KR20160146039A

KR20160146039A - Water processable polythiophene nanowires and methods for preparing the same

Info

Publication number: KR20160146039A
Application number: KR1020150082584A
Authority: KR
Inventors: 김범준; 김형준
Original assignee: 한국과학기술원
Priority date: 2015-06-11
Filing date: 2015-06-11
Publication date: 2016-12-21
Also published as: KR101743907B1

Abstract

The present invention relates to a polythiophene nanowire that can be processed in an aqueous solvent, and more particularly, to solution assembly, photo-crosslinking, and the like of azide-functionalized poly-3-hexylthiophene (P3HT) crosslinking, and functionalization with alkyne-terminated molecules. The present invention also relates to polythiophene nanowires which can be processed in aqueous solvents.
The functionalized P3HT-PEG nanowires according to the present invention can be stably dispersed in various alcohols and water while retaining their nanostructure and electronic characteristics for effective charge transport. Therefore, it is possible to efficiently transfer electric energy from water and alcohol, which are environmentally- . &Lt; / RTI >

Description

TECHNICAL FIELD [0001] The present invention relates to a polythiophene nanowire that can be processed in an aqueous solvent, and a method of preparing the same.

The present invention relates to a polythiophene nanowire that can be processed in an aqueous solvent, and more particularly, to solution assembly, photo-crosslinking, and the like of azide-functionalized poly-3-hexylthiophene (P3HT) crosslinking, and functionalization with alkyne-terminated molecules. The present invention also relates to polythiophene nanowires which can be processed in aqueous solvents.

Conjugated polymers have been extensively evaluated as active elements of cost-effective, lightweight, and flexible electronic devices due to their promising optoelectronic properties (Krebs, FC et al. Adv . Mater . 2014, 26, 29-39; Beaujuge, PM et al. J. Am . Chem . Soc . 2011, 133 (50), 20009-20029). Over the last decade, there has been much research and effort in the development of efficient organic electronics. As a result, conjugated polymer-based organic field effect transistors (OFETs) with charge carrier mobilities comparable to amorphous silicon have been demonstrated [Han, AR et al. Adv . Funct . Mater . 2015, 25, (2), 247-254] A polymer solar cell with power conversion efficiency exceeding the boundaries for successful commercialization was fabricated [You, J. et al. Nat . Commun . 2013, 4, 1446]. However, solution processing of high-efficiency organic electronic devices mostly involves only the use of halogenated solvents such as chloroform and chlorobenzene (Duan, C. et al. Engery Environ . Sci . 2013, 6, (10), 3022-3034]. Toxicity, environmental impact and high energy costs associated with these halogenated solvent-based processes make their use unsustainable [Chen, X. et al. Angew . Chem . Int . Ed . 2014, 53, (52), 14378-14381]. Moreover, the more stringent regulations on the mass production of halogenated solvents ( J. Adv . Funct. Mater . 2014, 24, (10), 1449-1457), which have the ultimate goal of eliminating the use of these chemicals, Strongly supports the need for the development of processes compatible with electro-active materials and environmentally benign solvents. Despite the increasing importance and interest of "green" solvents for the processing of organic electronic devices, there has been limited success to date [Chueh, C.-C. et al. Engery Environ . Sci . 2013, 6, (11), 3241-3248].

Solvents such as alcohols and water are attractive alternatives to halogenated solvents due to their reduced environmental impact, toxicity and cost. In particular, the development of an aqueous platform for the processing of polymer organic electronic devices represents an important step toward the goal of sustainable device manufacturing. Prior to this work, two important strategies for the synthesis of aqueous-soluble conjugated polymers have been reported. One approach involves the incorporation of medial ionic moieties into the polymer backbone, which provides solubility in alcohol and water [He, Z. et al. Adv . Mater . 2011, 23, (40), 4636-4643]. However, these charged groups quench the charge carriers and affect the energy levels of the polymers, resulting in poor device performance when these polymers are used as active layers (Chen, X. et al. Angew . Chem . Int . Ed . 2014, 53, (52), 14378-14381]. In a second approach, conjugated polymers are synthesized with nonionic, hydrophilic pendent groups or hydrophilic blocks (e.g., polyethylene glycol, PEG) (Duan, C. et al. Engery Environ . Sci . 2013, 6, (10), 3022-3034; Cativo, MHM et al. ACS Nano 2014, 8, (12), 12755-12762]. For example, the recently synthesized alcohol-soluble, narrow bandgap conjugated polymers of Duan et al. Have been functionalized with pendent amino groups and have demonstrated their use as active layers of PSCs [Duan, C. et al. Engery Environ. Sci . 2013, 6, (10), 3022-3034]. Despite their promising dissolution properties, however, the presence of amino-side groups in these conjugated polymers has resulted in degradation of device performance. Introduction of bulky or extended hydrophilic side chains to improve water solubility may hinder the formation of well-defined crystalline nanostructures (Kim, BJ et al. J. Adv . Funct . Mater. 2009, 19, ( 14), 2273-2281). Ensuring the accuracy of well-ordered crystalline nanostructures after the introduction of solubilizing groups is essential to achieve a conjugated polymer device capable of an efficient green-solvent process.

Solution assemblies of conjugated polymers in one-dimensional crystalline nanowires (NWs) have excellent optoelectronic properties provided by such well-organized structures with nanometer-scale cross-sectional dimensions, and long distance charge transport Path presents an attractive means for the process of organic optoelectronic devices [Lim, JA et al. Mater . Today 2010, 13, (5), 14-24]. For example, the conjugated polymer NW enhances charge carrier mobility [Briseno, AL et al. Nano Lett . 2007, 7, (9), 2847-2853], controlling bulk heterojunction morphology in solar cells [Berson, S. et al. Adv . Funct . Mater . 2007, 17, (8), 1377-1384), inducing percolated conducting structures in a blend with an insulating polymer [Qiu, L. et al. Adv . Mater . 2009, 21, (13), 1349-1353], and inorganic semiconductors and hybridization structures [Ren, S. et al. Nano Lett . 2011, 11, (9), 3998-4002). Surface modification of a pre-assembled conjugated polymer NW with a hydrophilic moiety can be accomplished by using a conjugated polymer that maintains a well-ordered crystalline nanostructure and excellent optoelectronic properties while allowing subsequent processing from aqueous suspensions It seems to suggest a simple approach to obtaining. For this strategy to be successful, maintaining the stability of the NW at functionalization (both for dissolution and coagulation) is a key challenge.

It is therefore an object of the present invention to provide a process for preparing a conjugated polymer NW having hydrophilic moieties which is capable of maintaining a well-ordered crystalline nanostructure and excellent optoelectronic properties while allowing subsequent processing from aqueous suspensions, And to provide a polythiophene nanowire that can be processed in a solvent.

It is another object of the present invention to provide an electrical irradiation comprising the nanowires.

Still another object of the present invention is to provide a process for producing polythiophene nanowires which can be processed in the aqueous solvent.

According to an aspect of the present invention, there is provided a polythiophene nanowire which is processable in an aqueous solvent, which comprises azide-functionalized poly-3-hexylthiophene (P3HT) linking, and functionalization with alkyne-terminated molecules. The present invention also relates to a method for producing the same.

In the present invention, the azide-functionalized P3HT may be P3HT-azide of formula (1).

In the present invention, the solution assembly may be induced by self assembly of the polymer using various solvents known in the art. For example, a solution of a polymer dissolved in a good solvent A mixed solvent method of inducing the growth of the crystalline nanowire by adding a poor solvent having poor solubility may be used. Specifically, tetrahydrofuran (THF) and 1-butanol (BuOH) may be used as solvents having good dissolving power, wherein the optimum solvent composition for nanowire self-assembly is 7: 1 (v / v ) THF / BuOH.

In the present invention, the photo-crosslinking can be carried out by exposure to UV light under a nitrogen atmosphere, preferably UV light (? = 254 nm, 0.76 mWcm ^-2 ).

In the present invention, the molecule having the alkyne-terminal is a molecule containing an alkyne capable of performing a click reaction with an azide group present in a self-assembled P3HT-azide NW, preferably PEG-alkyne .

According to another aspect of the present invention, there is provided an electric device including the nanowire as an active layer.

The functionalized nanowires (NW) can be stably dispersed in an aqueous solvent, and thus can be utilized in various electric device fields accordingly. Examples of the electric device include a field effect transistor, a polymer solar cell, a memory device, and an optical sensor.

As an example, an organic field effect transistor (OFET) comprising the nanowire may be fabricated as follows. An OFET can be prepared by preparing a Si / SiO ₂ substrate, depositing a gold electrode on the substrate, and then spin-casting the P3HT-PEG NW of the present invention.

According to another aspect of the present invention, there is provided a method of preparing a P3HT-azide nanowire comprising: a) forming a P3HT-azide NW through solution assembly of P3HT-azide; b) photo-crosslinking the P3HT-azide NW to produce a crosslinked NW; And c) functionalizing the crosslinked NW via a click reaction with PEG-alkyne. The present invention also provides a process for producing P3HT-PEG nanowires in an aqueous solvent.

The functionalized P3HT-PEG nanowires according to the present invention can be stably dispersed in various alcohols and water while retaining their nanostructure and electronic characteristics for effective charge transport. Therefore, it is possible to efficiently transfer electric energy from water and alcohol, which are environmentally- . &Lt; / RTI >

Figure 1 is a schematic diagram of photo-crosslinking and click-functionalization of solution assembled P3HT-azide NW.
Figure 2 (a) shows the UV / vis absorption spectrum of P3HT-azide in different solvent mixtures (THF / BuOH (v / v), 1 mg / cm <" ¹ >), with an FT-IR spectrum (inset). (c) shows a TEM image of P3HT-azide NW in a 7: 1 v / v THF / BuOH mixture after 0 minutes of UV light exposure, (d) after 60 minutes, and (e) after 120 minutes.
Figure 3 shows (a) heat and (b) solvent resistance of P3HT-azide NW in 7: 1 THF: BuOH (v / v) solution at different UV exposure times: 0, 10, 30 and 60 min.
Figure 4 (a) shows the functionalization of P3HT-azide NW photo-crosslinked with PEG-alkyne using a copper catalyzed azide-alkyne ring chemistry. After PEG functionalization, (b) the structure of the photo-crosslinked P3HT-azide NW was retained, while (c) the structure of the non-crosslinked P3HT-azide NW collapsed.
Figure 5 (a) shows X-ray scattering of the photo-crosslinked P3HT-azide NW and P3HT-PEG NW. (B) BuOH, (c) MeOH, and (d) P3HT-PEG NW dispersed in water, with a plot showing poorly dispersed P3HT NW (left) Image. (e) compares the hole mobility measured in FET devices fabricated from P3HT-PEG NW dispersed in various solvents (7: 1 THF / BuOH, BuOH, MeOH, and water).
Figure 6 shows ¹ H NMR of a P3HT-azide copolymer. The composition between 3-hexylthiophene and 3- (azidohexyl) thiophene was calculated from the intensity of CH ₂ N ₃ -peak at 0.92 ppm at 3.28 ppm versus CH ₂ CH ₃ -peak. By comparing the integrated peaks corresponding to the α-methylene proton of hexyl chains in head-to-tail vs. head-to-head connections with δ 2.81 and δ 2.58 positional regularities of P3HT-azide It was decided.
Figure 7 shows the FT-IR curves of P3HT-azide NW with different UV exposure times. At 2100 cm ^-1 , the azide peak gradually decreased with increasing UV exposure time.
Figure 8 shows the UV-vis spectra of (a) non-crosslinked, (b) 30 minute crosslinked, (c) 60 minute crosslinked P3HT-azide NW by increasing the temperature of the solution from 20 ° C to 50 ° C will be.
(A) non-crosslinked, (b) 30 minute crosslinked, (c) 60 minute crosslinked P3HT-azide NW as shown in FIG. 9 as part of the initial nanowire suspension volume. UV-vis spectrum.
Figure 10 shows the transfer characteristics of the (a) non-crosslinked, (b) 60 minute crosslinked P3HT-azide NW OTFT device with V _DS = -60 V; Bottom-gate, bottom-contact geometry was applied on SiO2 / Si wafers.
FIG. 11 shows the FT-IR curve of the P3HT-azide NW photo-crosslinked 60 minutes before and after the PEG-alkyne loop reaction. After the click reaction, the residual azide peak completely disappeared.
Figure 12 shows the UV / vis spectra of PEG-functionalized P3HT-azide NW with or without crosslinking. After functionalization, the 60-min photo-crosslinked P3HT-azide NW sample exhibits nearly the same UV / vis spectra as before the functionalization, including the oscillation peak at 510-650 nm. On the other hand, the non-crosslinked P3HT-azide NW's click-functionalization induced almost complete extinction of NW, as confirmed by a reduction in the vibration peak absorption.
Figure 13 shows the transistor characteristics ((a) output curve and (b) transfer curve) of a P3HT-PEG NW device made from a suspension of 7: 1 THF / BuOH.
Figure 14 shows the transfer curve of a P3HT-PEG device without cross-linking.
Figure 15 illustrates the synthesis of PEG with an alkyne end.

