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Biological processes in the human body are regulated through complex and precise arrangements of cell structures and their interactions. In vivo models serve as the most accurate choice for biological studies to understand these processes. However, they are costly, time-consuming, and raise ethical issues. Microphysiological systems have been developed to create advanced in vitro models that mimic in vivo-like microenvironments. They are often combined with integrated sensing technologies to perform real-time measurements to gain additional information. However, conventional sensing electrodes, made of inorganic materials such as gold or platinum, differ fundamentally from biological materials. Organic bioelectronic devices made from conjugated polymers are promising alternatives for biological sensing applications and aim to improve the interconnection between abiotic electronics and biotic materials. The widespread use of these devices is partly hindered by the limited availability of materials and low-cost fabrication methods. In this thesis, we provide new tools and materials that facilitate the use of organic bioelectronic devices for in vitro sensing applications. We developed a method to pattern the conducting polymer poly(3,4‑ethylenedioxythiophene) polystyrene sulfonate and to fabricate organic microelectronic devices using wax printing, filtering, and tape transfer. The method is low-cost, time-effective, and compatible with in vitro cell culture models. To achieve higher resolution, we further developed a patterning method using femtosecond laser ablation to fabricate organic electronic devices such as complementary inverters or biosensors. The method is maskless and independent of the type of conjugated polymer. Besides fabrication processes, we introduced a newly synthesized material, the semiconducting conjugated polymer p(g42T‑T)‑8%OH. This polymer contains hydroxylated side chains that enable surface modifications, allowing control of cell adhesion., Biologiska processer i människokroppen regleras genom komplexa och exakta arrangemang av cellstrukturer och deras interaktioner. In vivo modeller är det mest exakta valet för biologiska studier för att förstå dessa processer. Men de är dyra, tidskrävande och behäftade med etiska dilemman. Mikrofysiologiska system har utvecklats för att skapa avancerade in vitro-modeller för att efterlikna mikromiljöer som finns in vivo. Dessa system kombineras ofta med integrerade sensortekniker för att utföra mätningar i realtid för att få ytterligare information. Konventionella elektroder, gjorda av oorganiska material som guld eller platina, skiljer sig dock fundamentalt från biologiska material. Organiska bioelektroniska komponenter tillverkade av konjugerade polymerer är intressanta alternativ för biologiska sensortillämpningar eftersom de har potential att förbättra sammankopplingen mellan abiotisk elektronik och biotiska material. Deras användning hindras delvis av den begränsade tillgången på material och billiga tillverkningsmetoder. I den här avhandlingen tillhandahåller vi nya verktyg och material som underlättar användningen av organiska bioelektroniska komponenter för in vitro avkänningstillämpningar. Vi utvecklade en metod för att mönstra den ledande polymeren poly(3,4-etylendioxitiofen) polystyrensulfonat och tillverka organiska mikroelektroniska komponenter med hjälp av vaxtryck, filtrering och tejpöverföring. Metoden har låg kostnad, är tidseffektiv och kompatibel med in vitro cellodlingsmodeller. För att uppnå högre upplösning vidareutvecklade vi en mönstringsmetod med femtosekundlaserablation för att tillverka organiska elektroniska enheter såsom komplementära växelriktare eller biosensorer. Metoden involverar inga masker och är inte beroende av typen av konjugerad polymer. Förutom tillverkningsprocesser introducerade vi ett nytt material, den konjugerade polymeren p(g42T‑T)‑8%OH. Denna polymer innehåller hydroxylerade sidokedjor som möjliggör ytmodifieringar, vil, QC 2024-02-06

It is crucial to develop functional electronic materials that can be processed from green solvents to achieve environmentally sustainable and cost-efficient printing fabrication of organic electronic devices. Here, the design and cost-efficient synthesis of two hydrophilic and emissive conjugated polymers, TQ-OEG and TQ2F-OEG, are presented, which are rendered hydrophilic through the grafting of oligo(ethylene glycol) (OEG) solubilizing groups onto the thiophene-quinoxaline conjugated backbone and thereby can be processed from a water:ethanol solvent mixture. It is shown that the introduction of the OEG groups enables for a direct dissolution of salts by the neat polymer for the attainment of solid-state ion mobility. These properties are utilized for the design and development of light-emitting electrochemical cells (LECs), the active materials of which can be solution cast from a water:ethanol-based ink. It is specifically shown that such an LEC device, comprising an optimized blend of the TQ2F-OEG emitter and a Li salt as the active material positioned between two air-stabile electrodes, delivers deep-red emission (peak wavelength = 670 nm) with a radiance of 185 µW m−2 at a low drive voltage of 2.3 V. This study contributes relevant information as to how polymers and LEC devices can be designed and fabricated to combine functionality with sustainability.

