Precisely Patterned Growth of Ultra-Long Single-Crystalline Organic

Mar 17, 2016 - The high on/off ratio of 1600 is significantly better than other organic nanostructure-based optical switchers. More importantly, this ...
0 downloads 0 Views 7MB Size
Download PDF
Research Article www.acsami.org

Precisely Patterned Growth of Ultra-Long Single-Crystalline Organic Microwire Arrays for Near-Infrared Photodetectors Hui Wang,† Wei Deng,† Liming Huang, Xiujuan Zhang,* and Jiansheng Jie* Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology (NANO−CIC), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China S Supporting Information *

ABSTRACT: Owing to extraordinary properties, small-molecule organic micro/ nanocrystals are identified to be prospective system to construct new-generation organic electronic and optoelectronic devices. Alignment and patterning of organic micro/nanocrystals at desired locations are prerequisite for their device applications in practice. Though various methods have been developed to control their directional growth and alignment, high-throughput precise positioning and patterning of the organic micro/nanocrystals at desired locations remains a challenge. Here, we report a photoresist-assisted evaporation method for large-area growth of precisely positioned ultralong methyl-squarylium (MeSq) microwire (MW) arrays. Positions as well as alignment densities of the MWs can be precisely controlled with the aid of the photoresist-template that fabricated by photolithography process. This strategy enables large-scale fabrication of organic MW arrays with nearly the same accuracy, uniformity, and reliability as photolithography. Near-infrared (NIR) photodetectors based on the MeSq MW arrays show excellent photoresponse behavior and are capable of detecting 808 nm light with high stability and reproducibility. The high on/off ratio of 1600 is significantly better than other organic nanostructure-based optical switchers. More importantly, this strategy can be readily extended to other organic molecules, revealing the great potential of photoresist-assisted evaporation method for future high-performance organic optoelectronic devices. KEYWORDS: micro/nanocrystals, organic microwire arrays, precise positioning and patterning, photoresist-assisted evaporation method, near-infrared, photodetector

■

INTRODUCTION Compared with their inorganic counterparts, organic materials offer much more flexibility and diversity in material design and the tuning of properties.1−4 However, conventional organic films usually possess polycrystalline or amorphous structures and thus exhibit inferior electronic and optoelectronic properties.5 The difficulty in obtaining single-crystalline organic films is a major obstacle to promote their applications in integrated optoelectronic devices.6−10 In this context, recent advance in single-crystal one-dimensional (1D) organic micro/nanocrystals opens up the great opportunities to achieve highperformance, high-integration devices from this new material system.11,12 Various organic micro/nanocrystal-based devices, such as organic field-effect transistors (OFETs),13−15 photodetectors,16−18 and sensors19 with unprecedented performance have been demonstrated in recent years. In spite of the progress, the effort to integrate these organic devices is still thwarted by difficulties in controllable alignment and precise placement of the organic micro/nanocrystals as required. It is known that the as-prepared organic micro/nanocrystals tend to be distributed in a macroscopically random fashion on the substrate or solution. Disordered alignment of organic micro/ nanocrystals may significantly increase the overall cost due to © XXXX American Chemical Society

material consumption and also result in poor device stability and reproducibility.14 Up to now, various attempts have been made to achieve large-scale, highly ordered organic micro/nanocrystal arrays.6,9,14,20−23 For instance, a droplet-pinned crystallization method was utilized to grow large-area arrays of aligned C60 single crystals.24 A slot-die coating deposition technique was also reported to produce highly aligned TIPS-pentacene singlecrystal arrays on planar substrate for OFETs.25 A epitaxial growth method was used to fabricate aligned and periodic parahexaphenyl (p-6P) and α-sexi-thiophene (6T) nanofibers.26,27 Our group also developed an evaporation induced self-assembly technique that can enable the growth, alignment, and periodic patterning of organic 1D single-crystal nanowires (NWs)/ microwires (MWs) at solid/liquid or liquid/liquid interface.28−31 However, most of the resulting single-crystals have limited growth length, moreover, their position, orientation and density are difficult to be accurately controlled, which are all crucial for practical device applications. Received: December 14, 2015 Accepted: March 7, 2016

A

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces

Figure 1. (a) Flowchart for the large-area growth of controllably aligned and precisely placed MeSq MW arrays via photoresist-assisted evaporation method. (b) SEM image of the ultralong MeSq MW arrays with 5 μm spacing on the lateral sides of the photoresist stripes, with inset showing the corresponding cross-sectional view SEM image. (c) AFM image and height profile of the MeSq MW arrays. (d) Cross-polarized optical image of the MeSq MW arrays. (e) TEM image of a single MeSq MW. 1−3 show the corresponding SAED patterns recorded from three different positions on the MW.

