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Organic semiconducting polymers have attractive electronic, optical, and mechanical properties that make them materials of choice for large area flexible electronic devices. In these devices, the electronically active polymer components are micrometers in size, and sport negligible performance degradation upon bending the centimeter-scale flexible substrate onto which they are integrated. A closer look at the mechanical properties of the polymers, on the grain-scale and smaller, is not necessary in large area electronic applications. In emerging micromechanical and electromechanical applications where the organic polymer elements are flexed on length scales spanning their own micron-sized active areas, it becomes important to characterize the uniformity of their mechanical properties on the nanoscale. In this work, the authors use two precision nanomechanical characterization techniques, namely, atomic force microscope based PeakForce quantitative nanomechanical mapping (PF-QNM) and nanoindentation-based dynamical mechanical analysis (nano-DMA), to compare the modulus and the viscoelastic properties of organic polymers used routinely in organic electronics. They quantitatively demonstrate that the semiconducting near-amorphous organic polymer indacenodithiophene-co-benzothiadiazole (C16-IDTBT) has a higher carrier mobility, lower modulus, and greater nanoscale modulus areal uniformity compared to the semiconducting semicrystalline organic polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (C14-PBTTT). Modulus homogeneity appears intrinsic to C16-IDTBT but can be improved in C14-PBTTT upon chemical doping., QC 20220607

This dissertation is concerned with the fabrication and characterization of organic electrochemical transistors (OECTs) made from polyelectrolytes based on the material PCPDTBT-SO3-Na (CPE-Na). OECTs are electrolyte-gated transistors that allow the electrolyte to permeate into the bulk of the film and directly changes the doping state of the bulk of the semiconducting layer. The relationship between the molecular structure of the polyelectrolytes and the material properties are explored in the lens of optimizing device characteristics in OECTs. The first chapter of this thesis focuses on the development of OECTs made using PCPDTBT-SO3-K (CPE-K) as the active layer. While the large majority of OECT research still utilizes poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the active layer, a few new OECT materials have been recently reported. CPE-K has been used in the past for applications such as DNA-detection, thermoelectric devices and as interlayers in organic photovoltaic devices. Conjugated polyelectrolytes (CPEs) represent a promising and unique class of materials which are characterized by their conjugated carbon backbone and pendant ionic chains. Their water solubility in addition to their electronic and ionic conductivity makes them an ideal candidate for OECT applications. Using various spectroscopic and electric characterization techniques, CPE-K was fully characterized so that it could be accurately compared to other OECT materials reported in the literature. In fact, CPE-K is among the short list of high-performance OECT materials. The techniques used in this work was used to shed light on the operational mechanism of CPE-based OECTs. In addition, the effective use of interdigitated contacts was used to increase the transconductance of OECT devices.The second portion of this thesis expands on the work of CPE OECTs, by exploring their structure-property-relationship. A series of CPE-Na polymers with varying sidechain lengths were synt

The properties of organic semiconductors make them well-suited for certain applications in electronic devices or energy conversion. Because of their low inherent conductivity, organic semiconductors need to be doped to be used in many of these applications. The limited set of small molecules commonly used for organic semiconductor doping do not always have the desired combination of properties for some applications, such as high ionization energy or air stability. In addition to removing or adding charges, these small molecule dopants can significantly alter the semiconducting film structure through Coulombic interactions. These challenges suggest a need to explore new dopants and doping mechanisms and to better understand the effects of doping on the electronic structure and morphology of organic semiconductors. We used a combination of experimental methods and DFT calculations to explore new doping mechanisms based on Lewis acid-base pair chemistry. Combining UV-Vis-NIR spectroscopy, electrical transport measurements, and grazing incidence wide-angle X-ray scattering, we connected changes in the electronic structure to changes in morphology and transport in both amorphous and semicrystalline semiconductor systems. Our results suggest ways to control the electronic structure and morphology of organic semiconductors, as well as providing a starting point to further apply Lewis pair chemistry to doping.

Organic semiconductors (OSCs), including semiconducting small molecules (SSMs), polymers (SPs) and carbon nanotubes (s-CNTs), are a versatile class of materials. Their compatibility with low-cost solution processing techniques and potential for producing lightweight, flexible, electronic devices has already begun to revolutionize several technologies. Typical organic devices, including thermoelectrics (OTEs), photovoltaics (OPVs), field-effect transistors (OFETs), and light-emitting diodes (OLEDs) can be fabricated with flexible OSCs, and has spawned several novel applications including wearable electronics, foldable low-temperature thermoelectrics, and flexible displays. While the future of OSC technology is promising, several structure-property relationships remain poorly understood, likewise the link between molecular doping level and OSC carrier density is underdeveloped. In my dissertation, I demonstrate new solution processing techniques, connect processing methods to structure formation using X-ray and neutron scattering probes, and correlate processing and structure formation to vital optoelectronic properties. I begin by demonstrating an additive solution process for depositing multiple layers of mutually soluble SP films without disrupting layer continuity. I use neutron reflectometry to quantify film thickness changes during processing steps and demonstrate the fabrication of a 4-layered device. Next, I perform a hierarchal structural analysis of bulk heterojunction SSM OPVs using grazing incidence X-ray diffraction and small angle neutron scattering, and correlate peak OPV performance to an inflection in film crystallinity and phase purity. Third, I refined a doping process, termed anion exchange doping, and show its effectiveness for doping high ionization energy polymers. During which I developed the framework for quantifying and predicting doping levels and carrier densities in SPs. Finally, I reveal record carrier mobilities and OTE performance in s

This dissertation is concerned with the fabrication and characterization of organic electrochemical transistors (OECTs) made from polyelectrolytes based on the material PCPDTBT-SO3-Na (CPE-Na). OECTs are electrolyte-gated transistors that allow the electrolyte to permeate into the bulk of the film and directly changes the doping state of the bulk of the semiconducting layer. The relationship between the molecular structure of the polyelectrolytes and the material properties are explored in the lens of optimizing device characteristics in OECTs. The first chapter of this thesis focuses on the development of OECTs made using PCPDTBT-SO3-K (CPE-K) as the active layer. While the large majority of OECT research still utilizes poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the active layer, a few new OECT materials have been recently reported. CPE-K has been used in the past for applications such as DNA-detection, thermoelectric devices and as interlayers in organic photovoltaic devices. Conjugated polyelectrolytes (CPEs) represent a promising and unique class of materials which are characterized by their conjugated carbon backbone and pendant ionic chains. Their water solubility in addition to their electronic and ionic conductivity makes them an ideal candidate for OECT applications. Using various spectroscopic and electric characterization techniques, CPE-K was fully characterized so that it could be accurately compared to other OECT materials reported in the literature. In fact, CPE-K is among the short list of high-performance OECT materials. The techniques used in this work was used to shed light on the operational mechanism of CPE-based OECTs. In addition, the effective use of interdigitated contacts was used to increase the transconductance of OECT devices.The second portion of this thesis expands on the work of CPE OECTs, by exploring their structure-property-relationship. A series of CPE-Na polymers with varying sidechain lengths were synt

Organic semiconductors (OSCs), including semiconducting small molecules (SSMs), polymers (SPs) and carbon nanotubes (s-CNTs), are a versatile class of materials. Their compatibility with low-cost solution processing techniques and potential for producing lightweight, flexible, electronic devices has already begun to revolutionize several technologies. Typical organic devices, including thermoelectrics (OTEs), photovoltaics (OPVs), field-effect transistors (OFETs), and light-emitting diodes (OLEDs) can be fabricated with flexible OSCs, and has spawned several novel applications including wearable electronics, foldable low-temperature thermoelectrics, and flexible displays. While the future of OSC technology is promising, several structure-property relationships remain poorly understood, likewise the link between molecular doping level and OSC carrier density is underdeveloped. In my dissertation, I demonstrate new solution processing techniques, connect processing methods to structure formation using X-ray and neutron scattering probes, and correlate processing and structure formation to vital optoelectronic properties. I begin by demonstrating an additive solution process for depositing multiple layers of mutually soluble SP films without disrupting layer continuity. I use neutron reflectometry to quantify film thickness changes during processing steps and demonstrate the fabrication of a 4-layered device. Next, I perform a hierarchal structural analysis of bulk heterojunction SSM OPVs using grazing incidence X-ray diffraction and small angle neutron scattering, and correlate peak OPV performance to an inflection in film crystallinity and phase purity. Third, I refined a doping process, termed anion exchange doping, and show its effectiveness for doping high ionization energy polymers. During which I developed the framework for quantifying and predicting doping levels and carrier densities in SPs. Finally, I reveal record carrier mobilities and OTE performance in s

The properties of organic semiconductors make them well-suited for certain applications in electronic devices or energy conversion. Because of their low inherent conductivity, organic semiconductors need to be doped to be used in many of these applications. The limited set of small molecules commonly used for organic semiconductor doping do not always have the desired combination of properties for some applications, such as high ionization energy or air stability. In addition to removing or adding charges, these small molecule dopants can significantly alter the semiconducting film structure through Coulombic interactions. These challenges suggest a need to explore new dopants and doping mechanisms and to better understand the effects of doping on the electronic structure and morphology of organic semiconductors. We used a combination of experimental methods and DFT calculations to explore new doping mechanisms based on Lewis acid-base pair chemistry. Combining UV-Vis-NIR spectroscopy, electrical transport measurements, and grazing incidence wide-angle X-ray scattering, we connected changes in the electronic structure to changes in morphology and transport in both amorphous and semicrystalline semiconductor systems. Our results suggest ways to control the electronic structure and morphology of organic semiconductors, as well as providing a starting point to further apply Lewis pair chemistry to doping.

Chapter 1 provides an overview on the synthesis of graphene nanoribbons. Various types of edge structures and bottom-up synthetic strategies, on-surface and in-solution, are covered before discussing our group’s third approach, solid-state. This is followed by a description of the effect of heteroatomic substitutions on electronic properties of GNRs. Lastly a brief discussion on other semiconducting polymer structure and charge transfer properties are introduced.Chapter 2 details the synthesis of N = 8 armchair graphene nanoribbons (GNRs) using a two-step solid-state method. Four diarylbutadiyne precursors undergo topochemical polymerization to four distinct polydiacetylene (PDA) polymers, which subsequently cyclodehydrogenate and undergo side chain fragmentation to afford the same N =8 armchair GNR. Various spectroscopic and imaging techniques are used to characterize this transformation, in addition to calculations of the cyclization process on a model system used to verify the mechanism.Chapter 3 describes the synthesis of GNRs with a fjord-edge structure and site-specific nitrogen substitutions using the two-step approach above. Two dipyridylbutadiyne precursors polymerize and cyclize to afford N = 8 fjord-edge N-GNRs, with side chains still intact. Spectroscopic characterization, imaging and mechanistic calculations of a pyridyl model system verify the transformation from butadiyne to GNR.Lower the barrier of Hopf cyclizations, a step towards GNRs in our solid-state approach, through introduction of strained cycloalkenes could lead to room temperature GNR syntheses. Chapter 4 details the synthesis of two polydiacetylene synthons containing norbornadiene, a bis(norbornadienyl)1,3-butadiyne and trans-bis(norbornadienyl)enediyne. Challenges towards synthesizing both monomer units and future applications of other trans-enediynes towards GNRs are discussed.Chapter 5 describes the synthesis of an amphiphilic semiconducting polymer, poly(cyclopentadithiophene-alt-thio

Chapter 1 provides an overview on the synthesis of graphene nanoribbons. Various types of edge structures and bottom-up synthetic strategies, on-surface and in-solution, are covered before discussing our group’s third approach, solid-state. This is followed by a description of the effect of heteroatomic substitutions on electronic properties of GNRs. Lastly a brief discussion on other semiconducting polymer structure and charge transfer properties are introduced.Chapter 2 details the synthesis of N = 8 armchair graphene nanoribbons (GNRs) using a two-step solid-state method. Four diarylbutadiyne precursors undergo topochemical polymerization to four distinct polydiacetylene (PDA) polymers, which subsequently cyclodehydrogenate and undergo side chain fragmentation to afford the same N =8 armchair GNR. Various spectroscopic and imaging techniques are used to characterize this transformation, in addition to calculations of the cyclization process on a model system used to verify the mechanism.Chapter 3 describes the synthesis of GNRs with a fjord-edge structure and site-specific nitrogen substitutions using the two-step approach above. Two dipyridylbutadiyne precursors polymerize and cyclize to afford N = 8 fjord-edge N-GNRs, with side chains still intact. Spectroscopic characterization, imaging and mechanistic calculations of a pyridyl model system verify the transformation from butadiyne to GNR.Lower the barrier of Hopf cyclizations, a step towards GNRs in our solid-state approach, through introduction of strained cycloalkenes could lead to room temperature GNR syntheses. Chapter 4 details the synthesis of two polydiacetylene synthons containing norbornadiene, a bis(norbornadienyl)1,3-butadiyne and trans-bis(norbornadienyl)enediyne. Challenges towards synthesizing both monomer units and future applications of other trans-enediynes towards GNRs are discussed.Chapter 5 describes the synthesis of an amphiphilic semiconducting polymer, poly(cyclopentadithiophene-alt-thio

Carrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)-based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox-potential-driven. Remarkably, X-ray scattering shows that despite their large 2-nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film.