Conjugated polymers (CPs) with donor and acceptor units exhibit a flexible conformation due to the rotation of the single bond of the bridge groups which greatly hinders a precise study of their photodetection properties. Moreover, the modulation mechanism related to complex factors of CPs molecular conformation on photodetection performance is not clear, causing CP-based organic photodiodes (OPDs) to generally suffer from high dark current and low specific detectivity. In this work, we synthesized two novel PBQx-i-4F and PBQx-o-4F CPs by combining fluorinated BDT with DTQx units using i- and o-alkylated side chain-based thiophene linkages, respectively. Quantum simulation and photo-physics study revealed that PBQx-i-4F displayed a dominant trans conformation, a more planar molecule structure, and high utilization efficiency of photoinduced excitons. The OPDs based on PBQx-i-4F exhibited higher on–off ratios by over two orders of magnitude and higher detectivity (Dsh*) by nearly one order of magnitude compared with those based on PBQx-o-4F. PBQx-i-4F with the i-alkyl substitution on the thiophene linkage displayed enhanced planarity, resulting in more ordered packing and larger population of face-on orientation in film, where decreased trap density and trap-assisted recombination led to reduced dark current and improved charge transport. In summary, our work provides an insight into the relationship between the fine-tuning of the molecular conformation, planarity, and packing of CPs and their photodetection properties in OPDs. © 2024 Elsevier B.V.

Ionically and electronically conducting polymers are celebrated for their distinct electronic characteristics, flexibility, and processability, making them vital in diverse fields such as ion exchange membranes, energy devices, and biomedical technologies. This dissertation delves into polymeric charge conduction materials, distinguishing them based on the type of charge carriers involved: ions, electronic charge carriers (polarons), or a combination of both. The study differentiates between electronic doping, which introduces polaronic and ionic charges, and purely ionic doping, achieved by adding small-molecule salts to introduce ionic charges. The first section of the study explores the structure-property relationships, illustrating how disordered polymer domains are linked to ionic charge carrier conduction and ordered domains to electronic conductivity. This section emphasizes the significance of the coexistence of these different phases within a single material, which facilitates mixed conduction.A focal point of the research is the investigation of doping processes in polymers. The dissertation's second chapter examines the nuances of electronic doping, particularly the mechanisms of Brønsted acid-induced oxidation in conjugated polymer thin films. This investigation reveals that such doping leads to self-limiting diffusion, resulting in stable dopant concentration gradients, optimal for creating heterojunctions. Subsequently, the dissertation pivots to polyelectrolyte design, examining the interactions between ionic charge carriers (Li+) and photoresponsive azo moieties attached to a polymer backbone. A notable discovery here is that semicrystalline polymers can achieve up to sevenfold higher conductivity than their amorphous counterparts due to Li+ complexation, challenging the conventional wisdom that favors disorder for enhanced ionic conductivity. The final major contribution of this work is the development of resonant scattering techniques for simultane

Polymers (Greek: poly=many, meros=part) are large molecules made up of many small parts (monomers) in a repetitive way, as a term was introduced for the first time (1833) by the Swedish chemist, Jöns Jakob Berzelius. By the combination of different monomers, the resulting polymer can exhibit various properties, such as biodegradability, photosensitivity and electrical conductivity. The latter is the main characteristic of the polymers included in this thesis. Since their commercialization, in the late 20th century soft and biocompatible conductive polymers have been substituting stiff and bio-tolerable metals in numerous cases, especially in the medical field for in vivo applications. Polymers can also be found in nature, as a product of the life cycles of animals, plants and microorganisms. The variety of natural polymers is vast, and they are categorized mainly into the groups of polysaccharides, polypeptides and polynucleotides. In these categories belong some of the most well known and investigated materials, for instance, DNA, proteins, silk and cellulose. The combination of synthetic materials with natural materials has intrigued the scientific community for many decades, as a way to form functional materials with hybrid properties. In this thesis, synthetic polymers, particularly conjugated polymers were combined with cellulose, the most abundant biopolymer on earth to form 2D and 3D conducting composites that can find application in plant science and stimuli-responsive systems. In the first part of this thesis, the widely used conjugated polymer PEDOT:PSS was combined with cellulose nanofibers to form 3D porous conducting scaffolds. The scaffolds were developed by freeze-drying method and their electrochemical, mechanical and structural properties were characterized. We investigated the effect of the freezing method on the scaffold properties and found a correlation between the mechanical properties and the pore wall thickness. Furthermore, with micro-CT