As a mature technique, photolithography has been widely used for the patterning of inorganic materials in current microelectronic industry due to its high reliability, high resolution, high flexibility, and capability for wafer-scale production. However, organic materials are largely incompatible with the well-developed photolithography technique because of the inferior chemical/physical stability, which greatly limits the application of photolithography in the precise patterning of organic materials. On the other hand, the weak intermolecular forces make it difficult to obtain large-area single-crystalline organic films. Single-crystalline organic crystals thus usually have micro/nanoscale sizes and are selfassembled in solution or substrate. Nevertheless, differing from inorganic crystals, growth of organic micro/nanocrystals can take place in mild conditions in solution,28−31 offering the possibility of utilizing photoresist as template to direct the aligned, positioned growth of ultralong organic MWs via selfassembly. Herein, we report a novel method of using photoresist as template for large-area growth of ultralong organic MW arrays. The position and alignment density of the MWs could be precisely controlled by the location and periodicity of photoresist stripes that were prefabricated via photolithography. The MW arrays could span over the whole substrate with extremely high uniformity and reproducibility. High-performance near-infrared (NIR) photodetectors based on the organic MW arrays were constructed, verifying the great potential of the strategy for future high-performance, integrated organic crystal device applications. The strategy developed in this work bridges the photolithography technique with the growth of

organic micro/nanocrystals, enabling the large-area fabrication of organic MW arrays with near the same accuracy, uniformity, and reliability as photolithography.

■

RESULTS AND DISCUSSION Photoresist-Assisted Growth of the MW Arrays. Organic semiconductor methyl-squarylium (MeSq) was used in this study due to its excellent optoelectronic properties.32,33 Figure 1a is the schematic illustration of the growth process of ultralong MeSq MW arrays on the photoresist-patterned SiO2 (300 nm)/Si wafer. Typically, UV photolithography was first performed on SiO2/Si substrate to generate the periodic and parallel photoresist stripes (I in Figure 1a), and then the exposed areas between photoresist stripes were modified by octadecyltrichlorosilane (OTS) self-assembled monolayer (II in Figure 1a). Areas that covered by photoresist stripes was hydroxy-terminated and solution-wettable, while OTS coated areas were alkyl-terminated and nonwettable. Finally, the photoresist-patterned substrate was vertically immersed in MeSq/dichloromethane (CH2Cl2) solution (III in Figure 1a). Interestingly, with the solvent evaporation, MWs grow neither on OTS surface nor on the top of photoresist surface, but preferentially along the bilateral sides of the photoresist stripes (IV in Figure 1a). Figure 1b displays the scanning electron microscope (SEM) image of MeSq MW arrays fabricated by photoresist-assisted evaporation method. It can be seen that MWs parallelly aligned along both sides of photoresist stripes (inset in Figure 1b) with straight structure, uniform width, and smooth surface. Notably, the highly aligned MeSq MWs can extend over almost the whole substrate that dipped into B

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces solution (1 × 1 cm2) (Figure S1). Close examination shows that the MWs have width of around 2 μm and continuous length up to several mm. To verify the continuity of MWs, we provide the continuous SEM observation of a couple of MWs grown along one photoresist strip (Figure S2), indicating that no cracks appear in the MWs. Most of the MWs have width around 2 μm. Two shoulders in the height profile of atomic force microscope (AFM) image correspond to the MWs at both sides of photoresist stripes. Thickness of the MWs is measured to be 500−600 nm (Figure 1c). The large-area crosspolarized optical image, Figure 1d, of the MW arrays shows the uniform color change over the entire area, revealing the singlecrystal nature of the MeSq MWs. Moreover, selected-area electron diffraction (SAED) patterns were collected from a single MW at three different positions (Figure 1e). The presence of discrete diffraction points, along with the identical patterns obtained at different positions, clearly unveils the single-crystal nature of the MeSq MW. These results collectively demonstrate that single-crystal MeSq MW arrays were obtained by the photoresist-induced growth method. Figure 2a−d show the SEM images of the MW arrays fabricated with different photoresist stripe spacings of 5, 15, 30,