Polymeric semiconductors show potential as materials for electronic applications unrealizable by inorganic semiconductors, such as wearable and biocompatible devices. An important process to increase the electrical conductivity in polymers is through doping, where small molecules infiltrate the material to oxidize or reduce the polymeric backbone. Once the reaction takes place, the dopant molecule becomes ionized. A central concept that is not understood in polymeric semiconductors today is how these counter-ions and electrons (or holes) interact when in close proximity to one another, and how those interactions affect their respective conduction mechanisms. Additionally, the semi-crystalline nature of most semiconducting polymers complicates the relationship between morphology and electronic conduction.We aim to develop a better understanding of ionic effects on the electronic and morphological properties of semiconducting polymers using a combination of spectroscopic measurements, X-ray scattering, and electrical characterization. From this work, we find that the presence of dopant counter-ions manifest throughout a multitude of length scales that partially govern the electronic behavior at the device scale. This work indicates that significant differences exist between a doped polymer and its insulating state, signifying the importance of integrating doping-induced disorder into transport models for organic semiconductors.

One of the most effective ways to tune the electronic properties of conjugated polymers is to dope them with small-molecule oxidizing agents, creating holes on the polymer and molecular anions. Undesirably, strong electrostatic attraction from the anions of most dopants localizes the holes created on the polymer, reducing their mobility. Here, a new strategy utilizing a substituted boron cluster as a molecular dopant for conjugated polymers is employed. By designing the cluster to have a high redox potential and steric protection of the core-localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained. AC Hall effect measurements show that P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with F4 TCNQ, even though the boron-cluster-doped films have poor crystallinity. Moreover, the number of free carriers approximately matches the number of boron clusters, yielding a doping efficiency of ≈100%. These results suggest that shielding the polaron from the anion is a critically important aspect for producing high carrier mobility, and that the high polymer crystallinity required with dopants such as F4 TCNQ is primarily to keep the counterions far from the polymer backbone.

Polymeric semiconductors show potential as materials for electronic applications unrealizable by inorganic semiconductors, such as wearable and biocompatible devices. An important process to increase the electrical conductivity in polymers is through doping, where small molecules infiltrate the material to oxidize or reduce the polymeric backbone. Once the reaction takes place, the dopant molecule becomes ionized. A central concept that is not understood in polymeric semiconductors today is how these counter-ions and electrons (or holes) interact when in close proximity to one another, and how those interactions affect their respective conduction mechanisms. Additionally, the semi-crystalline nature of most semiconducting polymers complicates the relationship between morphology and electronic conduction.We aim to develop a better understanding of ionic effects on the electronic and morphological properties of semiconducting polymers using a combination of spectroscopic measurements, X-ray scattering, and electrical characterization. From this work, we find that the presence of dopant counter-ions manifest throughout a multitude of length scales that partially govern the electronic behavior at the device scale. This work indicates that significant differences exist between a doped polymer and its insulating state, signifying the importance of integrating doping-induced disorder into transport models for organic semiconductors.

One of the most effective ways to tune the electronic properties of conjugated polymers is to dope them with small-molecule oxidizing agents, creating holes on the polymer and molecular anions. Undesirably, strong electrostatic attraction from the anions of most dopants localizes the holes created on the polymer, reducing their mobility. Here, a new strategy utilizing a substituted boron cluster as a molecular dopant for conjugated polymers is employed. By designing the cluster to have a high redox potential and steric protection of the core-localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained. AC Hall effect measurements show that P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with F4 TCNQ, even though the boron-cluster-doped films have poor crystallinity. Moreover, the number of free carriers approximately matches the number of boron clusters, yielding a doping efficiency of ≈100%. These results suggest that shielding the polaron from the anion is a critically important aspect for producing high carrier mobility, and that the high polymer crystallinity required with dopants such as F4 TCNQ is primarily to keep the counterions far from the polymer backbone.

Mechanical softness and deformability underpin most of the advantages offered by semiconducting polymers. A detailed understanding of the mechanical properties of these materials is crucial for the design and manufacturing of robust, thin-film devices such as solar cells, displays, and sensors. The mechanical behavior of polymers is a complex function of many interrelated factors that span multiple scales, ranging from molecular structure, to microstructural morphology, and device geometry. This thesis builds a comprehensive understanding of the thermomechanical properties of polymeric semiconductors through the development and experimental-validation of computational methods for mechanical simulation. A predictive computational methodology is designed and encapsulated into open-sourced software for automating molecular dynamics simulations on modern supercomputing hardware. These simulations are used to explore the role of molecular structure/weight and processing conditions on solid-state morphology and thermomechanical behavior. Experimental characterization is employed to test these predictions—including the development of simple, new techniques for rigorously characterizing thermal transitions and fracture mechanics of thin films.

Semiconducting polymers—typically fabricated as thin films (~100 nm)—have always been associated with flexible applications, such as solar cells, active-matrix displays, and biomedical sensors. Mechanical flexibility of these materials, however, is not automatic. The thermal and mechanical properties of semiconducting polymers must be engineered by tuning the chemical structure, molecular weight, processing conditions, and interactions with other materials in the device stack. The thermal transition of semiconducting polymers that perhaps most greatly influences the mechanical response is the glass transition, and the temperature (Tg) at which it occurs. We develop a new technique that leverages the unique aggregation behavior of semiconducting polymers to measure the Tg. With ultraviolet−visible (UV−vis) spectroscopy, we measure changes in the absorption spectrum due to rearrangement of chains at the molecular scale and formation of photophysical aggregates on heating above the Tg.Thermal transitions are not the only properties of semiconducting polymers that scientists have had trouble measuring; the mechanical properties, too, of these materials are difficult to characterize due to the diverse range of fracture behavior that thin polymer films exhibit. In addition, the mechanics that govern ductile fracture—compared to brittle fracture—are underexplored. Understanding the mechanics of ductile fracture is crucial for the improved design and fabrication of mechanically robust organic electronics. For this mechanism of fracture, we find that diamond-shaped microvoids, which originate at pinholes and defects within the film, propagate with an aspect ratio that increases linearly with applied strain. We define the rate of change of the aspect ratio of a microvoid with respect to applied strain as the “microvoid-propagation number.” This dimensionless film parameter, previously unreported, is a useful measure of ductility in thin films supported by an elastomer.