Indacenodithiophene (IDT) copolymers are a class of conjugated polymers that have limited long-range order and high hole mobilities, which makes them promising candidates for use in deformable electronic devices. Key to their high hole mobilities is the coplanar monomer repeat units within the backbone. Poly(indacenodithiophene-benzothiadiazole) (PIDTC16-BT) and poly(indacenodithiophene-thiapyrollodione) (PIDTC16-TPDC1) are two IDT copolymers with planar backbones, but they are brittle at low molecular weight and have unsuitably high elastic moduli. Substitution of the hexadecane (C16) side chains of the IDT monomer with isocane (C20) side chains was performed to generate a new BT-containing IDT copolymer: PIDTC20-BT. Substitution of the methyl (C1) side chain on the TPD monomer for an octyl (C8) and 6-ethylundecane (C13B) afford two new TPD-containing IDT copolymers named PIDTC16-TPDC8 and PIDTC16-TPDC13B, respectively. Both PIDTC16-TPDC8 and PIDTC16-TPDC13B are relatively well deformable, have a low yield strain, and display significantly reduced elastic moduli. These mechanical properties manifest themselves because the lengthened side chains extending from the TPD-monomer inhibit precise intermolecular ordering. In PIDTC16-BT, PIDTC20-BT and PIDTC16-TPDC1 side chain ordering can occur because the side chains are only present on the IDT subunit, but this results in brittle thin films. In contrast, PIDTC16-TPDC8 and PIDTC16-TPDC13B have disordered side chains, which seems to lead to low hole mobilities. These results suggest that disrupting the interdigitation in IDT copolymers through comonomer side chain extension leads to more ductile thin films with lower elastic moduli, but decreased hole mobility because of altered local order in the respective thin films. Our work, thus, highlights the trade-off between molecular packing structure for deformable electronic materials and provides guidance for designing new conjugated polymers for stretchable electronics., source:https://pubs.acs.org/doi/10.1021/acspolymersau.2c00034

Owing to their versatile (opto)electronic properties, conjugated polymers have found application in several organic electronic devices. Cross-coupling reactions such as Stille, Suzuki, Kumada couplings, and direct arylation reactions have proved to be effective for their synthesis. More atom-efficient oxidative direct arylation polymerization has also been reported for making homopolymers. However, growing interest toward donor-acceptor polymers has led to the recent emergence of cross-dehydrogenative coupling (CDC) polymerization to synthesize alternating copolymers without any prefunctionalization of monomers. Metal-catalyzed cross-coupling of two simple arenes via double C−H activation, or of an arene with an alkene via oxidative Heck-type reaction have been used so far for CDC polymerization. In this article, we discuss the development of CDC polymerization protocols along with the relevant small molecule CDC reactions for an improved understanding of these reactions., source:https://onlinelibrary.wiley.com/doi/10.1002/anie.202301247

The acceptor crystallinity has long been associated with favourable Organic Solar Cell (OSC) properties such as high mobility and fill factor. In particular, this applies to acceptor materials such as fullerene derivatives and the most recent Non-Fullerene Acceptors (NFAs), which are now surpassing a Power Conversion Efficiency (PCE) of 19%. Although these advantages are commonly attributed to their 3-dimensional crystal packing motif in the single crystal, the bridge that links the acceptor crystal packing from single crystals to solar cells has not clearly been shown yet. In this work, we investigate the molecular organisation of seven NFAs (o-IDTBR, IDIC, ITIC, m-ITIC, 4TIC, 4TICO, and m-4TICO), following the evolution of their packing motif in single-crystals, powder, and thin films made with pure NFAs and donor:NFA blends. We observed a good correlation between the NFA single crystal packing motif and their molecular arrangement in the bulk heterojunction. The NFA packing motif affects the material's propensity to form a highly crystalline domain in the blend. We specifically found that 3D reticular packing motifs show stronger ordering than 0D herringbone ones. However, the NFA packing motif is not directly correlating with device performance parameters. Although higher NFA crystallinity yields higher mobility, we found the domain purity to be more important for obtaining high efficiency organic solar cells by governing bimolecular recombination.

