Dissertations / Theses on the topic 'Poly(3-hexylthiophene)'

This thesis describes the fabrication and electrical characterization of Schottky diodes based on the polymer semiconductor poly(3-hexylthiophene). Printed electronics may not be able to benefit from high vacuum processing, either for economic or technical reasons. The aim was to observe the effects on performance when Schottky diodes were built at atmospheric pressure. 200 nm thick films of poly(3-hexylthiophene) were formed on glass substrates by spinning a 1 wt% polymer solution in chloroform. Vacuum deposited aluminum and gold where used for the Schottky and ohmic contacts respectively. Two types of diodes were manufactured. One type (Au bottom) had its Schottky junction formed by evaporating aluminum onto the polymer under high vacuum. The other (Al bottom) had its Schottky junction formed by depositing the polymer onto aluminum at atmospheric pressure. The final yield of usable devices was 35% for Au bottom and 22% for Al bottom. The hole density and bulk mobility were derived from both DC and AC measurements. The bulk mobility was found to range from 2×10⁻⁵ cm²V⁻¹s⁻¹ to 6×10⁻⁵ cm²V⁻¹s⁻¹. The hole density was determined to be between 5×10¹⁶ cm⁻³ and 3x10¹⁷ cm⁻³. DC measurements showed that Au bottom devices had a current rectification ratio of 2×10⁴ at ±2 V, 100 times greater than Al bottom devices. The space charge limited current (SCLC) had to be considered to successfully model the DC behaviour. The small signal behaviour was modeled with a 2nd order series/parallel circuit, which was determined through impedance spectroscopy. Small signal performance of both device types was predicted to be poor. The corner frequency was determined to be less than 100 Hz for Al bottom devices, and less than 1 kHz for Au bottom devices. Large signal frequency performance of the diodes was tested with a half-wave peak rectifier. The maximum operating frequency was measured to be 40 kHz for Au bottom devices and 10 kHz for Al bottom devices.

In this thesis I present the development of a new type of experiment that extends the avenues of common time resolved measurements in the attosecond science field. The work presented here brings the tools of attosecond science to study electron dynamics in the systems that are the central topic in plastic electronics. A new experimental scheme is designed to study exciton formation and evolution in organic semiconductor Poly(3-HexylThiophene) (P3HT) that is used in organic solar cells. A variation of attosecond transient absorption spectroscopy was proposed to study the dynamics. The challenges of this experimental arrangement were to prepare the correct laser targets and both pump and probe pulses. Here I present the development of solid state polymer targets that were used for the transient absorption experiments. These targets have been succesfully prepared as free standing films in the range of 50 nm - 200 nm thickness and their X-ray absorption spectra were measured. Carrier envelope phase stable laser pulses centered at 1750 nm were achieved in a few optical cycle regime via Hollow Core Fiber (HCF) compression scheme developed in house. These pulses were used to drive High Harmonic Generation (HHG) beyond the 160 eV energy range in a differentially pumped Ne gas target. Strong CEP dependent half cycle cutoofs were observed in the HHG spectra confirming isolated attosecond pulses. X-ray absorption spectrum in P3HT targets was measured using this new source. Two routes for the optical pump generation have been explored. 17 fs, 2 mJ pulse was obtained from the 1750 nm driver via the cascaded third harmonic generation process in a non linear crystal and characterised using the SHG-FROG technique. This pulse was implemented as an optical pump in the transient absorption experiment. An interferometric optical setup was constructed that combines both the pump and the probe generation and the delay control between them. The setup was used to obtain the initial transient absorption experiment data.

Des copolymeres sequences polystyrene - poly(3-hexylthiophene) (ps-b-p3ht) ont ete synthetises et fractionnes. Leur caracterisation, par chromatographie d'exclusion sterique et spectroscopie uv-visible, a montre l'existence de copolymeres di et tri-blocs ainsi que d'agregats. La presence de triblocs est une donnee nouvelle concernant le mecanisme des reactions de propagation et de terminaison de la polymerisation oxydative des poly(3-alkylthiophenes). L'etude en solution, par diffusion de neutrons, de copolymeres fractionnes comportant une sequence polystyrene deuteriee a ete realisee. Elle a permis de mettre en evidence la structure lineaire des sequences p3ht, et une faible agregation de ces chaines a l'etat dope. L'etude a l'etat solide par calorimetrie differentielle et diffraction des rayons x, permet d'observer une separation en microphases des sequences ps et p3ht. L'obtention de morphologie en nids d'abeille, a partir de films de copolymeres dopes, est un argument en faveur de l'association en micelles des copolymeres, dans les conditions de l'experience. Le dopage p des copolymeres a ete effectue en solution et l'influence du temps d'exposition au dopage etudiee. Des mesures de conductivite en fonction de la frequence, montrent qu'une tres faible fraction en p3ht est necessaire pour obtenir des conductivites compatibles avec les absorbants hyperfrequences. L'etude des proprietes optoelectroniques de ces copolymeres, tant a l'etat neutre qu'a l'etat legerement dope, a permis l'elaboration de diodes electroluminescentes organiques dont les caracteristiques sont tres superieures a celles des diodes electroluminescentes developpees a partir de poly(3-alkylthiophenes)

Mestrado em Ciência dos Materiais
As células fotovoltaicas à base de compostos orgânicos e de híbridos do tipo orgânico/inorgânico têm recebido bastante atenção devido à sua potencial aplicação como fonte de energia limpa e económica. A utilização de nanoestruturas neste tipo de dispositivos tem também recebido especial atenção já que o confinamento quântico a elas associado promove a percolação, facilitando a passagem dos portadores de carga o que aumenta a sua eficiência. Nesta tese foram preparados dispositivos fotovoltaicos “bulk heterojunction” através da mistura de poli(3-hexiltiofeno) com diferentes nanoestruturas de ZnO. As nanoestruturas de ZnO (nanopartículas, nanofios e naofibras) foram preparadas por diferentes técnicas e caracterizadas por XRD, espectroscopia no UV-Vis, SEM e TEM. As nanopartículas e os nanofios de ZnO foram preparadas por métodos químicos em solução e decomposição térmica de acetato de zinco dihidratado respectivamente. As naonofibras de ZnO foram preparadas por calcinação de nanofibras compostas por alcóol polivinílico e acetato de zinco preparadas por “electrospinning”. As nanoestruturas preparadas foram ainda funcionalizadas com o ácido pireno-1-carboxílico. As nanoestruturas preparadas, funcionalizadas ou não funcionalizadas, foram misturadas com soluções de P3HT de modo a preparar dispositivos fotovoltáticos em duas configurações distintas. Numa delas os eléctrodos consistem em ITO e o alumínio depositado por evaporação térmica, na outra, os eléctrodos consistem em ITO e tinta de prata. O primeiro tipo de configuração utilizou a seguinte sequência: vidro/ITO/PEDOT:PSS/camada fotoactiva/Al. Na segunda configuração a sequência utilizada foi: vidro/ITO/ZnO/ camada fotoactiva/ PEDOT:PSS/Ag. As camadas de PEDOT:PSS bem como as camadas fotoactivas foram depositadas por spin coating. A caracterização dos dispositivos foi feita através de medições da corrente-tensão sob condições simuladas de iluminação padrão. Os dispositivos preparados apresentaram actividade fotovoltaica mas a sua eficiência ainda precisa de ser melhorada. ABSTRACT: Organic and organic/inorganic hybrid solar cells have been receiving a significant amount of attention due to their potential to yield environmentally friendly and cheap source of energy. As a result they are being investigated widely. Making use of nanostructures in such devices has also received a great attention as they provide percolative pathways for charge carriers by quantum confinement, helping in the improvement of the efficiency of the devices. In this thesis bulk heterojunction photovoltaic devices have been produced by blending different ZnO nanostructures and surface functionalized ZnO nanostructures with poly- 3-hexylthiophene. ZnO nanostructures (nanoparticles, nanowires and nanofibers) have been produced by different techniques and characterized by XRD, UV-Visible spectroscopy and SEM. ZnO nanoparticles and ZnO nanowires were prepared by wet chemical synthesis and thermal decomposition of zinc acetate dihydrate respectively. ZnO nanofibers were prepared by calcination of polyvinyl alcohol/zinc acetate composite nanofiber, which had been produced by the electrospinning process. These nanostructures were also surface functionalized with pyrene-1-carboxylic acid and characterized. Subsequently, these nanostructures and their surface functionalized forms were used to fabricate photovoltaic devices by combining them with P3HT and its whiskers. The photovoltaic devices have been prepared in two different configurations. In some ITO and aluminium deposited by thermal evaporation were used as the electrodes, while in the others ITO and silver paste were used. The first set of devices had the order glass/ITO/PEDOT:PSS/photoactive layer/Al, while the latter had the order lass/ITO/ZnO/photoactive layer/ PEDOT:PSS/Ag paste. The PEDOT:PSS and the photoactive layers were deposited by spin coating of the suspension of PEDOT:PSS in water and the suspension of the ZnO nanostructures in the poly-3-hexylthiophene solution respectively. The photovoltaic cells were finally characterized by current-voltage characteristics measurement under simulated standard illumination conditions. The photovoltaic devices prepared have demonstrated photovoltaic properties, but their efficiencies need further improvement.

