Patterned Taping: A High-Efficiency Soft Lithographic Method for

Feb 10, 2016 - As a universal lithographic technique for microscale/nanoscale film ... and distinct advantages of short operation time, supreme patter...
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Patterned Taping: A High-Efficiency Soft Lithographic Method for Universal Thin Film Patterning Sangyoon Oh, Sang Kyu Park, Jin Hong Kim, Illhun Cho, Hyeong-Ju Kim, and Soo Young Park* Center for Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea S Supporting Information *

ABSTRACT: As a universal lithographic technique for microscale/nanoscale film patterns, we develop a strategy for the use of soft lithographically patterned pressuresensitive tape (patterned tape) as a pattern-transporting stamp material. Patterning was successfully implemented through the selective detachment and/or attachment of various thin films, including organic and metallic layers demanding no subsequent physical, thermal, or chemical treatment, as this incurs the risk of the deformation of the thin film and the deterioration of its functionalities. Its features of universal adhesion and flexibility enable pressure-sensitive tapes to form patterns on a variety of surfaces: organic, polymeric, and inorganic surfaces as well as flat, curved, uneven, and flexible substrates. Moreover, the proposed technique boasts the unique and distinct advantages of short operation time, supreme patterning yield, and multilayer stacking capability, which suggest considerable potential for their application to advanced optoelectronic device fabrication. KEYWORDS: soft lithography, pressure-sensitive adhesives, universal adhesion, time-/cost-effective, high-performance optoelectronic device

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of soft lithographic printing techniques act as a potential destructive influence on the materials because they directly apply external stimuli such as heat, pressure, or a combination of these to the functional layer.18,21,22 These outer stimuli can lead to oxidation by heat23,24 as well as pressure deformation.19 These commonly used processes prevent the use of certain methods owing to deterioration in functionality or a shortening of the lifetime of the relevant device in case the target material is sensitive to external stimuli. In this regard, the nonevasive characteristic of the patterning method is advantageous for highly efficient microdevice fabrication.25−27 Further, soft lithographic printing has practical limitations related to efficiency in one or more of the following ways: (1) it is a time-consuming process, i.e., the application of heat or pressure is often required for a long time (over several minutes),18,28 and diffusion-dependent patterning19 is sometimes needed; (2) it requires additional steps such as modification of the surface of the substrate22 and the introduction of a sacrificial layer;21,29 (3) it is difficult to apply to a wide range of materials, e.g.,

icroscale or nanoscale pattern fabrication using lithographic techniques is widely studied for practical applications of electronic/optoelectronic devices1−4 such as commercially affordable light-emitting diodes (LEDs), smartphones, and personal computers (PCs). Similarly, the patterning of active layers and/or electrodes is indispensable to the construction of flexible electronic devices based on organic materials, such as organic light-emitting diodes (OLEDs),5,6 organic field-effect transistors (OFETs),7,8 and organic photovoltaic (OPV) cells.9,10 Optical lithography is commonly used to pattern commercial inorganic electronic devices through high-energy-beam irradiation and chemical etching. These harsh processing conditions for optical lithography compromise the functionality of materials (e.g., organic materials). In this sense, as an alternative to conventional optical lithography, a simpler and more costeffective technique called soft lithography has been extensively researched.11−16 Of the soft lithographic techniques, dry transfer printing methods, such as microcontact printing,17 hot lift-off,3,18 and others,19,20 have been widely used to pattern optoelectronic devices. These transfer printing approaches have opened new avenues for device application, high-speed processing, scalability, and the prevention of lateral diffusion or the swelling of a mold by a liquid. However, a large number © XXXX American Chemical Society

Received: December 2, 2015 Accepted: February 10, 2016

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ACS Nano organic materials.20,30 These limitations result in a loss of time and expenditure on patterning methods. The above drawbacks are potential obstacles to the implementation of practical organic devices. Hence, it is important to develop practical approaches for lithography that can solve the problems afflicting conventional techniques. We propose a soft lithographic printing technique for “patterned taping” that operates in two modes: selective removal of a pattern from a substrate (subtractive) and/or subsequent transfer of the pattern to another substrate (additive). Patterned taping has a short processing time (it is time-efficient) and low processing cost (it is cost-efficient) because of the simplicity/convenience of its procedures and does not involve any invasive treatment of the target materials (it is damage-free). Commercial adhesive tape has been widely utilized in a variety of methods for microstructured device fabrication,29,31−34 because of the fine adhesion ability and flexibility of adhesive tapes. Originally, our printing process employed soft lithographically patterned adhesive tape, which forms a thin film pattern over a large area (∼cm2 scale) with a virtually perfect yield of patterning (yield of picking and/or transferring patterns) and can construct patterns on a wide variety of substrates: flat, curved, uneven, and flexible. Through the property of universal adhesion in pressure-sensitive tapes, this method can be applied to various kinds of materials, including layers of organic, polymeric, metallic, and inorganic materials. In this article, we report the generation of extensively designed patterns of organic semiconductor films, thin metal films, micropixels, and lines of luminescent organic RGB films that emit white luminescence through patterned taping.