S3c−f depict the SEM images of MeSq MWs fabricated with channel spacing of 5, 15, 30, and 45 μm, respectively. However, some of the MWs are occasionally absent in the wettable channels, particularly when the channel spacing is decreased to 5 μm (Figure 3a, indicated by white arrows). This is mainly caused by the competition of MW nucleation between the adjacent wettable channels. In addition, if the wettable channel width is increased to 10 μm or more, curved MWs with many dendritic structures on the trunks can be observed, and some of the dendritic structures even extended out of the wettable channels (Figure 3b). Therefore, it can be seen that growth conditions need to be carefully controlled to ensure the confinement of MWs within the wettable channels. Fluctuation of experiment parameters, such as temperature and dewetting velocity, often leads to the deviation of MWs from the wettable channels (3 μm) (Figure 3c). It seems that the wider the wettable channel is, the weaker template effect it serves for the MWs growth. Although OTS-modified wettable channels can also offer the template effect to guide the growth of MeSq MW arrays, we do note that the effect is comparatively weak, since the thickness of OTS molecule layer is 26 Å,34 which is much thinner than that of the photoresist stripes (400−500 nm). Solvent evaporation velocity is another important factor for the formation of MW arrays.35−37 By controlling the processing temperature, solvent dewetting velocity (v) can be tuned in a wide range from 250 to 20 μm/min. SEM images in Figure 3d− g depict the velocity-dependent product morphologies. When the evaporation velocity is higher than 200 μm/min, periodic short rod-like MWs with random orientations are obtained (v = 250 μm/min), mainly induced by the “coffee-ring” effect (Figure 3d). If the evaporation velocity is decreased to be 160− 100 μm/min, some of the MWs are observed to grow along the photoresist stripes and the resulting nanostructure becomes longer (Figure 3e and 3f). Intervals between MW arrays are reduced as well. When v is less than 50 μm/min, ultralong MeSq MWs with parallel alignment are formed along the photoresist stripes (Figure 3g). This result manifests that the solvent evaporation velocity plays an important role in the formation of ultralong MW arrays in the photoresist-assisted evaporation method. The detailed mechanism is discussed below. Growth Mechanism of the MW Arrays. Figure 4 shows the schematic illustration of photoresist-assisted evaporation process. Solvent meets the lateral surface of the photoresist stripes at a nonzero contact angle (θ0) and the contact line is pinned due to the surface roughness (Figure 4a). It was measured that the OTS modified area shows less wettability (with contact angel of 110.9°) than that of photoresist (with contact angle of ∼76.3°) (Figure S4). Wettability difference, along with height difference between the photoresist stripe and OTS-modified substrate, will cause the formation of typical capillary meniscus as indicated in the Figure 4a. With solvent evaporation, the contact angle will decrease to θ1, and MeSq concentration at the highest points will become increasingly higher. When it reaches a certain threshold value, MeSq molecules begin to precipitate out, forming nuclei of MWs (Figure 4b). Concentration gradient in the solution will induce the formation of small rivulets at the bilateral sides of the photoresist stripes along the dewetting direction, as illustrated in Figure 4b and 4c. An upward solution radial flow will take MeSq molecules (or aggregates) from bulk solution to the rivulets to replenish the solvent evaporation loss at the highest points (Figure 4c).38,39 With the accumulation of molecules,

Figure 2. (a−d) SEM images of the MeSq MW arrays fabricated by using the photoresist-template with different photoresist stripe spacings of 5, 15, 30, and 45 μm, respectively.

and 45 μm, respectively. Intervals between adjacent MeSq MWs can match well with the spacing of the photoresist stripes. It is found that width of the MWs is about 2 μm and has no obvious relation with the widths or intervals of photoresist stripes. Significantly, the photoresist-assisted approach is highly reliable with extremely high reproducibility and stability. We note that the photoresist-template effect is critical for the formation of highly aligned MW arrays. In the control experiment, photoresist stripes were fully removed after OTS modification, leaving behind periodic wettable/nonwettable patterned molecular template on the substrate. During the same solvent evaporation process, organic molecules tend to nucleate and assemble selectively on the wettable channels, resulting in the formation of MW arrays as well (Figure S3). Also, by altering the spacing of adjacent wettable channels, intervals of the MW arrays can be roughly regulated. Figure C

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces

Figure 3. (a−c) SEM images of the MW arrays fabricated by using OTS molecular template. (a) The width and interval for the wettable channel are 3 and 5 μm, respectively. (b) The width and interval for the wettable channel are 10 and 30 μm, respectively. The wettable channel is marked by dash lines. (c) The width and interval for the wettable channel are 3 and 5 μm, respectively. During the experiment, the temperature is fluctuated between 283 and 288 K, which leads to the deviation of the MW growth. (d−g) SEM images of the MW arrays fabricated by SU8 photoresisttemplate. The dewetting velocity was well controlled by tuning the experimental temperature with (d) 250 μm/min @ 309 K, (e) 160 μm/min @ 303 K, (f) 100 μm/min @ 295 K, and (g) 20 μm/min @ 283 K.

