Doped Polymer Research Articles

Small molecule doped polymer hole transport layers for all solution processed inverted QLED with using green solvents

Small molecule doped polymer hole transport layers for all solution processed inverted QLED with using green solvents

Diamagnetic Carrier-Doping-Induced Continuous Electronic and Magnetic Crossover in One-Dimensional Coordination Polymers.

The potential to introduce tunable electrical conductivity and molecular magnetism through carrier doping in metal-organic coordination polymers is particularly promising for nanoelectronics applications. Precise control of the doping level is essential for determining the electronic and magnetic properties. In this study, we present a series of one-dimensional coordination polymers, {(HNEt3)0.5[CuxCo(1-x)(L)]}n (HNEt3 = triethylammonium, L = 1,2,4,5-tetrakis(methanesulfonamido)benzene), doped with diamagnetic Cu1+ carriers. Through comprehensive characterization of the structural, optical, and magnetic properties, we observed continuous electronic and magnetic crossover as the doping level was gradually increased. When x < 0.5, the doped compounds exhibit ferromagnetic insulating behavior with very high energy barriers (Ueff up to 560 K) and excellent slow relaxation of magnetization. At x = 0.5, {(HNEt3)0.5[Cu0.5Co0.5(L)]}n functions as a paramagnetic semiconductor at high temperatures and a single-molecule magnet at low temperatures. When x > 0.5, the doped compounds act as diluted antiferromagnetic semiconductors with narrow band gaps (Ea = 0.2 eV). The emergence of such rich electronic and magnetic crossovers is ascribed to the cooperation of the strong electron-donating ability of the ligand and the pronounced crystal-field effects. Our findings indicate that one-dimensional (1D) coordination polymers are promising for the design of novel low-dimensional magnetic semiconductors.

Elucidating the Role of Polymer–Dopant Interaction in the Electrical Properties of Polymers with Non-Conjugated Spacers

Elucidating the Role of Polymer–Dopant Interaction in the Electrical Properties of Polymers with Non-Conjugated Spacers

Electrical and Optical Studies of Polymer Electrolyte (PVA+KI) Films Doped with CuO Nanofillers

In this study, we investigate the impact of copper oxide (CuO) nanofillers on the electrical and structural properties of polymer composite electrolyte films. Poly(vinyl alcohol) (PVA) and Potassium iodide (KI) were chosen for the polymer electrolyte and nano-CuO was synthesized and used as nano-filler in the PVA-KI matrix. PVA-KI films are doped with varying concentrations of CuO nanoparticles to explore their influence on the film's conductivity, dielectric behaviour, and optical transmittance. Electrical measurements reveal that the addition of CuO nanofillers significantly enhances the ionic conductivity of the PVA-KI matrix. The conductivity increases with the concentration of CuO up to an optimal doping level, beyond which it decreases, likely due to agglomeration of nanoparticles. The dielectric constant and loss tangent also show a notable dependence on the CuO content, reflecting improved charge transport and polarization effects within the films. The combined electrical and optical data suggest that CuO nanofillers can be effectively utilized to tailor the properties of PVA-KI polymer electrolytes for various applications, including energy storage and optoelectronic devices. These findings provide insights into the mechanisms of ion conduction and light interaction in doped polymer systems, paving the way for further research and optimization of functional polymer-based materials.

Enhancing efficiency in double perovskite solar cells through bandgap reduction via organic polymer doping

Enhancing efficiency in double perovskite solar cells through bandgap reduction via organic polymer doping

Half-integer topological defects paired via string micelles in polar liquids.

Ferroelectric nematic (NF) liquid crystals present a compelling platform for exploring topological defects in polar fields, while their structural properties can be significantly altered by ionic doping. In this study, we demonstrate that doping the ferroelectric nematic material RM734 with cationic polymers enables the formation of polymeric micelles that connect pairs of half-integer topological defects. Polarizing optical microscopy reveals that these string defects exhibit butterfly textures, featured with a 2D polarization field divided by Néel-type kink walls into domains exhibiting either uniform polarization or negative splay and bend deformations. Through analysis of electrophoretic motion and direct measurements of polarization divergences, we show that the string micelles are positively charged, and their side regions exhibit positive bound charges. To elucidate these observations, we propose a charge double-layer model for the string defects: the positively charged cationic polymer chains and densely packed RM734 molecules form a Stern charge layer, while small anionic ions and positive bound charges constitute the charge diffusion layer. Notably, our experiments indicate that only cationic polymer doping effectively induces the formation of these unique string defects. These findings enhance our understanding of ionic doping effects and provide valuable insights for engineering polar topologies in liquid crystal systems.