Mechanical softness and deformability underpin most of the advantages offered by semiconducting polymers. A detailed understanding of the mechanical properties of these materials is crucial for the design and manufacturing of robust, thin-film devices such as solar cells, displays, and sensors. The mechanical behavior of polymers is a complex function of many interrelated factors that span multiple scales, ranging from molecular structure, to microstructural morphology, and device geometry. This thesis builds a comprehensive understanding of the thermomechanical properties of polymeric semiconductors through the development and experimental-validation of computational methods for mechanical simulation. A predictive computational methodology is designed and encapsulated into open-sourced software for automating molecular dynamics simulations on modern supercomputing hardware. These simulations are used to explore the role of molecular structure/weight and processing conditions on solid-state morphology and thermomechanical behavior. Experimental characterization is employed to test these predictions—including the development of simple, new techniques for rigorously characterizing thermal transitions and fracture mechanics of thin films.

Semiconducting polymers—typically fabricated as thin films (~100 nm)—have always been associated with flexible applications, such as solar cells, active-matrix displays, and biomedical sensors. Mechanical flexibility of these materials, however, is not automatic. The thermal and mechanical properties of semiconducting polymers must be engineered by tuning the chemical structure, molecular weight, processing conditions, and interactions with other materials in the device stack. The thermal transition of semiconducting polymers that perhaps most greatly influences the mechanical response is the glass transition, and the temperature (Tg) at which it occurs. We develop a new technique that leverages the unique aggregation behavior of semiconducting polymers to measure the Tg. With ultraviolet−visible (UV−vis) spectroscopy, we measure changes in the absorption spectrum due to rearrangement of chains at the molecular scale and formation of photophysical aggregates on heating above the Tg.Thermal transitions are not the only properties of semiconducting polymers that scientists have had trouble measuring; the mechanical properties, too, of these materials are difficult to characterize due to the diverse range of fracture behavior that thin polymer films exhibit. In addition, the mechanics that govern ductile fracture—compared to brittle fracture—are underexplored. Understanding the mechanics of ductile fracture is crucial for the improved design and fabrication of mechanically robust organic electronics. For this mechanism of fracture, we find that diamond-shaped microvoids, which originate at pinholes and defects within the film, propagate with an aspect ratio that increases linearly with applied strain. We define the rate of change of the aspect ratio of a microvoid with respect to applied strain as the “microvoid-propagation number.” This dimensionless film parameter, previously unreported, is a useful measure of ductility in thin films supported by an elastomer.

Typical device architectures in polymer-based optoelectronic devices, such as field effect transistors organic light emitting diodes and photovoltaic cells include sub-100 nm semiconducting polymer thin-film active layers, whose microstructure is likely to be subject to finite-size effects. The aim of this study was to investigate effect of the two-dimensional spatial confinement on the internal structure of the semiconducting polymer poly(9,9-dioctylfluorene) (PFO). PFO melts were confined inside the cylindrical nanopores of anodic aluminium oxide (AAO) templates and crystallized via two crystallization strategies, namely, in the presence or in the absence of a surface bulk reservoir located at the template surface. We show that highly textured semiconducting nanowires with tuneable crystal orientation can be thus produced. The results presented here demonstrate the simple fabrication and crystal engineering of ordered arrays of PFO nanowires; a system with potential applications in devices where anisotropic optical properties are required, such as polarized electroluminescence, waveguiding, optical switching and lasing.

Organic photovoltaics (OPVs) represent a promising alternative to silicon based photovoltaics because of they are lower cost and easier to process then current technology. A typical OPV consists of a semiconducting polymer that acts as the electron donor and primary photoabsorber combined with an electron acceptor, often a C60 fullerene derivative. Due to the low exciton diffusion length in organic blends, the two components must be blended on a fine enough length scale to enable efficient electron transfer. However, the components still need to be separated enough to maintain high conductivity in the pure domains for the extraction of the carriers. It can be difficult to create such a demanding structure and optimal morphology reproducibly. This work focuses on controlling the semiconducting polymer through self-assembly as a way to tune the overall nanoscale architecture of a blended system. In the first part of this dissertation, the effect of changing the crystallinity and orientation of semiconducting polymers will be examined as a way to tune the nanoscale morphology of a polymer/fullerene blend. The resulting device performance will be analyzed to gain further understanding of the optimal morphology required to maximize efficiency. Three polymer systems are used to explore how small changes in the crystallinity, regioregularity, and chain conformation can dramatically alter the resulting OPV device performance. Additionally, the changes in polymer morphology with two fullerene incorporation techniques, blend casting and sequential processing, will be compared. Since polymer morphology and characteristics can be determined, it will be shown that the processing method can be selected to match each intrinsic polymer, which are often more difficult to control.In the second part, self-assembly will be used as a method to precisely direct the polymer morphology in films and solution. It will be shown that through the use of an inorganic host, individual chains can

Organic photovoltaics (OPVs) represent a promising alternative to silicon based photovoltaics because of they are lower cost and easier to process then current technology. A typical OPV consists of a semiconducting polymer that acts as the electron donor and primary photoabsorber combined with an electron acceptor, often a C60 fullerene derivative. Due to the low exciton diffusion length in organic blends, the two components must be blended on a fine enough length scale to enable efficient electron transfer. However, the components still need to be separated enough to maintain high conductivity in the pure domains for the extraction of the carriers. It can be difficult to create such a demanding structure and optimal morphology reproducibly. This work focuses on controlling the semiconducting polymer through self-assembly as a way to tune the overall nanoscale architecture of a blended system. In the first part of this dissertation, the effect of changing the crystallinity and orientation of semiconducting polymers will be examined as a way to tune the nanoscale morphology of a polymer/fullerene blend. The resulting device performance will be analyzed to gain further understanding of the optimal morphology required to maximize efficiency. Three polymer systems are used to explore how small changes in the crystallinity, regioregularity, and chain conformation can dramatically alter the resulting OPV device performance. Additionally, the changes in polymer morphology with two fullerene incorporation techniques, blend casting and sequential processing, will be compared. Since polymer morphology and characteristics can be determined, it will be shown that the processing method can be selected to match each intrinsic polymer, which are often more difficult to control.In the second part, self-assembly will be used as a method to precisely direct the polymer morphology in films and solution. It will be shown that through the use of an inorganic host, individual chains can