Figure 4. (a−d) Schematic illustration of photoresist-assisted evaporation method for the preparation of ultralong organic MW arrays with high position/alignment precision.

tuned by varying the intervals of the photoresist stripes. Furthermore, as a template with three-dimensional (3D) geometry, photoresist stripe can also perfectly prevent the deviation of the solution rivulets and thus ensure the confined growth of MWs along the sidewalls of photoresist stripes (Figure 4d). This also explains why photoresist stripe can offer a much better template effect than that of wettable/unwettable OTS molecular template. In addition, the photoresist-assisted growth of organic MW arrays is highly versatile and suitable for the growth a variety of organic MW arrays, such as C60, N,N′dipentyl-3,4,9,10-perylenedicarboximide (PTCDI) 2,4-bis[4(N,Ndimethylamino)phenyl]squaraine (SQ), and 9,10-bis(phenylethynyl)anthracene (BPEA) molecule (Figure S5). As the SU-8 photoresist stripes can bear most of organic solvents (Figure S6), implying that this method can be extended to other organic solvents. Hopefully, this method also could to be scale up to a high throughput system by carefully controlling the growth conditions such as evaporation temperature and humidity in environment.

MeSq nanostructures will be gradually formed via self-assembly process. Due to the slow evaporation velocity, epitaxial growth will continue at the MWs/solution interface along photoresist sidewalls, giving rise to the formation of ultralong aligned MWs (Figure 4d). Evaporation velocity plays a critical role in the formation of MW arrays along both sides of photoresist stripes. At higher evaporation velocity, there is no sufficient time for MeSq molecules to grow preferentially along photoresist stripe. Coffee-ring effect will prevail over the template effect,28 and rapid slip of contact line will lead to the formation of periodic MWs with random orientations (Figure 3d). With the evaporation velocity decreased, contact line slip is suppressed, which can offer more time for MW growth and shorten the interval distance as well (Figure 3e and 3f). Slip of the contact line will be completely prohibited with contact angle maintaining at θ1 at very low evaporation velocity. Template effect of photoresist stripes will dominate in the formation process of the ultralong MW arrays. Since growth of MWs only takes place along the template, density of MWs can be readily D

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces

Figure 5. (a) SEM images of the devices fabricated on highly aligned MeSq MW arrays with photoresist spacing of (I) 48, (II) 33, (III) 18, and (IV) 8 μm, respectively. The corresponding I−V curves in the dark are shown in panel b. (c) Schematic illustration of the device configuration for photoresponse measurements. Ti/Au bilayer electrodes were used to enhance photoresponse of the photodetector. (d) I−V curves of the MeSq MW arrays measured in the dark and under 808 nm light illumination (200 mW cm−2), respectively. (e) Time response behavior of the photodetector under pulsed incident light illumination.

Optoelectronic Properties of the MW Arrays. Photoresist-assisted evaporation method provides a facile approach to achieve large-scale fabrication of single-crystal organic MW arrays with precise position and patterning, which is crucial to the development of integrated organic electronic devices. To exploit the potential of the highly aligned organic MW arrays for device applications, devices were constructed based on the MW arrays with different densities (Figure 5a). Figure 5b plots the typical current versus voltage (I-V) curves for the MeSq MW arrays with Au (50 nm) electrodes in the dark. Since SU-8 photoresist used in this work is highly insulating, existence of the photoresist stripes will not influence the electrical measurements. The linear shape of the curves reveals the ohmic contacts of Au electrodes with the MWs. Moreover, the conductance of the devices is approximately proportional to the density of the MW arrays; the ratio of the conductance is 1:2:4:6 for the MW arrays with photoresist periodicity of 48, 33, 18, and 8 μm (corresponding to effective MW channel width of 17, 30, 53, and 96 μm, respectively). Photodetectors based on the MeSq MW arrays were constructed by using Ti (3 nm)/Au (50 nm) bilayer electrodes (Figure 5c). Schottky contact of Ti with MeSq MWs can contribute to the enhancement of device performance by suppressing the dark current and facilitating the separation of photogenerated carriers.40 It is found that MeSq MW array-based photodetectors show pronounced photoresponse under NIR light illumination (808 nm, 200 mW cm−2), as shown in Figure 5d. We note that Ilight/Idark ratio of the photodetector is about 1600 (Figure 5e), which is much higher than other organic nanostructure-based optical switchers with typical Ilight/Idark ratio of 100−600 measured under similar conditions.28−30,32 Moreover, the response of MeSq MWs to the pulsed incident light is fast with a rise/fall time of 1.4/4.7 s and also exhibits excellent stability and repeatability. The excellent photoresponse can be attributed to the high crystal quality nature of the MeSq MW arrays. In comparison with random organic nanostructures, the highly aligned MeSq MW arrays offer the possibility to design and fabricate highly integrated photo-

sensing devices, such as image sensors, based on them due to the high reproducibility and high uniformity.