Previous studies have reported contradictory effects of small-molecule acceptors on the environmental stability of polymer:small-molecule blends, with one showing that a small-molecule acceptor stabilizes and another showing that it destabilizes the polymer donor. In this work, to investigate the origin of these contradictory results, the effects of the nanomorphologies of small-molecule acceptors on the environmental stability of polymer:small-molecule blends are demonstrated. Investigations on the environmental stabilities of polymer:fullerene blends of poly[[4, 8-bis[(2-ethylhexyl)oxy]benzo[1, 2-b:4, 5-b′]dithiophene-2, 6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3, 4-b]thiophenediyl]] (PTB7):phenyl-C₆₁-butyric acid methyl ester (PCBM) with contrasting nanomorphologies of PCBM reveal that dispersed PCBM in a mixed phase is the critical factor that causes triplet-mediated singlet oxygen generation and, hence, the severe photooxidation of PTB7, whereas an aggregated PCBM phase stabilizes PTB7 by reducing the formation of PTB7 triplet excitons. In addition, the photooxidation of PTB7 substantially degrades hole transport in the PTB7:PCBM blends by destroying the crystalline PTB7 phases within the films; this effect is strongly correlated with the efficiency losses of the PTB7:PCBM organic solar cells. These conclusions are also extended to polymer:nonfullerene blends of PTB7:ITIC and PTB7:Y6, thereby confirming the generality of this phenomenon for polymer:small-molecule organic solar cells.

Thin films of polymers are required for a myriad of technological applications, ranging from simple protective coatings to advanced multilayer laminates for flexible electronic devices. A class of polymers called conjugated polymers is of particular interest due to their ability to transport electronic charge while retaining mechanical deformability. These mechanical and electronic properties are easily tunable via synthetic modification of the polymer structure, resulting in a rich diversity of materials available for study. As such, conjugated polymers have been widely incorporated in next-generation thin-film photovoltaic technologies, as a layer added to improve charge transport, light absorption, or both. Nevertheless, the vast majority of studies of these materials utilize solution processing techniques (e.g. spin-coating, blade-coating, etc.) that inherently require planar substrates. This dissertation will discuss several polymer thin film processing techniques that yield large-area free-standing polymer films, which can then be coated onto a variety of flexible, textured, and non-planar surfaces. The development and characterization of a continuous, roll-to-roll deposition process is used to generate large-area organic solar cells, as well as to coat conjugated polymer films uniformly onto a textile substrate for flexible fabric-mounted PV. In addition, a batch process deposition technique will be shown for application of polymer films onto the surface of micro-pyramids, a key requirement for tandem perovskite silicon solar cells. Lastly, solar cell encapsulation techniques for extending the lifetime of perovskite solar cells will be discussed. Ultimately, such developments will help to advance the processability and performance of next-generation photovoltaic technologies.

Hydrogen production through photocatalytic water splitting under visible-light irradiation is an appealing approach to generate clean and economical renewable energy resources. The key challenge in this field of research is to design and engineer cost-effective, green, and efficient photocatalysts. Recently, carbon-based photocatalysts have attracted huge interest for visible-light-driven hydrogen evolution reactions due to their high chemical stability, excellent electrical conductivity, and tunable surface characteristics. Here, a critical review on how various carbon-based materials such as carbon nitride, conjugated polymers, metal-organic frameworks, functionalized carbon quantum dots, and graphene derivatives emerged as next-generation photocatalysts for hydrogen production in the last five years is provided. We also highlight how the size-modulation and functionalization of nano-carbon-based materials with active species can lead to improved photocatalytic performance. Furthermore, the potential of carbon dots and graphene-derivatives as noble metal-free co-catalysts and solid electron mediators in hydrogen evolution reaction under visible light illumination is discussed. The review finally elaborates the research gap and future perspectives, paving the way for new research to develop efficient photocatalysts for hydrogen production.