© 2015 Elsevier Ltd. All rights reserved. The generation of nanostructured polymer films has been a challenge during the last decades. Surface nanostructuring based on the imprinting of nanoscale patterns on a homogeneous surface or on the deposition of nanostructures on the surface serves advantageously for nanofabrication of functional polymer materials. Advanced nanolithography typically requires multiple-steps procedures involving clean-room facilities, high vacuum or complex mask fabrication. Alternatively, laser-based methods enable high spatial resolution patterning of soft polymeric matter and afford the sought versatility and reliability without the need of stringent ambient conditions. In particular, the technique of laser induced periodic surface structures (LIPSS) has been successfully applied to nanostructuring of polymer films using a polarized laser source at several laser wavelengths and pulse durations. In this paper the formation of LIPSS on polymer films will be described. In particular, the possibilities of tuning the period and shape of the structures will be discussed since the control of the characteristics of the superficial structures can be crucial in order to match the requirements of a particular application. Additionally, an overview about the main and potential applications of LIPSS in polymer films is provided. In particular, the use of rippled polymer films as substrates for cell culture/alignment, surface enhanced Raman scattering sensors, or applications in photovoltaics will be reviewed.

The chemical structure of conjugated semiconducting materials strongly influences the performance of organic photovoltaic (OPV) devices. Thus a good understanding of the structure-function relationships that govern the optoelectronic and physical properties of OPV materials is necessary. In this dissertation, organic polymers and small molecules are evaluated in terms of OPV device output parameters, and molecular design rules are elucidated.The development of molecules with alternating electron-rich and electron-deficient backbone units provides materials with suitable optoelectronic properties for OPVs and favorable modularity for organic semiconductor design. The choice of specific aromatic units and side chains for conjugated materials are shown to modulate the energy levels and architecture of OPV devices, affecting each of the four mechanistic steps of OPV operation.In Chapter 2, the relationship between molecular packing parameters and the bulkiness of aliphatic solubilizing group extending away from a polymer backbone is elucidated, and high-performance OPV devices are achieved. In Chapter 3, the inclusion of a post-processing functionality on a polymer side chain is found to have a positive effect on the bulk morphology and overall performance of OPV devices. In Chapter 4, the influence of electron-withdrawing and quinoidal monomers on the optoelectronic properties of conjugated polymers is established, and energy level modulation is shown to affect the electron accepting and donating capabilities of OPV materials in a blended device. In Chapter 5, small molecules are designed with complementary light absorption properties in order to investigate a rarely observed charge generation mechanism.

Organic photovoltaics (OPVs) have emerged as an alternative technology to current silicon-based systems for harvesting solar energy. The solution-processability of conjugated materials offers the potential for scalable, low-cost production of lightweight, flexible solar cells. In particular, OPVs containing a bulk-heterojunction (BHJ) architecture, where electron-donors and electron-acceptors form an interpenetrating network within the device active layer, have demonstrated high solar cell performance. The active layer components serve a crucial role in light absorption, charge generation and carrier transport. Through synthetic design and device characterization, this work focuses on elucidating design strategies and principles for the development of high-performing electron-donors for OPVs.Molecular packing parameters of conjugated materials can strongly impact charge transport in the solid state. With a model polymer backbone containing thiophene comonomers, it was shown that strategic substitution of furan for thiophene improved material solubility and allowed for the use of linear alkyl side chains to reduce insulating contents in devices. These structural modifications yielded polymers with sufficient solubility, favorable solid-state morphology, enhanced long-range packing order, and efficient OPV performance. In a separate study, conjugated small molecules were functionalized with symmetric, planar end-groups so that they could self-assemble and form an interpenetrating network with electron-acceptors in the active layer. This investigation demonstrates that directing self-assembly via end-groups is an effective strategy to enhance molecular interconnectivity and improve the performance of molecular semiconductors in organic solar cells.Alongside solid-state morphology, semiconducting materials need to exhibit optical and electronic properties that enable effective light absorption and charge generation in solar cells. We showed that incorporating antiaromat

Organic photovoltaics (OPVs) have emerged as an alternative technology to current silicon-based systems for harvesting solar energy. The solution-processability of conjugated materials offers the potential for scalable, low-cost production of lightweight, flexible solar cells. In particular, OPVs containing a bulk-heterojunction (BHJ) architecture, where electron-donors and electron-acceptors form an interpenetrating network within the device active layer, have demonstrated high solar cell performance. The active layer components serve a crucial role in light absorption, charge generation and carrier transport. Through synthetic design and device characterization, this work focuses on elucidating design strategies and principles for the development of high-performing electron-donors for OPVs.Molecular packing parameters of conjugated materials can strongly impact charge transport in the solid state. With a model polymer backbone containing thiophene comonomers, it was shown that strategic substitution of furan for thiophene improved material solubility and allowed for the use of linear alkyl side chains to reduce insulating contents in devices. These structural modifications yielded polymers with sufficient solubility, favorable solid-state morphology, enhanced long-range packing order, and efficient OPV performance. In a separate study, conjugated small molecules were functionalized with symmetric, planar end-groups so that they could self-assemble and form an interpenetrating network with electron-acceptors in the active layer. This investigation demonstrates that directing self-assembly via end-groups is an effective strategy to enhance molecular interconnectivity and improve the performance of molecular semiconductors in organic solar cells.Alongside solid-state morphology, semiconducting materials need to exhibit optical and electronic properties that enable effective light absorption and charge generation in solar cells. We showed that incorporating antiaromat

The chemical structure of conjugated semiconducting materials strongly influences the performance of organic photovoltaic (OPV) devices. Thus a good understanding of the structure-function relationships that govern the optoelectronic and physical properties of OPV materials is necessary. In this dissertation, organic polymers and small molecules are evaluated in terms of OPV device output parameters, and molecular design rules are elucidated.The development of molecules with alternating electron-rich and electron-deficient backbone units provides materials with suitable optoelectronic properties for OPVs and favorable modularity for organic semiconductor design. The choice of specific aromatic units and side chains for conjugated materials are shown to modulate the energy levels and architecture of OPV devices, affecting each of the four mechanistic steps of OPV operation.In Chapter 2, the relationship between molecular packing parameters and the bulkiness of aliphatic solubilizing group extending away from a polymer backbone is elucidated, and high-performance OPV devices are achieved. In Chapter 3, the inclusion of a post-processing functionality on a polymer side chain is found to have a positive effect on the bulk morphology and overall performance of OPV devices. In Chapter 4, the influence of electron-withdrawing and quinoidal monomers on the optoelectronic properties of conjugated polymers is established, and energy level modulation is shown to affect the electron accepting and donating capabilities of OPV materials in a blended device. In Chapter 5, small molecules are designed with complementary light absorption properties in order to investigate a rarely observed charge generation mechanism.