RESULTS AND DISCUSSION Patterned Taping. Figure 1a−g shows the procedure involved in patterned taping for thin films. The pressuresensitive tape is laid onto the prepatterned side of a master mold (Figure 1a), following which mild pressure (∼100 g/cm2) and heat (ca. 60 °C) are applied to the tape, which is adhesively attached to the master mold, for a few seconds (Figure 1b). This operation replicates the structures of the master mold (Figure 1h) onto the surface of the adhesive tape (Figure 1i). The application of mild heat lowers the viscosity of the adhesive polymer, and pressure induces the adhesives to fill the recessed areas of the stamp through viscous flow of the adhesive polymer. By the viscoelasticity of the adhesive element, the patterns on the structured master mold can be finely replicated onto the pressure-sensitive tape. This aspect of pattern replication onto the adhesive tape is analogous to capillary force lithography.35 Many kinds of materials can be chosen as a master mold for the adhesive tape without a restriction on the surface energy of the stamp, e.g., polydimethylsiloxane (PDMS, surface energy ∼25 mJ m−2), polyurethane acrylate (PUA, ∼ 20 mJ m−2), and photolithographically fabricated silicone (Si) (∼1500 mJ m−2). Having been cooled at room temperature for a few seconds, the adhesive recovers its elasticity, and the structure is replicated onto the adhesive tape as it is peeled off the stamp (Figure 1c, i). This patterned tape can be disposable after a single use or limited number of cycles (durable for more than 16 cycles; see Figure S6). By repeating the patterned taping procedure shown in Figure 1 with new adhesive tape, however, the completely identical patterned tape can be regenerated and reused. Therefore, it should be mentioned that the reusability of patterned taping is principally nonrestricted.

Figure 1. Patterned taping. (a−g) Schematic illustration of patterned taping. The yellow and green brackets represent subtractive patterned taping (a−e) and additive patterned taping a−g), respectively. (h) Prepatterned PDMS master mold. The darker area is recessed. (i) Patterned tape from the master mold in (h). The recessed area of the master mold protruded in the patterned tape.

The soft lithographically patterned pressure-sensitive tape is then used to cover the substrate on which the target thin film is deposited such that only protruding parts of the patterned tape make contact with the target layer (Figure 1d). Without applying physical or chemical stimuli to the thin film at room temperature (RT), the subsequent delamination of the patterned tape from the substrate yields a subtractive patterned thin film (Figure 1e). While direct pressure and/or heat application onto the target film (used in conventional soft lithography such as the “hot lift-off” method) often deforms the patterns of target, our patterned taping method does not induce any deformation in accurately replicating the the master mold structures (Figure S8). Due to the high capacity for adhesion of the pressure-sensitive tape,36 clear patterns without residues between lines (Figure S2) are attainable. To achieve such a structure, a higher delamination speed for the patterned tape is recommended for greater adhesion. The kinetic control of adhesion by regulating the peeling speed of the viscoelastic stamp is a well-known technique.37−39 Viscoelastic, polymerbased, pressure-sensitive tapes show large magnitudes of adhesion energy at higher peeling rates (>10 cm/s along the direction of peeling). B

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Figure 2. Subtractive pattern of a thin organic film. (a) Line-patterned thin organic film of semiconductor Hex-4-TFPTA. The patterning yield of subtractive patterned taping was close to unity. (b) SEM image of (a). (c) 1.2 cm × 1.2 cm patterned wafer of Hex-4-TFPTA with structural color. (d−f) Optical microscopy image of a microscale letter under UV light. (d) Hex-4-TFPTA on ODTS-treated SiO2 substrate. (e) DBDCS on bare SiO2 substrate. (f) Phase-transitioned thermally annealed DBDCS. The same microletter as that in (e).

Following subtractive patterned taping, the thin film of the target material was covered only on the protruding part of the patterned tape (Figure 1e). Softly covering an empty substrate with tape and sequent exfoliation transferred the pattern structure to the other (or the other types of) substrates owing to the adhesion interaction between the material and the substrate (Figure 1f,g). Moreover, the lamination and delamination of the additive patterned taping were carried out in conditions similar to those used for subtractive patterning (i.e., at room temperature and so on). The material attached to the adhesive stamp was also reusable and yielded daughter patterns on other substrates. The principle of additive patterned taping is consistent with graphene transfer onto a substrate studied in related research.37−39 Because thin adhesive tape is flexible, conformal contact with the target can be effected. In terms of time/cost efficiency, all processes were manually handled within 1−2 min, and the minimum expenditure per patterning process was the same as or less than one sheet of adhesive tape owing to the reusability of the master mold and the adhesive stamp. Subtractive Patterned Taping. Patterns of organic semiconductors occupying large areas were generated through subtractive patterned taping (Figure 2a−c). Figure 2a and b show subtractive patterned large-area organic micro-parallelline patterns using optical microscopy and SEM, respectively. According to the visible light interference effect of this microparallel-line patterns, clear structural color is seen in the whole 1.2 cm × 1.2 cm size substrate image (Figure 2c). The

patterning yield of subtractive patterned taping was close to perfection due to the accurately replicated structure of the master mold on the adhesive tape (Figure 1i) and the flexible nature of the thin tape (usually at the submillimeter scale). Patterned taping is also compatible with various shapes of patterns such as microletters, as shown in Figure 2d−f. Thousands of (∼3600) microsquares (length: 10 μm, spacing between squares: 6 μm) were fabricated within a 1 mm × 1 mm area by repeating subtractive lift-off in the vertical and horizontal directions (Figure 3a, Figure S1). Microsquare arrays of an organic semiconductor ((2E,2′E)-3,3′-(2,5-bis(hexyloxy)-1,4-phenylene)bis(2-(5-(4-(trifluoromethyl)phenyl)thiophen-2-yl)acrylonitrile), Hex-4-TFPTA)40 (Figure 3a) led to the massive patterning yield of the subtractive patterned taping method due to conformal contact of the patterned tape to targeted thin films. With the PDMS master mold of the adhesive tape, a microlevel pattern of various organic materials was constructed on different substrates: a hydrophobic octadecyltrichlorosilane (ODTS)-treated SiO2 substrate (static water contact angle ∼98°, Figures 3a−c) and a hexamethyldisilazane (HMDS)treated SiO2 substrate (static water contact angle ∼84°, Figure 3d). There were some leftovers between the lines on the bare hydrophilic SiO2 (static water contact angle ∼0°, Figure 3e) because adhesion between the bare SiO2 substrate and the target material (DBDCS, (2Z,2′Z)-2,2′-(1,4-phenylene)bis(3(4-butoxyphenyl)acrylonitrile)41 was not sufficiently trivial to yield a clear pattern. A microline pattern of a gold electrode C

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Figure 3. Optical microscopy image and SEM images of subtractive patterned thermally deposited materials on various substrates. (a) Square (■) array pattern on ODTS-treated SiO2 under UV light (patterned taping occurring twice in perpendicular directions) of Hex-4-TFPTA. (b) Submicro-line-patterned TIPS-pentacene on ODTS-treated SiO2 (inset: SEM image of ∼350 nm wide line pattern). (c) CuPC line pattern on ODTS-treated SiO2 surface. (d) Line pattern edge of thin pentacene film on HMDS-treated SiO2 surface. (e) DBDCS line pattern image under UV light on bare SiO2 surface. (f) Line pattern of gold thin film on bare SiO2 substrate. (SEM images in (a) and (d) are shown in Figures S1 and S2, respectively.)

(Figure 3f) was generated through subtractive patterned taping. The metallic bonds of the thin gold film along the in-plane direction were broken due to the universal adhesion of the pressure-sensitive tape. Nanometer-level patterns of 6,13bis(triisopropylsilylethynyl)−pentacene (TIPS−PEN) were built at a ∼350 nm scale (Figure 3b), and a structured Si wafer was used as the master mold for the adhesive tape. As master molds of patterned tape, polyurethane acrylate (PUA) and Si wafers can be utilized in order to construct the nano/ submicrostructures on the patterned tape. