The preparation of large area coverage of films with uniaxially aligned poly(3-hexylthiophene)(P3HT) nanofibers by using zone-casting approach is reported.The length and the orientation of the nanofibers are defined by the solubility of the solvent,the P3HT molecular weight and the substrate temperature.The length of the oriented nanofibers could be increased from 1 μm to more than 10 μm by adding poor solvent into the P3HT solution.It is found that for P3HT of relatively low molecular weight,a solvent with relatively low solubility has to be chosen to get the oriented film.While for the high molecular weight P3HT,the solvent with a relatively high solubility has to be used.The well-aligned film could be obtained because of the solute concentration gradient in the region where the critical concentration is reached during the zone-casting process.Particularly,the solvent evaporation rate and crystallization rate must be chosen properly to satisfy the stationary conditions above,which were controlled by an appropriate choice of solvent and substrate temperature.The film prepared by zone-casting approach had microcrystalline P3HT domains with more inter-chain order than spin-coating film.Meanwhile,the P3HT π-π stacking direction was parallel to the alignment direction of the nanofibers. 相似文献
In this article, the uniaxial alignment of poly(3-hexylthiophene) (P3HT) nanofibrils with a π-π stacking growth direction in which P3HT chains adopt a flat-on conformation was obtained by solvent directional evaporation using a glass cover slide and a poly(dimethylsiloxane) (PDMS) sheet to press the P3HT film in a carbon disulfide (CS(2)) atmosphere. By controlling the CS(2) vapor pressure during the film-forming process, we got a well-oriented P3HT film whose order parameter reached as high as 0.97. The orientation of the film was induced by the crystallization nucleation of P3HT and the directional evaporation of the solvent. Under a CS(2) vapor atmosphere, P3HT crystals preferred to adopt the form II modification, which started by nucleation. Owing to the solvent directional evaporation from the center to the margin, P3HT at the center of the sample would precipitate first to induce nucleation. Then the peripheral P3HT would directly diffuse, precipitate, and then adhere to the nucleus to form the uniaxial alignment of P3HT nanofibrils along the direction of solvent evaporation. Furthermore, in the P3HT nanofibrils, the π-π stacking direction of P3HT lamellae was parallel to the crystal growth direction, which would provide an effective path for charge transport. 相似文献
Hierarchical poly(3‐hexylthiophene)(P3HT)/carbon nanotube (CNT) supramolecular structures were fabricated through a bottom‐up CNT induced P3HT crystallization strategy. P3HT nanowires growing perpendicular from CNT surface have uniform width and height. The density and the length of these nanowires can be controlled by tuning the P3HT/CNT mass ratio. The quasi‐isothermal crystallization process monitored by in situ UV–Vis spectroscopy indicates that CNTs can greatly enhance the P3HT crystallization, and the P3HT nanowire formation follows first‐order kinetics. Such bottom‐up strategy provides a general approach to build 2D functional conductive supramolecular structures that will lead to numerous applications in nanoscale electronics.
The preparation of the poly(3-hexylthiophene) (P3HT) stripe structure with oriented nanofibrils prepared by controlled inclining evaporative technique is reported. The distance of the adjacent stripes could be controlled from 40 μm to 100 μm by decreasing the inclining angle. The oriented nanofibrils in the stripes can be obtained because the P3HT lamellae diffuse directionally and form 1D crystals at the three-phase contact line of the drop. In order to get the oriented P3HT stripes, the proper solvent evaporation rate which is controlled by the inclining angle and the wettability of the substrate must be carefully chosen to match the P3HT 1D crystallization rate. It is found that large inclining angle and the hydrophilic substrate (for example: glass and PEDOT) are beneficial to get P3HT stripe structure with oriented nanofibrils. 相似文献
Solid-state structures of regioregulated poly(3-hexylthiophene) (P3HT) and poly(3-butylthiophene) (P3BT) were investigated using Fourier transform infrared absorption (FT-IR) spectroscopy. This study revealed that a twist glass transition of thiophene twisting for P3HT exists around 300 K ( T gp). Additionally, the influence of annealing on population of glassy crystal, crystal, and plastic crystal phases was explored. The annealed sample is dominated by plastic crystal phase, and this phase increases with annealing temperature below T gp. The frustration against crystallization in P3HT is weaker than that in P3BT. Consequently, the plastic crystal phase is formed as a dominant structure, whereas P3BT forms both a well-defined crystal in the conventional sense and glassy crystal. 相似文献
In this article, we present the research on the influence of the composition of thin films of a blend of poly (3-hexylthiophene −2,5-diyl) - P3HT with fullerene derivatives [6,6]-phenyl-C71-butyric acid methyl ester – PC70BM and [6,6]-phenyl-C61-butyric acid methyl ester – PC60BM on their thermal transitions. The influence of molar mass (Mw) of P3HT (Mw = 65.2; 54.2 and 34.1 kDa) and PCBM (PC60BM – Mw = 911 g/mol and PC70BM – Mw = 1031 g/mol) is examined in details. The article presents significantly expanded research compared to our previous work on thermal transitions in thin films of blend P3HT (Mw = 65.2 kDa) with PC60BM. For this reason, we also compare current results with previous ones. Here, we present for the first time a phase diagram of thin films of the P3HT(Mw = 65.2 kDa):PC70BM blend using variable-temperature ellipsometry. Our research reveals the presence of characteristic temperatures of pure phases in thin films of P3HT: PCBM blends. It turns out that the cold crystallization temperature of the P3HT phase in P3HT(Mw = 65.2 kDa):PC70BM blend films is lower than corresponding temperature in P3HT(Mw = 65.2 kDa):PC60BM blend films. At the same time, the cold crystallization temperature of the PC70BM phase behaves inversely. We demonstrate also that variable-temperature spectroscopic ellipsometry is a very sensitive technique for studying thermal transitions in these thin films. In addition, we show that the entire phase diagram can be determined based on the raw ellipsometric data analysis, e.g. using a delta angle at wavelength λ = 280 nm. 相似文献
We designed and synthesized the all-conjugated diblock copolymers poly(3-hexylthiophene-block-3-(2-ethylhexyl)thiophene)s (P(3HT-b-3EHT)s) via a modified Grignard metathesis (GRIM), a type of quasi-living polymerization, and studied their microphase-separated structures. The P(3HT-b-3EHT)s synthesized had well-controlled molecular weights and very narrow polydispersity indices (PDIs), which demonstrates the usefulness of GRIM polymerization for the synthesis of semiconducting block copolymers. P(3HT-b-3EHT)s self-organized to form clear microphase-separated patterns upon thermal treatment, as observed by AFM. Interestingly, the enhancement of the interchain interaction of the P3HT segments compared with the P3HT homopolymer was clearly observed from the UV-vis spectra, despite the fact that the amount of crystalline P3HT fraction was reduced to 83% of the total polymer amount in P(3HT-b-3EHT). It is suggested that the relatively unconstrained, amorphous segments of P3EHT can enhance the crystallization of P3HT segments to form an ordered self-organized nanostructure. 相似文献
How the conjugated polymers affect the crystallization of DR3TBDTT, in addition to the corresponding morphology and performance, is not well understood. In this work, the weakly crystalline polymer PTB7‐Th and highly crystalline polymers of PCDTBT and P3HT were incorporated into DR3TBDTT:PC71BM system to investigate the variation of crystallization, morphology and performance. It is demonstrated that PTB7‐Th is the most effective additive to improve the PCE value of DR3TBDTT:PC71BM to 5.7%, showing the nucleating agent reducing the crystallization correlation length (CCL) value of DR3TBDTT from 18.7 nm to 17.0 nm, in addition to the optimized morphology. In contrast, the PCDTBT and P3HT could induce the crystallization of DR3TBDTT, leading to much higher CCL value as well as obvious phase separation. Despite of energy level alignment, the crystallization of DR3TBDTT influenced by polymers determines the corresponding morphology of active layers and photovoltaic performance. 相似文献
Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/semiconducting poly(3-hexyl thiophene) (P3HT) blend systems have drawn great attention with their potential use for electronic applications, particularly non-volatile memory devices. It is essential to grasp a full understanding of the crystallization habits of the two polymers on different substrates for purposeful control of the structures of the blend and therefore the properties of the devices. Here, the effects of structure and morphology of the blend films generated at different substrate surfaces on the ferroelectric and switching properties of related devices are reported. It is identified that P(VDF-TrFE)/P3HT blend films prepared on graphene substrate show not only an obvious optimization in the ferroelectric behavior of P(VDF-TrFE), but also an enhancement of the charge transport within P3HT domains. By employing sandwich structure constructed by silver electrode and P3HT/P(VDF-TrFE) blend film on graphene substrate, high-performance ferroelectric memory devices have been obtained, which exhibit a great electrical switching behavior with high ON/OFF ratio of about 1000 and low coercive voltage of approximately 5 V. These findings provide useful guidance for fabricating high-performance ferroelectric memory devices.
Poly(3‐hexylthiophene) (P3HT) supramolecular structures are fabricated on P3HT‐dispersed reduced graphene oxide (RGO) monolayers and surfactant‐free RGO monolayers. P3HT is able to disperse RGO in hot anisole/N,N‐dimethylformamide solvents, and forms nanowires on RGO surfaces through a RGO induced crystallization process. The TEM and AFM investigation of the resultant P3HT/RGO composites shows that P3HT nanowires grow from RGO, and connect individual RGO monolayers. Raman spectroscopy confirms the interaction between P3HT and RGO, which allows the manipulation of the RGO electrical properties. Such a bottom‐up approach provides interesting graphene‐based composites for nanometer‐scale electronics.
Crystallization‐induced vertical stratified structures were constructed based on double‐crystalline poly(3‐hexylthiophene) (P3HT)/poly(ethylene glycol)s (PEG) systems at room temperature, in which the P3HT crystallinity and the mechanism were investigated. Vertical stratified microstructures with highly crystalline P3HT network on the surface were formed when depositing from marginal solvents, while lateral phase‐separated structures or low P3HT crystallinity were observed for good solvents. The morphological differences came from the solvent effect. In marginal solvents, p‐xylene and dichloromethane, P3HT large‐scale microcrystallites were generated in solution, which ensured the priority of P3HT crystalline sequence, and phase separation began in the liquid states. When the PEG matrix began to crystallize, great energy from which the second phase separation was induced drove P3HT crystallites to the surface, resulting in the formation of vertical stratified microstructures with highly crystalline P3HT network on the surface. The method, crystallization‐induced phase segregation of crystalline–crystalline blends in marginal solvent, provides a facile way to construct vertically stratified structures, in which P3HT highly crystalline network is favored.
An exemplary system suitable for optoelectronics applications, i.e. poly(3-hexylthiophene), hereinafter P3HT, deposited by spin casting onto silicon substrates functionalised by three selected molecules and then properly annealed, has been examined. Grazing Incidence X-ray Scattering (GIXS) measurements have been performed with 4-circle diffractometer, allowing for a fine control of sample axes movement.By choosing different grazing incident angles, diffraction patterns from different layers of polymeric thin films have been recorded. Both in-plane and out-of-plane geometries have been combined in order to obtain complementary structural information. In this way structural and orientational differences of the polymer along with the film thickness (?50 nm) have been highlighted. For all P3HT films spun on functionalized Si wafer, macromolecular layers close to the substrate surface give some evidence of higher order and orientation than those outmost the surface, and this behaviour is pronounced to a different extent depending on the functionalized molecules used. Contrariwise P3HT layers deposited onto bare Si wafer display reduced orientation and decreased crystallite size, especially at buried interface. 相似文献
We report on the evolution of the chain orientation of a representative π-conjugated polymer, poly(3-hexylthiophene) (P3HT), during the solution-casting process, as monitored using polarized Raman spectroscopy. These measurements point to the formation of a liquid-crystalline phase of P3HT solutions within a specific time period during solvent evaporation, which leads to a conducting channel. These conclusions are based on the angular dependence of polarized Raman scattering peaks, the anisotropy in the fluorescence background signal, analysis of the scattering-peak shape, and direct observations of the three-phase contact line in an optical microscope under crossed polarizers. These results shed new light on the evolution of chain alignment and thus materials nanostructure, specifically in solution-processed P3HT and more generally in π-conjugated systems. They may further enable the design of improved materials and processes for this important class of polymers. 相似文献