V (vs Ag/AgCl), thereby driving thermodynamically favored electron transfer in both directions across the abiotic‐biotic interface that involves the outer membrane cytochromes and flavins of Shewanella oneidensis MR‐1. Electrochemical tests show that injection from an external electrode into Shewanella oneidensis MR‐1 is enabled at negative potentials (−0.6 V), while electron extraction is possible at positive potentials (0.2 V). Relative to controls, the biohybrid shows a sixfold increase in biocurrent generation and a 35‐fold increase in current uptake for the bioelectrosynthesis of succinate from fumarate. This demonstrated abiotic‐biotic synergy provides new strategies for designing multifunctional biohybrids.

Conjugated polyelectrolytes (CPEs) comprised of conjugated backbones and pendant ionic functionalities are versatile organic semiconductors with myriad optoelectronic applications. Although polarons are dominant charge carriers in conducting CPEs owing to strong electron‐phonon coupling, their properties are not well understood, especially from a first‐principles perspective. In this study, a comprehensive study on the stability, structural deformation, electronic structure, and optical absorption of positive (or hole)/negative (or electron) polarons and bi‐polarons in CPEs is conducted. It is explored how these properties depend on the electrostatic interaction between the polarons and ionic functionalities, including alkyl chains, ionic groups, and counterions. It is then examined how the bandgap, polaron binding energy, and optoelectronic structure of CPEs can be tuned by various combinations of the donor and acceptor units in their backbones. Finally, electrochemical stability of CPEs is studied and light is shed on the absence of negative polarons in CPEs. The strategy to improve the electrochemical stability of n‐doped CPEs is also discussed. [ABSTRACT FROM AUTHOR]

Due to their distinctive intrinsic advantages, the nanoaggregates of conjugated polyelectrolytes (CPEs) are fascinating and attractive for various luminescence applications. Generally, the emission luminescence of CPEs is determined by the conjugated backbone structure, i.e., different conjugated backbones of CPEs produce emission luminescence with different emission wavelength bands. Here, we polymerized the bis(boronic ester) of benzothiadiazole and an alkyl sulfonate sodium-substituted dibromobenzothiatriazole to provide PBTBTz-SO3Na with different molecular weights via controlling the ratio of the monomer and the catalyst. Theoretically, the CPEs with the same molecular structure usually display similar photoelectronic performances. However, the resulting PBTBTz-SO3Na reveal a similar light absorption property, but different luminescence. The higher molecular weight is, the stronger the fluorescence intensity of PBTBTz-SO3Na that occurs. PBTBTz-SO3Na with different molecular weights have different colors of luminescence. It is well known that the molecular aggregates often led to weaker luminescent properties for most of the conjugated polymers. However, PBTBTz-SO3Na exhibits a higher molecular weight with an increasing molecular chain aggregation, i.e., the nanoaggregates of PBTBTz-SO3Na are beneficial to emission luminescence. This work provides a new possible chemical design of CPEs with a controllable, variable luminescence for further optoelectronics and biomedicine applications. [ABSTRACT FROM AUTHOR]

Successful practical implementation of bioelectrochemical systems (BES) requires developing affordable electrode structures that promote efficient electrical communication with microbes. Recent efforts have centered on immobilizing bacteria with organic semiconducting polymers on electrodes via electrochemical methods. This approach creates a fixed biocomposite that takes advantage of the increased electrode's electroactive surface area (EASA). Here, it is demonstrated that a biocomposite comprising the water‐soluble conjugated polyelectrolyte CPE‐K and electrogenic Shewanella oneidensis MR‐1 can self‐assemble with carbon paper electrodes, thereby increasing its biocurrent extraction by ≈6‐fold over control biofilms. A ≈1.5‐fold increment in biocurrent extraction is obtained for the biocomposite on carbon paper relative to the biocurrent extracted from gold‐coated counterparts. Electrochemical characterization revealed that the biocomposite stabilized with the carbon paper more quickly than atop flat gold electrodes. Cross‐sectional images show that the biocomposite infiltrates inhomogeneously into the porous carbon structure. Despite an incomplete penetration, the biocomposite can take advantage of the large EASA of the electrode via long‐range electron transport. These results show that previous success on gold electrode platforms can be improved when using more commercially viable and easily manipulated electrode materials. [ABSTRACT FROM AUTHOR]

A facile synthesis of low band gap water soluble dyad materials comprising of fullerenol and poly thiophene carboxylic acids is demonstrated. Fullerene‐conjugated polyelectrolytes dyad materials were prepared using polythiophene‐3‐acetic acid (PT3AA) and polythiophene‐3‐malonic acid (PT3MA) as donors and fullerenol as acceptor in microwave synthesizer at 70°C. The reaction has several advantages over conventional reflux methods; easy to handle, fast reaction and good quality products. Fullerene core star‐like dyad structures having single‐ or di‐carboxylic acid group in each thiophene ring were synthesized. Thermal methods (TGA & DSC) estimated about six to seven exohedrally attached polymer units to fullerene core. The electrochemical band gaps of ~1.17 and 1.21 eV were recorded for fullerenol poly thiophene 3‐acetic acid (FPT3AA) and fullerenol polythiophene‐3‐malonic acid (FPT3MA) dyads, respectively. The UV–vis analyses record a red shifting of absorbance maxima for mono carboxylic acid (408 nm FPT3AA vs. 263 nm PT3AA) and blue shifting in di‐carboxylic acid (263 nm FPT3MA vs. 396 nm PT3MA). The strong quenching and substantial red shifting of emission peaks of dyad materials compared to both fullerenol and polymers demonstrate charge transfer exciplex formation in excited state. [ABSTRACT FROM AUTHOR]

The ability to assemble artificial systems that mimic aspects of natural light‐harvesting functions is fascinating and attractive for materials design. Given the complexity of such a system, a simple design pathway is desirable. Here, we argue that associative phase separation of oppositely charged conjugated polyelectrolytes (CPEs) can provide such a path in an environmentally benign medium: water. We find that complexation between an exciton–donor and acceptor CPE leads to formation of a complex fluid. We interrogate exciton transfer from the donor to the acceptor CPE within the complex fluid and find that transfer is highly efficient. We also find that excess molecular ions can tune the modulus of the inter‐CPE complex fluid. Even at high ion concentrations, CPEs remain complexed with significantly delocalized electronic wavefunctions. Our work lays the rational foundation for complex, tunable aqueous light‐harvesting systems via the intrinsic thermodynamics of associative phase separation. [ABSTRACT FROM AUTHOR]

Conducting polymer hydrogels (CPHs) are an attractive class of materials that synergize the electrical properties of organic semiconductors with the physical properties of hydrogels. Of particular interest is the implementation of CPHs as electrode materials for electrochemical energy storage by taking advantage of redox‐tunable conjugated backbones and the large electroactive surface area. Herein, the use of 2D electrolytes as an effective post‐polymerization additive to enhance the pseudocapacitive performance of CPHs, is demonstrated. By using the self‐doped conjugated polyelectrolyte CPE‐K hydrogel as a model system, improvements in cycling stability, specific capacitance and working voltage window upon addition of the 2D electrolytes, are shown. Furthermore, positively charged 2D electrolytes to be more effective than their negatively charged counterparts are revealed. Rheology measurements and SEM imaging indicate that the 2D electrolytes serve as non‐covalent cross‐linkers that help in forming a mechanically more robust and highly percolated conducting network. These results provide a new and simple to execute post‐polymerization strategy to optimize the electrochemical performance of CPH‐based pseudocapacitors. [ABSTRACT FROM AUTHOR]

The development of luminescent materials is critical to humankind. The Nobel Prizes awarded in 2008 and 2010 for research on the development of green fluorescent proteins and super-resolved fluorescence imaging are proof of this (2014). Fluorescent probes, smart polymer machines, fluorescent chemosensors, fluorescence molecular thermometers, fluorescent imaging, drug delivery carriers, and other applications make fluorescent polymers (FPs) exciting materials. Two major branches can be distinguished in the field: (1) macromolecules with fluorophores in their structure and (2) aggregation-induced emission (AIE) FPs. In the first, the polymer (which may be conjugated) contains a fluorophore, conferring photoluminescent properties to the final material, offering tunable structures, robust mechanical properties, and low detection limits in sensing applications when compared to small-molecule or inorganic luminescent materials. In the latter, AIE FPs use a novel mode of fluorescence dependent on the aggregation state. AIE FP intra- and intermolecular interactions confer synergistic effects, improving their properties and performance over small molecules aggregation-induced, emission-based fluorescent materials (AIEgens). Despite their outstanding advantages (over classic polymers) of high emission efficiency, signal amplification, good processability, and multiple functionalization, AIE polymers have received less attention. This review examines some of the most significant advances in the broad field of FPs over the last six years, concluding with a general outlook and discussion of future challenges to promote advancements in these promising materials that can serve as a springboard for future innovation in the field. [ABSTRACT FROM AUTHOR]

Two benzimidazole-based conjugated polyelectrolytes (+)-PPBIPV and (-)-PPBIPV which have opposite charges on their side chains were synthesized via Heck coupling reaction and characterized by 1H-NMR, UV-vis and PL spectroscopy. These two polyelectrolytes are both consisted of benzimidazole derivatives and phenylenevinylene units. The absorption and emission spectra reveal that the polymers both have solvent-dependency and concentration-dependency, and they exhibit aggregation effect in aqueous solution. In the respect of ion detection, the aqueous solution of (+)-PPBIPV has excellent selectivity and sensitivity for Fe3+. Moreover, Pd2+ can almost completely quench the fluorescence of (+)-PPBIPV in methanol solution, and its quenching constant KSV is 5.93×104 M-1. For (-)-PPBIPV, Sn2+ can double the fluorescence intensity of its aqueous solution, while (-)-PPBIPV has good identification for Fe3+ in methanol with a KSV = 3.44×105 M-1. Hence, two polyelectrolytes have considerable potential to become effective fluorescent sensing materials for some specific metal ions. All of the stoichiometric relationships between metal ions and conjugated polyelectrolytes were calculated using Benesi-Hildebrand equation.

[Display omitted] • Conjugated polyelectrolytes with FRET pairs act as proximity sensors in an assembly. • Polycationic spermine can be detected via binding-induced fluorescence quenching. • Bulky tryptamine dissociates charge-driven complexes by creating steric hindrance. • Charge-driven complexes serve as a platform for small analyte detection via FRET. We developed sensing platforms to detect and differentiate various types of biogenic amines, cadaverine, putrescine, spermine, histamine, tyramine and tryptamine by monitoring the changes in fluorescence signal. The sensing platforms comprised a carboxylated polyfluorene derivative doped with benzothiadiazole acceptor moieties in a small fraction (20%). When utilized as an individual sensing component, the conjugated polyelectrolyte detects all BAs nonselectively via binding-induced fluorescence quenching. If the conjugated polyelectrolyte forms an intermediary charge-driven complex with an oppositely charged surfactant, a Förster resonance energy transfer (FRET) response is triggered. Biogenic amines are detected through their effects on the FRET signal as enhancement, reduction, or no effect. We formed intermediary charge-driven complexes at nonstoichiometric, cation deficient and excess conditions. Supramolecular interactions governed the co-assembly and disassembly caused by the targeted amines on the conjugated polyelectrolyte-surfactant complex. Therefore, structural and charge-related differences enabled their selective detection in our sensing platforms. Among them, spermine exhibited the highest FRET enhancement effect due to its polycationic aliphatic structure by engaging in multi-point interchain contacts among conjugated polyelectrolyte chains. In contrast, tryptamine showed a unique quenching effect on the FRET signal due to the steric hindrance created by its bulky, heterocyclic structure, leading to the dissociation of the complexes. [ABSTRACT FROM AUTHOR]

Phosphonium‐based polythiophene conjugated polyelectrolytes (CPEs) with three different counterions (dodecylsulfate, octylsulfate and perfluorooctane sulfonate) are synthesized to determine how the nature of the counterion affects the thermal properties, the self‐assembly in thin films and the performance as the cathode interfacial layer in polymer solar cells (PSCs). The counterion has a significant effect on the thermal properties of the CPEs, affecting both their glass transition and crystalline behaviour. Grazing‐incidence wide‐angle X‐ray scattering studies also indicate that changing the nature of the counterion influences the microstructural organization in thin films (face‐on versus edge‐on orientation). The affinity of the CPEs with the underlying photoactive layer in PSCs is highly correlated with the counterion species. Finally, in addition to an increase of the power conversion efficiency of ca 15% when using these CPEs as cathode interfacial layers in PSCs, a higher device stability is noted, compared to a reference device with a calcium interlayer. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

This work presents solution- and solid-state evidence of the enhancement of J-like aggregation of a cationic polythiophene (CPT) with isothiouronium functionalities (PT1), caused by a decrease in the polarity and hydrogen-bonding (H-bonding) capacity of the solvent, generated by using a 50:50 v/v 1,4-dioxane-water mixture (W-DI) instead of water. In solution, the presence of 1,4-dioxane (DI) seems to generate selective solvation, tuning the energy transfer within PT1 from inter-chain into intra-chain, enhancing J-like aggregation. On the other hand, during the casting process, the presence of DI directs the interaction with solid-substrates, generating an increase in the solid-state fluorescence, modifying the morphology from one similar to ballistic-aggregation (BA) into one similar to attachment limited aggregation (ALA), DI also modifies the SFE by increasing slightly its polar contribution (γS p ) and decreasing the dispersive one (γS d ). These results can be explained to be caused by a "coating" effect in presence of DI (as proposed before experimentally and computationally). Our results show a clear correlation between the solution- and solid-state properties of PT1 in each solvent, further validating the use of the fluorescence excitation spectra to trace J-like aggregation of water-soluble conjugated polymeric fluorophores in solution. This information could be useful for predicting and designing specific mesoscopic architectures of CPTs (and conjugated polyelectrolytes in general), which are molecules lacking of clear structure-function guidelines for designing high-performance polythiophene-based interlayer materials, especially for CPTs (and conjugated polyelectrolytes (CPEs) in general), particularly those with H-bonding capabilities. To the best of our knowledge the use of solution-state fluorescence excitation spectra to identify J-like aggregation of water-soluble conjugated polymers (CPs) has been scarcely used/discussed in literature and no correlation with solid-state properties was reported previously. [ABSTRACT FROM AUTHOR]