Hereinafter, the features of the present invention and specific details thereof will be described.

The present invention provides photo-crosslinking with UV light to provide stability and subsequent functionalization with alkyne-terminated molecules (Kim, HJ et al. ACS Nano 2014, 8, (10), 10461-10470], azide-functionalized poly (3-hexylthiophene). Photo-crosslinked P3HT-azide NWs appear to be very stable for temperature and solvent treatment and maintain their nanostructural integrity and electronic performance. These photo-crosslinked NWs are then successfully functionalized with a copper-catalyzed cycloaddition reaction using the remaining azide unit of the NW surface with an alkyl-terminated PEG (PEG-alkyne). The resulting functionalized P3HT-PEG NW can be stably dispersed in a variety of alcohols and water while maintaining its nanostructure and electronic properties for efficient charge transport, thus providing efficient OFET processes from environmentally benign solvent-water and alcohol .

P3HT-azide copolymers were synthesized according to previously reported procedures [Kim, HJ et al. Chem. Mater . 2011, 24, (1), 215-221). Random copolymerization of 3- (azidohexyl) thiophene and 3-hexylthiophene was performed with feed ratios of 20 and 80 mole%, respectively. The actual content of 3- (azidohexyl) thiophene in the copolymer product was measured at 21 ± 1 mole% using ¹ H-NMR (FIG. 6). The polymerization conditions were rigorously optimized to obtain a high yield of regioregular P3HT having a relatively high molecular weight; These properties enable the formation of crystalline NW with long-distance charge transport pathways and optimal optoelectronic properties. The P3HT-azide copolymer is highly positionally ordered (> 98%) with a number average molecular weight (Mn) of 35,000 g / mol and a polydispersity (PDI) of 1.4, as determined by ¹ H-NMR.

Solution assembly of P3HT-azide copolymer was induced by mixed solvent method [Bokel, FA et al. Macromolecules 2011, 44, (7), 1768-1770]. Briefly, in a solution of P3HT-azide dissolved in a good solvent tetrahydrofuran (THF,? = 9.52 cal ^1/2 cm ^-3/2 ), a poor solvent 1 -Butanol (BuOH, delta = 11.30 cal ^1/2 cm ^-3/2 ) drives the growth of crystalline NW. These solvents were chosen because they have a low UV cut-off (THF = 212 nm, BuOH = 215 nm), a critical consideration for azide photo-crosslinking. As the relative concentration of BuOH in the P3HT-azide solution was increased, a gradual decrease in the intensity of the absorption peak associated with the dissolved P3HT (? = 450 nm) was observed by UV / vis spectrophotometry. At the same time, vibronic bands appeared at 564 and 611 nm and their intensity increased, indicating π-electron delocalization of the P3HT-azide chain associated with NW formation (FIG. 2 a) . The optimum solvent composition for NW self-assembly was determined with 7: 1 (v / v) THF / BuOH. Under these conditions, well-defined NWs with lateral dimensions of 18-20 nm and lengths of several micrometers were formed and visualized using transmission electron microscopy (TEM) (Figure 2c) . Surprisingly, like the outlined NW, which is typically similar to that formed from P3HT homopolymers [Johnson, CE et al. J. Polym . Sci ., Part B: Polym . Phys . 2014, 52, (7), 526-538], the incorporation of 20 mol% azides in the P3HT-azide copolymer did not appear to interfere largely with molecular packing and self-assembly of the copolymer.