Machine‐Learning‐Assisted Process Optimization for High‐Performance Organic Thermoelectrics

AbstractOptimizing the processing conditions of conjugated polymers is a key step in improving the performance of various organic electronic devices, including organic thermoelectric (TE) devices that are capable of harvesting energy from waste heat. However, the inherent structural and energetic disorders in these materials and their unpredictable property changes after processing complicate the optimization principles, requiring numerous trial‐and‐error experiments to maximize the TE performance. Here, a machine‐learning (ML)‐based design of experiments approach is introduced to address these challenges, and its effectiveness is demonstrated using a representative thiophene‐based doped polymer system for organic TE. This approach not only helps to quantitatively understand how each processing parameter affects the TE properties of the polymer but also facilitates the prediction of optimal processing conditions, leading to achieve maximum TE performance with minimal experiments within a large parameter space. Furthermore, the ML‐based approach is validated by revealing the origins of the power factor maximization at the ML‐predicted processing conditions through analysis of the morphology and electronic states of the doped polymer films. The proposed methodology is applicable to the majority of polymer systems for organic thermoelectric energy conversion and will provide guidelines for determining optimal process conditions and improving TE performance with minimal effort.

Asymmetric Diaphragms and Their Influence on Gas Crossover in Alkaline Electrolysis

Many novel lab-scale diaphragms, as well as commercial state-of-the-art diaphragms for alkaline water electrolysis are prepared by non-solvent based phase inversion processes. On the lab-scale, the fabrication process is often asymmetric. The polymer dope is coated onto a glass plate similar to conventional film forming techniques, after which the glass substrate carrying the film is immersed into a non-solvent bath to rapidly precipitate the constituting polymer. As the film is initially only exposed to the non-solvent on the top surface, the resulting pore structure at the top surface of the film differs from that at the glass plate side.This contribution explores a number of phase-inversion prepared diaphragms towards their pore structure, and in particular investigate how the asymmetric nature influences the electrolysis behavior at single cell level. Reference diaphragms based on polysulfone (PSU) are used as reference materials, and the investigation is extended to include diaphragms based on more novel polymers systems.Significant differences are observed in the relative crossover of hydrogen to oxygen (HTO) as well as the oxygen to hydrogen (OTH), depending on the orientation of the diaphragm. Specifically, towards which electrode the skin layer is oriented matters. More than an order of magnitude in apparent crossover flux can be observed in some cases at otherwise identical conditions. Introducing an electrode-diaphragm gap can alleviate severe supersaturation and reduce crossover flux, whereas over compressed cells exhibit more severe degrees of crossover.

Highly Elastic Full Hydrocarbon Ultralong RTP Polymers with Visible Light Excitable S0→T1 Population

AbstractHighly elastic ultralong organic room temperature phosphorescence (RTP) polymers are highly desired in wearable optoelectronic fields, but they are hardly realized in rubbers since chain segment motions deactivate triplet excitons. In the current work, it is revealed that polystyrene (PS) can inhibit triplet thermal deactivation of coronene (Cor), and it is the serious oxygen diffusion and quenching that disables RTP emission of Cor/polymers. In view of oxygen barrier function of rubbers, PS−polyisoprene−PS tri‐block elastomers (SIS) are used as Cor's doping matrices. The results show that Cor/SIS sheets show bright and ultralong afterglow with RTP lifetime up to 3.64 s in air after brief 365 nm light excitation. More impressively, Cor/SIS and its red fluorescent dye doped sheets all exhibit ultralong room temperature afterglow under large dynamic elastic deformation. Further, all these sheets exhibit long‐wave blue light excited afterglow despite Cor/SIS having no visible light absorption band, and the unique photoexcitation and emission mechanism is verified. This work not only provides the development strategy of the latest elastic RTP materials, but also will evoke a fresh understanding on organic doped RTP polymers.

Effective Model Reduction Scheme for the Electronic Structure of Highly Doped Semiconducting Polymers.