Dans cette étude, des copolymères à blocs rigide-flexible comprenant des segments donneur [poly(3-hexylthiophène) régiorégulier, (rr-P3HT)] et accepteurs d’électrons (C60) ont été synthétisés. L’auto-assemblage en masse de ces copolymères à blocs avait pour objectif d’atteindre des morphologies dont la taille des domaines coïncide avec la distance idéale de transport de l’exciton (~10 nm) en vue d’utiliser ces systèmes comme matériaux de couche active dans les cellules photovoltaïques organiques de type P3HT-PCBM.La maîtrise et l'optimisation des conditions de synthèse de rr-P3HT de fonctionnalité terminale bien définie nous ont permis d'accéder à différentes architectures de copolymères linéaires di- et triblocs, constitués de P3HT comme bloc rigide et de polystyrène ou poly(4-vinylpyridine) comme bloc ‘flexible’. La fonctionnalisation du bloc flexible avec des dérivés du fullerène (C60 ou PCBM) a ensuite été réalisée et ces copolymères utilisés comme additifs pour stabiliser la morphologie de la couche active des cellules solaires organiques de type P3HT/PCBM. Les caractéristiques photovoltaïques des matériaux ainsi préparés ont été déterminées et corrélées aux analyses morphologiques de la couche active
The performance of organic photovoltaic cells mainly depends on the active layer nano-morphology. Rod-coil block copolymers (BCPs) are well known in their ability to self-assemble into well-ordered nanoscopic morphologies. BCPs containing electron-donor and acceptor segments are of particular interest for use in photovoltaic cells because electronic light-excited states exist over distances similar to the typical size of block copolymer domains (~10 nm). Therefore, we designed novel donor-acceptor BCPs to exploit this coincidence in dimensions. This thesis is focused on BCPs based on regioregular poly(3-hexylthiophene) (rr-P3HT) due to its high hole mobility and good processibility from various solvents. Simplified and versatile syntheses of donor-acceptor rod-coil di- and tri- BCPs consisting of the donor block P3HT (rod) and polystyrene or poly(4-vinylpyridine) (coil) blocks to carry the acceptor C60 in different ways were developed. These materials were used as surfactants to stabilize the nano-morphology of reference P3HT: [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) based devices. Photovoltaic characterizations were then tied to copolymer structural data with the help of AFM and a range of complementary characterization techniques

In this work a purification method for carbon nanotubes was first developed. Purified nanotubes were characterized by AFM, TGA, RAMAN, NIR-PL and then used to prepare composite materials in conjunction with semiconducting polymers. Electrical and optical properties of this composite material were investigated and finally a nanostructuring technique able to create thin hybrid films with nanoscale phase separation was developed.

The aim of the present work was to screen the main methods for the synthesis of conjugated polymers for their suitability in the preparation of conductive polymer brushes. The main focus was put on the grafting of intrinsically soluble substituted regioregular polyalkylthiophenes because of their excellent optoelectronic properties. The resulting polymer films were characterized and their optoelectrical properties studied. For the first time, a synthesis of conductive polymer brushes on solid substrates using “grafting-from” method was performed. The most important, from my opinion, finding of this work is that regioregular head-to-tail poly-3-alkylthiophenes – benchmark materials for organic electronics - can be now selectively grafted from appropriately-terminated surfaces to produce polymer brushes of otherwise soluble polymers - the architecture earlier accessible only in the case of non-conductive polymers. In particular, we developed a new method to grow P3ATs via Kumada Catalyst Transfer Polymerization (KCTP) of 2-bromo-5-chloromagnesio-3-alkylthiophene. Exposure of the initiator layers to monomer solutions leads to selective chain-growth polycondensation of the monomers from the surface, resulting into P3AT brushes in a very economical way. The grafting process was investigated in detail and the structure of the resulting composite films was elucidated using several methods. The obtained data suggests that the grafting process occurs not only at the poly(4-bromstyrene) (PS-Br)/polymerization solution interface, but also deeply inside the swollen PS-Br films, penetrable for the catalyst and for the monomer The grafting process was investigated in detail and the structure of the resulting composite film was elucidated using ellipsometry, X-ray Photoelectron Spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and Conductive atomic force microscopy (C-AFM). The obtained data suggests that the grafting process occurs not only at the poly(4-bromostyrene), PS-Br/polymerization solution interface, but also deeply inside the swollen PS-Br film, which is penetrable for the catalyst and the monomer. The process results in an interpenetrated PS-Br/P3HT network, in which relatively short poly(3-hexylthiophene), P3HT grafts emanate from long, cross-linked PS-Br chains. A further method investigated during our work was to covalently graft regioirregular P3HT to substrates modified by macromolecular anchors using oxidative polymerization of 3HT with FeCl3. P3HT layers with variable thicknesses from 30 nm up to 200 nm were produced using two steps of polymerization reaction. The P3HT obtained by oxidative polymerization had always an irregular structure, which was a result of the starting monomer being asymmetric, which is undesired for electronic applications. The third method for the production of conductive polymer brushes was to graft regioregular poly(3,3''-dioctyl-[2,2';5',2'']terthiophene) (PDOTT) by electrochemical oxidative polycondensation of symmetrically substituted 3,3''-dioctyl-[2,2';5',2'']terthiophene (DOTT). A modification of the supporting ITO electrode by the self-assembled monolayers (SAMs) of compounds having polymerizable head-groups with properly adjusted oxidative potentials was found to be essential to achieve a covalent attachment of PDOTT chains. The polymer films produced show solvatochromism and electrochromism, as well as the previous two methods. After polymerization, the next step towards building organic electronic devices is applying the methods obtained in nano- and microscale production. Block copolymers constitute an attractive option for such surface-engineering, due to their ability to form a variety of nanoscale ordered phase-separated structures. However, block copolymers containing conjugated blocks are less abundant compared to their non-conjugated counterparts. Additionally, their phase behaviour at surfaces is not always predictable. We demonstrated in this work, how surface structures of non-conductive block copolymers, such as P4VP-b-PS-I, can be converted into (semi)conductive P4VP-b-PS-graft-P3HT chains via a surface-initiated polymerization of P3HT (Kumada Catalyst Transfer Polymerization (KCTP) from reactive surface-grafted block copolymers. This proves that our method is applicable to develop structured brushes of conductive polymers. We believe that it can be further exploited for novel, stimuli-responsive materials, for the construction of sensors, or for building various opto-electronic devices. The methods developed here can in principle be adapted for the preparation of any conductive block copolymers and conductive polymers, including other interesting architectures of conductive polymers, such as block copolymers, cylindrical brushes, star-like polymers, etc. To this end, one needs to synthesize properly-designed and multi-functional Ni-initiators before performing the polycondensation.

P3HT (Poly(3-hexylthiophene)) is an organic polymer that shows promise as an active material in semiconducting electronics. It is important to study the electronic properties of this material in order to determine its efficacy in such devices. However, many current studies of thiophene only examine the oligomer, since it is a simpler material to investigate. In this study, several P3HT interfaces were analyzed to determine their electronic properties. The P3HT was deposited on Au, highly-ordered pyrolitic graphite (HOPG), and indium tin oxide (ITO) substrates via electrospray deposition. The depositions were performed in several steps, with x-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) measurements taken between each step without breaking the vacuum. The resulting series of spectra allowed orbital line-up diagrams to be generated for each interface, giving detailed analysis of the interfacial properties, including the charge injection barriers and interface dipoles. The results, when compared to similar oligomer-based investigations, show a difference in the orbital line-up between oligomeric and polymeric P3HT junctions.

Organic electronics based on π-conjugated semi-conductor raises new technology, such as organic film transistors, e-paper, and organic photovoltaic cells that can be implemented cost-effectively on large-area applications. Currently, the device performance is limited by low charge carrier mobility. Poly(3-hexylthiophene) (P3HT) and organic field effect transistors (OFET) is used as a model to investigate morphology of the organic film and corresponding electronic properties. In this thesis, processing parameters such as boiling points and solubility are controlled to impact the micro- and macro-morphology of the film to enhance the charge transport of the device. Alternative approach to improve ordering of polymer chains and increase in charge transport without post-treatment of P3HT solution is studied. The addition of high boiling good solvent to the relatively low boiling main solvent forms ordered packing of π-conjugated polymers during the deposition process. We show that addition of 1% of dichlorobenzene (DCB) to the chloroform based P3HT solution was sufficient to improve wetting and molecular structures of the film to increase carrier mobility. Systematic study of solvent-assisted re-annealing technique, which has potential application in OFET encapsulation and fabrication of top-contact OFET, is conducted to improve mobility of OFET, and, to suggest a cost-effective processing condition suitable for industrial application. Three process parameters: boiling point, polarity, and solubility are investigated to further understand the trend of film response to the solvent-assisted technique. We report the high boiling non-polar solvents with relatively high RED values promote highest improvement in molecular packing and formulate crystalline structure of the thin film, which increases the device performance.