Photo-bridging of P3HT-azide NW is accomplished by exposure to UV light (λ = 254 nm, 0.76 mW cm ^-2 ) which drives the decomposition of azides in highly reactive nitrenes leading to crosslinking via CH insertion , Using a solution in quartz cuvettes under a nitrogen atmosphere [ Angew . Chem . Int . Ed . 2005, 44, (33), 5188-5240]. The conversion of the azide group was confirmed by monitoring the decrease in azide stretch at 2100 cm ^-1 using Fourier transform infrared spectroscopy (FT-IR) (Fig. 7). Figure 2b illustrates the relative amounts of residual azide residues after different UV exposure times; Azide peak intensity decreases with prolonged UV irradiation, which indicates successful conversion of the azide in solution. Interestingly, the morphology of the photo-crosslinked P3HT-azide NW did not change as determined using TEM (d and e in FIG. 2), regardless of the degree of crosslinking. The photo-crosslinked P3HT-azide NW irradiated during 60 minutes (60% azide conversion, Figure 2d) and 120 minutes (90% azide conversion, Figure 2e) Structure. Such a photo-crosslinking method does not require the use of additional chemicals, and does not require the chemical crosslinking method previously reported [Hammer, BAG et al. Chem . Mater . 2011, 23, (18), 4250-4256] is particularly attractive because it avoids all of the excess NW aggregation that typically occurs except under dilute conditions.

Thermal stability and solvent resistance of the photo-crosslinked P3HT-azide NW was investigated by monitoring the absorption of vibronic bands in the UV / vis spectrum (FIG. 8-9). The relative intensity of the vibration peak at 564 nm is constructed according to the solution temperature (a in FIG. 3) and the volume equivalent of the added chlorobenzene (CB) (FIG. 3b). Increasing the temperature from 25 to 50 占 폚 induces complete dissolution of the non-crosslinked P3HT-azide NW, as shown by the disappearance of the vibration peak. On the other hand, the photo-crosslinked NW retained significant absorption at 564 nm, such as irradiated for 60 minutes with little reduction in intensity after heat treatment, indicating a high degree of structural stability. A similar tendency was observed for solvent resistance. The addition of the same amount of CB, which is one of the best solvents for P3HT to the non - crosslinked NW, induced complete dissolution, but the NW irradiated for 60 minutes almost retained the original peak band intensity after the addition of the same amount of CB. Interestingly, only 60% azide conversion (60 minutes of UV irradiation) was sufficient to obtain a very stable NW, leaving a residual azide group of 40% available as a reactive site for further functionalization.

To investigate the effect of photo-crosslinking on the electrical properties of P3HT-azide NW, the hole transport mobility of an OFET device was measured as summarized in Table 1 below.

Mobility
(10 ^-3 cm ² V ^-1 s ^-1 ) On / off
ratio (10 ³ ) V _t (V) UV 0 min 1.4 ± 1.0 7.5 ± 6.8 10.5 ± 1.9 UV 30 min 1.8 ± 0.2 7.1 ± 3.8 -11.5 ± 5.0 UV 60 min 1.4 ± 0.3 6.9 ± 3.7 -6.9 ± 4.5 UV 90 min 0.6 ± 0.1 4.2 ± 2.1 -14.6 ± 4.5

A series of devices based on P3HT-azide NW treated with UV exposure times of 30, 60 and 90 minutes were fabricated in bottom-contact, bottom-contact geometry. A gold electrode was placed on a silicon wafer coated with 300 nm of thermally grown oxide with a channel length of 10 [mu] m and a channel width of 300 [mu] m. Without cross-linking, P3HT-azide NW is ^{1.4 × 10 -3 cm 2 V -1} s -1 hole mobility (hole mobility) were shown to which a well arranged with no surface treatment of the previously reported SiO ₂ / Si P3HT of Which is consistent with the hole mobility of the film [Kim, HJ et al. Chem . Mater . 2011, 24, (1), 215-221). The present inventors have found that 30 of 60 nm, and the light ^{- 1.8 × 10 -3 cm 2 V} -1s -1 and 1.4 × 10 ^-3 cm ² V ^-1 s ^-1 similar transport of holes to the P3HT-azide NW device having a cross-linked Respectively. The fact that the devices were crosslinked for 60 minutes, although some degradation in performance was observed by further investigation (hole mobility of 0.6 × 10 ^-3 cm ² V ^-1 s ^-1 at 90 min), their structural integrity but exhibit similar mobility and transistor properties as non-crosslinked devices, indicating that the azide-functionalized conjugated polymer is an efficient means of producing highly stable crosslinked NWs possessing electrical properties.