Highly doped organic polymers have emerged as prominent candidates within novel technological disciplines, yet the fundamental correlation between structure and charge transport characteristics still remains missing. Toward this objective, an efficient model reduction scheme for highly doped polymer chains is developed considering the paradigmatic case of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS). The reduced model accounts for the chemical and structural details of the conducting polymer chain in addition to the long-range Coulombic interactions between charge carriers (holes) and dopant ions and the Coulombic repulsion between holes residing on the PEDOT chain. The model is shown to reproduce the intrachain hole-density profile of bulk polymer chains within a mean-field description. Furthermore, and critically, the model is adept at determining the energy distribution of doped PEDOT samples that in effect, influences the hole distribution among polymer chains. The hole distribution so obtained broadly upholds the approximation of a homogeneous charge-carrier distribution in doped polymers commonly found in the literature. In addition, it is observed that the spin configuration of the charge carriers dictates the energetics of the doped chains while it is a critical function of the chain length, carrier density, and disorder parameters.

Highly conductive and uniform PEDOT on poly(acrylic acid-vinylbenzyl chloride) functionalized surfaces

This study demonstrates increasing the uniformity and conductivity of poly(3,4-ethylene dioxythiophene) (PEDOT) thin films synthesized by vapor phase polymerization (VPP) through the utilization of a thin interfacial prime layer on the substrate surface. The prime layer, which is a copolymer of acrylic acid (AA) and vinylbenzyl chloride (VBC), was coated on the substrate surface using initiated chemical vapor deposition (iCVD) method. FTIR and XPS were used to analyze the structure of as-deposited films. The use of P(AA-VBC) copolymer as a prime layer allowed uniform and complete coverage of the oxidant solution on the substrate surface due to the hydrophilic nature of the AA constituent. During the VPP, the existence of the chlorine ions originating from the VBC constituent allowed in-situ doping of the as-deposited polymer, which contributes to the increased uniformity and the conductivity. The experimental studies were carried out to show the increase in uniformity, conductivity and adherence of the as-deposited PEDOT film in the presence of the prime layer. There was nearly a 4-fold increase in the conductivity of as-deposited PEDOT in the presence of the prime layer, with measured conductivity uniformity as high as 96% over a 5×5 cm2 glass surface.

Near-Infrared Room-Temperature Phosphorescence from Monocyclic Luminophores.

Compact luminophores with long emission wavelengths have aroused considerable theoretical and practical interest. Organics with room-temperature phosphorescence (RTP) are also desirable for their longer lifetimes and larger Stokes shifts than fluorescence. Utilizing the low electronic transition energy intrinsic to thiocarbonyl compounds, electron-withdrawing groups were attached to the 4H-pyran-4-thione core to further lower the excited state energies. The resulting mini-phosphors were doped into suitable polymer matrices. These purely organic, amorphous materials emitted near-infrared (NIR) RTP. Having a molar mass of only 162 g·mol-1, one of the phosphors emitted RTP that peaked at 750 nm, with a very large Stokes shift of 15485 cm-1 (403 nm). Thanks to the good processability of the polymer film, light-emitting diodes (LEDs) with NIR emission were easily fabricated by coating doped polymer on ultraviolet LEDs. This work provides an intriguing strategy to achieve NIR RTP using compact luminophores.

Near‐Infrared Room‐Temperature Phosphorescence from Monocyclic Luminophores

Compact luminophores with long emission wavelengths have aroused considerable theoretical and practical interest. Organics with room‐temperature phosphorescence (RTP) are also desirable for their longer lifetimes and larger Stokes shifts than fluorescence. Utilizing the low electronic transition energy intrinsic to thiocarbonyl compounds, electron‐withdrawing groups were attached to the 4H‐pyran‐4‐thione core to further lower the excited state energies. The resulting mini‐phosphors were doped into suitable polymer matrices. These purely organic, amorphous materials emitted near‐infrared (NIR) RTP. Having a molar mass of only 162 g·mol‐1, one of the phosphors emitted RTP that peaked at 750 nm, with a very large Stokes shift of 15485 cm‐1 (403 nm). Thanks to the good processability of the polymer film, light‐emitting diodes (LEDs) with NIR emission were easily fabricated by coating doped polymer on ultraviolet LEDs. This work provides an intriguing strategy to achieve NIR RTP using compact luminophores.

Revealing Energy Density in Porous Carbon Supercapacitors Using Hydroquinone Sulfonic Acid as Cathodic and Alizarin Red S as Anodic Redox Electrolytes.