■

CONCLUSION In summary, we have developed a facile photoresist-assisted evaporation method to grow large-area ultralong singlecrystalline MeSq MW arrays with controlled alignment and placement. By controlling the evaporation velocity of the solvent, organic MWs could grow along the sides of photoresist stripes, forming ultralong parallel aligned MW arrays. Density and position of the MW arrays could be readily regulated by varying the photoresist spacing via photolithography. Mechanism was systematically investigated. Devices based on the MW arrays showed a density-dependent electrical conduction. Photoresponse of the devices were further investigated under 808 nm NIR light illumination. High switching ratio of 1600 was observed, which is higher than many organic nanostructure-based optical switchers. The ability to grow small molecular organic crystal MW arrays with highly defined spatial and parallel ordering opens up great opportunities for a variety of high-performance organic electronic and optoelectronic devices.

■

EXPERIMENTAL SECTION

Surface Patterning and Modification. SiO2 (300 nm)/Si substrates were cleaned by sonication in acetone and ethanol, respectively, for 10 min right before use. Surface modifications with alkyl and hydroxy groups were used to obtain unwettable and solutionwettable surface regions, respectively. First, we made the surface of SiO2/Si substrates hydrophilic and wettable by immersing it in piranha solution (H2SO4/H2O2 = 3:1) for 60 min and treating with oxygen plasma for 10 min at 300 W. UV Photolithography was then performed to generate periodic and parallel photoresist stripes on the substrate by using negative photoresist (SU-8) on a UV aligner (SUSS MicroTec MJB-4). Afterward, the exposed regions between photoresist stripes were treated with OTS solution (OTS/methylbenzene = 1:100) under a nitrogen atmosphere for 20 min. The OTS monolayer prepared by this method has been shown to produce a stable and complete monolayer with thickness of 26 Å. The photoresist stripes E

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces were kept on the substrate and served as the template due to the higher wettability and 3D geometry. Alternatively, periodic wettable/ nonwettable surface patterned molecule template was obtained by removing the photoresist by a lift-off process in acetone. Growth and Characterizations of MeSq MW Arrays. In a typical dip-coating experiment, a piece of pretreated SiO2/Si substrate with photoresist template was immersed vertically in a MeSq/CH2Cl2 solution (6 mL, 0.03 mM) in a cylindrical container. The photoresist stripes were parallel to the dewetting direction. Dichloromethane was then allowed to gradually evaporate at slow dewetting velocity (20 μm/min). The whole evaporation process was accomplished at 10 °C inside a fume cupboard where humidity was lower than 40%, so that the rate of solvent evaporation could be well controlled. During the evaporation of solvent, MeSq MWs that parallel to the dewetting direction could selectively deposit only along the sidewalls of photoresist stripes. The dewetting velocity could be controlled by tuning the evaporation temperature. Morphologies and structures of the product were characterized by SEM (FEI Quanta 200 FEG) and TEM (FEI Tecnai G2 F20). AFM images of the MW arrays were taken by a Multi-Mode V AFM (Veeco). Device Construction and Characterization. To measure the conductance of the MeSq MW arrays, Au (50 nm) ohmic contacts were evaporated onto the MW arrays via a high-vacuum e-beam evaporation system (Kurt J. Lesker, PVD 75) with the assistance of a shadow mask that consisted of 20 μm aluminum wires. Photodetectors based on the MeSq MW arrays were constructed by the same approach except for the use of Ti (3 nm)/Au (50 nm) bilayer electrode. All the electrical measurements were conducted at room temperature with a semiconductor characterization system (Keithley, 4200-SCS) on a probe station (M150, Cascade). The NIR light (808 nm, 200 mW cm−2) was used as the light source for detection of the photoconductive properties of the MeSq MW arrays.