Domains rich in different blend components phase-separate during deposition, creating a film morphology that determines the performance of active layers in organic electronics. However, morphological control either relies on additional fabrication steps or is limited to a small region where an external interaction is applied. Here, we show that different semiconductor-insulator polymer composites can be rapidly dip-coated with the film structure electrically switched between distinct morphologies during deposition guided by the meniscus formed between the stationary barrier and horizontally drawn solid substrate. Reversible and repeatable changes between the morphologies used in devices, e.g., lateral morphologies and stratified layers of semiconductors and insulators, or between phase-inverted droplet-like structures are manifested only for one polarity of the voltage applied across the meniscus as a rectangular pulse. This phenomenon points to a novel mechanism, related to voltage-induced doping and the doping-dependent solubility of the conjugated polymer, equivalent to an increased semiconductor content that controls the composite morphologies. This is effective only for the positively polarized substrate rather than the barrier, as the former entrains the nearby lower part of the coating solution that forms the final composite film. The mechanism, applied to the pristine semiconductor solution, results in an increased semiconductor deposition and 40-times higher film conductance.

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., This work studies the use of thin layers of polyethylenimine (PEI) as an interface film to produce electron selective contacts for photovoltaic applications in crystalline silicon. Generally, in conjugated polyelectrolytes such as PEI with a high Lewis basicity, charge is accumulated along the chain of the polymer and counter anions from the solvent create an intense dipole array. In this work, part of the amine groups in PEI are protonated by the solvent that behaves as a weak Bronsted acid during the process. The PEI band modification is able to eliminate Fermi level pinning at metal/semiconductor junctions as it shifts the work function of the metallic electrode by more than 1 eV. As a consequence, induced charge transport between the metal and the semiconductor forms an electron accumulation region and promotes enhanced selectivity., This research has been supported by Spanish government through Grants PID2019-109215RB-C41 (SCALED), PID2019-109215RB-C43, PID2020-116719RB-C41 (MATER ONE) and PID2020-115719RB-C21 (GETPV) and funded by MCIN/AEI/ 10.13039/501100011033. Besides this the work is also supported by the international Grants SENESCYT-2018 funded by Ecuadorian government., Peer Reviewed, Postprint (author's final draft)

Three conjugated polymers consisting of truxene donor units and different acceptor units are synthesized and prepared into polymer dots for photocatalytic H2O2 production, exhibiting performance of over 100 mmol h(-1) g(Pdots)(-1). The best external quantum efficiency is determined to be 8.4% at 450 nm in 60 min which is higher than the majority of conjugated polymeric photocatalysts. Optical properties and surface reaction capabilities of Pdots are studied to understand the origin of the photocatalytic performance. The degradation pathway of Pdots is investigated and explained with the help of various spectroscopic characterizations.

Even though thermofluorochromic materials are eternal candidates for their use in multiple applications, they are still limited as they require complex synthetic strategies to accomplish tunable optical properties and/or provide optical changes only over a very wide temperature range. By taking advantage of the high sensitivity of the optical properties of conjugated polymers and oligomers to the external environment, herein phase change material (PCM)-based thermofluorochromic mixtures are created, where the solid-to-liquid transition of the PCM host triggers a sharp fluorescence color change of the dispersed polymers/oligomers. Fluorophore conjugation length, concentration, and PCM nature can be used to vary the spectral properties of the resulting materials along the visible region, covering a large part of the CIE 1931 color space. For the preparation of functional devices, this behavior can be directly transferred to the solid state by soaking or printing cellulose papers with the obtained thermofluorochromic mixtures as well as by structuring them into solid lipid particles that can be dispersed within polymer matrices. The resulting materials show very promising features as thermal sensors and anticounterfeiting labels.

Solar irradiation provides critical energy to conduct chemical reactions. Many light-sensitive materials, such as semiconductors, guide photoredox-induced chemical pathways to tailor favored chemical conversions. Polymer synthesis by light is popular, however mainly addressed by conducting radical-based polymerization strategies. Oxidative photopolymerization is an advanced method to form functional polymers that are otherwise formed through complicated reactions. Herein, infant-stage oxidative photopolymerization will be introduced with examples in the field., Aerospace Manufacturing Technologies