Exploration of innovative strategies aiming to boost energy densities of supercapacitors without sacrificing the power density and long-term stability is of great importance. Herein, highly porous nitrogen-doped carbon spheres (NPCS) are decorated onto the graphite sheets (GSs) through a hydrothermal route, followed by a chemical activation. The capacitive performance of the NPCS is then enhanced by hydroquinone sulfonic acid (HSQA) incorporation in both cathodic electrolyte and electrode materials. Later, NPCS are decorated with polypyrrole (PPY), in which HSQA takes a versatile role as conjugated polymer dopant and cathodic redox additive. The capacitive performance of the negative electrodes is enhanced by incorporating of alizarin red S (ARS) as anodic redox additive. Finally, PPY(HQSA)@NPCS-GS//NPCS-GS asymmetric supercapacitor is assembled and tested in dual redox electrolyte system containing HQSA-cathodic and ARS-anodic electrolytes. This device delivers a remarkable energy density of 60.37 Wh kg-1, which is close or even better than lead acid batteries. Thus, the present work provides a novel pathway to develop high energy supercapacitors using redox active electrolytes for next-generation energy storage applications.

Tetra dansylamides substituted cyclen and cyclam macrocycles as fluorescent sensing probes for metal ions and temperature-responsive materials in dopped polymers

Two novel tetra-dansyl derivatives incorporating cyclen (1,4,7,10-tetraazacyclododecane) and cyclam (1,4,8,11-tetraazacyclotetradecane) macrocycles have been synthesized, thoroughly characterized, and their photophysical properties examined, both in solution and in the solid state. These compounds exhibit fluorescence emission with quantum yields up to 40 %, varying significantly with different solvents. They also display positive solvatofluorochromic behavior, with emissions ranging from green to yellow colours. Kamlet-Taft studies were conducted to better understand solute-solvent interactions. Furthermore, aggregation-induced emission was observed in solutions with high water content, confirmed via dynamic light scattering. Given the intrinsic properties of these compounds, their potential for environmental remediation was explored through metal ion sensing studies. Compounds L1 and L2 demonstrated high sensitivity to Cu2+ and Hg2+ ions, significantly modulating their emission, with L2 capable of detecting and quantifying Hg2+ concentrations as low as 2–3 μM. Additionally, the solid-state emission of these compounds encouraged an investigation into their potential as temperature sensors. Several doped polymer thin films were fabricated, establishing a linear relationship with temperature beyond their melting point. These findings suggest that these tetra-chromophoric compounds hold promise as molecular thermometers.

Impact of PTQ11 polymer doping on the optoelectronic and structural properties of a CH3NH3PbI3 perovskite photovoltaic cell

At present, one of the most swiftly progressing domains in solar photovoltaics is perovskite-based solar cells. Chemical modification of perovskites with foreign atoms represents a potentially fruitful approach to customizing material characteristics with the aim of enhancing the functionality and durability of solar cells. In this study, we first documented the inverted structure of PTQ11 polymer-doped perovskite solar cells composed of CH3NH3PbI3 (MAPbI3) perovskite thin film. The findings indicate that the active layer morphology is enhanced through PTQ11 doping, leading to rapid suppression of photoluminescence and delayed carrier recombination. The XRD and Raman spectral analyses revealed the crystalline, single phase, tetragonal, and highly pure MAPbI3 thin film with the preferred (220) orientation. Energy gaps ranging from 1.596 eV to 1.577 eV and absorption coefficients exceeding 105 cm−1 were characteristics of the doped thin film, which varied with the doping concentration. A transition occurred on the perovskite film’s surface to form smooth, compressed pores measuring 1.63 µm in diameter. This modification potentially enhanced the photovoltaic performance by facilitating charge transport. With an open circuit voltage of 1.11 V, a power conversion efficiency (PCE) of 18.24 %, a short-circuit current density of 22.32 mA/cm2, and a fill factor of 73.65 %, the PTQ11-9 mg/mL sample constituted the solar cell device base. Hence, the findings suggest that the doping of PTQ11 polymer represents a potentially effective approach to improve the performance of perovskite solar cells.

Nanoscale ZnO doping in prosthetic polymers mitigate wear particle-induced inflammation and osteolysis through inhibiting macrophage secretory autophagy

Wear particles produced by joint replacements induce inflammatory responses that lead to periprosthetic osteolysis and aseptic loosening. However, the precise mechanisms driving wear particle-induced osteolysis are not fully understood. Recent evidence suggests that autophagy, a cellular degradation process, plays a significant role in this pathology. This study aimed to clarify the role of autophagy in mediating inflammation and osteolysis triggered by wear particles and to evaluate the therapeutic potential of zinc oxide nanoparticles (ZnO NPs).We incorporated ZnO into the prosthetic material itself, ensuring that the wear particles inherently carried ZnO, providing a targeted and sustained intervention. Our findings reveal that polymer wear particles induce excessive autophagic activity, which is closely associated with increased inflammation and osteolysis. We identified secretory autophagy as a key mechanism for IL-1β secretion, exacerbating osteolysis. Both in vitro and in vivo experiments demonstrated that ZnO-doped particles significantly inhibit autophagic overactivation, thereby reducing inflammation and osteolysis.In summary, this study establishes secretory autophagy as a critical mechanism in wear particle-induced osteolysis and highlights the potential of ZnO-doped prosthetic polymers for targeted, sustained mitigation of periprosthetic osteolysis.

Hierarchical Dual‐Mode Efficient Tunable Afterglow via J‐Aggregates in Single‐Phosphor‐Doped Polymer

AbstractThe development of polymer‐based persistent luminescence materials with color‐tunable organic afterglow and multiple responses is highly desirable for applications in anti‐counterfeiting, flexible displays, and data‐storage. However, achieving efficient persistent luminescence from a single‐phosphor system with multiple responses remains a challenging task. Herein, by doping 9H‐pyrido[3,4‐b]indole (PI2) into an amorphous polyacrylamide matrix, a hierarchical dual‐mode emission system is developed, which exhibits color‐tunable afterglow due to excitation‐, temperature‐, and humidity‐dependence. Notably, the coexistence of the isolated state and J‐aggregate state of the guest molecule not only provides an excitation‐dependent afterglow color, but also leads to a hierarchical temperature‐dependent afterglow color resulting from different thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) behaviors of the isolated and aggregated states. The complex responsiveness based on the hierarchical dual‐mode emission can serve for security features through inkjet printing and ink‐writing. These findings may provide further insight into the regulated persistent luminescence by isolated and aggregated phosphors in doped polymer systems and expand the scope of stimuli‐responsive organic afterglow materials for broader applications.

Hierarchical Dual-Mode Efficient Tunable Afterglow via J-Aggregates in Single-Phosphor-Doped Polymer.

The development of polymer-based persistent luminescence materials with color-tunable organic afterglow and multiple responses is highly desirable for applications in anti-counterfeiting, flexible displays, and data-storage. However, achieving efficient persistent luminescence from a single-phosphor system with multiple responses remains a challenging task. Herein, by doping 9H-pyrido[3,4-b]indole (PI2) into an amorphous polyacrylamide matrix, a hierarchical dual-mode emission system is developed, which exhibits color-tunable afterglow due to excitation-, temperature-, and humidity-dependence. Notably, the coexistence of the isolated state and J-aggregate state of the guest molecule not only provides an excitation-dependent afterglow color, but also leads to a hierarchical temperature-dependent afterglow color resulting from different thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) behaviors of the isolated and aggregated states. The complex responsiveness based on the hierarchical dual-mode emission can serve for security features through inkjet printing and ink-writing. These findings may provide further insight into the regulated persistent luminescence by isolated and aggregated phosphors in doped polymer systems and expand the scope of stimuli-responsive organic afterglow materials for broader applications.

ESR, UV–vis–NIR and FTIR spectroscopic characterization of charge carriers in copper salen polymeric complexes

In this work, we present spectroscopic investigation of charge carriers in copper(II) salen-type polymeric complexes. The polymers comprising monomeric complexes of copper(II) ion with N2O2 Schiff base ligands are analyzed to understand the influence of the paramagnetic metal center and electron-donating substituents in the ligand on the spectroscopic properties of oxidized polymers. Potential-driven structural changes in the polymeric complexes were monitored using electron spin resonance (ESR), ultraviolet−visible − near infrared (UV−vis − NIR) and Fourier Transform Infrared (FTIR) spectroelectrochemistry. By EPR spectroelectrochemistry, we gained insight into the magnetic properties of charge carriers formed during the initial and deep oxidation of the polymers as well as the interactions between the Cu(II)–ligand spins and ligand–ligand ones. By FTIR spectroelectrochemistry, it has been shown that the charge in the low doped polymers is delocalized within the whole repeat unit.