■

Foundation of China (No. 91333208), the National Natural Science Foundation of China (No. 61422403, 51401138), the Natural Science Foundation of Jiangsu Province (No. BK20131162), QinLan project, and A Project Funded by the A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

■

(1) Zhao, Y.; Guo, Y. L.; Liu, Y. Q. 25th Anniversary Article: Recent Advances in n-Type and Ambipolar Organic Field-Effect Transistors. Adv. Mater. 2013, 25, 5372−5391. (2) Wang, C. L.; Dong, H. L.; Hu, W. P.; Liu, Y. Q.; Zhu, D. B. Semiconducting π-Conjugated Systems in Field-Effect Transistors: A Material Odyssey of Organic Electronics. Chem. Rev. 2012, 112, 2208− 2267. (3) Deng, W.; Zhang, X. J.; Gong, C.; Zhang, Q.; Xing, Y. L.; Wu, Y. M.; Zhang, X. W.; Jie, J. S. Aligned Nanowire Arrays on Thinflexible Substrates for Organic Transistors with High Bending Stability. J. Mater. Chem. C 2014, 2, 1314−1320. (4) Gentili, D.; Foschi, G.; Valle, F.; Cavallini, M.; Biscarini, F. Applications of Dewetting in Micro and Nanotechnology. Chem. Soc. Rev. 2012, 41, 4430−4443. (5) Peumans, P.; Yakimov, A.; Forrest, S. R. Small Molecular Weight Organic Thin-Film Photodetectors and Solar Cells. J. Appl. Phys. 2003, 93, 3693−3723. (6) Wu, Y. C.; Feng, J. G.; Jiang, X. Y.; Zhang, Z.; Wang, X. D.; Su, B.; Jiang, L. Positioning and Joining of Organic Single-Crystalline Wires. Nat. Commun. 2015, 6, 6737. (7) Diao, Y.; Tee, B. C. K.; Giri, G.; Xu, J.; Kim, D. H.; Becerril, H. A.; Stoltenberg, R. M.; Lee, T. H.; Xue, G.; Mannsfeld, S. C. B.; Bao, Z. N. Solution Coating of Large-Area Organic Semiconductor Thin Films with Aligned Single-Crystalline Domains. Nat. Mater. 2013, 12, 665− 671. (8) He, D. W.; Zhang, Y. H.; Wu, Q. S.; Xu, R.; Nan, H. Y.; Liu, J. F.; Yao, J. J.; Wang, Z. L.; Yuan, S. J.; Li, Y.; Shi, Y.; Wang, J. L.; Ni, Z. H.; He, L.; Miao, F.; Song, F. Q.; Xu, H. X.; Watanabe, K.; Taniguchi, T.; Xu, J. B.; Wang, X. R. Two-Dimensional Quasi-Freestanding Molecular Crystals for High-Performance Organic Field-Effect Transistors. Nat. Commun. 2014, 5, 5162. (9) Yuan, Y.; Giri, G.; Ayzner, A. L.; Zoombelt, A. P.; Mannsfeld, S. C. B.; Chen, J.; Nordlund, D.; Toney, M. F.; Huang, J.; Bao, Z. N. Ultra-High Mobility Transparent Organic Thin Film Transistors Grown by An Off-Centre Spin-Coating Method. Nat. Commun. 2014, 5, 3005. (10) Wu, Y. M.; Zhang, X. J.; Pan, H. H.; Deng, W.; Zhang, X. H.; Zhang, X. W.; Jie, J. S. In-Situ Device Integration of Large-Area Patterned Organic Nanowire Arrays for High-Performance Optical Sensors. Sci. Rep. 2013, 3, 3248. (11) He, P.; Tu, Z. Y.; Zhao, G. Y.; Zhen, Y. G.; Geng, H.; Yi, Y. P.; Wang, Z. R.; Zhang, H. T.; Xu, C. H.; Liu, J.; Lu, X. Q.; Fu, X. L.; Zhao, Q.; Zhang, X. T.; Ji, D. Y.; Jiang, L.; Dong, H. L.; Hu, W. P. Tuning the Crystal Polymorphs of Alkyl Thienoacene via Solution Self-Assembly Toward Air-Stable and High-Performance Organic Field-Effect Transistors. Adv. Mater. 2015, 27, 825−830. (12) Li, L. Q.; Gao, P.; Schuermann, K. C.; Ostendorp, S.; Wang, W. C.; Du, C.; Lei, Y.; Fuchs, H.; Cola, L. D.; Mullen, K.; Chi, L. F. Controllable Growth and Field-Effect Property of Monolayer to Multilayer Microstripes of an Organic Semiconductor. J. Am. Chem. Soc. 2010, 132, 8807−8809. (13) Reyes-Martinez, M. A.; Crosby, A. J.; Briseno, A. L. Rubrene Crystal Field-Effect Mobility Modulation via Conducting Channel Wrinkling. Nat. Commun. 2015, 6, 6948. (14) Liu, S. H.; Wang, W. M.; Briseno, A. L.; Mannsfeld, S. C. B.; Bao, Z. N. Controlled Deposition of Crystalline Organic Semiconductors for Field-Effect-Transistor Applications. Adv. Mater. 2009, 21, 1217−1232.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.5b12190. Photograph of the large-area uniform MeSq MW arrays grown on substrate, SEM images of the continuous MWs grown along one photoresist strip, schematic illustration of MeSq MW arrays fabricated by using OTS molecular template, contact angle measurements of SiO2/Si substrate, SU-8 photoresist, and OTS coated SiO2/Si substrate, SEM images of the PTCDI, C60, SQ, and BPEA MW arrays fabricated by the photoresist-assisted evaporation method, and optical microscope images of the photoresist stripes after dipping into other organic solvents (PDF)

■

REFERENCES

AUTHOR INFORMATION

Corresponding Authors

*Tel: +86-512-65881265. E-mail: [email protected]. *Tel: +86-512-65880955. E-mail: [email protected]. Author Contributions †

H.W. and W.D. contributed equally to this manuscript. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by the National Basic Research Program of China (Nos. 2013CB933500, 2012CB932400), the Major Research Plan of the National Natural Science F

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces (15) He, T.; Stolte, M.; Burschka, C.; Hansen, N. H.; Musiol, T.; Kalblein, D.; Pflaum, J.; Tao, X. T.; Brill, J.; Wurthner, F. SingleCrystal Field-Effect Transistors of New Cl2-NDI Polymorph Processed by Sublimation in Air. Nat. Commun. 2015, 6, 5954. (16) Arnold, M. S.; Zimmerman, J. D.; Renshaw, C. K.; Xu, X.; Lunt, R. R.; Austin, C. M.; Forrest, S. R. Broad Spectral Response Using Carbon Nanotube/Organic Semiconductor/C60 Photodetectors. Nano Lett. 2009, 9, 3354−3358. (17) Zhou, Y.; Wang, L.; Wang, J.; Pei, J.; Cao, Y. Highly Sensitive, Air-Stable Photodetectors Based on Single Organic Sub-micrometer Ribbons Self-Assembled through Solution Processing. Adv. Mater. 2008, 20, 3745−3749. (18) Tang, Q. X.; Li, L. Q.; Song, Y. B.; Liu, Y. L.; Li, H. X.; Xu, W.; Liu, Y. Q.; Hu, W. P.; Zhu, D. B. Photoswitches and Phototransistors from Organic Single-Crystalline Sub-Micro/nanometer Ribbons. Adv. Mater. 2007, 19, 2624−2628. (19) Li, L. Q.; Gao, P.; Baumgarten, M.; Müllen, K.; Lu, N.; Fuchs, H.; Chi, L. F. High Performance Field-Effect Ammonia Sensors Based on a Structured Ultrathin Organic Semiconductor Film. Adv. Mater. 2013, 25, 3419−3425. (20) Wang, W. C.; Chi, L. F. Area-Selective Growth of Functional Molecular Architectures. Acc. Chem. Res. 2012, 45, 1646−1657. (21) Mei, J. G.; Diao, Y.; Appleton, A. L.; Fang, L.; Bao, Z. N. Integrated Materials Design of Organic Semiconductors for FieldEffect Transistors. J. Am. Chem. Soc. 2013, 135, 6724−6746. (22) Feng, J.; Wu, Y.; Su, B.; Jiang, L. Large-Scale Assembly of Organic Highly Crystalline Multicomponent Wires through SurfaceEngineered Condensation and Crystallization. Small 2015, 11, 5759− 5765. (23) Wu, Y.; Feng, J.; Su, B.; Jiang, L. 3D Dewetting for Crystal Patterning: Toward Regular Single-Crystalline Belt Arrays and Their Functionality. Adv. Mater. 2016, 28, 2266−2273. (24) Li, H. Y.; Tee, B. C. K.; Cha, J. J.; Cui, Y.; Chung, J. W.; Lee, S. Y.; Bao, Z. N. High-Mobility Field-Effect Transistors from Large-Area Solution Grown Aligned C60 Single Crystals. J. Am. Chem. Soc. 2012, 134, 2760−2765. (25) Chang, J. J.; Chi, C. Y.; Zhang, J.; Wu, J. S. Controlled Growth of Large-Area High-Performance Small-Molecule Organic SingleCrystalline Transistors by Slot-Die Coating Using A Mixed Solvent System. Adv. Mater. 2013, 25, 6442−6447. (26) Simbrunner, C. Epitaxial Growth of Sexi-Thiophene and ParaHexaphenyl and Its Implications for the Fabrication of Self-Assembled Lasing Nano-Fibres. Semicond. Sci. Technol. 2013, 28, 053001. (27) Kjelstrup-Hansen, J.; Simbrunner, C.; Rubahn, H.-G. Organic Surface-Grown Nanowires for Functional Devices. Rep. Prog. Phys. 2013, 76, 126502. (28) Zhang, C. Y.; Zhang, X. J.; Zhang, X. H.; Ou, X. M.; Zhang, W. F.; Jie, J. S.; Chang, J. C.; Lee, C. S.; Lee, S. T. Facile One-Step Fabrication of Ordered Organic Nanowire Films. Adv. Mater. 2009, 21, 4172−4175. (29) Wang, Z. L.; Bao, R. R.; Zhang, X. J.; Ou, X. M.; Lee, C. S.; Chang, J. C.; Zhang, X. H. Semiconductor Nanowires by Controlled Evaporation of Confined Microfluids. Angew. Chem., Int. Ed. 2011, 50, 2811−2815. (30) Bao, R. R.; Zhang, C. Y.; Zhang, X. J.; Ou, X.-M.; Lee, C. S.; Jie, J. S.; Zhang, X. H. Self-Assembly and Hierarchical Patterning of Aligned Organic Nanowire Arrays by Solvent Evaporation on Substrates with Patterned Wettability. ACS Appl. Mater. Interfaces 2013, 5, 5757−5762. (31) Deng, W.; Zhang, X. J.; Wang, L.; Wang, J. C.; Shang, Q. X.; Zhang, X. H.; Huang, L. M.; Jie, J. S. Wafer-Scale Precise Patterning of Organic Single-Crystal Nanowire Arrays via a PhotolithographyAssisted Spin-Coating Method. Adv. Mater. 2015, 27, 7305−7312. (32) Zhang, X. J.; Jie, J. S.; Zhang, W. F.; Zhang, C. Y.; Luo, L. B.; He, Z. B.; Zhang, X. H.; Zhang, W. J.; Lee, C. S.; Lee, S. T. Photoconductivity of a Single Small-Molecule Organic Nanowire. Adv. Mater. 2008, 20, 2427−2432.