The aim of the present work was to screen the main methods for the synthesis of conjugated polymers for their suitability in the preparation of conductive polymer brushes. The main focus was put on the grafting of intrinsically soluble substituted regioregular polyalkylthiophenes because of their excellent optoelectronic properties. The resulting polymer films were characterized and their optoelectrical properties studied. For the first time, a synthesis of conductive polymer brushes on solid substrates using “grafting-from” method was performed. The most important, from my opinion, finding of this work is that regioregular head-to-tail poly-3-alkylthiophenes – benchmark materials for organic electronics - can be now selectively grafted from appropriately-terminated surfaces to produce polymer brushes of otherwise soluble polymers - the architecture earlier accessible only in the case of non-conductive polymers. In particular, we developed a new method to grow P3ATs via Kumada Catalyst Transfer Polymerization (KCTP) of 2-bromo-5-chloromagnesio-3-alkylthiophene. Exposure of the initiator layers to monomer solutions leads to selective chain-growth polycondensation of the monomers from the surface, resulting into P3AT brushes in a very economical way. The grafting process was investigated in detail and the structure of the resulting composite films was elucidated using several methods. The obtained data suggests that the grafting process occurs not only at the poly(4-bromstyrene) (PS-Br)/polymerization solution interface, but also deeply inside the swollen PS-Br films, penetrable for the catalyst and for the monomer The grafting process was investigated in detail and the structure of the resulting composite film was elucidated using ellipsometry, X-ray Photoelectron Spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and Conductive atomic force microscopy (C-AFM). The obtained data suggests that the grafting process occurs not only at the poly(4-bromostyrene), PS-Br/polymerization solution interface, but also deeply inside the swollen PS-Br film, which is penetrable for the catalyst and the monomer. The process results in an interpenetrated PS-Br/P3HT network, in which relatively short poly(3-hexylthiophene), P3HT grafts emanate from long, cross-linked PS-Br chains. A further method investigated during our work was to covalently graft regioirregular P3HT to substrates modified by macromolecular anchors using oxidative polymerization of 3HT with FeCl3. P3HT layers with variable thicknesses from 30 nm up to 200 nm were produced using two steps of polymerization reaction. The P3HT obtained by oxidative polymerization had always an irregular structure, which was a result of the starting monomer being asymmetric, which is undesired for electronic applications. The third method for the production of conductive polymer brushes was to graft regioregular poly(3,3''-dioctyl-[2,2';5',2'']terthiophene) (PDOTT) by electrochemical oxidative polycondensation of symmetrically substituted 3,3''-dioctyl-[2,2';5',2'']terthiophene (DOTT). A modification of the supporting ITO electrode by the self-assembled monolayers (SAMs) of compounds having polymerizable head-groups with properly adjusted oxidative potentials was found to be essential to achieve a covalent attachment of PDOTT chains. The polymer films produced show solvatochromism and electrochromism, as well as the previous two methods. After polymerization, the next step towards building organic electronic devices is applying the methods obtained in nano- and microscale production. Block copolymers constitute an attractive option for such surface-engineering, due to their ability to form a variety of nanoscale ordered phase-separated structures. However, block copolymers containing conjugated blocks are less abundant compared to their non-conjugated counterparts. Additionally, their phase behaviour at surfaces is not always predictable. We demonstrated in this work, how surface structures of non-conductive block copolymers, such as P4VP-b-PS-I, can be converted into (semi)conductive P4VP-b-PS-graft-P3HT chains via a surface-initiated polymerization of P3HT (Kumada Catalyst Transfer Polymerization (KCTP) from reactive surface-grafted block copolymers. This proves that our method is applicable to develop structured brushes of conductive polymers. We believe that it can be further exploited for novel, stimuli-responsive materials, for the construction of sensors, or for building various opto-electronic devices. The methods developed here can in principle be adapted for the preparation of any conductive block copolymers and conductive polymers, including other interesting architectures of conductive polymers, such as block copolymers, cylindrical brushes, star-like polymers, etc. To this end, one needs to synthesize properly-designed and multi-functional Ni-initiators before performing the polycondensation.

Conjugated polymers represent a class of semi-conducting materials with numerous applications in optoelectronic devices, including organic light-emitting diodes, field-effect transistors, and photovoltaics. Because of the numerous advantages of macromolecular systems, including solution processing and mechanical flexibility, conjugated polymers have become a burgeoning field of research with the hopes of producing cost-effective solution-based electronics. Importantly, optoelectronic device performance is heavily influenced by conjugated polymer backbone orientation and overall thin film morphology. As such, the processing conditions of these systems are important to the construction of high- performance optoelectronics. Polythiophenes are model conjugated polymers that have been studied extensively in halogenated organic solvents. However, the self- assembly of these systems from dilute solution to the solid state remains ambiguous for solvents with high dielectric constants. Here, two derivative compounds of poly(3-hexylthiophene) are correspondingly investigated in high dielectric solvents by way of ultraviolet-visible absorption and fluorescence spectroscopy, Fourier transform infrared spectroscopy, small-angle X-ray scattering, polarized optical microscopy, and four- point probe conductivity measurements. In dilute solutions, both systems are found to undergo self-assembly when exposed to various stimuli, including temperature, solvent composition, and side-chain characteristics. The kinetics of these transitions are investigated, and a model is put forth to explain contrasting self-assembly mechanisms. At higher concentrations, both systems form lyotropic liquid crystalline phases. Characteristics of the liquid crystalline phases are found to be heavily influenced by dilute solution self-assembly mechanisms and processing. Through the application of a mechanical shear force along still-wet liquid crystal films, alignment of the polythiophene long axis is attained. This morphological characteristic is found to carry over to the solid-state for both systems, and clear optoelectronic anisotropy of the thin films is observed. As such, these methodologies may provide a route to the production of environmentally friendly high-performance optoelectronic devices.

Philosophiae Doctor - PhD
The continuous increase in energy consumption and decrease in fossil fuels reserves are a primary concern worldwide; especially for South Africa. Therefore, there is an urgent need for alternative energy resources that will be sustainable, and environmentally friendly in order to tackle the ecological degradation generated by the use of fossil fuels. Among many energy ‘niches’, solar energy appears to be one of the most promising and reliable for the African continent because of the constant availability of sun light. Organic conjugated polymers have been identified as suitable materials to ensure proper design and fabrication of flexible, easy to process and cost-effective solar cells. Their tendency to exhibit good semiconducting properties and their capability to absorb photons from the sunlight and convert it into electrical energy are important features that justify their use in organic photovoltaic cells. Many different polymers have been investigated as either electron donating or electron accepting materials. Among them, poly(3-hexylthiophene) is one of the best electron donor materials that have been used in organic photovoltaic cells. It is a good light absorber and its Highest Occupied Molecular Orbital (HOMO) energy level is suitable to allow electron transfer into an appropriate electron acceptor. On the other hand, the molecular ordering found in dendrimers attracted some interest in the field of photovoltaics as this feature can ensure a constant flow of charges. In this work, I hereby report for the first time, the chemical synthesis of a highly crystalline dendritic star copolymer generation 1 poly(propylene thiophenoimine)-co-poly(3-hexylthiophene) (G1PPT-co-P3HT) with high molecular weight and investigate its application as donating material in bulk heterojunction organic photovoltaics.

>Magister Scientiae - MSc
This thesis starts with the reviewing of studies on the loading of noble metals and nanostructured metal oxides into bulk heterojunction organic solar cell device architectures. The reviews focused on the innovative developments in the use of various fullerene derivatives as electron acceptors in organic solar cells. It additionally reflected on the effect of metallic nanoparticles (NPs), such as gold (Au) and silver (Ag), on the performance of organic solar cells. Besides the metallic NPs, the effect of metal oxide nanoparticle loading, e.g. CuO, ZnO and TiO2, on the organic solar cell performance, and the use of noble metals doped TiO2 on the gas sensing application were reviewed.
2024