We have fabricated organic bottom-contact top-gate field-effect transistors with an indenofluorene-phenanthrene co-polymer semiconductor, exhibiting ON/OFF ratio of 10(7) and uncommonly high mobility for an amorphous conjugated polymer of up to 0.3 cm(2)/Vs. Lack of crystallinity in this material is indicated by atomic force microscopy, grazing incidence wide angle X-ray scattering, and differential scanning calorimetry data. Nevertheless, fitting transistor data to the Gaussian disorder model gives low energetic disorder of sigma = 48 meV and high prefactor mobility mu(0) = 0.67 cm(2)/Vs. The measured transistor mobility is also exceptionally stable in ambient conditions, decreasing only by approximately 15% over two months. (C) 2012 American Institute of Physics

We have fabricated organic bottom-contact top-gate field-effect transistors with an indenofluorene-phenanthrene co-polymer semiconductor, exhibiting ON/OFF ratio of 10(7) and uncommonly high mobility for an amorphous conjugated polymer of up to 0.3 cm(2)/Vs. Lack of crystallinity in this material is indicated by atomic force microscopy, grazing incidence wide angle X-ray scattering, and differential scanning calorimetry data. Nevertheless, fitting transistor data to the Gaussian disorder model gives low energetic disorder of sigma = 48 meV and high prefactor mobility mu(0) = 0.67 cm(2)/Vs. The measured transistor mobility is also exceptionally stable in ambient conditions, decreasing only by approximately 15% over two months. (C) 2012 American Institute of Physics

A new heteroarylene-vinylene donor-acceptor polymer P(BDT-V-BTD) with reduced bandgap has been synthesized and its photophysical, electronic and photovoltaic properties investigated both experimentally and theoretically. The structure of the polymer comprises an unprecedented combination of a strong donor (4,8-dialkoxy-benzo[1,2-b:4,5-b']dithiophene, BDT), a strong acceptor (2,1,3-benzothiadiazole, BTD) and a vinylene spacer. The new polymer was obtained by a metal-catalyzed cross-coupling Stille reaction and fully characterized by NMR, UV-vis absorption, GPC, TGA, DSC and electrochemistry. Detailed ab initio computations with solvation effects have been performed for the monomer and model oligomers. The electrochemical investigation has ascertained the ambipolar character of the polymer and energetic values of HOMO, LUMO and bandgap matching materials-design rules for optimized organic photovoltaic devices. The HOMO and LUMO energies are consistently lower than those of previous heteroarylene-vinylene polymer while the introduction of the vinylene spacer afforded lower bandgaps compared to the analogous system P(BDT-BTD) with no spacer between the aromatic rings. These superior properties should allow for enhanced photovoltages and photocurrents in photovoltaic devices in combination with PCBM. Preliminary photovoltaic investigation afforded relatively modest power conversion efficiencies of 0.74% (AM 1.5G, 100 mW/cm 2), albeit higher than that of previous heteroarylene-vinylene polymers and comparable to that of P(BDT-BTD). © 2012 Wiley Periodicals, Inc.

Conjugated polymers were grafted onto cellulose substrates in an effort to create a general method for the synthesis of conjugated polymer/cellulose hybrid materials. In this report, we describe the grafting of poly(fluorene), poly(fluorenevinylene), and a poly(fluorene-ethynylene-phenylene) onto modified cellulose paper substrates using Suzuki, Heck, and Sonogashira-type polymerizations, respectively. The application of these three widely used coupling chemistries to surface-grafted conjugated polymers on cellulose provides a general route to cellulose-based hybrid materials tunable with almost any aromatic repeat structure for specific applications., QC 20110623

Organic solar cells show great promise as an economically and environmentally friendly technology to utilize solar energy because of their simple fabrication processes and minimal material usage. However, new innovations and breakthroughs are needed for organic solar cell technology to become competitive in the future. This article reviews research efforts and accomplishments focusing on three issues: power conversion efficiency, device stability and processability for mass production, followed by an outlook for optimizing OSC performance through device engineering and new architecture designs to realize next generation organic solar cells.

We report the Heck coupling of 2-vinyl-4,5-dicyanoimidazole (vinazene) with selected di- and trihalo aromatics in an effort to prepare linear and branched electron-accepting conjugated materials for application in organic electronics. By selecting the suitable halo-aromatic moiety, it is possible to tune the HOMO - LUMO energy levels, absorption, and emission properties for a specific application. In this regard, materials with strong photoluminescence from blue → green → red are reported that may have potential application in organic light-emitting diodes (OLEDs). Furthermore, derivatives with strong absorption in the visible spectrum, coupled with favorable HOMO-LUMO levels, have been used to prepare promising organic photovoltaic devices (OPVs) when combined with commercially available semiconducting donor polymers.

In the present project for the first time the polyaniline, polydifenilamine, polycarbazole of the set structure (including functional groups) and morphology of nano-sized particles with the optimal radiowaves absorption rate was elaborated. From the obtained semiconducting polymers, elastic and flexible composite materials including nano-composites were developed. We find out that the silicon compositions and nano-sized compositions have the highest adsorption properties. We suggest that the development of these nano-sized compositions and their derivatives is very promising from the point of obtaining new coating materials, having higher adsorption properties. However, in the framework of present project, our technical possibility did not allow us to study their adsorption properties at different frequency of modulated and non-modulated MW, as well as their multisided physicochemical and structural characteristics. For the study of MW adsorption properties of synthetised polymers film a new microcalorimetric and radiometric methods were elaborated. However, for obtaining more precise data on specific adsorption rate of MW at different frequency for different materials these new methods need the future modification. For estimation of the protective (shielding) properties of organisms from non-thermal biological effect of MW, two extrasensitive methods were used: a) luminescent method measuring the hydrogen peroxide (H2O2) formation in shielded and non-shielded water samples and b) isolated snail heart muscle contractility. Thus, by performing the present project it was established the necessary theoretical chemo-technical basis for synthesis of aromatic polymers and for studying their MW adsorption properties from the point of public health., ISTC Project no. 1571P.

Two types of highly soluble oligothiophene based swivel cruciform are presented as semiconducting materials in OFETs. Transistor made from one of these oligomers exhibited mobilities of more than 0.01 cm^2/Vs and current on/off ratio of >105. This is among the highest values reported to date for wet processed OFETs utilizing oligothiophenes. In fact, the OFET-mobilities are comparable to values extracted from pulse-radiolysis time resolved microwave conductivity (PR-TRMC) experiment, indicating that carrier trapping is insignificant. In depth examination of the morphological, optical characteristics and thermal stability of the materials were carried to obtain information on the packing of the oligomers in the layer. Finally, the correlation between the transistor performance and the crystallinity of the layers is addressed.

Dendritic encapsulation of poly(phenyleneethynylene)s or PPEs has been shown to enhance photoluminescent quantum efficiency and facilitate energy transfer by funneling photonic energy absorbed on the dendron periphery efficiently to the conjugated polymeric core. The research presented herein focuses on incorporating degradable dendron onto PPEs, examining whether or not similar benefits were conferred upon the proposed system and controlling polymer luminescence through the elimination of the insulating macromolecules. PPEs appended with disassembling dendrons of various generation sizes were synthesized and their optical properties studied. Polymer luminescence was then quenched via chemical degradation of the disassembling dendrons. Furthermore, the macromolecules resulting from disassembly exhibited tunable luminescence properties upon manipulation of pH. Consequently, it was determined that polymer luminescence could be controlled upon forming phenolic moieties along the PPE backbone. Tunable emission was later realized in the thin film as well through the integration of crosslinkable dendrons onto the polymer core.Recently, helical synthetic linear polymers have demonstrated the ability to facilitate stereoselective processes such as catalysis, recognition and separation. Consequently, it has become increasingly desirable to develop new platforms capable of imparting asymmetry. The work presented herein describes the synthesis of a series of polymers based upon chiral hydrobenzoin and the subsequent conformational analysis performed on these materials. It was envisioned that these polymeric materials might inherently possess conformational asymmetry and as result could be able to impart configurationally chirality by introducing a diastereomeric bias for the formation of one enantiomer over the other during the course of the reaction.

Two types of highly soluble oligothiophene based swivel cruciform are presented as semiconducting materials in OFETs. Transistor made from one of these oligomers exhibited mobilities of more than 0.01 cm^2/Vs and current on/off ratio of >105. This is among the highest values reported to date for wet processed OFETs utilizing oligothiophenes. In fact, the OFET-mobilities are comparable to values extracted from pulse-radiolysis time resolved microwave conductivity (PR-TRMC) experiment, indicating that carrier trapping is insignificant. In depth examination of the morphological, optical characteristics and thermal stability of the materials were carried to obtain information on the packing of the oligomers in the layer. Finally, the correlation between the transistor performance and the crystallinity of the layers is addressed.

Two types of highly soluble oligothiophene based swivel cruciform are presented as semiconducting materials in OFETs. Transistor made from one of these oligomers exhibited mobilities of more than 0.01 cm^2/Vs and current on/off ratio of >105. This is among the highest values reported to date for wet processed OFETs utilizing oligothiophenes. In fact, the OFET-mobilities are comparable to values extracted from pulse-radiolysis time resolved microwave conductivity (PR-TRMC) experiment, indicating that carrier trapping is insignificant. In depth examination of the morphological, optical characteristics and thermal stability of the materials were carried to obtain information on the packing of the oligomers in the layer. Finally, the correlation between the transistor performance and the crystallinity of the layers is addressed.

A series of detailed studies is presented in which heat-induced interdiffusion is used to create a gradient bulk-heterojunction of 2-methoxy-5-(2(')-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) copolymer and C-60. Starting from a bilayer of spin-cast MEH-PPV and sublimed C-60, films are heated in the vicinity of the glass transition temperature of the polymer to induce an interdiffusion of polymer and fullerene. Variation of the polymer layer thickness shows that the photocurrents increase with decreasing layer thickness within the examined thickness regime as transport of the separated charges out of the film is improved. The interdiffusion was observed in situ by monitoring the photocurrents during the heating process and exhibited a rapid rise during the first five minutes. Cross-sectional transmission electron microscopy studies show that C-60 forms clusters of up to 30 nm in diameter in the polymer bulk of the interdiffused devices. This clustering of the fullerene molecules puts a significant constraint on the interdiffusion process that can be alleviated by use of donor-acceptor combinations with better miscibility.

A series of detailed studies is presented in which heat-induced interdiffusion is used to create a gradient bulk-heterojunction of 2-methoxy-5-(2(')-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) copolymer and C-60. Starting from a bilayer of spin-cast MEH-PPV and sublimed C-60, films are heated in the vicinity of the glass transition temperature of the polymer to induce an interdiffusion of polymer and fullerene. Variation of the polymer layer thickness shows that the photocurrents increase with decreasing layer thickness within the examined thickness regime as transport of the separated charges out of the film is improved. The interdiffusion was observed in situ by monitoring the photocurrents during the heating process and exhibited a rapid rise during the first five minutes. Cross-sectional transmission electron microscopy studies show that C-60 forms clusters of up to 30 nm in diameter in the polymer bulk of the interdiffused devices. This clustering of the fullerene molecules puts a significant constraint on the interdiffusion process that can be alleviated by use of donor-acceptor combinations with better miscibility.

A series of detailed studies is presented in which heat-induced interdiffusion is used to create a gradient bulk-heterojunction of 2-methoxy-5-(2(')-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) copolymer and C-60. Starting from a bilayer of spin-cast MEH-PPV and sublimed C-60, films are heated in the vicinity of the glass transition temperature of the polymer to induce an interdiffusion of polymer and fullerene. Variation of the polymer layer thickness shows that the photocurrents increase with decreasing layer thickness within the examined thickness regime as transport of the separated charges out of the film is improved. The interdiffusion was observed in situ by monitoring the photocurrents during the heating process and exhibited a rapid rise during the first five minutes. Cross-sectional transmission electron microscopy studies show that C-60 forms clusters of up to 30 nm in diameter in the polymer bulk of the interdiffused devices. This clustering of the fullerene molecules puts a significant constraint on the interdiffusion process that can be alleviated by use of donor-acceptor combinations with better miscibility.