Toxic Cr(VI) polluted wastewater is worldwide recognized because of the wide application of chromium substances in various industrial sectors. Sustainable water pollution approaches are on demand now more than ever. In terms of Cr(VI), many homogenous and heterogenous techniques are applying to intensify its removal form water. Photocatalytic reduction of Cr(VI) has been suggested widely by the scientific community over the last two decades. This report addresses the current research state of the photocatalytic Cr(VI) reduction by addressing the most advances in terms of materials design and mechanistic pathways depending on the working conditions. The photocatalytic activity of different classes of materials such as single or heterojunction semiconductors, hybridization of photocatalyst nanoparticles (NPs) with sorbing materials, i.e., carbonaceous materials, metal-organic frameworks (MOFs), and conjugated polymers, is discussed in depth. The photodeposition of photoproduced Cr(III) on the surface of photocatalysts, and approaches to boost its desorption was addressed as well. The review discusses also the simultaneous photocatalytic reduction of Cr(VI) and oxidation of organic pollutants. A critical analysis of the current state and how to transfer substantial fundamental research to present world application was given by addressing the pros and cons of photocatalytic technology for Cr(VI) reduction compared to existing technologies. Positive research suggestions were provided to enhance the ability of photocatalytic technology for possible use, even for the purification of small volumes of industrial wastewater.

Fine tuning of blend morphology is a key factor that limits the performance of the bulk-heterojunction organic photovoltaics (BHJ-OPVs). Herein, the morphological control of the binary (PM6:Y7) and ternary (PM6:Y7:PC70BM) blends is conducted through 1-chloronaphthalene (CN) solvent additive and thermal annealing (TA) treatment with respect to their influence on the photovoltaic performance. Moreover, a distinct study is accomplished on the optical and electronic properties of the treated and nontreated binary and ternary devices by external quantum efficiency measurements and impedance spectroscopy. The results indicate that these treatments affect the performance of the binary and ternary OPVs differently. Regarding the 2% CN addition, the current density of the binary devices is improved by approximate to 27%, whereas the fill factor of the ternary devices shows a pronounced increment of approximate to 22%. A contradictory behavior is exhibited by TA for the binary and ternary OPVs. The PCEs for binary devices (with/without CN) and 2% CN-treated ternary ones are improved, while diminishing the PCEs of the ternary ones with 0% CN. Accordingly, the highest efficiencies of the binary and ternary OPVs are obtained due to the dual effect of 2% CN solvent additive along with the TA treatments.

Herein, we study hole transport properties in various conjugated conducting polymers blended with polystyrene (PS) as an insulating polymer. By analyzing macroscopic current density–voltage characteristics, we found that the mobility is improved for the conjugated conducting polymers diluted in the PS matrix that exhibit a redshift in absorption spectra. This is probably ascribed to more ordered polymer chains caused by the addition of PS. We believe that such a dilution of polymer chains would be versatile strategies to enhancing charge transport properties, which will offer a breakthrough towards highly efficient wearable optoelectronic devices based on the conjugated polymers.

Semiconducting polymers show promise for use in a variety of applications such as photovoltaic cells, light emitting diodes, and thermoelectric generators. For many of these devices, the electronic properties are tuned through the introduction of chemical dopants. This dissertation is focused on understanding several key aspects of the chemical doping process. The first chapter gives an overview of semiconducting polymers, introduces doping by sequential processing methods and looks at how the chemical doping process works on a basic level. We also explore dopant transport methods, discuss the electrical and thermoelectrical characterization of these materials, and finally consider the structural morphology of conjugated polymer thin films. Chapter 2 takes an analytical approach to understanding how the underlying morphology and electrical/thermoelectrical properties of doped polymer films are affected when introducing the dopant either via the solutionphase or using vapor transport. Chapter 3 explores the fundamental charge transfer interactions that occur between polymer and dopant. We introduce a novel processing technique that enables the tunable production of dopant-polymer charge transfer complexes (CTCs), which represent a poorly understood but widely seen doping mechanism in these materials. We provide the first comprehensive picture of the forces that drive CTC formation and offer guidelines for limiting CTC occurrence in doped conjugated polymers as their electrical properties are usually undesirable. Finally, in Chapter 4 we solve a long-standing mystery in the literature of the highly variable vibrational spectra of certain dopant molecules, which should nominally show consistent and predictable frequencies. We show that the wide range of vibrational energies observed for these dopant molecules can be fully understood through the framework of the vibrational Stark effect. Our experimental evidence shows a clear and predictable shift for these modes as a