A distinct advantage of the P3HT-azide system is that the residual azide functional group on the photo-crosslinked NW can then be functionalized with an alkyne-terminated molecule by copper catalyzed cycloaddition . We chose PEG as a model for functionalization because of its excellent aqueous solubility (Fig. 4a). The alkyne-terminated monomethyl ether PEG (PEG-alkyne, Mn = 3.00 kg / mol, PDI = 1.05) J. Polym . Sci ., Part A: Polym . Chem . 2009, 47, (16), 4001-4013] (Fig. 15). PEG-alkyne NW was coupled with a photo-crosslinked P3HT-azide NW (60 min UV exposure) in a 7: 1 THF / BuOH solution with CuBr catalyst. After a click reaction, the azide peak disappeared in the FT-IR spectrum, which means the complete reaction of the residual azide with PEG-alkyne (Figure 11). Extra PEG-alkyne was removed by centrifugation and the resulting product was treated with Cuprisorb ^™ to remove residual copper. The TEM image (FIG. 4 b) shows that the P3HT-PEG NW possesses essentially the same morphology as the pristine P3HT-azide NW. In contrast, functionalization with PEG of the non-crosslinked P3HT-azide NW was evidenced by a significant reduction in the intensity of the oscillation band in the UV / vis spectrum (FIG. 12) and disappearance of the NW morphology in the TEM image (FIG. 4c) As shown, the NW structure was almost completely destroyed.

Wide-angle X-ray scattering (WAXS) of cross-linked P3HT-azide and P3HT-PEG NWs was investigated to determine the possibility of change in molecular packing of P3HT-azide NW after PEG functionalization (Fig. 5 (a)). The light-crosslinked P3HT-azide NW has a document value for the distance between the polythiophene backbones separated by an interdigitated side chain 100 and a piπ stacking distance 010, [Kim, BJ et al. Adv . Funct . Mater . 2009, 19, (14), 2273-2281], with two distinct peaks with d-spacings of 1.69 and 0.37 nm. After PEG functionalization, the distance between adjacent P3HT-azide chains was essentially unchanged at 1.69 and 0.37 nm, indicating that molecular packing in the P3HT-azide NW, a crucial factor in determining optoelectronic properties, Which means that they have not been altered by them. The inventors conclude that the molecular packing structure of NW can be preserved due to photo-crosslinking, while P3HT-azide NW provides an excellent platform for various functionalities on NW surfaces using easy click chemistry .

To confirm the effect of PEG functionalization on the electronic performance of NW, an OFET device was fabricated by casting the film using 7: 1 THF / BuOH as solvent (Figure 13). Devices based on P3HT-PEG NW exhibited higher off current values than P3HT-azide NW, which can induce p-type doping in the active layer [Lee, MY et al . Adv . Mater . 2014, 10.1002 / adma.201404707], and the polarity of the PEG side chain. However, in particular, the hole mobility for P3HT-PEG NW is 2.1 × 10 ^-4 cm ² V ^-1 s ^-1 , whereas for devices made from non-crosslinked P3HT NW functionalized with PEG, the measured values are close to 2 (4.3 × 10 ^-6 cm ² V ^-1 s ^-1 , Figure 14). These results clearly demonstrate that the photo-crosslinking of the P3HT-azide NW provides sufficient stability to add additional functionality to the NW surface without loss of significant structural and electronic properties.

Figure 5b shows the structure of the P3HT-PEG NW dispersed in various polar solvents. To demonstrate the suitability of this functionalized NW for processes using environmentally benign solvents, the P3HT-PEG NW was isolated by centrifugation of the suspensions in 7: 1 THF / BuOH and the BuOH ( δ = was dispersed in ^{11.30 cal 1/2 cm -3/2), MeOH} (δ = 14.28 cal 1/2 cm -3/2) and water ^{(δ = 23.50 cal 1/2} cm -3/2). In all cases, the P3HT-PEG NW formed a stable dispersion for agglomeration, while the unfunctionalized P3HT-azide NW remained fairly agglomerated. To demonstrate the potential of this material for organic electronic devices made from highly polar solvents, an OFET device was prepared from P3HT-PEG NW suspended in each solvent. The hole mobility of devices based on P3HT-PEG NW dispersed in BuOH, MeOH and water was 1.7 × 10 ^-4 , 2.2 × 10 ^-4 and 0.51 × 10 ^-4 cm ² V ^-1 s ^-1 , respectively 5 e). The slightly lower mobility of the water-based device appears to be the result of high surface tension, which results in a relatively non-uniform film. It should be noted that this is the first demonstration of water-processed P3HT-based organic electronics, thus demonstrating the excellent potential of P3HT-azide for the formation of stable and functional NW structures.

Accordingly, the present invention discloses a platform for producing a chemically or thermally functionalized functionalized conjugated polymer NW that facilitates device processing using highly polar and environmentally benign solvents. Based on P3HT, a copolymer comprising 20 mol% azide-functionalized thiophene unit undergoes solution assembly to make crystalline in NW, similar to P3HT homopolymer. The irradiation with 254 nm UV light forms a crosslink, with 60% conversion of the azide unit providing excellent stability both for heat and solvent treatment. Surface modification of nanowires crosslinked with PEG-alkyne using a residual azide group allows the stable dispersion of functionalized NW in alcohol and water, enabling the processing of P3HT-based OFET devices from environmentally benign solvents . The present inventors expect that this approach to very stable and functionalized NW will provide useful and flexible means for the processing of various types of conjugated polymer-based devices, including photovoltaics and sensors.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are intended to further illustrate the present invention, and the scope of the present invention is not limited to these examples.

Example 1. solution-assembled P3HT - azide NW Manufacturing

First, P3HT-azide was dissolved in tetrahydrofuran (THF) at 10 mg / ml by thermal and ultrasonic treatment. The solution was then slowly added with 1-butanol (BuOH) to the solution while passing through a PTFE syringe filter (0.45 μm) and vigorously stirring to induce homogenous nucleation of the NW. The resulting solution having a concentration of 1 mg / ml and a volume ratio of 7: 1 THF / BuOH was aged at room temperature for 48 hours with stirring.

Example 2. Light-crosslinking and click-functionalization

The P3HT-azide NW solution was placed in a quartz cuvette under a nitrogen atmosphere and exposed to UV light (? = 254 nm) from a low-power mobile lamp (UVP UVGL-25, 0.76 mWcm ^-2 ) with gentle stirring. For the click reaction, all procedures were performed under a nitrogen atmosphere to avoid oxidation of the Cu catalyst. After photo-crosslinking, excess PEG-alkyne (1.5 eq, 0.015 mmol, 35 mg) was added to a 60 minute photo-crosslinked P3HT-azide NW solution (10 mL, 0.01 mmol of azide unit) Respectively. Next, a mixed solution of 0.14 mL (1 eq, 0.01 mmol) of CuBr (10 mg, 0.07 mmol) and PMDETA (14.55 μL, 0.07 mmol) dissolved in 1 mL of 7: 1 THF / BuOH Was added to initiate the click reaction. The prepared solution was stirred overnight at 40 < 0 > C. Thereafter, to remove the copper catalyst by the addition of Cuprisorb ^TM (1 mg) in I, and then, centrifuged to PEG-alkyne in excess. The collected suspension of P3HT-PEG NW was redispersed in THF / BuOH, BuOH, MeOH or water to a concentration of 10 mg / mL.

Example 3. Electronic device manufacturing and measurement

The OFET device was fabricated on a heavily doped n-type silicon wafer with a SiO ₂ layer (C _i = 10 nF cm ^-2 ) thermally grown to a thickness of 300 nm. The Si / SiO ₂ substrate was ultrasonicated in acetone, deionized water and isopropanol, and then 50 nm gold with a channel length of 10 μm and a channel width of 300 μm was evaporated by thermal treatment on the substrate. The suspension containing 10 mg / mL of P3HT-PEG NW dissolved in 7: 1 THF / BuOH, BuOH, MeOH or water was spin cast at 2000 rpm for 90 seconds, Baking for a minute. Field effect transistor characteristics were obtained at room temperature and atmospheric conditions using a Keithley 4200 SCS and a Micromanipulator 6150 probe station.

Experimental Example

General Information

Unless otherwise stated, commercially available reagents were used without further purification. The progress of the monomer reaction was checked by thin layer chromatography (TLC) analysis using Merck silica gel 60 F254 precoated plate (0.25 mm) with fluorescent label and visualized with UV light (254 and 365 nm). Column chromatography was performed on Merck silica gel 60 (230-400 mesh). All ¹ H NMR spectra were recorded at 500 MHz using CDCl ₃ as solvent. The chemical shifts of all ¹ H NMR spectra refer to the residual signal of CDCl 3 (δ 7.26 ppm) using a Bruker 500 MHz NMR instrument.

Size exclusion chromatography ( SEC ) Measure

The molecular weight (Mn) and polydispersity (PDI) of the P3HT-azide copolymer were analyzed by SEC (Waters 2414) using UV and RI detectors calibrated to polystyrene standards.

FT - IR ( Fourier transform infrared spectroscopy ) Measure

FT-IR measurements were obtained using a PerkinElmer Spectrum 100 FT-IR spectrometer. Solution The assembled NW was collected by centrifugation and measured after drying the residual solvent by nitrogen flow.

UV / vis Measure

The UV / vis absorption spectrum of the NW solution was obtained using a Hitachi U-3010 UV / visible spectrophotometer. The NW solution was diluted to 0.1 mg / ml and placed in a quartz cuvette with a path length of 1 mm.

Alkin - having a terminal, Monomethyl ether PEG ( PEG - alkyne )

The monomethyl ether PEG (Mn = 3000 g / mol, PDI = 1.05) sold was dried in azeotropic distillation in toluene and separated into fine white solids of good quality. The dried monomethyl ether PEG (5.05 g, 2.5 mmol) was then added to the oven-dried RB plast, dried with sodium benzophenone as a label and dissolved in distilled THF (30 mL). Sodium hydride (0.29 g, 12.1 mmol) was carefully added to the RB plast and the resulting suspension was stirred at room temperature for 1 hour under a nitrogen atmosphere. Propargyl bromide (80 wt% in toluene, 0.32 ml, 3 mmol) was then added to the RB plast and the reaction solution was stirred at room temperature overnight under nitrogen. The excess sodium hydride was then quenched by the slow addition of aqueous 0.1 M HCl solution. The THF was removed by rotary evaporation and the resulting aqueous solution was extracted with dichloromethane (3 x 50 mL). After the organic layer is combined and dried with Na ₂ SO _4, solvent was removed by rotary evaporation. The remaining solids were then dissolved in a minimum of dichloromethane and precipitated with diethyl ether (400 mL). The precipitate was separated by vacuum filtration, dissolved in a small amount of dichloromethane, and precipitated in a second diethyl ether (400 mL). The precipitate was recovered by vacuum filtration and dried in a high vacuum. PEG-alkyne was isolated as a good white precipitate with a yield of 69%. ^{1 H-NMR (500 MHz,} CDCl 3): δ = 2.43 (s), 3.37 (s), 3.63 (br), 4.19 (s) ppm. ¹³ C-NMR (125 MHz, CDCl ₃ ):? = 58.58, 59.14, 69.23, 70.69, 72.07, 74.40, 79.82 ppm.

Wide angle X-ray scattering

The properties of the nanostructures were determined using Ganesha 300XL wide-angle X-ray scattering (WAXS). X-ray irradiation was performed at 50 kV / 0.6 mA from a Cu anode having a wavelength of 0.154 nm.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims

Azide-functionalized poly-3-hexylthiophene (P3HT) is used for solution assembly, photo-crosslinking, and functionalization with alkyne-terminated molecules. (Polythiophene) nanowires, which can be processed in an aqueous solvent.

3. The polythiophene nanowire of claim 1, wherein the azide-functionalized P3HT is P3HT-azide of Formula 1:
[Chemical Formula 1]

.

The nanowire according to claim 1, wherein the solution granulation is conducted by a mixed solvent method using tetrahydrofuran (THF) and 1-butanol (BuOH).

The nanowire of claim 1, wherein the photo-crosslinking is performed by exposure to UV light under a nitrogen atmosphere.

The nanowire of claim 1, wherein the molecule having the alkyne-terminus is PEG-alkyne.

An electric device comprising the nanowire according to claim 1 as an active layer.

The electric device according to claim 6, wherein the electric device is an organic field effect transistor, a polymer solar cell, a memory device, or an optical sensor.

a) forming a P3HT-azide nanowire (P3HT-azide NW) through solution assembly of P3HT-azide;
b) photo-crosslinking the P3HT-azide NW to produce a crosslinked NW; And
c) functionalizing the crosslinked NW with a PEG-alkyne by a click reaction. 2. The process according to claim 1, wherein the crosslinked NW is functionalized by a reaction with PEG-alkyne.