(33) Beverina, L.; Salice, P. Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications. Eur. J. Org. Chem. 2010, 2010, 1207−1225. (34) Wasserman, S. R.; Whitesides, G. M.; Tidswell, I. M.; Ocko, B. M.; Pershan, P. S.; Axe, J. D. Axe, J. D. The Structure of SelfAssembled Monolayers of Alkylsiloxanes on Silicon: A Comparison of Results from Ellipsometry and Low-Angle X-ray Reflectivity. J. Am. Chem. Soc. 1989, 111, 5852−5861. (35) Fabiano, S.; Pignataro, B. Selecting Speed-Dependent Pathways for a Programmable Nanoscale Texture by Wet Interfaces. Chem. Soc. Rev. 2012, 41, 6859−6873. (36) Huang, J. X.; Kim, F.; Tao, A. R.; Connor, S.; Yang, P. D. Spontaneous Formation of Nanoparticle Stripe Patterns Through Dewetting. Nat. Mater. 2005, 4, 896−900. (37) van Hameren, R.; Schon, P.; van Buul, A. M.; Hoogboom, J.; Lazarenko, S. V.; Gerritsen, J. W.; Engelkamp, H. P.; Christianen, C. M.; Heus, H. A.; Maan, J. C.; Rasing, T.; Speller, S.; Rowan, A. E.; Elemans, J. A. A. W.; Nolte, R. J. M. Macroscopic Hierarchical Surface Patterning of Porphyrin Trimers via Self-Assembly and Dewetting. Science 2006, 314, 1433−1436. (38) Jang, J.; Nam, S.; Im, K.; Hur, J.; Cha, S. N.; Kim, J.; Son, H. B.; Suh, H.; Loth, M. A.; Anthony, J. E.; Park, J.; Park, C. E.; Kim, J. M.; Kim, K. Highly Crystalline Soluble Acene Crystal Arrays for Organic Transistors: Mechanism of Crystal Growth During Dip-Coating. Adv. Funct. Mater. 2012, 22, 1005−1014. (39) Giri, G.; Verploegen, E.; Mannsfeld, S. C. B.; Atahan-Evrenk, S.; Kim, D. H.; Lee, S. Y.; Becerril, H. A.; Aspuru-Guzik, A.; Toney, M. F.; Bao, Z. N. Tuning Charge Transport in Solution-Sheared Organic Semiconductors Using Lattice Strain. Nature 2011, 480, 504−509. (40) Zhang, Y. P.; Deng, W.; Zhang, X. J.; Zhang, X. W.; Zhang, X. H.; Xing, Y. L.; Jie, J. S. In Situ Integration of Squaraine-NanowireArray-Based SchottkyType Photodetectors with Enhanced Switching Performance. ACS Appl. Mater. Interfaces 2013, 5, 12288−12294.

G

DOI: 10.1021/acsami.5b12190 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX