Este trabalho tem como objetivo estudar filmes finos de polímeros semicondutores preparados a partir de dispersões coloidais de poli(3,4 etilenodioxitiofeno)/poli(estirenosulfonato de sódio) (PEDOT:PSS), submetidos a tratamentos físico-químicos para alterar as suas características morfológicas e estruturais, melhorando a condutividade elétrica e mantendo um bom nível de transmitância óptica na faixa de comprimento de onda da luz visível. Foram utilizadas no estudo duas dispersões coloidais comerciais de PEDOT:PSS, identificadas como P1 e P2. O P1 descrito pelo fornecedor como de grau condutivo (1 S.cm-1) e P2 de grau altamente condutivo (<100 ?/?). Foram produzidos filmes finos em três procedimentos diferentes e realizadas medidas de resistência elétrica e transmitância óptica. Na primeira série, os filmes foram preparados por spin-coating da dispersão coloidal original de PEDOT:PSS e seguidos pelo recozimento na estufa. Na segunda série, foi adicionado à dispersão coloidal original de PEDOT:PSS um solvente orgânico polar, o dimetilsulfóxido (DMSO), após a centrifugação, a dispersão sobrenadante foi depositada para a preparação de filmes finos como descrito na etapa anterior. Na terceira série, à parte sobrenadante da dispersão coloidal de PEDOT:PSS preparada na segunda série, foi adicionada uma solução precursora de nanopartículas de prata (Tinta Reativa de Prata) (TRP2) e a dispersão coloidal foi depositada para formar filmes finos como descrito anteriormente. As resistividades elétricas com os valores mais significativos foram de filmes de P1 e de P2 depositados a 2000 rpm. Para P1 foram observadas resistividades de 1,37 ?.cm, 0,34 ?.cm e 0,18 ?.cm, para as dispersões coloidais P1 original, P1 tratado com DMSO e P1 tratado com DMSO/TRP2, respectivamente, correspondendo a uma redução de 87% do valor da resistência elétrica da primeira para a terceira série. A transmitância óptica dos filmes a 550 nm se manteve entre 80~90% para todas as séries, nas análises por espectroscopia no UV-Vis. Para os filmes de P2, depositadas a 2000 rpm, as resistividades elétricas nos filmes foram de 0,76 ?.cm, 0,015 ?.cm e 0,0012 ?.cm, para P2 original, P2 tratado com DMSO e P2 tratado com DMSO/TRP2, respectivamente, correspondendo a uma redução de 99,8% do valor da resistência elétrica da primeira para a terceira série. O valor da transmitância óptica dos filmes a 550 nm manteve-se entre 85~90% na primeira e segunda série, entretanto para os filmes da terceira série, devido à presença da fase prata grosseira, reduziu-se para o intervalo entre 40~60%. / This work aims to study thin films of semiconducting polymers prepared from colloidal dispersions of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT: PSS), submitted to physicochemical treatments in order to change their microstructural features and improve their electrical conductivity, while maintaining a good level of optical transmittance in the visible wavelength range. Two types of commercial colloidal dispersions of PEDOT:PSS were used in the study, named as P1 and P2. The P1 is described as a conductive grade (250 ?/?) and P2, highly conductive grade (<100 ?/?). Thin films were produced from colloidal dispersions through three different procedures and their electrical resistance and optical transmittance were measured. In the first series, films were prepared by spin-coating of the PEDOT: PSS pristine colloidal dispersion, followed by annealing in the oven. In the second series, to the pristine colloidal dispersion of PEDOT:PSS a polar organic solvent dimethylsulfoxide (DMSO) was added, then after centrifugation, the supernatant colloidal dispersion was deposited to form thin films as described previously. In the third series, to the supernatant colloidal dispersion of PEDOT:PSS prepared in the second series, a silver nanoparticle precursor solution (Reactive Silver Ink) (TRP2) was added and the colloidal dispersion was deposited to form thin films as described previously. Electrical resistivity with the most significant values from P1 and P2 films deposited at 2000 rpm. For the films from P1, 1.37 ?.cm, 0.34 ?.cm and 0.18 ?.cm were observed, for pristine colloidal dispersion, with DMSO and with DMSO and TRP2, respectively; corresponding to a reduction of 87% of the electrical resistance from the first to the third series. The optical transmittance of films at 550 nm, as measured by UV-Vis spectroscopy, was maintained in the range 80~90% for all series. For the films from P2, the electrical resistances were observed to vary from 0.76 ?.cm to 0.015 ?.cm and 0.0012 ?.cm, for pristine P2 colloidal dispersion, after DMSO addition and with DMSO and TRP2, respectively, corresponding to a reduction of 99.8% in the electrical resistance from the first series to the third one. The optical transmittance of films at 550 nm was observed to remain in the range 85~90% for the first and second series, while the third series, due to the massive presence of a coarse silver phase, dropped to the range 40~60%.

In organischen Leuchtdioden (OLEDs) werden üblicherweise anorganische Materialien wie Indium-Zinn-Oxid (ITO) als transparente leitfähige Anoden verwendet. ITO besitzt allerdings eine geringe Austrittsarbeit und kann deshalb Löcher nicht effizient in organische Materialien injizieren. Weiterhin ist ITO eine Quelle von Indium- und Sauerstoff-Ionen, die in die organischen Materialien diffundieren und dort mit der Organik reagieren bzw. als effiziente Exzitonenvernichter agieren. Eine mögliche Alternative zu ITO sind hoch leitfähige Polymere wie PEDOT:PSS und Polyaniline. Diese Studie untersucht die physikalischen Aspekte von OLEDs mit elektrisch dotierten Ladungstransportschichten auf Polymeranoden. Hierbei werden pin-OLEDs auf ITO mit OLEDs auf Polymeranoden direkt verglichen und mit dem derzeitigen Stand der Technik diskutiert. Die Untersuchungen zeigen, daß OLEDs auf PEDOT:PSS Anoden eine höhere Effizienz erreichen als OLEDs auf ITO Anoden. Um die physikalischen Unterschiede von pin-OLEDs auf ITO und PEDOT:PSS Anoden zu untersuchen, werden optische Simulationen sowie Ultraviolett-Photoemissions-Spektroskopie (UPS) und Lebensdauermessungen durchgeführt. Die optischen Simulationen zeigen, daß die Polymeranoden durch ihren geringen Brechungsindex eine höhere Lichtauskopplungseffizienz besitzen als OLEDs mit einer ITO-Anode. Außerdem finden UPS-Messungen eine geringere Löcherinjektionsbarriere von PEDOT:PSS zu dotierten und undotierten Lochtransportschichten. Aus diesem Grund ist die Ladungsträgerinjektion an der Anoden-Organik-Grenzfläche effizienter, wenn eine PEDOT:PSS-Anode verwendet wird. Lebensdauermessungen von pin-OLEDs auf PEDOT:PSS-Anoden zeigen eine vergleichbare Lebensdauer zu OLEDs auf ITO-Anoden. Die Ergebnisse dieser Untersuchungen zeigen eindeutig, daß Polymeranoden das Potential besitzen, ITO als Anode zu ersetzen und zusätzlich die OLED-Effizienz zu erhöhen.

Este trabalho tem como objetivo estudar filmes finos de polímeros semicondutores preparados a partir de dispersões coloidais de poli(3,4 etilenodioxitiofeno)/poli(estirenosulfonato de sódio) (PEDOT:PSS), submetidos a tratamentos físico-químicos para alterar as suas características morfológicas e estruturais, melhorando a condutividade elétrica e mantendo um bom nível de transmitância óptica na faixa de comprimento de onda da luz visível. Foram utilizadas no estudo duas dispersões coloidais comerciais de PEDOT:PSS, identificadas como P1 e P2. O P1 descrito pelo fornecedor como de grau condutivo (1 S.cm-1) e P2 de grau altamente condutivo (<100 ?/?). Foram produzidos filmes finos em três procedimentos diferentes e realizadas medidas de resistência elétrica e transmitância óptica. Na primeira série, os filmes foram preparados por spin-coating da dispersão coloidal original de PEDOT:PSS e seguidos pelo recozimento na estufa. Na segunda série, foi adicionado à dispersão coloidal original de PEDOT:PSS um solvente orgânico polar, o dimetilsulfóxido (DMSO), após a centrifugação, a dispersão sobrenadante foi depositada para a preparação de filmes finos como descrito na etapa anterior. Na terceira série, à parte sobrenadante da dispersão coloidal de PEDOT:PSS preparada na segunda série, foi adicionada uma solução precursora de nanopartículas de prata (Tinta Reativa de Prata) (TRP2) e a dispersão coloidal foi depositada para formar filmes finos como descrito anteriormente. As resistividades elétricas com os valores mais significativos foram de filmes de P1 e de P2 depositados a 2000 rpm. Para P1 foram observadas resistividades de 1,37 ?.cm, 0,34 ?.cm e 0,18 ?.cm, para as dispersões coloidais P1 original, P1 tratado com DMSO e P1 tratado com DMSO/TRP2, respectivamente, correspondendo a uma redução de 87% do valor da resistência elétrica da primeira para a terceira série. A transmitância óptica dos filmes a 550 nm se manteve entre 80~90% para todas as séries, nas análises por espectroscopia no UV-Vis. Para os filmes de P2, depositadas a 2000 rpm, as resistividades elétricas nos filmes foram de 0,76 ?.cm, 0,015 ?.cm e 0,0012 ?.cm, para P2 original, P2 tratado com DMSO e P2 tratado com DMSO/TRP2, respectivamente, correspondendo a uma redução de 99,8% do valor da resistência elétrica da primeira para a terceira série. O valor da transmitância óptica dos filmes a 550 nm manteve-se entre 85~90% na primeira e segunda série, entretanto para os filmes da terceira série, devido à presença da fase prata grosseira, reduziu-se para o intervalo entre 40~60%. / This work aims to study thin films of semiconducting polymers prepared from colloidal dispersions of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT: PSS), submitted to physicochemical treatments in order to change their microstructural features and improve their electrical conductivity, while maintaining a good level of optical transmittance in the visible wavelength range. Two types of commercial colloidal dispersions of PEDOT:PSS were used in the study, named as P1 and P2. The P1 is described as a conductive grade (250 ?/?) and P2, highly conductive grade (<100 ?/?). Thin films were produced from colloidal dispersions through three different procedures and their electrical resistance and optical transmittance were measured. In the first series, films were prepared by spin-coating of the PEDOT: PSS pristine colloidal dispersion, followed by annealing in the oven. In the second series, to the pristine colloidal dispersion of PEDOT:PSS a polar organic solvent dimethylsulfoxide (DMSO) was added, then after centrifugation, the supernatant colloidal dispersion was deposited to form thin films as described previously. In the third series, to the supernatant colloidal dispersion of PEDOT:PSS prepared in the second series, a silver nanoparticle precursor solution (Reactive Silver Ink) (TRP2) was added and the colloidal dispersion was deposited to form thin films as described previously. Electrical resistivity with the most significant values from P1 and P2 films deposited at 2000 rpm. For the films from P1, 1.37 ?.cm, 0.34 ?.cm and 0.18 ?.cm were observed, for pristine colloidal dispersion, with DMSO and with DMSO and TRP2, respectively; corresponding to a reduction of 87% of the electrical resistance from the first to the third series. The optical transmittance of films at 550 nm, as measured by UV-Vis spectroscopy, was maintained in the range 80~90% for all series. For the films from P2, the electrical resistances were observed to vary from 0.76 ?.cm to 0.015 ?.cm and 0.0012 ?.cm, for pristine P2 colloidal dispersion, after DMSO addition and with DMSO and TRP2, respectively, corresponding to a reduction of 99.8% in the electrical resistance from the first series to the third one. The optical transmittance of films at 550 nm was observed to remain in the range 85~90% for the first and second series, while the third series, due to the massive presence of a coarse silver phase, dropped to the range 40~60%.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-05-03T14:10:04Z No. of bitstreams: 1 pedrovictoralmeidapessanha.pdf: 2319111 bytes, checksum: 6718ea3032cf8200f1974eed7e9ba421 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-09-03T15:57:11Z (GMT) No. of bitstreams: 1 pedrovictoralmeidapessanha.pdf: 2319111 bytes, checksum: 6718ea3032cf8200f1974eed7e9ba421 (MD5) / Made available in DSpace on 2018-09-03T15:57:11Z (GMT). No. of bitstreams: 1 pedrovictoralmeidapessanha.pdf: 2319111 bytes, checksum: 6718ea3032cf8200f1974eed7e9ba421 (MD5) Previous issue date: 2018-02-26 / O PEDOT:PSS (poli(3,4-etilenodioxitiofeno):poli(estirenossulfonato)) é um polímero condutor da classe dos politiofenos amplamente utilizado como camada aceitadora de lacunas na confecção de dispositivos fotovoltaicos. Neste trabalho estudou-se via espectroscopia Raman ressonante, SERS e de absorção UV-VIS-NIR as propriedades ópticas do PEDOT:PSS puro e na presença de AuNPs. O PEDOT:PSS foi sintetizado por polimerização oxidativa com persulfato de sódio e da mistura de persulfato com sulfato férrico hidratado, seguida de purificação com resina de troca iônica ou diálise em água deionizada. A evolução das sínteses foi monitorada através de espectroscopia UV-VIS-NIR, pela qual evidenciou-se a existência de dois regimes eletrônicos distintos para o processo de síntese do PEDOT:PSS, com uma cinética de reação mais rápida para as sínteses realizadas com a mistura de sais. Os polímeros formados apresentam elevado grau de oxidação, caracterizado pela forte absorção de radiação eletromagnética pelas espécies que contém pólarons em torno de 800 nm e bipólarons em cerca de 950 nm. Verificou-se a eficiência dos métodos de purificação por agitação com resina de troca iônica e diálise em água deionizada. A purificação por diálise mostrou-se distinta da obtida por agitação com resinas de troca iônica, rendendo polímeros menos dopados que aqueles purificados com resinas, o que foi atribuído à reorganização das cadeias do polímero mediante a migração via difusão simples e pressão osmótica de íons pequenos e das menores cadeias de PSS para a solução de alimentação. A evolução do perfil vibracional foi monitorada através da espectroscopia Raman ressonante com comprimento de excitação de 633, 785 e 1064 nm. A variação para região de maior número de onda das bandas atribuídas ao grupo tiofeno, responsável pela alta deslocalização de carga das espécies condutoras, indicou que os polímeros formados possuem alto grau de oxidação, com a existência de dois regimes para a evolução do perfil vibracional. A dopagem que ocorre durante o processo de síntese favorece a formação das espécies mais oxidadas na matriz polimérica, e o processo de purificação do PEDOT:PSS altera a estrutura do polímero. Filmes finos e opacos foram obtidos, e apresentaram resistência de folha comparável àquela obtida com polímeros disponíveis comercialmente. Observou-se ainda, através da espectroscopia SERS de cadeias pequenas de PEDOT:PSS adsorvidas sobre nanopartículas de ouro, com radiação incidente de 1064 e 785 nm, a intensificação de modos vibracionais característicos das espécies oxidadas, mais próximos da superfície metálica, embora não exista evidência de interação específica entre o polímero e as nanoestruturas. / PEDOT: PSS is a conductive polymer of the polythiophene class widely used as the hole injection layer in photovoltaic devices. In this work, resonance Raman, SERS and UVVIS-NIR spectroscopies were used to study the optical properties of pure PEDOT: PSS and modified with AuNPs. PEDOT: PSS was synthesized via oxidative polymerization with sodium persulfate and with persulfate mixture with ferric sulfate hydrate, followed by purification with ion exchange resin or dialysis in deionized water. The evolution of the syntheses was monitored via UV-VIS-NIR spectroscopy, in which the existence of two distinct electronic regimes for the synthesis process was evidenced, with a faster kinetics for the syntheses performed with the mixture of salts. The polymers formed exhibited a high level of oxidation, characterized by a strong absorption of electromagnetic radiation by the species that contain polarons and bipolarons. The efficiency of purification methods with ion exchange resin compared to dialysis in deionized water was also evaluated. Purification by dialysis proved to be distinct from stirring with ion exchange resins, yielding less doped polymers than those purified with resins, which was attributed to the rearrangement of the polymer chains by migration of small ions and the small PSS chains for the feed solution. The evolution of the vibrational profile was monitored by resonant Raman spectroscopy with excitation wavelength of 633, 785 and 1064 nm. The variation for the region of high wavenumber of the bands attributed to the thiophene group, responsible for the high delocalization of charge in the conducting species, indicated that the polymers formed have a high degree of oxidation, with the existence of two regimes for the evolution of the vibrational profile. Doping that occurs during the synthesis process favored the formation of more oxidized species in the polymeric matrix, and the purification process of PEDOT: PSS changed the structure of the polymer. Thin and opaque films were obtained, and showed sheet resistance comparable to that obtained with commercially available polymers. It was also observed, through SERS spectroscopy of small chains of PEDOT:PSS adsorbed on gold nanoparticles, using incident radiation of 1064 and 785 nm, the intensification of vibrational modes characteristic of the oxidized species, probably near the metallic surface, although there was no evidence of specific interaction between the polymer and the nanostructures.

Major efforts have been spent during recent years in worldwide attempts to achieve an electronic paper technology; the common name for novel flexible displays utilizing substrates such as paper, plastics or thin metal sheets. Various kinds of technology are available that potentially will be used for an electronic paper, which differs from each other mainly with respect to the choice of active materials, substrates and manufacturing techniques. There are many applications for electronic paper technology, ranging from high-resolution displays used in electronic books to updateable large-area billboards. The latter suggests a novel electronic display function that could extend the utilization of cellulose-based paper, which is one of the most common materials ever produced by mankind, by using the paper as a thin and flexible carrier. The requirement for fast update speed in such large area applications would probably be a bit more relaxed compared to traditional display technologies, while low-power consumption and bi-stability are among the factors that should be further emphasized, together with the utilization of well-established printing techniques to enable low-cost manufacturing of the displays. The choice of active materials is therefore crucial in order to reach these objectives in reality and this paves the way for printable conjugated polymers with electrochromic properties. Chemical synthesis of these materials during the last decades has resulted in a vast variety of electrochromic polymers with custom-tailored functionality covering a broad range of optical absorption and electrical conductivities. This thesis review the studies done on the electrochemical switching of poly(3,4-ethylenedioxythiophene) (PEDOT). For this material both the electrical conductivity and the optical absorption is controlled by the oxidation state. Active matrix addressed displays that are printed on flexible substrates have been obtained by arranging electrochemical smart pixels, based on the combination of electrochemical transistors and electrochromic display cells, into cross-point matrices. The resulting polymer-based active-matrix displays are operated at low voltages and the same active material can be used in electrochemical transistors and conducting lines and in electrochromic display cells employing the electronic and the opto-electonic properties of the material, respectively. In addition to this, a switchable optical polarizer is briefly discussed. This is a device utilizing electrochromism of stretch-aligned polyaniline (PANI). The combination of two identical devices in a vertical architecture, orthogonally oriented with respect to each other, results in a filter in which the orientation of the polarized optical absorption is governed by the voltage polarity applied to the device. / Report code: LiU-TEK-LIC- 2006:18

O presente trabalho apresenta resultados de preparação, caracterização e aplicação de membranas de DNA e DNA-PEDOT:PSS como material transportador de buracos (HTM) em células solares sensibilizadas por corante (DSSC). As análises por UV-Vis das amostras revelaram 80% de transparência em 600 nm para o DNA-isolado e diminuindo para 62% em 550 nm para o DNA-2% PEDOT:PSS. As análises das amostras por FTIR revelaram os picos característicos tanto do DNA quanto do PEDOT:PSS, confirmando a incorporação deste último nas membranas. Os resultados de análises térmicas DSC evidenciaram a presença de Tg em -67ºC e o seu desaparecimento com a adição de PEDOT:PSS na formulação de HTM. As análises de TGA mostraram o aumento da estabilidade das amostras com a adição de PEDOT:PSS atingindo 200ºC. Todas as amostras apresentaram 19% de resíduos em 900ºC. As membranas a base de DNA também foram submetidas às medidas de condutividade iônica revelando o maior valor de 3,2x10-4 S/cm2 em temperatura ambiente e aumentando para 0,1x10-3 S/cm2 em temperatura de 75ºC, para a amostra de DNA-isolado. As amostras de DNA-PEDOT:PSS mostraram valores de condutividade de 4,67x10-5 S/cm2 para a amostra DNA -2% PEDOT:PSS, em temperatura ambiente e diminuíram com o aumento de porcentagem de PEDOT:PSS. Dos difratogramas de raios-X observou-se um aumento da cristalinidade das amostras com a adição de PEDOT:PSS sendo o maior valor encontrado de 77,8% foi para a amostra de DNA-10% PEDOT:PSS. As DSSCs apresentaram a diminuição de eficiência solar após a introdução de membranas de DNA de 2.04% para 1,49% fenômeno explicado em termos de aumento de reflectância e rugosidade das amostras que dificultou o transporte de carga e recombinação do par redox do eletrólito nas células solares sensibilizadas por corante. / This paper presents results of preparation, characterization and application of DNA and DNA-PEDOT:PSS-based membranes as hole-carrier material (HTM) in dye-sensitized solar cells (DSSC). The UV-Vis analysis of the samples revealed 80% of transparency at 600 nm for the isolated DNA and 62% at 550 nm for DNA-2% PEDOT:PSS. The FTIR analysis of the samples showed characteristic peaks of both the DNA and PEDOT:PSS, confirming its incorporation into membranes. The results of DSC analysis revealed the presence of Tg at -67ºC and its disappearance with the addition of PEDOT:PSS to the formulation of HTM. The TGA analysis showed increased stability of the samples with the addition of PEDOT:PSS reaching 200ºC. All samples showed 19% of ashes at 900ºC. The DNA-based membranes were also subjected to ionic conductivity measurements showing the highest value of 3.2x10-4 S/cm2 at room temperature and of 0.1x10-3 S/cm2 at 75ºC for the isolated DNA. Samples of DNA-PEDOT:PSS showed conductivity value of 4.67x10-5 S/cm2 for DNA-2% PEDOT:PSS sample at room temperature which decreased with increasing percentage of PEDOT:PSS. X-ray diffraction revealed an increase of the crystallinity of the samples with the addition of PEDOT:PSS and the highest value found was 77.8% for the sample of DNA-10% PEDOT:PSS. The DSSCs showed a reduction of solar efficiency from 2.04% to 1.49% after the introduction of DNA-based membranes. This phenomenon was explained in terms of increased reflectance and surface roughness of the samples that difficult the transport and recombination of charge carrier species.

With regard to the recent interests in smart textiles,this research activity has been conducted with the aim of producing a pattern changing design on textiles. In order to fulfill the demands of such dynamic patterns a combinationof conductive polymer and thermochromic pigments wereused. The textile substrate was coated by conductive polymer dispersion(PEDOT:PSS) and it was followed with printing thermochromic pigments on the surface of coating.The driving force of such thermochromic reaction has to be provided by the heat generated from conductive layer dueto the current of electricity passing through the conductivelayer. These experiments were continued by changing thecoating recipe in order to achieve the highest possible electrical resistance,which leads to the best initiation ofthermochromic reactions. / Program: Master programme in Textile Technology

Les surfaces manufacturées par l’homme sont facilement colonisées par des micro-organismes, qui limitent leurs performances. Ici, nous caractérisons en milieu aqueux, le polymère électro-actif poly(3,4-éthylènedioxythiophène):polystyrène sulfonate, afin d’évaluer son aptitude à limiter l’encrassement biologique en milieu marin. Premièrement, nous nous intéressons à l’évolution de sa mouillabilité et de ses propriétés mécaniques en fonction de sa composition chimique quand il est vieilli ou stimulé électriquement. Nos mesures d’angle de contact sur 6 mois révèlent que, indépendamment du taux de réticulant couramment utilisé pour stabiliser le polymère, son interface change grandement avec le temps et les conditions de caractérisation ou de stockage (influence de l’humidité et de la température). Puis, via des études de microscopie en champ proche, nous quantifions son taux d’hydratation et son élasticité lorsqu’il est immergé. Semblable aux hydrogels, il peut absorber jusqu’à 10 fois son volume et présente un module d’Young inférieur à 1 MPa. Mais le réticulant impacte sévèrement ces propriétés sans assurer une excellente stabilité de l’interface. Enfin, siège de phénomènes d’électromouillage, le polymère subit des variations de 30° de son angle de contact sans présenter d’actionnement mécanique dans nos conditions de test. Deuxièmement, nous étudions l’adhésion de bactéries marines TC8 (Pseudoalteromonas lipolytica) sur le polymère pour évaluer ses propriétés antisalissure en fonction du taux de réticulant. Activable, facilement structurable à l’échelle micrométrique et limitant l’adhésion des bactéries, le PEDOT:PSS est un candidat intéressant pour les revêtements marins. / Manmade surfaces often experience rapid fouling by a wide range of micro-organisms which impact their performances. Here, we characterize in aqueous solution, the electro-active polymer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate in order to assess its ability to limit biofouling in marine environment. Firstly, we evaluate the evolution of its wettability and mechanical properties as a function of chemical composition when samples are left to age or are stimulated electrically. Our contact angle measurements performed over 6 months reveal that the polymer interface changes drastically with time and conditions in which the polymer is characterized or stored (influence of the relative humidity and the temperature) regardless of the concentration of cross-linker added to stabilize it and with. Using atomic force microscopy, we quantify the swelling and elastic modulus of the immersed polymer. Like hydrogels, the native polymer is able to absorb 10 times its volume and its Young modulus is smaller than 1MPa. However, the cross-linker addition alters these properties without insuring a good stability of the interface. Applying an electric field as a way to modulate PEDOT:PSS properties is also investigated. We demonstrate a 30° modulation of its contact angle by electrowetting, but no mechanical actuation can be measured under our test conditions. Secondly, we study its anti-biofouling properties as a function of crosslinker concentration. Tests using the marine bacteria TC8 (Pseudoalteromonas lipolytica) show that this polymer limits bacterial adhesion. Electro-active, easily micropatterned and anti-adhesive, PEDOT:PSS could be interesting for marine coatings.

<p>Major efforts have been spent during recent years in worldwide attempts to achieve an electronic paper technology; the common name for novel flexible displays utilizing substrates such as paper, plastics or thin metal sheets. Various kinds of technology are available that potentially will be used for an electronic paper, which differs from each other mainly with respect to the choice of active materials, substrates and manufacturing techniques. There are many applications for electronic paper technology, ranging from high-resolution displays used in electronic books to updateable large-area billboards. The latter suggests a novel electronic display function that could extend the utilization of cellulose-based paper, which is one of the most common materials ever produced by mankind, by using the paper as a thin and flexible carrier. The requirement for fast update speed in such large area applications would probably be a bit more relaxed compared to traditional display technologies, while low-power consumption and bi-stability are among the factors that should be further emphasized, together with the utilization of well-established printing techniques to enable low-cost manufacturing of the displays. The choice of active materials is therefore crucial in order to reach these objectives in reality and this paves the way for printable conjugated polymers with electrochromic properties. Chemical synthesis of these materials during the last decades has resulted in a vast variety of electrochromic polymers with custom-tailored functionality covering a broad range of optical absorption and electrical conductivities.</p><p>This thesis review the studies done on the electrochemical switching of poly(3,4-ethylenedioxythiophene) (PEDOT). For this material both the electrical conductivity and the optical absorption is controlled by the oxidation state. Active matrix addressed displays that are printed on flexible substrates have been obtained by arranging electrochemical smart pixels, based on the combination of electrochemical transistors and electrochromic display cells, into cross-point matrices. The resulting polymer-based active-matrix displays are operated at low voltages and the same active material can be used in electrochemical transistors and conducting lines and in electrochromic display cells employing the electronic and the opto-electonic properties of the material, respectively. In addition to this, a switchable optical polarizer is briefly discussed. This is a device utilizing electrochromism of stretch-aligned polyaniline (PANI). The combination of two identical devices in a vertical architecture, orthogonally oriented with respect to each other, results in a filter in which the orientation of the polarized optical absorption is governed by the voltage polarity applied to the device.</p> / Report code: LiU-TEK-LIC- 2006:18

In organic solar cell, the surface characteristic plays an important role in the power conversion efficiency of solar cell device. According to the literatures, the increased roughness can increase the contact area at the interface between PEDOT:PSS and active layer, improving hole extraction to the anode. Furthermore, a rough interface may cause a scattering effect on the incident light, which can reflect the out-lost-light back into the active layer and leads an efficient light absorbed. There are many ways to change the morphology of hole transporting layer, such as solvent-treated, or additives adding. However, the above process methods are easily affected by the external environmental conditions. It¡¦s difficult to get the surface morphology been well controlled, resulting in a process instability and low reproducibility. In this research, we will create regular grooves on hole transporting layer by rubbing method. By changing baking temperature and rubbing pressure adjustment of PEDOT:PSS layer; we can precisely control the groove depth and surface morphology. This method makes the process simple and high stability. We found that the PEDOT:PSS hole transporting layer with a suitable depth grooves can enhance the power conversion efficiency. The power conversion efficiency of samples were measured under AM 1.5G 100mW/cm2 illumination. In our results, we found that the device possess about 14.52nm-depth of groove structure, the power conversion efficiency of devices can be increased from 2.03% to 2.36% (which is 17.6% improved). This consequence can be attributed to a short current density increasing from 5.67mA/cm2 to 6.67mA/cm2 based on the device structure is ITO(1500Å)/Rubbing-PEDOT:PSS(500Å)/P3HT:PCBM(800Å)/Al(2000Å).