Orientador: Prof. Dr. Ivo Alexandre Hümmelgen
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Curso de Pós-Graduação em Física. Defesa: Curitiba, 15/12/2017
Inclui referências : f. 93-102
Resumo: O trabalho atual investiga a melhoria das propriedades de transporte de carga em transistores de efeito de campo de baixa tensão (FETs), que utilizam poli(3-hexiltiofeno-2,5-diil) (P3HT) não-100% e 100% regioregular como os semicondutores orgânicos, e poli(álcool vinílico) reticulado (cr-PVA) como isolante. O trabalho de pesquisa realizado durante o projeto pode ser dividido em duas partes. A primeira parte investiga a melhoria das propriedades de transporte de carga na interface cr-PVA/P3HT, e a influência de defeitos de regioregularidade de P3HT nas propriedades da interface. A segunda parte demonstra a preparação de filmes finos que consistem em moléculas alinhadas de P3HT 100% regioregular e, consequentemente, a aplicação desses filmes alinhados para o desenvolvimento de dispositivos de alto desempenho. No caso da primeira parte, o problema essencial é que o transporte de carga na interface de cr-PVA/P3HT está limitado pela presença de armadilhas na interface que correspondem aos dipolos de superfície de cr-PVA. Esses dipolos de superfície possuem a capacidade de modificar a distribuição de carga em moléculas adjacentes de P3HT, o que pode levar à localização e a captura de cargas. Isso representa um problema fisico complexo, sendo que a variação de energia potencial na interface depende da posição e orientação das armadilhas dipolares em relação às moléculas de P3HT. No entanto, a solução é conceitualmente simples, pois, em princípio, é apenas necessário passivar as armadilhas. Para conseguir isso, é apresentada uma técnica experimental econômica, na qual a superfície de cr-PVA é tratada com um surfactante catiônico, brometo de hexadeciltrimetilamónio (CTAB). As cabeças hidrofílicas carregadas positivamente de CTAB visam a passivação das armadilhas carregadas negativamente da superfície de cr-PVA. A deposição de CTAB sobre o cr-PVA, em relação ao cr-PVA somente, resulta em aumento significativo na capacitância do isolanate (Ci), e as imagens de microscopia de força atômica (AFM) mostram que a superfície de cr-PVA é coberta com grãos de surfactante bem conectados. Em caso de dispositivos baseados em P3HT não-100% regioregular, este tratamento resulta em uma melhora da mobilidade de efeito de campo (?FET) por um fator de ~3 (?FET médio de 0.44 cm2/V.s) quando comparado aos dispositivos não tratados. Para investigar como o tratamento do surfactante modifica o transporte de carga na interface, a variação de ?FET em função da espessura efetiva do gargalo do canal (l0) também é analisada e discutida detalhadamente. Curiosamente, ao contrário dos dispositivos baseado em P3HT não-100% regioregular, o tratamento com surfactante em dispositivos baseado em P3HT 100% regioregular resulta em degradação de ?FET e do desempenho geral dos dispositivos. Isso indica que a interação de defeitos de regioregularidade e armadilhas de superfície de cr-PVA é um fator crítico que afeta as propriedades de transporte de carga na interface cr-PVA/P3HT. Para investigar este assunto, a interação das moléculas de P3HT não-100% e 100% regioregular com dipolos de superfície de cr-PVA é investigada usando espectroscopia de absorbância, AFM e cálculos de química quântica. Observa-se que, dependendo da presença ou ausência de defeitos de regioregularidade de P3HT (e, portanto, da planaridade molecular), o contato entre as moléculas de P3HT e os dipolos de superfície de cr-PVA afeta a ordem molecular do P3HT de forma diferente. Por causa dos defeitos de regioregularidade, as moléculas de polímero não-100% regioregular produzem momentos de dipolo mais altos em comparação com moléculas 100% regioregular. Consequentemente, discute-se como a interação de moléculas de P3HT não-100% e 100% regioregular com dipolos de cr-PVA contribuem à desordem energética na interface cr-PVA/P3HT. Neste caso, o transporte de carga em dispositivos de FET é investigado para quatro espessuras diferentes de P3HT não-100% e 100% regioregular. Os resultados elétricos mostram que o comportamento de ?FET × l0 e a dependência de ?FET na espessura do canal são uma função forte da presença ou ausência de defeitos de regioregularidade de P3HT. Neste trabalho, os dispositivos (não tratados) baseados em P3HT 100% regioregular demonstram ?FET tão alto quanto 1.20 cm2/V.s. Esses valores tornam esses dispositivos reconhecíveis para a integração em várias aplicações comerciais. No entanto, um desenho de circuitos para muitas outras aplicações de alto desempenho impõem um requisito de ?FET mais rigoroso (> 5 cm2/V.s). Para alcançar este marco, na segunda parte do projeto de pesquisa, está apresentada uma técnica de deposição simples (chamado, floating-film transfer method, em inglês), que permite o alinhamento supra-molecular das moléculas de P3HT 100% regioregular. A aplicação de filmes de polímero alinhados em FETs resulta em valores de ?FET de até 8 cm2/V.s, que é o valor mais alto reportado até agora para os FETs baseados em P3HT. Palavras-chaves: Transistores orgânicos de efeito de campo, poli(3-hexiltiofeno-2,5-diil) livre de defeitos, regioregularidade, poli(álcool vinílico) reticulado, interface isolante/semicondutor, armadilhas dipolares.
Abstract: The current work investigates the improvement of charge transport properties in low-voltage organic field-effect transistors (OFETs) that utilize non-100% and 100% regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) as the organic semiconductors, and cross-linked poly(vinyl alcohol) (cr-PVA) as the gate insulator. The essential research work performed during the project can be divided into two parts. The first part investigates the improvement of charge transport properties at the cr-PVA/P3HT interface, and the influence of regioregularity defects of P3HT on interface properties. The second part demonstrates the development of high performance OFETs based on supra-molecularly aligned thin films of 100% regioregular P3HT. In the case of the first part, the essential problem in hand is that charge transport at the cr-PVA/P3HT interface is limited by the presence of charge traps at the interface corresponding to the surface dipoles of cr-PVA. These surface dipoles hold the ability to modify charge distribution on adjacent P3HT molecules, which can lead to localization and trapping of otherwise mobile charge carriers. This presents a physically complex problem, since the potential energy variations at the interface depends on the position and orientation of the dipolar traps with respect to P3HT molecules. However, the solution is conceptually simple since, in principle, it is only required to passivate the traps. In order to achieve this, a cost-effective experimental technique is presented, in which the cr-PVA surface is treated with a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). The positively charged hydrophilic heads of CTAB are aimed at passivating the negatively charged traps of the cr-PVA surface. The deposition of CTAB over cr-PVA leads to significant enhancement in gate insulator capacitance (Ci), and the atomic force microscopy (AFM) images show that the cr-PVA surface is covered with well-connected surfactant grains. In the case of non-100% regioregular P3HT OFETs, this treatment results in an improvement of field-effect mobility (?FET) by a factor of ~3 (average ?FET of 0.44 cm2/V.s) when compared to untreated devices. In order to investigate how the surfactant treatment modifies charge transport at the interface, variation of ?FET as a function of the effective bottleneck thickness of the conducting channel (l0) is also analyzed and thoroughly discussed. Quite interestingly, contrary to non-100% regioregular P3HT devices, the surfactant treatment in 100% regioregular P3HT devices leads to degradation of ?FET and overall device performance. This indicates that the interaction of regioregularity defects and cr-PVA surface traps is a crucial factor affecting charge transport properties at the cr-PVA/P3HT interface. In order to address this issue, the interaction of non-100% and 100% regioregular P3HT molecules with cr-PVA surface dipoles is investigated using UV-vis absorbance spectroscopy, AFM and quantum chemical calculations. It is observed that, depending on the presence or absence of regioregularity defects of P3HT (and thus the molecular planarity); the intimate contact between P3HT molecules and cr-PVA surface dipoles affects the molecular order of P3HT differently. Because of the regioregularity defects, the non-100% regioregular polymer molecules produce higher dipole moments compared to 100% regioregular molecules. Consequently, it is discussed how the interaction of non-100% and 100% regioregular P3HT molecules with cr-PVA surface dipoles contribute differently to the potential energy variations at the cr-PVA/P3HT interface. In this case, the charge transport in FET devices is investigated for four different thicknesses of both non-100% and 100% regioregular P3HT. The electrical results reveal that the behavior of ?FET × l0 and the dependence of ?FET on channel thickness are a strong function of the presence/absence of the regioregularity defects of P3HT. In this project, the untreated 100% regioregular P3HT devices demonstrate ?FET as high as 1.20 cm2/V.s. Such high values make these devices recognizable for translation to various commercial applications. However, the circuit designs of many other high performance applications impose a more stringent ?FET requirement (> 5 cm2/V.s). In order to achieve this landmark, in the second part of the research project, a simple and cost-effective deposition technique (floating-film transfer method) is presented, which allows supra-molecular alignment of 100% regioregular P3HT molecules. The application of aligned polymer films in FET devices leads to the demonstration of ?FET values as high as 8 cm2/V.s, which is the highest value reported so far for P3HT based OFETs. Keywords: Organic field-effect transistors, defect-free poly(3-hexylthiophene-2,5-diyl), regioregularity, cross-linked poly(vinyl alcohol), insulator/semiconductor interface, dipolar charge traps.

Conjugated polymers have attracted much interest as promising alternatives to inorganic semiconductors, due to their low-temperature, solution-based processability, which may provide for low-cost, large-area electronic device fabrication. However, commercialization of polymer-based electronic devices has been restricted owing to low device performance of solidified thin-films. In order to enhance charge transport of polymer semiconductor thin-films, the self-organization of organic polymer semiconductors into ordered supramolecular assemblies has been achieved by tuning a range of process parameters including film deposition method (spin vs. drop cast), solvent boiling point (low vs. high boiling point), polymer-dielectric interface treatment, and post-deposition processing (solvent vapor or thermal annealing). However, these strategies give rise to limitations for large-scale high-throughput processing due to associated pre- and/or post semiconductor deposition steps. Therefore, in this thesis, we identify alternative processing parameters (i.e., hydrogen bonds between good and poor solvents, UV irradiation to polymer precursor solutions, and combination of sonication and subsequent UV irradiation to polymer precursor solutions) which can contribute to enhancement in charge transport of a model polymer semiconductor, poly(3-hexylthiophene) (P3HT), eliminating the additional pre- and/or post-steps mentioned above. Further, we understand of how the processing parameters effect intra- and intermolecular interactions of the polymer chains, micro- through macroscopic morphologies, and charge transport characteristics of the resultant films.

碩士
國立交通大學
應用化學系碩博士班
102
In this study, we have successfully introduced commercial N-heterocyclic carbene-based palladium catalysts to conduct direct C-H bond arylation polymerization and poly(3-hexylthiohphene) (P3HT), poly(3-hexylselenophene) (P3HS), and poly(3-hexylthiophene-alt-3-hexylselenophene) (P3HTS) were synthesized accordingly. Under our optimized conditions, high molecular weight P3HT (Mn = 26.9 k, PDI = 3.56) with high head-to-tail regioregularity (94%) was prepared through C-H bond arylation polymerization catalyzed by NHC-Pd(II) [1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene]chloro[3-phenylallyl]palladium(II). P3HS was obtained by a similar manner and this is the first example of preparing P3HS by direct C−H bond arylation. NHC-Pd(II) exhibits a wide range of working temperature spanning from 70°C to 140°C) and good catalytic reproducibility relative to conventional phosphine-based palladium catalysts. For this first time head-to-tail poly(3-hexylthiophene-alt-3-hexylselenophene) was prepared by direct C-H bond arylation polymerization by the help of NHC-Pd(II), offering an opportunity to study the physical properties of P3HTSThe results reveal that P3HTS retains many advantageous properties of P3HT and P3HS, including broad UV-Vis absorption, good crystallinity, and high thermal stability (Td = 428 °C). Moreover, owing to the regular alternating arrangement of thiophene and selenophene units, it also exhibits various advantages over either P3HT or P3HS, such as more red-shifted absorption maximum (462 nm) than P3HT, narrower electrochemical HOMO−LUMO gap (2.21 eV) and better solubility relative to P3HS. In brief, our results provide an economical and convenient method for the direct C−H bond arylation polymerization of thiophene-selenophene alternating copolymer. It is envisaged that the employed methodology in this study can be further applied to synthesis of other alternating copolymers such as thiophene-tellurophene andselenophene-tellurophene alternating copolymers.

碩士
國立中正大學
化學工程研究所
99
We synthesize the alternative copolymer P3HT-alt-PT by Suzuki coupling reaction and random copolymer P3HT-ram-PT by Modified Grignard Metathesis(GRIM), comparing the advantages and the disadvantage of these two polymers, and finally we use some equipment to identify their characterization. LC/MS, 1H-NMR and FTIR can show the structure; TGA can show the temperature of decompose Td; DSC can show the glass transition temperature Tg and the melting point Tm; UV-Vis can show the absorption wavelength range of the visible light; PL can show the wavelength range of the fluorescence emitting; CV can show the HOMO, LUMO and band gap. Finally, these two polymers are used as the semi-conducting layer for the solar cell, and then we use the Oriel® Sol3A TM Class AAA Solar Simulators to identify the efficiency and the other relative characterization, expecting that they can be applied for the solar cell well. Key words: Suzuki, Grignard, efficiency, solar cell

碩士
輔仁大學
化學系
98
In this research, we’d like to study the morphology of P3HT in solution by controlling spin rate in solution state and also its morphology in films. UV-Vis and PL were used to monitor the state of aggregation under different shear force. Viscosity measurements were conducted to elucidate molecular conformation of P3HT in solution and to explain the results from UV-Vis and X-ray measurements. We found morphology of films prepared by aggregation of P3HT itself in solution was different from that prepared by extra shear force. Aggregation of P3HT itself in solution was destroyed during the film formation by spin-coating process. Packing of P3HT by extra shear force was maintained during the spin-coating process because shear force pushed the P3HT molecules in helical form to pack together tightly furing the stirring process. The results were different by using different solvents and they are related to the conformation of P3HT in solution. With this concept of organic solar cells can be used to process the above. We can create without annealing can produce highly ordered P3HT in close gatherings of activity layer, in order to save resources in the production of batteries and costs.

碩士
國立臺灣大學
高分子科學與工程學研究所
93
To achieve high efficient organic photovoltaics, we propose to use self-assemble highly ordered block-copolymer as active layer to facilitate high charge carrier transport rate. In this study, we used anionic polymerization to synthesize block-copolymer poly(3-hexylthiophene)-b-poly(2-vinylpyridine)(P3HT-b-P2VP) with two compositions, 1: 2and 1: 49 (weight ratio). Their properties were studied by UV-vis, PL, TGA and TEM and compared them with pure P3HT and blend of P3HT-P2VP. In UV-vis and PL spectra, copolymers showed a blue-shift as compared with pure P3HT or blend. A red-shift was observed due to the aggregation of P3HT when a poor solvent, methanol, was added into pure P3HT or blend dissolved in THF. However, the optical spectra of block-copolymer did not change when they were dissolved either in tetrahydrofuran (THF) or methanol. The chemical bond between P3HT and P2VP in the copolymer has retarded the aggregation of P3HT in poor solvent. The decomposition temperatu of copolymer was greatly improved as compared with the neat P2VP, even with only a small amount of 2wt％ P3HT, from 352℃ to 381℃. This copolymer containg 2wt％ P3HT exhibitsa spherical morphology. In conclusion, we have synthesized P3HT-b-P2VP copolymer which will be used in photovoltaics.

碩士
崑山科技大學
材料工程研究所
101
ABSTRACT In this work, we provided insights into the gelation behavior and aggregation structure of poly(3-hexylthiophene) (P3HT) and P3HT blended with nano-carbon materials in xylene solutions through the optical microscope (OM), polarized optical microscope (POM), UV-vis absorption (UV-vis), photoluminescence (PL), scanning electron microscope (SEM) and transmission electron microscope (TEM). In the second chapter, we determined the gelation behavior and aggregation structure of P3HT in xylene solutions through the OM, POM, UV-vis, PL, SEM and TEM. In the work, Xylene for P3HT conjugated polymer chains as belonging to the poor solvent, thus the P3HT polymer chains easily occurred the liquid-liquid phase separation or spinodal decomposition because in the diluted solution region. However, the P3HT/xylene solution can separate into polymer rich and solvent rich regimes through the spinodal decomposition behavior. The P3HT polymer chains associate to the 3-8 nm aggregate particles by π-π interaction. This P3HT aggregate particles self-assemble subsequence into the P3HT nanowhiskers structure through the coarsening process. However, the length of the P3HT nanowhiskers increases as increasing ageing time. As the aging time further increasing, the P3HT nanowhisker aggregates into three-dimensional network structure and/or sheet-like aggregation structure. However, the P3HT polymer chains re-arrange for an ordered - stacked structures/nanocrystals within P3HT nanowhiskers with nucleation and growth depressed. Therefore, we can clean to see a lot of nanocrystals or - stacked domains, c.a. 3-8 nm, with disordered direction of the - stacked in the P3HT nanowhiskers. In the third chapter, we identified the gelation behavior and aggregation structure of P3HT blended with phenyl-C61-butyric acid methyl ester (PCBM) (P3HT/PCBM) in xylene solutions through the OM, POM, UV-vis, PL, SEM and TEM. Herein, we found that the gelation time of P3HT/xylene solution markedly increases as the PCBM is added in the P3HT/xylene solution. It is let us consider that, in the P3HT/xylene solution, the PCBM molecules act an effetely solvency through the - interaction and P3HT conjugated polymers. In the P3HT/PCBM/xylene solution, the P3HT/PCBM composites in xylene solution occur easily the liquid-liquid phase separation or spinodal decomposition. The P3HT/PCBM/xylene solution separates into a polymer enrich and a solvent enrich regimes by the spinodal decomposition behavior. However, in the P3HT/PCBM enriched domains, The P3HT polymer chains associate to the 3-8 nm aggregate particles by π-π interaction, subsequently these P3HT particles self-assemble into the P3HT nanowhiskers structure through the coarsening process. As the same time, the PCBM molecules associate into the PCBM aggregates. As the aging time further increasing, the P3HT nanowhisker aggregates into three-dimensional network structure and/or sheet-like aggregation structure. The PCBM become the PCBM nanocrystals with nucleation and growth process. However, the P3HT nanowhisker and sheet-like aggregates were absorbed by the aggregated PCBM nanocrystals to form the cabbage-like or flowers-like structures. Moreover, within P3HT nanowhiskers, it is interesting to note that a lot of P3HT nanocrystals or - stacked domains with diameter ranges are c.a. 3-8 nm, with disordered direction of the - stacked were observed. In the fourth chapter, we identified the gelation behavior and aggregation structure of P3HT blended with graphene (P3HT/graphene) in xylene solutions through the OM, POM, UV-vis, PL, SEM and TEM. In the research, we found that, in the P3HT/xylene solution, the graphene particles aggregate easily as the aging is raised. It is let us consider that, the graphene aggregates act an effetely absorb ability to the P3HT polymer chains through the - interaction. Therefore, In the P3HT/graphene/xylene solution, liquid-liquid phase separation or spinodal decomposition behavior of the P3HT/graphene/xylene also occurs to form the P3HT/grapheme enriched domains. In the P3HT/graphene enriched domains, the graphene molecules associate into the graphene aggregates. These graphene aggregates in the P3HT/grapheme enriched domain absorb the P3HT polymer chains on the surface of graphene aggregates. Subsequently, the highly ordered P3HT nanowhiskers assemble by the P3HT polymer chains through the - interaction is obserbed. As the prolonged aging, the the highly ordered P3HT nanowhiskers grows to form the long and high crystalline P3HT nanowhiskers. In the P3HT nanowhiskers, the direction of the - stacked is parallel to the nanowhisker axis. As the aging time further increasing, the high crystalline P3HT nanowhiskers grow with staggered and permeated forming the cocoon-like structure. Therefore, within P3HT nanowhisker and graphene, we can find a high order P3HT - stack structures of P3HT polymer chains or benzene ring were discussed.

碩士
國立臺灣大學
高分子科學與工程學研究所
99
The synthesis, characterization and morphology study of copolymers of poly(3-hexylthiophene) (P3HT) and poly(3-thiophene hexylacetate) (P3THA) are performed in this thesis. By using GRIM method, polymers with high regioregularity, narrow polydispersity and controlled molecular weight can be obtained. From the optoelectronic properties characterization, the ester-functionalized P3THA shows a blue-shift UV-Vis spectrum and lower HOMO as compared to P3HT. These results are contributed to the bulky and the electron-withdrawing ester group which decrease the conjugated length. The amount of blue shift is directly proportional to the amount of P3THA in the block copolymer. From the CV measurements, each respective HOMO and LUMO is observed in each block segment of block copolymer which does not present in the random copolymers. The thermal and phase behaviors of the block copolymers were investigated by DSC, WAXS, GIWAXS and AFM. The crystalline morphology of copolymers is dependent on the block compositions of P3HT-b-P3THA. Phase separation is observed as the P3HT block higher than 50% molar ratio. When the molar ratio of P3THA is larger than 80%, the cocrystalline structure is observed. Thus, the crystalline morphology can be tuned by changing the block copolymer compositions. The results are useful for the design and fabrication of nanostructured conducting polymers.

碩士
國立東華大學
材料科學與工程學系
90
Abstract In this study, Regioregular Poly(3-hexylthiophene) (RR-P3HT) films were prepared by using spin-coating technique. The molecular structure of these films was discussed and the characteristics of the organic diodes and thin film transistors made by these films were investigated. The molecular structure of these organic films was characterized by wide angle X-ray diffraction, UV-VIS absorption spectroscopy, and raman spectroscopy. As the concentration of RR-P3HT solution is increased and spinning speed is lowered，the structure order of RR-P3HT films will be better and the effective conjugate length will be longer and lamellar structures will increase. For the organic diode, the performance of device structure will be better as the electrodes were deposited upon the organic layer. ITO was the better material for electrodes. For the organic thin film transistor, the transistor work obviously as it was fabricated by using 0.88wt% and 2wt% of RR-P3HT solution, and the mobility in the order of 10-3 cm2/Vs. There was no transistor performance as the device was fabricated using 0.05wt% of RR-P3HT solution.

碩士
國立中正大學
光機電整合工程研究所
100
The study is to synthesis high regioregular Poly(3-hexylthiophene)(rr-P3HT) by Modified Grignard Metathesis(GRIM), and then functionalize this polymer with a thiol terminal group by anionic polymerization(P3HT-(Si(OCH3)3)2). The structure of polymer has been confirmed by NMR. The element of polymer has been confirmed by EDS and XPS. The thermal properties have been investigated by TGA. The UV-Vis spectrum shows that the thin film samples have red shift compared to the solution samples, and the silicon caused a blue shift of the wavelength. The crystallinity and orientation have been investigated by AFM and XRD. Finally, P3HT of different molecular weights and corresponding P3HT-(Si(OCH3)3)2 were used as the semi-conducting layer for fabricating Organic Thin Film Transistors(OTFTs). The saturation current increases from 11 nA to 47 nA, the mobility increases from 3.75x10-5 cm2/V.s to the maximal 3.44x10-4 cm2/V.s and the threshold voltage decreases from 11 V to -6V.

碩士
輔仁大學
化學系
102
Bulk-heterojunction process has been widely used in organic solar cells. The active layer was thermally treated to enhance the morphology of active layer. Unfortunately, the thermal treatment process also induced phase separation between the p-type semiconductor and n-type semiconductor. An isothermal crystallization process was applied to the fabrication of Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butryic acid methyl ester (PCBM) based solar cells accompanied with a hydroxyl group end-functionalized poly(3-hexylthiophene) (HOC-P3HT-COH). HOC-P3HT-COH compatibilized the P3HT and PCBM active layer and also homogenized the distribution of P3HT/PCBM active layer. The isothermal crystallization process was then applied to the active layer to study the crystallization behavior of the active layer comparing to the conventional spin-coating process. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to characterize the crystallization behavior. Scanning electron microscope (SEM) was used to probe the surface morphology of the active layer. Transmission electron microscope (TEM) was used to investigate the morphology of P3HT/PCBM layer. Experimental results indicated that P3HT/PCBM layer achieved a better crystal form than the thermal treatment process and the carrier mobility was enhanced by ten times which is favorable for the solar cells applications.

碩士
中原大學
化學研究所
95
In this research, the derivative of pyrrole, N-(3-hydroxypropyl) pyrrole (HPPY) has been synthesized and identified by 1H-NMR, 13C-NMR, FT-IR, UV-vis and GC-Mass spectroscopies.The homopolymers of poly(3-hexylthiophene) (P3HT) and poly N-(3-hydroxypropyl)pyrrole (PHP) and their copolymer poly(3-hexylthiophene-co-N-3-hydroxy)pyrrole have been prepared by electrochemical polymerization on the ITO glass. The electrochromic properties as-prepared copolymer coated ITO glass was innestigated by spectrum electrochemistry studies. The as-prepared copolymer was characterized by Fouier Transform Infrared (FT-IR) and Element analysis (EA). Effect of copolymer composition on the thermal stability, optical properties, electrochemistry, crystallinity. and surface morphology was evaluated by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC),UV-Uisible absorption spectroscopy, cyclic voltaminetry (CV) studies,powder X-ray diffraction (XRD)pattern and scanning electron microscopy(SEM).

碩士
國立中正大學
化學工程研究所
99
With an aim to improve the hole mobility of P3HT, carbon nanotubes (CNTs) have recently been incorporated into P3HT. The advantages of CNTs over other nanomaterials arise from good conductivity,and excellent chemical stability. Particularly, multi-walled carbon nanotubes (MWCNTs) have widely been used as a conduction bridge because of high conductivity and relatively high work function.However,since it is well-know that homogeneous distributions of CNTs in polymer is difficult to achieve,it is expected that P3HT-MWNTs can improve the dispersion when the organic thin film transistors (OTFT) fabricated with it. In this work, multiple-walled carbon nanotubes (MWNTs) were chemically modified by a ligand-exchange reaction of ferrocene (Cp-Fe-MWNTs).The modified MWNTs (Cp-Fe-MWNTs) were next monolithiated by sec-butyllithium and functionalized by poly (3-hexylthiophene)(rr-P3HT).In the second part, H-NMR, TGA, DSC, UV/Vis, SEM, TEM, and Four-Probe were used to analyze the material P3HT-MWNTs. Finally, the P3HT-MWNTs composite blended with pure P3HT was used as the semi-conducting layer for fabricating on Organic Thin Film Transistors(OTFTs). P3HT-MWNTs have been successfully synthesized and homogeneously dispersed in P3HT matrix for the purpose of obtaining high field-effect mobility of P3HT.

碩士
國立成功大學
光電科學與工程研究所
97
In this study, we have successfully fabricated regioregular poly(3-hexylthiophene) (RR-P3HT)-based organic thin-films transistors (OTFTs) using polyimide (PI) with nanoimprinted grooves as the dielectrics layers to investigate the electronic transport behaviors. The contact-transferred and mask-embedded lithography technology was employed to form the PI-nanogrooves. Good orientation of the RR-P3HT polymer chains along the trench of the PI-nanogrooves was achieved by inkjet-printing the RR-P3HT on the PI-nanogrooves to result in high field-effect mobility OTFTs in which the field-effect is as high as 2.58×10-2 cm2/Vs. Especially, high mobility anisotropies (μ// /μ⊥), which is defined as the ratio of the carrier mobility along the PI-nanogrooves to that across the PI-nanogrooves, was obtained in the PI-nanogrooves OTFTs. In order to realize the properties of RR-P3HT films within the trench of the PI-nanogroove, atomic force microscopy, scanning electron microscope, and polarized micro-Raman spectroscopy were used to study the orientation of the RR-P3HT polymer chains. Keywords: Organic thin film transistors, P3HT, Polyimide, Nanoimprint lithography technology, Micro-Raman.

博士
國立清華大學
化學工程學系
103
Conjugated polymers composed of semirigid backbone and the flexible side chains for facilitating their solubility in common organic solvents are the key materials of polymer-based optoelectronics, including solar cells, light-emitting diodes and thin-film transistors (TFTs). In the case of bulk heterojunction (BHJ) polymer solar cells, poly(3-hexylthiophene) (P3HT) has been considered as one of the most promising donor materials due to a good combination of charge transport properties, solution processability and the ease of synthesis with controllable regioregularity and molecular weight. The morphology of the active layer, which has a significant impact on the power conversion efficiency of the BHJ polymer solar cell, is strongly influenced by the dissolution condition of the conjugated polymer for film casting due to the existence of the memory effect; therefore, investigating the structure of the solution structure of conjugated polymer and its effect on the morphology of the subsequently cast film is an important fundamental task. This thesis is focused on elucidating the structures and phase transformation processes of P3HT in the solution and bulk state. We systematically studied the gelation process of the semidilute solution of P3HT with xylene induced by prolonged aging. A macrophase separation generating P3HT-enriched phase and solvent-rich phase of μm in length scale occurred during the aging. Phenomenologically, the phase separation took place via the nucleation-and-growth mechanism driven by the formation of nanowhiskers in the P3HT-enriched domain. The P3HT-enriched macrodomains were mechanically stabilized by the networking of the nanowhiskers and their jamming in the system led to the gel property. Therefore, P3HT/xylene gel was characterized by a hierarchical structure with distinct morphological entity at different length scales, namely, the macrodomains with μm length scale composed of the nanowhiskers assembled by the crystallites. The addition of PCBM was found to greatly slow down the gelation, which implied the existence of favorable interaction between P3HT and PCBM in xylene. The effect of the solution structure on the crystallization kinetics and relevant structural development in the subsequently cast films of P3HT has been studied to resolve the memory effect underlying the morphological formation of conjugated polymer films. We compared the crystallization rate of P3HT in the film cast from the gel (called “gel-cast film”) with that in the film cast from the liquid solution (called “solution-cast film”) to understand the effect of solution structure on the structural development in the subsequently cast film of conjugated polymer. The in-situ SAXS measurement and thermal analysis revealed that both the cold and melt crystallization of P3HT in the gel-cast film were much slower than those in the solution-cast counterpart. The retardation of crystallization rate in the gel-cast film was attributed to the abundance of the nanowhiskers, which remained largely undisrupted even when the temperature was higher than the crystal melting point. In this case, the the crystallization of P3HT occurred predominantly within the individual nanowhiskers and the meshes in the networks of the whiskers, where their limited sizes in at least one dimension imposed a strong spatial constraint to the crystal growth and chain motion for crystallization. Finally, we attempt to resolve the role of regioregularity on the self-assembly process of P3HT. The regioregularity of P3HT is normally characterized by the regioregularity (RR) value defined as the mole percentage of head-to-tail (HT) dyad in the backbone. Here we revealed that the by the content of HT-HT triad also plays an important role governing the self-assembly of P3HT in solution and bulk state by investigating the gelation rate and crystallization kinetics of two P3HT samples bearing almost identical RR value and average molecular weight. It was found that the semidilute xylene solution of the sample with slightly smaller RR value exhibited a faster gelation driven by the formation of crystalline nanowhiskers. In the bulk state, this sample also displayed a faster crystallization kinetics and higher melting points. Detailed characterization of the configurational structure by nuclear magnetic resonance (NMR) spectroscopy showed that the sample with smaller RR value contained an obviously higher population of HT-HT triad sequence. Therefore, in addition to the amount of HT dyad represented by the RR value, the population of the consecutive HT sequence along the polymer chain plays a significant role in the self-assembly processes of P3HT. Knowledge on this system parameter, which can be deduced conveniently from 13C NMR spectroscopy, is hence essential for the delicate control of the morphology of P3HT. This thesis has thus provided a systematic understanding of the structures and crystallization behavior of P3HT in both solution and bulk state. The results shall be fundamentally important for understanding and controlling the morphological formation of the P3H film induced by crystallization for opto-electronic applications.

碩士
國立中正大學
化學工程所
98
The first part of this research is the synthesis of composite material －Poly(3-hexylthiophene)/ multi-walled carbon nanotube (P3HT/MWCNT), and the second part is the characterization of this composite material P3HT/MWCNT, as well as the organic thin film transistors (OTFT) fabricated with it. In the first part, Modified Grignard Metathesis was used to synthesize regioregular P3HT, and the MWCNT is functionalized by a mixture of strong oxidizing acids such as HNO3 or H2SO4 with the adding of thionyl chloride (SOCl2) to convert the carboxyl groups into acyl chlorides. Then Octadecylamine (ODA) was added to react withn the MWCNT-COCl to form MWCNT-ODA. After that, RR-P3HT and MWCNT-ODA was blended at a as the ratio of 5wt% MWCNT, 15wt% MWCNT, 25wt% MWCNT to form the composite material P3HT/MWCNT. In the second part, FT-IR, Dynamic Laser Scattering (DLS), and SEM were used to analyze the MWCNT and MWCNT-ODA, and FT-IR and H1-NMR were used to analyze the RR-P3HT. Finally, TGA, DSC, UV/Vis, PL, TEM, Four-Probe were used to analyze the composite material P3HT/MWCNT. We also used this composite material as a semiconducting layer in the fabrication of OTFT and we have found that with an increase in the MWCNT weight ratio of the composite material, the mobitility increase from 0.0011 cm2/Vs to 0.037 cm2/Vs.

Research Doctorate - Doctor of Philosophy (PhD)
The main purpose of this thesis was to develop a synthetic process that would allow for the low cost production of regioregular poly(3-hexylthiophene) at high levels of reproducibility in terms of regioregularity and molecular weight that could ultimately be transformed into a large-scale manufacturing process. The synthetic procedures were divided into two steps: firstly the optimisation of the bromination of 3-hexylthiophene to form 2,5-dibromo-3-hexylthiophene, the precursor monomer to rrP3HT, and secondly the optimisation of the synthesis of regioregular poly(3-hexylthiophene) itself. Ultimately both synthetic procedures were successfully converted from batch synthesis techniques to novel low pressure flow synthesis techniques. A mechanism was proposed for the bromination of 3-hexylthiophene using N-bromosuccinimide that suggests that N-bromosuccinimide acts as an electrophile and first attacks the 2 position on 3-hexylthiophene for the first bromination and then the 5 position on the second bromination. This proposition, based on empirically derived rate constants and activation energies, refutes earlier theories that N-bromosuccinimide acts as a source of Br₂and that it is Br₂that is the actual brominating agent. Both bromination reactions were determined to be first order reactions, which conforms to earlier work on bromination of thiophene with N-bromosuccinimide. Kinetic studies of both the monobromination of 3-hexylthiophene and the monobromination of 2-bromo-3-hexylthiophene has provided the respective activation energies (Eₐ), frequency factors (A) and rate constants (k) which have never before been published for the bromination of 3-hexylthiophene using N-bromosuccinimide in dimethylformamide. Through the use of the Arrhenius equation, rate constants can now be calculated at any temperature, which therefore allows us to predict reaction times under different temperature conditions, and can assist in modelling the ideal reaction conditions for the synthesis of 2,5-dibromo-3-hexylthiophene. Upper temperature boundaries have been established based on the formation of Br₂from N-bromosuccinimide. It was established that when using the solvent tetrahydrofuran, variable induction times, particularly for the monobromination of 3-hexylthiophene, can lead to unpredictable reaction times. Dimethylformamide however did not display induction times for either the first bromination or second bromination of 3-hexylthiophene and was therefore chosen as the preferable solvent for brominating 3-hexylthiophene to form 2,5-dibromo-3-hexylthiophene. Synthetic methods were developed to produce pure 2-bromo-3-hexylthiophene and pure 2,5-dibromo-3-hexylthiophene in a short timeframe. Using models developed from our kinetic studies and from understanding the exothermic nature of the first bromination reaction and the isothermal nature of the second bromination reaction we have been able to develop a synthetic method that operates at two temperatures: 15˚C for the bromination of 3-hexylthiophene and 30˚C for the bromination of 2-bromo-3-hexylthiophene. Choosing these two temperatures significantly reduced the time to synthesise 2,5-dibromo-3-hexylthiophene from multiple hours to less than 40 minutes and with full conversion to 2,5-dibromo-3-hexylthiophene, producing significant benefits with regard to time reduction and fewer purification steps compared to any synthetic method for 2,5-dibromo-3-hexylthiophene published in the literature. The achievement of this optimisation of the 2,5-dibromo-3-hexylthiophene synthesis, the monomer precursor to regioregular poly(3-hexylthiophene), will assist our overarching goals of reducing the cost of producing regioregular poly(3-hexylthiophene). A low pressure flow reactor for the synthesis of 2,5-dibromo-3-hexylthiophene was designed and built at a fraction of the cost of commercial high pressure flow reactors. Using this equipment 2,5-dibromo-3-hexylthiophene was synthesised using 3-hexylthiophene and N-bromosuccinimide in dimethylformamide in quantitative yield and with 100% purity. Importantly the space-time yields obtained greatly exceeded those measured for the synthesis of 2,5-dibromo-3-hexylthiophene using conventional batch chemistry by a minimum factor of 1356. There is also the potential to further increase the space-time yields for the flow synthesis of 2,5-dibromo-3-hexylthiophene using 3-hexylthiophene and N-bromosuccinimide by varying the temperature of the reaction and the concentration of 3-hexylthiophene, and also by reducing the residency time of the reactants in the reaction coil. In addition, one of the great concerns with the batch bromination reaction of 3-hexylthiophene with N-bromosuccinimide is the exothermic first bromination reaction, i.e. the conversion of 3-hexylthiophene to 2-bromo-3-hexylthiophene. This reaction has the potential to be quite hazardous, especially if it is run in THF. However in the flow reaction the heat exchange is so efficient between the reactants and the water bath that the exothermic hazard is greatly minimised, allowing the monobromination of 3-hexylthiophene using N-bromosuccinimide in dimethylformamide to be heated rather than cooled as is the case in the batch bromination situation. The increased temperature greatly increases the rate of reaction for the bromination of 3-hexylthiophene to form 2,5-dibromo-3-hexylthiophene. The goals of producing high quantities of regioregular poly(3-hexylthiophene) and hence benchmarking their space-time yields have been achieved using batch synthesis. It would appear that generally the space-time yields for small scale reactions are similar to those of large scale batches. We were able to produce a batch of regioregular poly(3-hexylthiophene) of up to 135 g in size that had high regioregularity (95%) and low PDI (2.03) with a M_n of 21,400 gmol⁻¹. In addition the regioregular poly(3-hexylthiophene) produced during this thesis has been incorporated into bulk heterojunction organic photovoltaic devices that have achieved high power conversion efficiency values, in excess of 5%, which places them at amongst the highest PCEs published. Using a custom designed and built low pressure flow reactor we demonstrated, for the first time, that low pressure flow synthesis of regioregular poly(3-hexylthiophene) is capable of producing a range of molecular weights (M_w) between 6,240 and 40,300 gmol⁻¹ and that the polydispersity indexes and regioregularities compare favourably to those of regioregular poly(3-hexylthiophene) produced using batch synthesis methods prior to soxhlet extraction. Yields have been obtained ranging from 32-55% and at the higher end compare with those reported in the literature for batch synthesis of regioregular poly(3-hexylthiophene), of 65%. A device made from regioregular poly(3-hexylthiophene) generated from flow synthesis techniques developed in this PhD thesis produced PCEs of 2.1%, which is about 0.7% less than typical OPV devices produced with regioregular poly(3-hexylthiophene) synthesised using batch chemistry techniques. The reduction in PCE has been attributed to a possible contamination from the nickel initiator. Through monitoring the output of a flow synthesis experiment on regioregular poly(3-hexylthiophene) we have been able to show that a consistent production of regioregular poly(3-hexylthiophene) can be made with all its physical properties, i.e. molecular weight, polydispersity index and regioregularity produced within a narrow tolerance exceeding the performance of published batch synthesis results. Importantly the space-time yields calculated for the flow synthesis of regioregular poly(3-hexylthiophene) shows a 1600-fold increase over batch synthesis methods, which will have a significant impact on reducing the costs of making regioregular poly(3-hexylthiophene). The work represented in this thesis has developed methods that will enable the manufacture of low cost, highly controlled regioregular poly(3-hexylthiophene) which will contribute to realising lower manufacturing costs for the production of organic photovoltaic devices and importantly producing a consistently performing active layers within the bulk heterojunction organic photovoltaic device.

碩士
輔仁大學
化學系
100
Bulk heterojunction morphology has been widely used in the research of polymer solar cells. Interfacial area between the p-type material and the n-type material has been increased significantly, which leads to an increase in current density (Jsc). Among the p-type and the n-type materials, poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are the most commonly used active layer materials. Unfortunately, morphology stability is not easy to control in the P3HT / PCBM film because of poor compatibility between them. PCBM tends to aggregate and form large domains in the P3HT/PCBM blended film, which results in decreased interfacial area between P3HT and PCBM. Performance of the P3HT / PCBM based polymer solar cells become inconsistent. A C60 derivative, [6,6]-phenyl-C61-butane (PCB), is synthesized to diminish aggregation of PCBM in this study. PCB has a similar chemical structure to PCBM and can act as an impurity of PCBM. Aggregation behavior of PCBM will decrease as its purity is decreased. Therefore, the agglomeration of PCBM will be more controllable by incorporation of PCB to the P3HT / PCBM. Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FT-IR) are used to characterize the synthesis of PCB. Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) are used to investigate morphology of annealed P3HT / PCBM and annealed P3HT / PCBM / PCBM films. Experimental results show that thermal stability of P3HT/PCBM film is improved upon addition of PCB to the P3HT / PCBM film.

碩士
國立高雄應用科技大學
化學工程系碩士班
96
The polymer photovoltaic cells have attracted much attention due to their possibilities of low-production cost, light-weight, flexible and easy manufacturing by solution process in recent years. Several laboratories have reported high-performance polymer photovoltaic cells using poly(3-hexylthiophene) (P3HT) as an electron donor and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an electron acceptor. As a photo-active layer material in polymer photovoltaic cells: first, the conjugated polymers need effective absorption of visible light and the band-width of their absorption must be broad enough; second, it needs characteristics of both low band gap and high charge-separating (electron and hole) ability. Although the optical/electrical properties of active layer themselves are the most important one for the efficient charge generation and transport. Thus, two alternative copolymers: poly{(3-hexylthiophene)-alt-(3,4-ethylene- dioxythiophene)}(PT6EDOT-alt.) and poly{(3-hexylthiophene)-alt-(pyridine)}(PT6-Pys) were prepared. In addition, random copolymers (PT6EDOT-ran.) were copolymerized by oxidative method based on different ratios of 3-hexylthiophene and 3,4-ethylene- dioxythiophene units. However, to study in the effect of the regioregularity of poly(3-hexylthiophene) on the performances of polymer photovoltaic devices, three types of poly(3-hexylthiophene) (P3HTs) were used this work. To identify structure nuclear magnetic resonance (NMR) was used, physical properties via gel permeation chromatography (GPC), thermal stability properties via thermogravimetric analysis (TGA) and differential scanning calorimetry analysis (DSC). Optical properties, UV-visible absorption (UV-vis), fluorescence (PL), and photo-electron spectroscopy in air (PESA) spectra were compared with commercial regioregular HT-P3HT. In addition, surface morphologies and device properties were measured by atomic force microscope (AFM) and solar simulator system (SMU), respectively. The observed characteristics are sufficiently better to make these polymers highly promising for the polymer photovoltaic cell applications.

碩士
中原大學
化學研究所
89
Abstract A series of Nanocomposite materials that consisted of layered montmorillonite (MMT) clay and poly(3-hexylthiophene) (P3HT) were prepared by effectively dispersing the inorganic nanoclayers of MMT clay in organic poly(3-hexylthiophene) matrix via in-situ polymerization. Organic 3-Hexylthiophene monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by a one-step oxidative polymerization. The as-synthesized poly(3-hexylthiophene)/ clay lamellar nanocomposite materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. Poly(3-hexylthiophene)/clay Nanocomposites in the form of coating with clay loading (e.g., 5%) on cold-rolled steel (CRS) were found superior in corrosion protection over those of conventional Poly(3-hexylthiophene) based on a series of electrochemical measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt-% aqueous NaCl electrolyte. The molecular weights of P3HT extracted from poly(3-hexylthiophene)/clay materials and bulk poly(3-hextythiophene) were determined by gel permeation chromatography (GPC) with THF as eluant. Effects of the material composition on the gas barrier property, thermal stability, flame retardant and mechanical strength of P3HT along with poly(3-hexylthiophene)/clay materials, in the form of both fine powder and free-standing film , were also studied by gas permeability measurements, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI) measurements and dynamic mechanical analysis (DMA).

碩士
國立成功大學
光電科學與工程學系
103
In this study, we investigated the effects of solvents on the self-assembly of poly(3-hexylthiophene) (P3HT) polymer chains during film formation from solution. The morphologies and microstructures of the resulting P3HT films were analyzed by using absorption spectroscopy, atomic force microscope (AFM), and conductive-AFM (C-AFM). Nanofibers and micro-domains were observed by using AFM in the P3HT films made with anisole and chloroform (CF), respectively. The absorption spectra indicated that the P3HT films made with CF exhibited the strongest band at 603 nm, thereby indicating that this film had the longest effective conjugation length as suggested by theoretical calculations. The topography of the anisole specimen by C-AFM is consistent with its current mapping. The correlation between the nanoscale morphology and the C-AFM current mapping of P3HT is discussed.

碩士
輔仁大學
化學系
103
A high crystallized poly(3-hexylthiophene) (P3HT) film has been prepared by incorporation of a carboxylic acid end-functionalized P3HT (HOOC-P3HT-COOH) into the pristine P3HT. Crystal size increase from ~16.5 nm for the pristine P3HT to ~20 nm after adding 10 wt.% HOOC-P3HT-COOH to P3HT. The crystal size is further enlarged to ~24 nm by stirring the P3HT solution before adding HOOC-P3HT-COOH. Transmission Electron Microscopy (TEM) is used to characterize the morphological change between different processes. UV-vis spectroscopy (UV-vis) is used to study the aggregation behavior of P3HT films. Experimental results indicate that P3HT tends to form larger crystals by adding 10 wt.% HOOC-P3HT-COOH into the P3HT solution and allows to aggregate in solution for 30 minutes. The absorption peak in the UV-vis spectrum is also intensified which at 610 nm agrees with the results from XRD study. TEM images show that P3HT fibers become larger and connected after the addition of HOOC-P3HT-COOH and especially after standing and stirring processes.

Insight into the relationship between the Ionization Energy (IE) offsets between donor and acceptor materials and the performance of the organic solar cells (OSC) could improve the charge generation efficiency. Charge generation can proceed through two different paths in Bulk Heterojunction (BHJ) based OSCs which are electron transfer from donor to acceptor and hole transfer from acceptor to donor. Electron transfer can be controlled by electron affinities and hole transfer can be controlled by ionization energies. In this work, large IE offsets were investigated in poly(3-hexylthiophene-2,5-diyl)(P3HT):Non Fullerene Acceptor (NFA) based OSCs by fabricating and characterizing devices, also conducting several experiments to optimize the processing conditions for the devices. These results provide an overview of the charge transfer and IE offsets dependence, also a general picture of the photophysics in P3HT:NFAs based OSCs. Moreover, using wide bandgap polymer donor which has shallow IE such as P3HT with low-bandgap NFAs may provide sufficient IE offsets between donor and acceptors enabled us to reach the inverted Marcus regime. In this regime, the electron transfer rate decreases upon decreasing the charge transfer (CT) state energy compared to the exciton energy. The decrease of the internal quantum efficiency (IQE) upon increasing the IE offset suggests that we are in that regime.

碩士
國立中正大學
化學工程研究所
104
The particle size and structural feature of regiorandom P3HT (RRa-P3HT) in two solution systems, toluene and chlorobenzene, with two distinct concentrations (0.7 mg/mL and 7.0 mg/mL, respectively), were investigated by dynamic/static light scattering (DLS/SLS), depolarized dynamic light scattering (DDLS), small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) analysis. According to the SLS experiment, RRa-P3HT formed sphere-like structure in both solvents, but the aggregate size found in toluene is always larger. Results from the DDLS experiment agree with the SLS analysis, suggesting that RRa-P3HT formed isotropic structure in all solutions investigated. In the DLS analysis, the decay rate of the fast mode shows q2 dependence, while the slow mode is q0-dependent in both solution systems. Moreover, the aggregate size found in 7.0 mg/mL chlorobenzene solution is similar to that formed in 0.7 mg/mL toluene solution, which implies that solvent quality plays an important role dictating the aggregation properties of RRa-P3HT.

碩士
臺灣大學
高分子科學與工程學研究所
95
A novel route for preparing poly(3-hexylthiophene)-based core shell like copolymer via click chemistry approach has been developed. First, regioregular ethynyl group ended poly(3-hexylthiophene)s (P3HT) were synthsized using a ethynyl-terminated Grignard reagent. Then, multifunctional initiators for atom transfer radical polymerization (ATRP) were prepared by reacting molecules containing three, six, or twelve hydroxyl groups with 2-bromoisobutyryl bromides to yield the corresponding 2-bromoisobutyrates moiety. The starburst poly(methyl acrylate)s (PMA) were produced by using these initiators in a controlled manner by ATRP, and the ω-bromo ends of these star polymers were subsequently modified to generate the same number of azide functional groups in the presence of trimethylsilylazide (TMS-N3). Finally, the PMA core and P3HT shell were combined to form core shell like diblock copolymers by click reaction. Chemical structure and molecular weight characteristics of these copolymers were studied by IR、1H & 13C NMR、GPC and MALDI-TOF techniques. The core shell like diblock copolymers were well soluted in chloroform. The UV-visible absorption spectra (UV-vis) showed the λmax=450nm, and the photoluminescence spectra (PL) showed the light emission wavelength were about 575nm. By comparing the UV-vis and PL spectra, the optical properties of these copolymers are the same as pure P3HT.

碩士
輔仁大學
化學系
106
The research is mainly divided into two parts. The first part is about the molecular morphology of the active layer in organic solar cells. The second part is about the anti-corrosion of conductive polymer P3HT on iron. At present, organic heterojunction structure is mainly used in the research of organic solar cells. But the PCBM tends to aggregate after thermal annealing treatment. The surface morphology is not easily controlled and leads to severe the phase separation. In this study, two C60 derivatives, phenyl C61-hexane (PCH) and phenyl C61-3-methylbutane (PCMB), were compared to phenyl C61-butane (PCB) in studying the concept of "similar structure" additives to the P3HT / PCBM blend system, by decreasing the purity of PCBM and disrupted its arrangement and crystallization, thereby, inhibiting the generation of large amounts of PCBM aggregates. OM and TEM studies show that, compared to PCB and PCMB, P3HT / PCBM / PCH blended film shows more PCBM agglomerates after thermal- trectment indicating PCH has less influence on the aggregation of PCBM. XRD, DSC, and Absorption spectra results confirm that PCH tends to interact with P3HT with its long alkyl side-chain and, therefore, restrain itself to interact with PCBM. In the second part, P3HT with different regioregularities were processed with different solvent and heat treatment to investigate how crystallinity affect anticorrosion properties on iron. Additionally, P3OT was blended with P3HT to control crystallinity. Electrochemical study by CV shows that anticorrosion properties of P3HT on iron can be improved at higher crystallinity.