Fluorescence imaging using poly(phenylene ethynylene) (PPE) based conjugated polyelectrolytes (CPEs) has garnered considerable attention in the recent past due to their remarkable photophysical properties. In this report, we studied the fluorescence imaging properties of a set of six PPE‐based CPEs appended with side chains varying in structure and number of cationic charges. The photophysical and aggregation features of the CPEs depend on the overall charge density on the polymer in water. The cytotoxicity of the CPEs was evaluated against MCF‐7 mammalian cells, which revealed that polyelectrolytes with less cationic charge are less cytotoxic and vice versa. Confocal laser scanning microscopy (CLSM) studies showed that all the CPEs could efficiently penetrate into the MCF‐7 cells after 10 h of incubation. The transit of CPEs into the lysosomes was confirmed by comparison with the uptake of LysoTracker Red DND‐99 dye, which also revealed that the polyelectrolytes are highly photostable. We also demonstrated that the imidazolium‐functionalized CPEs could selectively stain bacteria over mammalian cells, suggesting the importance of CPEs for clinical applications. [ABSTRACT FROM AUTHOR]

Doping provides an efficient strategy to control the electronic properties of organic semiconductors. However, compared with the widely reported p‐type doping protocols, n‐type doping of organic semiconductors still remains a challenge. Herein, a series of novel n‐doped conjugated polyelectrolytes (CPEs) with high doping levels and conductivity are designed. These CPEs are synthesized via a facile, metal‐free, and high‐yield aldol condensation protocol from bis‐isatin and bis‐oxindole monomers. The designed CPEs possess a n‐type electron‐deficient and rigid conjugated backbone, resulting in easy charge delocalization, enhanced n‐doping behaviors, and high conductivity. The evolution on the counterions of these CPEs further alters their n‐doping behaviors, charge transporting properties, and work function tunability, etc. By using these CPEs as electron transport materials (ETMs) for nonfullerene polymer solar cells (NF–PSCs), high power conversion efficiencies (PCEs) over 16% can be achieved when PM6:Y6 is used as the active component. Moreover, these CPEs can enable efficient NF–PSCs even if their thicknesses are up to 60 nm, indicating the potential of these CPEs as thickness‐insensitive ETMs for the fabrication of large‐area NF–PSCs. [ABSTRACT FROM AUTHOR]

Conjugated polyelectrolytes are π-conjugated polymers that contain ionic charged groups such as sulfonate (R-SO 3 - ), carboxylate (R-COO - ) combined with a π-conjugated backbone. This perspective provides a summary review of the key developments in the field, starting from the first reports of their synthesis and properties to application-focused developments. The applications include optical sensors for molecular and biomolecular targets, organic electronic applications, and specific biological applications including cellular imaging and photodynamic therapy. This perspective concludes with a discussion of where the field of conjugated polyelectrolytes is expected to lead in the coming years.3 + ) combined with a π-conjugated backbone. This perspective provides a summary review of the key developments in the field, starting from the first reports of their synthesis and properties to application-focused developments. The applications include optical sensors for molecular and biomolecular targets, organic electronic applications, and specific biological applications including cellular imaging and photodynamic therapy. This perspective concludes with a discussion of where the field of conjugated polyelectrolytes is expected to lead in the coming years.

Robust photosensitizers with strong red/NIR fluorescence, efficient reactive oxygen species (ROS) generation and high photostability are highly desired for photodynamic therapy (PDT). Herein, three novel red conjugated polyelectrolytes (CPEs) with tetraphenylethene and 2,1,3-benzothiadiazole on the main chains and triphenylphosphonium on the side chains are developed. These CPEs display apparent aggregation-induced emission feature and high fluorescence quantum yields in the aggregated state. They can target lysosome in HeLa cells for fluorescence bioimaging. By virtue of the good retention effect and high photostability, these CPEs show ultralong-term tracing performance of subcutaneous tumors, and the tumor site can still be visualized for 20 days after injection. Owing to their good biocompatibility and strong ROS generation ability, the image-guided PDT based on these CPEs can effectively inhibit the growth of subcutaneous tumor and significantly prolong the survival of tumor bearing mice. The H&E and IHC staining reveal that the PDT of these CPEs depress the proliferation of tumor cells, and promote apoptosis and necrosis process. These new CPEs may be employed both as fluorescent probes for in vitro and in vivo long-term tracing and as photosensitizers for image-guided PDT of tumors. [ABSTRACT FROM AUTHOR]

The use of π‐conjugated polymers (CPs) in conductive hydrogels remains challenging due to the water‐insoluble nature of most CPs. Conjugated polyelectrolytes (CPEs) are promising alternatives because they have tunable electronic properties and high water‐solubility, but they are often difficult to synthesize and thus have not been widely adopted. Herein, we report the synthesis of an anionic poly(cyclopentadienylene vinylene) (aPCPV) from an insulating precursor under mild conditions and in high yield. Functionalized aPCPV is a highly water‐soluble CPE that exhibits low cytotoxicity, and we found that doping hydrogels with aPCPV imparts conductivity. We also anticipate that this synthetic strategy, due to its ease and high efficiency, will be widely used to create families of not‐yet‐explored π‐conjugated vinylene polymers. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution is viewed as a promising green strategy to utilize the inexhaustible solar energy and provide clean hydrogen fuels with zero‐emission characteristic. The nature of semiconductor‐based photocatalysts is the key point to achieve efficient photocatalytic hydrogen evolution. Conjugated materials have been recently emerging as a novel class of photocatalysts for hydrogen evolution and photocatalytic reactions due to their electronic properties can be well controlled via tailor‐made chemical structures. Hydrophilic conjugated materials, a subgroup of conjugated materials, possess multiple advantages for photocatalytic applications, thus spurring remarkable progress on both material realm and photocatalytic applications. This minireview aims to provide a brief review of the recent developments of hydrophilic conjugated polymers/small molecules for photocatalytic applications, and special concern on the rational molecular design and their impact on photocatalytic performance will be reviewed. Perspectives on the hydrophilic conjugated materials and challenges to their applications in the photocatalytic field are also presented. [ABSTRACT FROM AUTHOR]

Interface engineering is an effective means to enhance the performance of thin‐film devices, such as perovskite solar cells (PSCs). Herein, a conjugated polyelectrolyte, poly[(9,9‐bis(3′‐((N,N‐dimethyl)‐N‐ethyl‐ammonium)‐propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)]di‐iodide (PFN‐I), is used at the interfaces between the hole transport layer (HTL)/perovskite and perovskite/electron transport layer simultaneously, to enhance the device power conversion efficiency (PCE) and stability. The fabricated PSCs with an inverted planar heterojunction structure show improved open‐circuit voltage (Voc), short‐circuit current density (Jsc), and fill factor, resulting in PCEs up to 20.56%. The devices maintain over 80% of their initial PCEs after 800 h of exposure to a relative humidity 35–55% at room temperature. All of these improvements are attributed to the functional PFN‐I layers as they provide favorable interface contact and defect reduction. [ABSTRACT FROM AUTHOR]

Poly(6‐(4,7‐dimethyl‐2H‐benzo[d][1,2,3]triazol‐2‐yl)‐N,N,N‐trimethylhexan‐1 aminium iodide) (PBTz‐TMAI) and poly(sodium 4‐(4,7‐dimethyl‐2H‐benzo[d] [1,2,3]triazol‐2‐yl)butane‐1‐sulfonate) (PBTz‐SO3Na) based on the same benzotriazole‐conjugated backbone but with ammonium and sulfonated side chains are designed and synthesized through side‐chain functionalization and Yamamoto polymerization, respectively, and are used as the cathode interlayers in fullerene‐ and non‐fullerene‐based polymer solar cells. The interfacial modification of PBTz‐TMAI and PBTz‐SO3Na onto the active layer achieves good energy alignment at cathode electrodes and optimized exciton‐dissociation efficiency from the active layer. Consequently, the power conversion efficiencies (PCEs) of 7.8% and 9.6% are obtained for the fullerene PTB7:PC71BM‐based and non‐fullerene PBDB‐T:ITIC‐based polymer solar cells (PSCs) with PBTz‐SO3Na interlayer. The PCS devices based on PTB7:PC71BM and PBDB‐T:ITIC active layers with PBTz‐TMAI interlayer achieved a remarkably improved performance with PCEs of 8.2% and 10.2%, respectively. [ABSTRACT FROM AUTHOR]

The large depletion region width at the electrode interface may cause serious energy loss in charge collection of organic solar cells (OSCs), depressing the open-circuit voltage and power conversion efficiency (PCE). Herein, a pH neutral solution-processed conjugated polyelectrolyte PIDT-F:IMC as hole transport layer (HTL) to reduce the depletion region width in efficient OSCs is developed. By utilizing "mutual doping" strategy, the doping density of PIDT-F:IMC is increased by more than two orders of magnitude, which significantly reduces the depletion region width at the anode interface from 55 to 7.4 nm, playing an effective role in decreasing the energy loss in hole collection. It is also revealed that the optimal thickness of HTL should be consistent with the depletion region width for achieving the minimum energy loss. The OSC modified by PIDT-F:IMC shows a high PCE of 18.2%, along with an amazing fill factor of 0.79. Moreover, a PCE of 16.5% is achieved in the 1 cm 2 OSC by using a blade-coated PIDT-F:IMC HTL, indicating the good compatibility of PIDT-F:IMC with large-area processing technology. The PIDT-F:IMC-modified OCS exhibits a lifetime of 400 h under operational conditions, which is ten times longer than that of the PEDOT:PSS device., (© 2023 Wiley‐VCH GmbH.)

Fluorescent polyelectrolytes have attracted tremendous attention due to their unique properties and wide applications. However, current research objects of fluorescent polyelectrolytes mainly focus on side-chain charged polyelectrolytes, and the applications of polyelectrolytes in plant cytomembrane imaging with long time and high specificity still remain challenging. Herein, long-time and targeted fluorescence imaging of plant cytomembranes was achieved for the first time using main-chain charged polyelectrolytes (MCCPs) with aggregation-induced emission (AIE). A series of MCCPs were designed and synthesized, among which the red-emissive and AIE-active MCCP with a triphenylamine linker and a cyano group around the cationic ring-fused heterocyclic core showed the best fluorescence imaging performance of plant cells. Unlike other MCCPs and its neutral form of polymer, this cyano-substituted conjugated polyelectrolyte can specifically target the cytomembrane of plant cells within a short staining time with many advantages, including wash-free staining, high photostability and imaging integrity, excellent durability (at least 12 h), and low biotoxicity. In addition to onion epidermal cells, this AIE fluorescence probe also shows good imaging capabilities for other kinds of plant cells such as Glycine max and Vigna radiata . Such an AIE-active MCCP-based imaging system provides an effective design strategy to develop fluorescence probes with high specificity and long-term imaging ability toward plant plasma membranes.

We report the light-activated antibacterial activity of a new class of phosphonium (R-PMe 3 )-substituted conjugated polyelectrolytes (CPEs). These polyelectrolytes feature a poly(phenylene ethynylene) (PPE) conjugated backbone substituted with side groups with the structure -O-(CH + )-substituted conjugated polyelectrolytes (CPEs). These polyelectrolytes feature a poly(phenylene ethynylene) (PPE) conjugated backbone substituted with side groups with the structure -O-(CH 2 ) n PMe 3 + , where n = 3 or 6. The length of the side groups has an effect on the hydrophobic character of the CPEs and their propensity to interact with bacterial membranes. In a separate study, these phosphonium-substituted PPE CPEs were demonstrated to photosensitize singlet oxygen ( 1 O 2 ) and reactive oxygen species, a key factor for the photoinduced inactivation of bacteria. In this study, in vitro antibacterial assays against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were performed by employing the series of polyelectrolytes under both dark and illumination conditions. In general, the phosphonium-substituted CPEs displayed profound light-activated biocidal activity, with >99% colony forming unit (CFU) reduction after 15 min of light exposure (16 mW cm -2 ) at a ≤20 μM CPE concentration. Strong biocidal activity was also observed in the dark for a CPE concentration of 20 μM against S. aureus ; however, higher concentrations (200 μM) were needed to enable dark inactivation of E. coli . The dark activity is ascribed to bacterial membrane disruption by the CPEs, supported by a correlation of dark biocidal activity with the chain length of the side groups. The light-activated biocidal activity is associated with the ability of the CPEs to sensitize ROS, which is cytotoxic to the microorganisms. Serial dilution bacterial plating experiments revealed that the series of CPEs was able to induce a >5-log kill versus E. coli with 15 min of exposure to a blue LED source (16 mW cm -2 ).

