We report the covalent immobilization of a state-of-the-art p-type dopant, azido-functional radialene-based CN5HexN3-CP (6-azidohexyl-2-(2,3-bis(dicyanomethylene)-cyclopropylidene)-2-cyanoacetate) onto alkyne-functionalized carbazole polymers, representing, to our knowledge, the first demonstration of covalent binding of a high-oxidizing p-dopant. The dopant salts (CN5HexN3-CP-2Na and CN5HexN3-CP-2TBA) were attached via thermal Huisgen cycloaddition and copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, allowing precise control over the dopant fraction, which was confirmed by NMR spectroscopy. Due to the extreme reactivity of the neutral dopant, direct immobilization in its active state is not feasible, therefore the dopant was introduced on the polymer backbone in its reduced, inert form. Cyclic voltammetry demonstrated that the immobilized dopant retains its intrinsic redox properties, while polymer backbone doping is prevented by the energy level mismatch. External oxidation experiments confirm the feasibility of ion exchange and formation of partial charge-transfer interactions, providing a proof-of-concept for covalent dopant immobilization. Conceptually, this work addresses a fundamental challenge in organic electronics: the creation of stable multilayer doping profiles as a prerequisite for organic p/n junctions. By immobilizing both dopant and polymer matrix, counterion migration is suppressed, providing a chemically defined framework for localized charge stabilization.

We report an externally initiated, Pd-catalyzed chain-growth polycondensation using Buchwald-type precatalysts for the synthesis of acetylene-end-functionalized poly(bithiophene-naphthalene diimide), P(TNDIT), conjugated polymers. Screening of six commercial precatalysts identified (t-BuXPhos)Pd (precatalyst 1), having in the structure phosphine ligands bearing two tert-butyl and one biphenyl ligand, as enabling efficient polymerization under mild conditions with moderate molecular weight control. The method supports the transfer of synthetically versatile, complex end-groups directly in the initiating step, an approach rarely achieved in catalyst-transfer polycondensation and unprecedented for donor-acceptor monomers such as TNDIT. NMR and MALDI-TOF end-group analysis, aided by fractionation, confirm that functionalization occurs during initiation and supports a chain-growth mechanism facilitated by Pd ring-walking. By varying initiator loading and timing, either mono- or bis-functionalized polymers can be selectively accessed. This strategy enables the high-yield synthesis of functionalized n-type conjugated polymers with tailored end-groups, offering new opportunities for postpolymer modification, block copolymer construction, cross-linking, and supramolecular assembly.

In this study, a diketopyrrolopyrrole (DPP)-based small molecule, 3,6-bis-(5'-(2-octyldodecyl)-[2,2'-bithiophen]-5-yl)-2,5-dipropyl-2,5-dihydropyrrolo-[3,4-c]-pyrrole-1,4-dione (DBT-I), was synthesized via Stille coupling. The thin-film morphology, crystallinity, and organic field-effect transistor (OFET) performance of DBT-I were systematically investigated under various solution-processing techniques and solvent environments. Particular emphasis was placed on understanding the influence of processing conditions on film microstructure and their correlation with device performance. It was found that the appropriate combination of solvent, deposition method, and thermal treatment significantly enhances the crystallinity of the DBT-I thin films. Since the electrical properties are influenced by the chemical structure and morphology of the semiconductor, the obtained low-bandgap material was integrated into OFETs fabricated by solution-processing methodologies, such as spin coating and solution-shearing. The optimal performance in OFETs was achieved with the shear-coated DBT-I films, showcasing a mobility of 0.26 cm2 V-1 s-1 and a current on-off ratio of 106. The OFET performance correlated with morphology features such as crystallinity and grain size opens the possibility for a rational optimization of OFET characteristics.

Enhancing both ionic conductivity and mechanical robustness remains a major challenge in designing solid-state electrolytes for lithium batteries. This work presents a novel approach in designing mechanically robust and highly conductive solid-state electrolytes, which involves ionic liquid-based cross-linked polymer networks incorporating polymeric ionic liquids (PILs). First, linear PILs with different side groups were synthesized for optimizing the structure. Molecular weights of the PIL samples, ranging from 30 to 40 kDa, were determined using a complimentary combination of thermal field-flow fractionation (ThFFF) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The aimed for networks were synthesized through the photo-initiated polymerization of a network-forming monomer and a cross-linker, in the presence of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and a PIL bearing quaternized imidazolium groups. The resulting cross-linked membranes – semi-interpenetrating networks – exhibit substantial mechanical strength, with a Young’s modulus of 40–50 MPa, surpassing the threshold for solid-state battery separators, while maintaining high ionic conductivity in the range of 4 × 10−4 S·cm−1 at 60°C. Notably, the introduction of oligo(ethylene glycol) moieties into the PIL structure significantly enhances ionic conductivity and allows for incorporation of a larger amount of the lithium salt compared to the alkyl-substituted analogs. Moreover, although cross-linking often impairs ionic transport as a result of restricted segmental mobility of the polymer chains, incorporation into the network of highly conductive linear PILs circumvents this issue. This unique combination of properties positions the developed membranes as promising candidates for application in solid-state lithium batteries, effectively addressing the traditional trade-off in electrolyte design.

This paper reports methacrylate resins incorporating biobased building blocks, synthesized using commercially available galactarate (GalX) and xylofuranose (IPrXF), modified with methacrylate groups through efficient transesterification. The study revealed that these biobased resins, GalX Me DMA and IPrXF DMA, cure at significantly lower temperatures (100-110 degrees C) compared to the commercial UMA 121 derived from urethane methacrylate containing methylene bisphenyl isocyanate building blocks. Thermal analysis showed that these cured resins exhibit exceptional thermostability, with an initial decomposition temperature exceeding 230 degrees C and a 50% weight loss temperature above 380 degrees C, outperforming UMA 121 thermosets. Mechanical testing using quantitative nanomechanical mapping with atomic force microscopy revealed elastic modulus values ranging from 2.9 to 3.8 GPa, which significantly outperforms previously published biobased thermosets and was closely comparable to UMA 121, which demonstrated an elastic modulus of 4.7 GPa. Pressure testing further corroborated these findings, confirming the robust mechanical performance of the biobased resins. The biobased resins exhibited remarkable enzymatic stability against degradation by polyester hydrolase PHL7 and demonstrated excellent resistance to chemical exposure. Notably, the sugar-based resins developed in this work contain a relatively high weight percentage of biobased components, reaching up to 70%. The biobased thermosets are transparent, colorless, and exhibit excellent film-forming properties. Overall, these resins offer promising performance for sustainable, durable coatings, combining high thermal stability, mechanical strength, and favorable environmental properties.

State-of-the-art Li batteries suffer from serious safety hazards caused by the reactivity of lithium and the flammable nature of liquid electrolytes. This work develops highly efficient solid-state electrolytes consisting of imidazolium-containing polyionic liquids (PILs) and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). By employing PIL/LiTFSI electrolyte membranes blended with poly(propylene carbonate) (PPC), we addressed the problem of combining ionic conductivity and mechanical properties in one material. It was found that PPC acts as a mechanically reinforcing component that does not reduce but even enhances the ionic conductivity. While pure PILs are liquids, the tricomponent PPC/PIL/LiTFSI blends are rubber-like materials with a Young’s modulus in the range of 100 MPa. The high mechanical strength of the material enables fabrication of mechanically robust free-standing membranes. The tricomponent PPC/PIL/LiTFSI membranes have an ionic conductivity of 10−6 S·cm−1 at room temperature, exhibiting conductivity that is two orders of magnitude greater than bicomponent PPC/LiTFSI membranes. At 60 °C, the conductivity of PPC/PIL/LiTFSI membranes increases to 10−5 S·cm−1 and further increases to 10−3 S·cm−1 in the presence of plasticizers. Cyclic voltammetry measurements reveal good electrochemical stability of the tricomponent PIL/PPC/LiTFSI membrane that potentially ranges from 0 to 4.5 V vs. Li/Li+. The mechanically reinforced membranes developed in this work are promising electrolytes for potential applications in solid-state batteries.

Semiconducting polymers enable the fabrication of low-cost, large-area electronic devices by using low-temperature solution-processing methodologies on flexible substrates. This work presents three novel host materials for the emitting layer (EML) of organic light-emitting diodes (OLEDs). Efficient hosts should possess a number of properties, such as high triplet energy, good and balanced charge-carrier transport, suitable frontier orbital levels that match those of the neighboring layers, and morphological stability. To this end, carbazole-based polymers featuring the electron-withdrawing group (EWG) phenylphosphine oxide at different positions of the chain were designed and synthesized by Suzuki coupling. Chemical and optical characterizations of the polymers were performed prior to the charge -transport property analysis through the fabrication of single-carrier devices. Finally, these materials were incorporated into a green OLED architecture as solution processed EML where tris(2-phenylpyridine)iridium(III) (Ir(ppy)(3)) acts as phosphorescent emitter dopant.

Based on a recently developed selective etching process for silicon samples with buried implants, this work presents a method for utilizing the generated material contrast between silicon and silicon oxide to selectively deposit polymers on the patterned surface. Besides depositing polystyrene selectively on the etched parts via drop-casting and dewetting, polymer chains are selectively grafted to the oxidic surface parts. To this end, the oxide surfaces are selectively modified via functional alkoxysilanes, whereas etched silicon surfaces are unreactive. Using either a two-step or a straight-forward one-step process employing commercially available chemicals, atom transfer radical polymerization (ATRP) initiator functions are attached selectively to the non-etched surface areas, and subsequently used to polymerize either methyl methacrylate (MMA) or N-isopropyl acrylamide (NIPAM) in a controlled surface-initiated activator regenerated by electron transfer (ARGET)-ATRP process. This procedure allows for the further self-aligned functionalization of the micropatterned samples, enabling the production of highly functional, patterned surfaces, potentially suitable for applications in areas such as cell adsorption, microfluidics, or functional microsystems, e.g., MEMS.

Abstract The understanding and applications of electron‐conducting π‐conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n‐doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n‐doped backbone. Here, the n‐type conducting NDI polymer with enhanced stability of its n‐doped states for prospective “in‐water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping‐induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n‐doped states in water and the high electron conductivity of polymers.

A pair of hole‐conducting polymers comprising 3,6‐linked carbazole and meta‐linked anisole derivatives having solubilizing moieties to enable their solution processability, and complementarily reactive side‐groups (azide and alkyne) for cross‐linking, are synthesized and characterized. The polymers can be cross‐linked either by thermal annealing at relatively low temperatures in the 85–110 °C range, or by UV irradiation. A general applicability of the latter for a photolithographic patterning of the hole conducting polymer is proven. The polymers have an ionization potential (IP) of 5.8 eV, close to the IP of a small molecule hole‐conductor tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA). In combination with a strong dopant hexacyano‐trimethylene‐cyclopropane (CN6CP), but not with commercial 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ), the polymers can be efficiently p‐doped to increase their conductivity by 5–6 orders of magnitude, as measured in devices with a lateral setup. Taken together, these characteristics suggest that the synthesized polymers are promising candidates for their use in solution‐processable organic light‐emitting diodes as hole‐injection layer and hole‐transporting layer materials, which will be verified in the upcoming work.

We investigate a blend of a low optical-gap diketopyrrolopyrrole polymer and a fullerene derivative, with near-zero driving force of 50 meV for interfacial electron transfer. Using femtosecond transient absorption and electro-absorption spectroscopy, we quantify the charge transfer (CT) and recombination dynamics as well as the transport at early timescales. Electron transfer is found to be ultrafast, which is consistent with a semiclassical Marcus-Levich-Jortner description at low driving force and low reorganization energy. However, we observe significant geminate recombination and unusually short S1 and CT state lifetimes in the investigated system (13-14 ps). At low S1-CT offset, a short excited state lifetime mediates charge recombination because i) back-transfer from the CT to the S1 state followed by S1 recombination can occur and ii) additional S1-CT hybridization can decrease the CT lifetime. Both effects are confirmed by density functional theory calculations. In addition, we observe relatively slow (tens of picoseconds) dissociation of charges from the interfacial CT state, in contrast to polymer:fullerene blends with high CT driving force. We identify low local charge carrier mobility as a primary reason for the slow rise of free charge population. Simulations using a four-state kinetic model entailing the effects of energetic disorder reveal that the free charge yield could be increased from the observed 12% to 60% by increasing the S1 and CT lifetimes to 150 ps. Alternatively, decreasing interfacial CT state disorder while increasing bulk disorder of free charges enhances the yield to 65% in spite of the short lifetimes.

Imprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top-down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL-produced polydimethylsiloxane stamp. Atomically smooth facet, single-crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO2) slab waveguide, producing waveguide-plasmon polariton modes with superior 10 nm spectral line-width. Plasmon-induced hot electrons are confirmed via two-terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO2 heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large-scale implementation in optoelectronic devices.

We investigate a blend of a low optical-gap diketopyrrolopyrrole polymer and a fullerene derivative, with near-zero driving force of 50 meV for interfacial electron transfer. Using femtosecond transient absorption and electro-absorption spectroscopy, we quantify the charge transfer (CT) and recombination dynamics as well as the transport at early timescales. Electron transfer is found to be ultrafast, which is consistent with a semiclassical Marcus-Levich-Jortner description at low driving force and low reorganization energy. However, we observe significant geminate recombination and unusually short S1 and CT state lifetimes in the investigated system (13-14 ps). At low S1-CT offset, a short excited state lifetime mediates charge recombination because i) back-transfer from the CT to the S1 state followed by S1 recombination can occur and ii) additional S1-CT hybridization can decrease the CT lifetime. Both effects are confirmed by density functional theory calculations. In addition, we observe relatively slow (tens of picoseconds) dissociation of charges from the interfacial CT state, in contrast to polymer:fullerene blends with high CT driving force. We identify low local charge carrier mobility as a primary reason for the slow rise of free charge population. Simulations using a four-state kinetic model entailing the effects of energetic disorder reveal that the free charge yield could be increased from the observed 12% to 60% by increasing the S1 and CT lifetimes to 150 ps. Alternatively, decreasing interfacial CT state disorder while increasing bulk disorder of free charges enhances the yield to 65% in spite of the short lifetimes.

A typical microstructuring process utilizes photolithographic masks to create arbitrary patterns on silicon substrates in a top‐down approach. Herein, a new, bottom‐up microstructuring method is reported, which enables the patterning of n‐doped silicon substrates to be performed without the need for application of etch‐masks or stencils during the etching process. Instead, the structuring process developed herein involves a simple alkaline etching performed under illumination and is remotely controlled by the p‐doped micro‐sized implants, buried beneath a homogeneous n‐doped layer at depths of 0.25 to 1 µm. The microstructuring is realized because the buried implants act upon illumination as micro‐sized photovoltaic cells, which generate a flux of electrons and increase the negative surface charge in areas above the implants. The locally increased surface charge causes a local protection of the native silicon oxide layer from alkaline etching, which ultimately leads to the microstructuring of the substrate. In this way, substrates having at their top a thick layer of homogeneously n‐doped silicon can be structured, reducing the need for costly, time‐consuming photolithography steps.

A blend of a low‐optical‐gap diketopyrrolopyrrole polymer and a fullerene derivative, with near‐zero driving force for electron transfer, is investigated. Using femtosecond transient absorption and electroabsorption spectroscopy, the charge transfer (CT) and recombination dynamics as well as the early‐time transport are quantified. Electron transfer is ultrafast, consistent with a Marcus–Levich–Jortner description. However, significant charge recombination and unusually short excited (S1) and CT state lifetimes (≈14 ps) are observed. At low S1–CT offset, a short S1 lifetime mediates charge recombination because: i) back‐transfer from the CT to the S1 state followed by S1 recombination occurs and ii) additional S1–CT hybridization decreases the CT lifetime. Both effects are confirmed by density functional theory calculations. In addition, relatively slow (tens of picoseconds) dissociation of charges from the CT state is observed, due to low local charge mobility. Simulations using a four‐state kinetic model entailing the effects of energetic disorder reveal that the free charge yield can be increased from the observed 12% to 60% by increasing the S1 and CT lifetimes to 150 ps. Alternatively, decreasing the interfacial CT state disorder while increasing bulk disorder of free charges enhances the yield to 65% in spite of the short lifetimes.

Polymer semiconductors (PSCs) are an essential component of organic field‐effect transistors (OFETs), but their potential for stretchable electronics is limited by their brittleness and failure susceptibility upon strain. Herein, a covalent connection of two state‐of‐the‐art polymers—semiconducting poly‐diketo‐pyrrolopyrrole‐thienothiophene (PDPP‐TT) and elastomeric poly(dimethylsiloxane) (PDMS)—in a single triblock copolymer (TBC) chain is reported, which enables high charge carrier mobility and low modulus in one system. Three TBCs containing up to 65 wt% PDMS were obtained, and the TBC with 65 wt% PDMS content exhibits mobilities up to 0.1 cm 2 V −1 s −1 , in the range of the fully conjugated reference polymer PDPP‐TT (0.7 cm 2 V −1 s −1 ). The TBC is ultrasoft with a low elastic modulus (5 MPa) in the range of mammalian tissue. The TBC exhibits an excellent stretchability and extraordinary durability, fully maintaining the initial electric conductivity in a doped state after 1500 cycles to 50% strain.

A novel mechanism for well-pronounced mechanochromism in blends of a pi-conjugated polymer based on reversible conformational transitions of a chromophore rather than caused by its aggregation state, is exemplified. Particularly, a strong stretching-induced bathochromic shift of the light absorption, or hypsochromic shift of the emission, is found in blends of the water-soluble poly(3-tri(ethylene glycol)) (P3TEOT) embedded into the matrix of thermoplastic polyvinyl alcohol. This counterintuitive phenomenon is explained in terms of the concentration dependency of the P3TEOT's aggregation state, which in turn results in different molecular conformations and optical properties. A molecular flexibility, provided by low glass transition temperature of P3TEOT, and the fact that P3TEOT adopts an intermediate, moderately planar conformation in the solid state, are responsible for the unusual complex mechanochromic behavior.

This paper reports a comprehensive investigation of 2D and quasi-2D perovskites that are based on rather long-chain octylammonium iodide (OA) and have the a general formula (OA)2(MA)n, PbnI3n+1. Surprisingly, we noticed for 2D and quasi-2D perovskites the presence of significant amounts of the lead state having unusually low binding energy for Pb2+ which resembles unsaturated-valence Pb0 species. The low binding energy of Pb reflects the more electron-rich (compared to 3D counterparts) environment around the Pb centers of the 2D perovskites, which is their inherent property and a consequence of a distinctly different chemical compositions of 2D compared to 3D perovskites. It was found that 2D perovskite-based photodetectors having a lateral arrangement of electrodes show a superior photocurrent yield, compared to quasi-2D (n = 2,3) and 3D (n = infinity) perovskites. Furthermore, 2D and 3D perovskite films exhibit comparable conductivity in the vertical direction, despite of a high content of the insulating component in the OA-based 2D perovskites. The high conductivity was attributed to excellent film-forming properties, high environmental stability as well as favored charge transport morphology of 2D perovskite films. We also propose that inclusions of PbI2 in the organic interlayers may explain the improved charge transportation in these materials. Cross-sectional analysis of the perovskite films and spatially-resolved conductive mode atomic force microscopy measurements support this assumption.

Derivatives of the hexacyano‐[3]‐radialene anion radical (CN6‐CP •− ) emerge as a promising new family of p‐dopants having a doping strength comparable to that of archetypical dopant 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyano‐quinodimethane (F4TCNQ). Here, mixed solution (MxS) and sequential processing (SqP) doping methods are compared by using a model semiconductor poly(3‐hexylthiophene) (P3HT) and the dopant CN6‐CP •− NBu 4 + (NBu 4 + = tetrabutylammonium). MxS films show a moderate yet thickness‐independent conductivity of ≈0.1 S cm −1 . For the SqP case, the highest conductivity value of ≈6 S cm −1 is achieved for the thinnest (1.5–3 nm) films whereas conductivity drops two orders of magnitudes for 100 times thicker films. These results are explained in terms of an interfacial doping mechanism realized in the SqP films, where only layers close to the P3HT/dopant interface are doped efficiently, whereas internal P3HT layers remain essentially undoped. This structure is in agreement with transmission electron microscopy, atomic force microscopy, and Kelvin probe force microscopy results. The temperature‐dependent conductivity measurements reveal a lower activation energy for charge carriers in SqP samples than in MxS films (79 meV vs 110 meV), which could be a reason for their superior conductivity.

Here we report on reorganization on heating of a perspective organic semiconductor poly(3-(2′-ethyl)hexylthiophene) (P3EHT). P3EHT is an analogue of a well-known poly(3-hexylthiophene) (P3HT), which has comparable optoelectronic properties and the advantage of a lower processing temperature. The processes of structural reorganization during heating of P3EHT have been explored with a combination of synchrotron X-ray scattering and ultrafast chip calorimetry. The signature of reorganization has been identified from an increase of d-spacing of 100 peak of the P3EHT unit cell. It was observed that reorganization operates during heating of P3EHT at conventional rates of a DSC experiment (i.e., at 10 deg/min), whereas it is largely suppressed at a heating rate of 100 deg/s. Despite the absence of reorganization at high heating rates the calorimetric curves exhibit pronounced double melting, which corroborates the model of the negative pressure building up during crystallization of semi-rigid chain polymers.