Táto diplomová práca sa zaoberá analýzou povrchových vlastností s dôrazom na drsnosť povrchu a hydrofilitu tenkých vrstiev pripravených z čistých a modifikovaných organických konjugovaných polymérov na báze poly(3,4-etyléndioxytiofénu) (PEDOT) z hľadiska ich potencionálneho využitia v bioelektronických aplikáciach. Hlavným predmetom práce bola povrchová analýza materiálu poly(3,4-etyléndioxytiofén):poly(dodecylbenzosulfonát) (PEDOT:DBSA) a ďalej bol pozorovaný vplyv prídavku sekundárnych dopantov ako (3-glycidyloxypropyl)trimetoxysilánu (GOPS), etylénglykolu (EG) a dodecylbenzosulfonovej kyseliny (DBSA) na zmenu povrchových vlastností polyméru PEDOT:DBSA, s cieľom pripraviť materiál s optimalizovanými povrchovými vlastnosťami pre bioelektronické aplikácie. V prvej časti experimentálnej činnosti bola skúmaná povrchová energia tenkých vrstiev pomocou stanovenia kontaktných uhlov. V druhej časti práce boli pozorované a porovnané morfologické vlastnosti povrchov pripravených tenkých vrstiev pomocou mikroskopie atomárnych síl (AFM), skenovacej elektrónovej mikroskopie (SEM) a profilometrie., This master's thesis deals with the analysis of surface properties, with an emphasis on surface roughness and hydrophilicity of thin films prepared from pure and modified organic conjugated polymers based on poly(3,4-ethylenedioxythiophene) (PEDOT) for their potential use in bioelectronic applications. The main subject of the work was the surface analysis of the material poly(3,4-ethylenedioxythiophene):poly(dodecylbenzenesulfonate) (PEDOT:DBSA), and the influence of secondary dopants such as (3-glycidyloxypropyl)trimethoxysilane (GOPS), ethylene glycol (EG), and dodecylbenzenesulfonic acid (DBSA) on the change of surface properties of the PEDOT:DBSA polymer was also observed, with the aim of preparing a material with optimized surface properties for bioelectronic applications. In the first part of the experimental work, the surface energy of thin films was investigated by determining contact angles. In the second part of the work, the morphological properties of the surfaces of the prepared thin films were observed and compared using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry.

Táto diplomová práca sa zaoberá analýzou povrchových vlastností s dôrazom na drsnosť povrchu a hydrofilitu tenkých vrstiev pripravených z čistých a modifikovaných organických konjugovaných polymérov na báze poly(3,4-etyléndioxytiofénu) (PEDOT) z hľadiska ich potencionálneho využitia v bioelektronických aplikáciach. Hlavným predmetom práce bola povrchová analýza materiálu poly(3,4-etyléndioxytiofén):poly(dodecylbenzosulfonát) (PEDOT:DBSA) a ďalej bol pozorovaný vplyv prídavku sekundárnych dopantov ako (3-glycidyloxypropyl)trimetoxysilánu (GOPS), etylénglykolu (EG) a dodecylbenzosulfonovej kyseliny (DBSA) na zmenu povrchových vlastností polyméru PEDOT:DBSA, s cieľom pripraviť materiál s optimalizovanými povrchovými vlastnosťami pre bioelektronické aplikácie. V prvej časti experimentálnej činnosti bola skúmaná povrchová energia tenkých vrstiev pomocou stanovenia kontaktných uhlov. V druhej časti práce boli pozorované a porovnané morfologické vlastnosti povrchov pripravených tenkých vrstiev pomocou mikroskopie atomárnych síl (AFM), skenovacej elektrónovej mikroskopie (SEM) a profilometrie., This master's thesis deals with the analysis of surface properties, with an emphasis on surface roughness and hydrophilicity of thin films prepared from pure and modified organic conjugated polymers based on poly(3,4-ethylenedioxythiophene) (PEDOT) for their potential use in bioelectronic applications. The main subject of the work was the surface analysis of the material poly(3,4-ethylenedioxythiophene):poly(dodecylbenzenesulfonate) (PEDOT:DBSA), and the influence of secondary dopants such as (3-glycidyloxypropyl)trimethoxysilane (GOPS), ethylene glycol (EG), and dodecylbenzenesulfonic acid (DBSA) on the change of surface properties of the PEDOT:DBSA polymer was also observed, with the aim of preparing a material with optimized surface properties for bioelectronic applications. In the first part of the experimental work, the surface energy of thin films was investigated by determining contact angles. In the second part of the work, the morphological properties of the surfaces of the prepared thin films were observed and compared using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry.

Táto diplomová práca sa zaoberá analýzou povrchových vlastností s dôrazom na drsnosť povrchu a hydrofilitu tenkých vrstiev pripravených z čistých a modifikovaných organických konjugovaných polymérov na báze poly(3,4-etyléndioxytiofénu) (PEDOT) z hľadiska ich potencionálneho využitia v bioelektronických aplikáciach. Hlavným predmetom práce bola povrchová analýza materiálu poly(3,4-etyléndioxytiofén):poly(dodecylbenzosulfonát) (PEDOT:DBSA) a ďalej bol pozorovaný vplyv prídavku sekundárnych dopantov ako (3-glycidyloxypropyl)trimetoxysilánu (GOPS), etylénglykolu (EG) a dodecylbenzosulfonovej kyseliny (DBSA) na zmenu povrchových vlastností polyméru PEDOT:DBSA, s cieľom pripraviť materiál s optimalizovanými povrchovými vlastnosťami pre bioelektronické aplikácie. V prvej časti experimentálnej činnosti bola skúmaná povrchová energia tenkých vrstiev pomocou stanovenia kontaktných uhlov. V druhej časti práce boli pozorované a porovnané morfologické vlastnosti povrchov pripravených tenkých vrstiev pomocou mikroskopie atomárnych síl (AFM), skenovacej elektrónovej mikroskopie (SEM) a profilometrie., This master's thesis deals with the analysis of surface properties, with an emphasis on surface roughness and hydrophilicity of thin films prepared from pure and modified organic conjugated polymers based on poly(3,4-ethylenedioxythiophene) (PEDOT) for their potential use in bioelectronic applications. The main subject of the work was the surface analysis of the material poly(3,4-ethylenedioxythiophene):poly(dodecylbenzenesulfonate) (PEDOT:DBSA), and the influence of secondary dopants such as (3-glycidyloxypropyl)trimethoxysilane (GOPS), ethylene glycol (EG), and dodecylbenzenesulfonic acid (DBSA) on the change of surface properties of the PEDOT:DBSA polymer was also observed, with the aim of preparing a material with optimized surface properties for bioelectronic applications. In the first part of the experimental work, the surface energy of thin films was investigated by determining contact angles. In the second part of the work, the morphological properties of the surfaces of the prepared thin films were observed and compared using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry.