Inhomogeneity of Spin-Coated and Cast Non-Regioregular Poly(3-hexylthiophene) Films. Structures and Electrical and Photophysical Properties

Kobashi, Motoi; Takeuchi, Hisao

doi:10.1021/ma980632u

Cited by 87 publications

(70 citation statements)

References 25 publications

(56 reference statements)

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“…Furthermore, a shoulder peak appeared around 600 nm, which can be assigned to vibronic structure with a 0-0 transition (-Ã transition originated fromelectron orbital overlap between adjacent thiophene rings). 2,19 Such a spectral profile is in agreement with that of P3HT colloidal dispersions in various solvents, [12][13][14][15] indicating thatstacking interaction caused by aggregation of polymer chains would take place in the particle. Figure 3 also shows that the increased polymer concentrations led to a larger red shift and a broader spectrum, suggesting that interchain interaction would be stronger as the concentration became higher.…”

supporting

confidence: 72%

Preparation and Characterization of Water Self-dispersible Poly(3-hexylthiophene) Particles

Shimizu

Yamada

Wada

et al. 2007

Polym J

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The present paper describes the preparation and characterization of stable aqueous dispersions of poly (3-hexylthiophene) (P3HT) by a precipitation method. P3HT was first synthesized by oxidative polymerization of 3HT with iron(III) chloride as an oxidant. Number-average molecular weight (M n ) of P3HT increased with an increase in 3HT concentration. Colloidal particles were prepared by adding a tetrahydrofuran (THF) solution of P3HT into a large amount of distilled water. TEM observations showed that the particle size increased with an increase in the concentration and M n of P3HT. The size of the particles was in the range of 50 to 600 nm. The spectral features of the aqueous dispersions were investigated by means of UV-vis spectroscopy. P3HT provided the -Ã absorption band at 436 nm in THF. On the other hand, the dispersions brought about a bathochromic shift of the bands and a larger red shift was observed as the polymer concentration became higher, indicating that P3HT would take a well-stacked structure in the particles. Temperature dependence of UV-vis absorption spectra for P3HT aqueous dispersions was also studied in the temperature range of 0 to 80 C, which revealed that P3HT in the dispersed state showed a thermochromism similar to that of P3HT in THF.KEY WORDS: Polythiophene / -Conjugated Polymer / Poly(3-hexylthiophene) / Colloidal Particle / Conducting Polymer / Precipitation Method / Thermochromism / Poly(3-hexylthiophene) (P3HT) is a subject of extensive study because of its solubility, fusibility, and environmental stability.1 P3HT also exhibits unique properties such as thermochromism and solvatochromism. [2][3][4][5][6] This functional polymer is viewed as potentially useful materials in fieldeffect transistors, optical and electronic sensors, light-emitting devices, nonlinear optical materials, etc. 7-9Our attention has focused on colloidal dispersions of P3HT particles. Colloidal particles are of great importance due to their interesting physical properties as well as their potential technological applications.10,11 Several attempts have been made so far to produce P3HT particles. Yamamoto et al. employed a reprecipitation method to prepare colloidal dispersions of P3HT. Methanol, which is a poor solvent for P3HT, was added to the CHCl 3 solution of P3HT, resulting in the formation of P3HT particles. 12,13 Takeuchi and Kobashi also investigated in detail the kinds of poor solvents and clarified the precipitation conditions for improved yields. 14 Furthermore, it has been reported that the use of a nonionic surfactant, Tween 80, provided stable aqueous dispersions of P3HT. 15To our knowledge, few reports on water self-dispersible P3HT particles have been published. 15 There is hence a lack of information about colloidal properties of P3HT water dispersions, such as particle size, particle morphology, optical property, etc. Development and characterization of such dispersions are of great significance from an environmental as well as industrial aspect. The purpose of the present study is to de...

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supporting

confidence: 72%

Preparation and Characterization of Water Self-dispersible Poly(3-hexylthiophene) Particles

Shimizu

Yamada

Wada

et al. 2007

Polym J

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“…P3HT has been widely studied in the past and is well known as being an effective hole transport polymer, with higher hole mobility than many other conjugated polymers, including the poly(phenylenevinylene)s. 2 Initially, however, rather low hole mobilities were reported for regiorandom P3HT. 3 However, when head-to-tail regioregularly substituted P3HT became available, the hole mobilities were found to be dramatically improved. [4][5][6] The increase in mobility was related to side-chain-induced self-organization into a well-ordered twodimensional lamellar structure.…”

mentioning

confidence: 99%

High ambipolar and balanced carrier mobility in regioregular poly(3-hexylthiophene)

Choulis

Kim

Nelson

et al. 2004

Applied Physics Letters

207

120

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The carrier transport of carefully purified regioregular poly(3-hexylthiophene) films has been studied using time-of-flight photocurrent measurements. We find balanced ambipolar transport with a room-temperature mobility for holes of 3 Ã 10 −4 cm 2 V −1 s −1 and for electrons of 1.5Ã 10 −4 cm 2 V −1 s −1 at electric fields ജ10 5 V / cm. The transport is relatively field independent and weakly temperature dependent, pointing to a high degree of chemical regioregularity and purity. Conjugated polymers are of increasing interest as new materials for electronic applications, offering the potential for low fabrication cost, easy processing, and flexibility. Organic light-emitting diodes (OLEDs), field-effect transistors (FETs), photodiodes, and solar cells are all applications under intense study and first products are already emerging. One of the limitations for the utilization of such organic semiconductors is that they have relatively poor carrier transport properties in terms both of absolute mobility and with respect to the balance between hole and electron mobility. Low mobilities can limit practical applications, for instance, of OLEDs in passive matrix addressed displays due to low current densities in the space-charge-limited current regime, and unbalanced transport can reduce OLED-based display emission efficiency. Low mobility also impacts on switching speed in FETs and on solar cell efficiency, and again unbalanced transport has additional drawbacks in both of these applications.In general, electron transport in conjugated polymers is much worse than hole transport, and tends to be highly dispersive, with no clear transit time observed in time-offlight (ToF) photocurrent measurements. 1 Better electron transport polymers are, therefore, much needed in order to achieve the desired combination of enhanced and balanced carrier transport. We report here a study that reveals unexpected promise for poly(3-hexylthiophene) (P3HT) as a material with both good electron and hole transport. P3HT has been widely studied in the past and is well known as being an effective hole transport polymer, with higher hole mobility than many other conjugated polymers, including the poly(phenylenevinylene)s. 2 Initially, however, rather low hole mobilities were reported for regiorandom P3HT. 3 However, when head-to-tail regioregularly substituted P3HT became available, the hole mobilities were found to be dramatically improved. [4][5][6] The increase in mobility was related to side-chain-induced self-organization into a well-ordered twodimensional lamellar structure. 2 In contrast, electron transport has not been reported up to now in P3HT, most probably because electrons are heavily trapped. Molecular oxygen impurities have been proposed as one possible trap, 7 but little has been done to systematically address the issue. The extensive literature for P3HT highlights the importance of both structural and chemical influences on transport properties.In this letter, we present results concerning carrier transport in regioregular (RR)...

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“…Impurities and defects in the film will generate trapping and localization of charges, thus decreasing the mobility. Typical values for the mobility are 10 -6 -10 -3 cm 2 s -1 V -1 , [16] but by increasing the order of the film it can be greatly improved to values reaching 0.6 cm 2 s -1 V -1 and above. [17,18] It is also possible to have regions within the same film with different structural order, having high mobility in certain domains surrounded by larger amorphous areas with relatively lower mobility.…”

Section: Charge Transportmentioning

confidence: 99%

Electronic Control of Cell Cultures Using Conjugated Polymer Surfaces

Persson¹

2014

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In the field of bioelectronics various electronic materials and devices are used in combination with biological systems in order to create novel applications within cell biology and medicine. A famous example of a successful bioelectronics application is the pacemaker. Metals are the most common electrical conductors, whereas polymers are generally considered being insulators. However, in the late 1970s it was shown that a special class of polymers with conjugated double bonds, could in fact, after some chemical modifications, conduct electricity. This was the start of the research field known as conducting polymers, and then later on organic electronics, a research area that has grown rapidly during the last decades. Conjugated polymers are also suitable to interact and interface with cells and tissues, as they are generally soft, flexible and biocompatible. In addition, their chemical properties can be tailor-made through synthesis to fit biological requirements and functions. During the last years applications using organic bioelectronics have become numerous. This thesis describes applications based on different conjugated polymers aiming to stimulate and control cell cultures. When culturing cells it is of interest to be able to control events such as adhesion, spreading, proliferation, differentiation and detachment. First, the impact of different polymer compositions and redox states on the adhesion of bacteria and subsequent biofilm formation was investigated. Similar polymer electrodes were also used to steer differentiation of neural stem cells, through changes in the surface exposure of a relevant biomolecule. Controlled delivery of molecules was achieved by coating nanoporous membranes with polymers that swell and contract when changing the redox state. Finally, electronic control over cell detachment using a water-soluble polymer was achieved. When applying a positive potential to this polymer, it swells, cracks and finally detaches, taking the cells that was cultured on top along with it. Together, the work and results presented in this thesis demonstrate a versatile conjugated polymer technology to achieve electronic control of the different growth stages of cell cultures as well as cellular functions. POPULÄRVETENSKAPLIG SAMMANFATTNINGOlika plaster finns numera överallt omkring oss och utgör ett av de absolut vanligaste materialen i vår vardag. Även elektronik har blivit en naturlig del av vår tillvaro och finns i en mängd olika produkter. Inom medicinsk teknik kommer allt fler applikationer som innefattar elektronik, ett exempel är pacemakern. Arbetet som ligger till grund för denna avhandling strävar efter att kombinera plaster och elektronik för tillämpningar inom medicin och cellbiologi.Plaster består till största delen av polymerer samt olika tillsatser för att få ett material med önskade egenskaper. Polymerer är i sin tur uppbyggda av långa kedjor av identiska molekylära byggstenar, så kallade monomerer. Monomerens kemi och struktur bestämmer även egenskaperna hos polymeren. Med hjä...

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Inhomogeneity of Spin-Coated and Cast Non-Regioregular Poly(3-hexylthiophene) Films. Structures and Electrical and Photophysical Properties

Cited by 87 publications

References 25 publications

Preparation and Characterization of Water Self-dispersible Poly(3-hexylthiophene) Particles

Preparation and Characterization of Water Self-dispersible Poly(3-hexylthiophene) Particles

High ambipolar and balanced carrier mobility in regioregular poly(3-hexylthiophene)

Electronic Control of Cell Cultures Using Conjugated Polymer Surfaces

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