En l'actual era de la Internet de les Coses (de l'anglès, IOT), els dispositius de detecció intel·ligents estan canviant molt el món en què vivim, des de com percebem el nostre entorn fins a com gastem l'energia. Fonts d'energia per a aquests dispositius seran essencials, especialment si no requereixen manteniment, són flexibles, barates, altament processable o fins i tot d'un sol ús. Els materials termoelèctrics orgànics --- semiconductors que poden transformar la calor en electricitat --- poden complir aquestes característiques. No obstant això, en els materials d'última generació encara hi ha aspectes que necessiten ser millorats; com el rendiment termoelèctric, estimat mitjançant la figura de mèrit ZT i l'estabilitat termoelèctrica sota continu estrès tèrmic. Aquesta tesi informa sobre estratègies per millorar l'eficiència i estabilitat termoelèctriques. Com a sistema de referència fem servir PBTTT dopat amb l'acceptor molecular F4TCNQ. Com a eina transversal per als nostres estudis, desenvolupem mètodes de fabricació i caracterització d'alt rendiment basats en gradients de tractament tèrmic, dopat i gruix per estudiar i correlacionar la relació entre la microestructura, les propietats termoelèctriques i l'estabilitat en una gran quantitat de mostres. A la primera secció de resultats proposem una estratègia per millorar l'estabilitat termoelèctrica. Hem demostrat que la formació de complexos de càrrega (CTC per les seves sigles en anglès) generen mostres tèrmicament més resistents, encara que elèctricament menys conductores. Al desenvolupar un mètode per ajustar la relació de transferència de càrrega parcial a una transferència completa, podem millorar l'estabilitat a llarg termini sense sacrificar la conductivitat elèctrica. La segona secció de resultats aborda la relació entre la cristal·linitat, el transport tèrmic i el transport elèctric. Hem demostrat que el grau de cristal·linitat determina en gran mesura la conductivitat tèrmica de capa fina de polímer. U, En la actual era de la Internet de las Cosas (del inglés, IoT), los dispositivos de detección inteligentes están cambiando mucho del mundo en el que vivimos, desde cómo percibimos nuestro entorno hasta cómo gastamos la energía. Fuentes de energía para tales dispositivos serán esenciales, especialmente si no requieren mantenimiento, son flexibles, baratas, altamente procesable o incluso desechables. Los materiales termoeléctricos orgánicos --- semiconductores que pueden transformar el calor en electricidad --- pueden cumplir estas características. Sin embargo, en los materiales de última generación todavía hay aspectos que necesitan ser mejorados; como el rendimiento termoeléctrico, estimado mediante la figura de mérito ZT y la estabilidad termoeléctrica bajo continuo estrés térmico. Esta tesis informa sobre estrategias para mejorar la eficiencia y estabilidad termoeléctricas. Como sistema de referencia empleamos PBTTT dopado con el aceptor molecular F4TCNQ. Como herramienta transversal para nuestros estudios, desarrollamos métodos de fabricación y caracterización de alto rendimiento basados en gradientes de tratamiento térmico, dopado y espesor para estudiar y correlacionar la relación entre la microestructura, las propiedades termoeléctricas y la estabilidad en una gran cantidad de muestras. En la primera sección de resultados proponemos una estrategia para mejorar la estabilidad termoeléctrica. Demostramos que la formación de complejos de carga (CTC) generan muestras térmicamente más resistentes, aunque menos eléctricamente menos conductora. Al desarrollar un método para ajustar la relación de transferencia de carga parcial a entera, podemos mejorar la estabilidad a largo plazo sin sacrificar la conductividad eléctrica. La segunda sección de resultados aborda la relación entre cristalinidad, transporte térmico y eléctrico. Demostramos que el grado de cristalinidad determina en gran medida la conductividad térmica de capa fina de polímero. Tras dopar, incluso un co, In the current Internet of Things (IoT) era, smart sensing-devices are changing much about the world we live in, from how we sense our surroundings to the way we spend energy. On-site power generators for such devices will be essential, especially if they are maintenance-free, flexible, cheap, printable, or even disposable. Organic thermoelectric materials --- semiconductors that can transform heat into electricity at near-room temperature --- can fulfill these characteristics. Nevertheless, there are still issues in the current state-of-the-art materials that need improvement, such as the thermoelectric performance, benchmarked by the dimensionless ZT, and the thermoelectric stability under continuous thermal stress. This thesis reports on strategies to improve thermoelectric efficiency and stability. As a testbed material system, we employ PBTTT doped with the molecular acceptor F4TCNQ. As a transversal tool for our studies, we developed high-throughput fabrication and characterization methods based on annealing-, doping- and thickness-gradients to study and correlate the relationship between microstructure, thermoelectric properties, and stability for many samples. The first set of results reports on a strategy to improve thermoelectric stability. We demonstrate that the formation of charge transfer complexes (CTCs) leads to more thermally enduring samples, although less electrically conductive. By developing a method to adjust the partial to integer charge-transfer ratio, we can improve the long-term stability without sacrificing the electrical conductivity. The subsequent chapter centers on the relationship between crystallinity and thermal and electric transport. We demonstrate that the degree of crystallinity largely determines the thermal conductivity of the film. Upon doping, even a relatively small dopant content increases the electrical conductivity several orders of magnitude but lowers the thermal conductivity without noticeable deterioration in the cry, Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència de Materials

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.

Nanocomplexes are made of different components, benefiting from properties of each of the constituent material. As such, nanocomplexes present unique properties including chemical activity due to high surface area, tuneable size and morphology, variable surface charges and efficient uptake by cells. They have been used in different therapeutic approaches such as drug delivery systems, biosensors and tissue engineering. Introducing an electrically conductive material, such as metal or conjugated polymer, as one component of nano-complexes adds electronic and optical properties to the system, broadening their applications. While metals are excellent conductors, their hard nature does not match the soft tissue. Conjugated polymers on the other hand, as organic materials, are soft and flexible; thus, they are the choice material in this thesis for the development of soft and hard conjugated polymer nanocomplexes. Liposome and anionic polymeric nanoparticles with a core morphology were used as soft and hard templates, respectively, around which conjugated polymers, polyaniline and polypyrrole, were synthesised. Their chemical, physical, electrochemical and biomedical properties were optimised and fully characterised. A single-step synthesis was developed for fabricating the soft polyaniline-liposome nano-complexes in which polyaniline, doped with phytic acid, was either embedded in the liposome bilayer or bound on the liposome outer surface. Hard polypyrrole nanocomplexes were based on the anionic poly(potassium 3- sulfopropyl methacrylate)-block- poly (benzyl methacrylate) nanoparticle. In a novel step, the nanoparticle served as the dopant for the conjugated polymer. The conjugated polymer nanocomplexes were water-dispersible, conductive and exhibited low impedance. In-vitro cell studies demonstrated the complexes are not cytotoxic with capability of targeted cell uptakes. This research presents novel and promising routes for xiv fabrication of water-dispersible conduc

Organic electronics based on conjugated polymers (CPs) are being explored as active semiconductor materials in the bioelectronics field. CPs can be embedded in flexible substrates to obtain a passive conductive device or employed in active devices such as organic electrochemical transistors (OECTs). Their potential use in the clinic hinges on their development into advanced bioelectronic circuitry for higher functionalities. Furthermore, their translation into the clinic will require their sterilization without degrading their physical and electronic properties, as well as consideration of self-powering functionalities. The thesis objective was to address these challenges by 1) developing a complementary logic circuit based on polyaniline (PANI) as the active channel, 2) investigating the effect of sterilization methods on PANI properties, and 3) exploring its optoelectronic properties towards a flexible wireless optoelectronic device. In this thesis, a complementary logic circuit was built from a single PANI based active channel OECT, exhibiting a gain of 7.2. It was also engineered into a flexible bioelectronic circuit that operates in aqueous electrolyte. An in vivo study was performed on PANI-patches sterilized by ethylene oxide and gamma radiation. Results showed that the patches maintained their mechanical and conductive nature after sterilization, and the inflammatory response after implantation significantly diminished by week 4. The optical properties of PANI were also exploited; the PANI-patch showed photoconductivity when illuminated with visible light. In conclusion, the electrochemical properties of PANI were exploited to build a new flexible complementary circuit featuring two identical OECTs. This drastically simplifies the manufacturing process eliminating the need for materials with matching performance. Sterilized patches maintained their mechanical and electrical properties and induced a minimal inflammatory response. Additionally, the demonstrate