As some of the most promising candidates for constituting bioinspired electronics, polymer memristors with analog-type switching behavior exhibit great potential for synaptic mimicking and neuromorphic computing systems. By using highly soluble conjugated polyelectrolyte poly[9,9-bis(6-(3-methyl-1-imidazolium-yl)hexyl)fluorene]-covalently modified black phosphorus (BP) nanomaterial (BP-PF-NMI + Br - ) as the active layer, an electronic device with the BP-PF-NMI + Br - film sandwiched between the aluminum and indium tin oxide electrodes is successfully fabricated. This device exhibits an excellent amount of electricity-dependent memristive performance at a small sweep voltage range of ±1 V. With increasing amount of electricity flowing through the device, the device resistance gradually decreased in a linear pattern. The changes in frequency, amplitude, and duration of voltage pulses do not affect the linear relationship between the amount of electricity passing through the device and the resistance value achieved after each state reached equilibrium at different numbers of the same voltage pulse stimulations. Both the synaptic potentiation/depression and learning/memorizing/forgetting functions of biological systems have been emulated. In contrast to BP-PF-NMI + Br - , the pure PF-NMI + Br - -based device shows a write-once-read-many-times effect at the same scanning voltage range, while the BP:PF-NMI + Br - blends exhibit very unstable memristive performances.

A subclass of organic semiconductors known as conjugated polyelectrolytes (CPEs) is characterized by a conjugated backbone with ionic pendant groups. The water solubility of CPEs typically hinders applications of thin films in aqueous media. Herein, it is reported that films of an anionic CPE, namely CPE-K, drop cast from water produces single-component solid-state pseudocapacitive electrodes that are insoluble in aqueous electrolyte. That X-ray diffraction experiments reveal a more structurally ordered film, relative to the as-obtained powder from chemical synthesis, and dynamic light scattering measurements show an increase in aggregate particle size with increasing [KCl] indicate that CPE-K films are insoluble because of tight interchain contacts and electrostatic screening by the electrolyte. CPE-K film electrodes can maintain 85% of their original capacitance (84 F g -1 ) at 500 A g -1 and exhibit excellent cycling stability, where a capacitance retention of 93% after 100 000 cycles at a current density of 35 A g -1 . These findings demonstrate that it is possible to use initially water soluble ionic-organic materials in aqueous electrolytes, by increasing the electrolyte concentration. This strategy can be applied to the application of conjugated polyelectrolytes in batteries, organic electrochemical transistors, and electrochemical sensors, where fast electron and ion transport are required., (© 2023 Wiley-VCH GmbH.)

Thermal sensing in thin films polymers has been a significant limitation towards optimizing the heat dissipation in micro- and nano-electronic devices as well as many other thin film-based technologies. In this work, we report on poly (phenylene ethynylene) fluorescent-based conjugated polyelectrolyte capable of detecting thermal fluctuations in polymer films prepared from polyvinylpyrrolidone-co-vinyl acetate. The sensor was first optimized in solution by testing two polyvinylpyrrolidone (PVP) copolymers (co-vinyl acetate (VA) and co-polystyrene (PS)) before it was spun cast onto quartz slides and imaged using a DSLR camera at different temperatures. The images were analyzed and showed a change in color with the increase in temperature. When not illuminated, the polymer thin film is clear and transparent. Image 1 • We have develop a temperature sensor for thin-polymer films. • The film was spun cast onto quartz slides and imaged using a DSLR camera at different temperatures. • The images were analyzed and showed a thermochromic response with the increase in temperature. • When not illuminated, the polymer thin film is clear and transparent. [ABSTRACT FROM AUTHOR]

Conjugated polyelectrolytes based on benzotriazole (BT) and benzothiadiazole (BTz) alt unit with a pendant sulfonate ion but different countercations were synthesized and named PBTBTz-SO3Na and PBTBTz-SO3TBA. PBTBTz-SO3Na was used as a cathode interface applied to polymer solar cells (PSCs), and ITO/PEDOT:PSS/active layer/cathode interlayer/Al was set as a device structure. The PSCs displayed an average power conversion efficiency (PCE) of 7.7%, revealing an unchanged efficiency in comparison with that of the control device fabricated from a CH3OH interlayer. TBA+, a different counteraction, was used instead of Na+ to further study the influence of counterions on the electrical property of PBTBTz-SO3−. PBTBTz-SO3TBA was used as a cathode interface to fabricate two types of PSCs based on PTB7:PC71BM and PBDB-T:ITIC, and their improved average PCEs were 8.6% and 9.1%, respectively. [ABSTRACT FROM AUTHOR]

Organic semiconductors for photocatalytic application have received wide attention recently. However, developing organic photocatalysts for highly efficient photocatalytic hydrogen evolution is a great challenge. Herein, we show highly efficient photocatalytic hydrogen evolution from a series of novel conjugated polyelectrolytes (CPEs) by modulating their interaction with co-catalysts. The water-soluble CPEs greatly enhance the photocatalytic performance with 50-fold improvement over that of their non-dissolved precursor conjugated polymer. More importantly, the photocatalytic activity of these CPEs can be optimized by regulating their interaction with Pt co-catalysts through molecular engineering on the side chain species and counterions of CPEs. The cationic CPEs perform better than anionic CPEs due to the robust interaction between quaternary ammonium side chains in cationic CPEs and Pt co-catalysts. It is found that the optimized interface contact between cationic CPEs and Pt co-catalysts can result in more efficient charge transfer and higher photocatalytic activity. Image 1 • A series of novel conjugated polyelectrolytes (CPEs) are dispersed into water to form nano-grade polymer micelles. • CPEs enable much enhanced photocatalytic hydrogen evolution. • The interaction between CPEs and Pt co-catalysts is well-regulated via their side chain species and counterions. • The intimate interface contact between cationic CPEs and Pt co-catalysts enables more efficient charge transfer and separation. [ABSTRACT FROM AUTHOR]

Abstract Conjugated polyelectrolytes (CPEs) have been successfully applied in organic photovoltaics and organic light-emitting diodes, and recently those with inorganic cations became to serve as a hole-transporting layer (HTL) in inverted perovskite solar cells (iPSCs), whereas the CPE HTL materials with organic cations are really limited. In this work, we design a CPE whose side-chains are end-capped by CH 3 NH 3 + cations, the same cations as that in the perovskite layer. The CPE is found to be more compatible to the perovskite material, and shows stronger abilities to reduce the traps both at the surface and in the bulk of the perovskite layer, compared with the typical poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). The resulting iPSC presents much improved photovoltaic properties and a better long-term stability, with a power conversion efficiency of 19.76%, which is the highest value ever reported for iPSCs based on CPE HTLs. Graphical abstract A conjugated polyelectrolyte with organic cations CH 3 NH 3 + as the hole-transporting layer presents a power conversion efficiency of up to 19.76% for inverted perovskite solar cells. fx1 Highlights • A polyelectrolyte with organic cations CH 3 NH 3 + is designed to replace PEDOT:PSS. • Much higher power conversion efficiency of up to 19.76% is obtained. • Higher compatibility and reduced defects to the perovskite layer is achieved. [ABSTRACT FROM AUTHOR]

Abstract Cationic π-conjugated polyelectrolytes (CPEs) were successfully intercalated into layered titanate (TiO 2), while exfoliated layered titanates were reassembled into lamellar structures. The resulting composites showed significantly enhanced visible light absorbance and enhanced photocatalytic activity with respect to layered titanate, which was proven by the photodegradation of methylene blue in aqueous media under irradiation by visible light. Notably, some amount of tetrabutylammonium (TBA) used for the delamination of a layered titanate could be co-intercalated with CPEs, and the residual TBA could be removed via continuously repeating the intercalation process, maintaining the spatial arrangement and content of CPEs in the confined area of layered titanates. However, with the presence of TBA, the hybrid demonstrated greater performance in the photodegradation of methylene blue at any given period of time and almost complete degradation of such dye within 8 min. The significant difference in photocatalytic efficiency with or without TBA suggested that the TBA effectively reduced the surface energy at the interface between the organic components and aqueous medium, which was evidenced by the dispersity assessment of hybrids with or without TBA. Graphical abstract Cationic π-conjugated polyelectrolytes (CPEs) were successfully intercalated into layered titanate (TiO 2). The resulting composites showed significantly enhanced photocatalytic activity which was proven by the photodegradation of methylene blue in aqueous media under irradiation by visible light. Notably, with the presence of TBA, the hybrid demonstrated greater performance in the photodegradation of methylene blue at any given period of time and almost complete degradation of such dye within 8 min. fx1 [ABSTRACT FROM AUTHOR]

Conjugated polymers with ionic pendant groups (CPEs) are receiving increasing attention as solution-processed interfacial materials for organic solar cells (OSCs). Various anionic CPEs have been successfully used, on top of ITO (Indium Tin Oxide) electrodes, as solution-processed anode interlayers (AILs) for conventional devices with direct geometry. However, the development of CPE AILs for OSC devices with inverted geometry is an important topic that still needs to be addressed. Here, we have designed three anionic CPEs bearing alkyl-potassium-sulfonate side chains. Their functional behavior as anode interlayers has been investigated in P3HT:PC61BM (poly(3-hexylthiophene): [6,6]-phenyl C61 butyric acid methyl ester) devices with an inverted geometry, using a hole collecting silver electrode evaporated on top. Our results reveal that to obtain effective anode modification, the CPEs’ conjugated backbone has to be tailored to grant self-doping and to have a good energy-level match with the photoactive layer. Furthermore, the sulfonate moieties not only ensure the solubility in polar orthogonal solvents, induce self-doping via a right choice of the conjugated backbone, but also play a role in the gaining of hole selectivity of the top silver electrode.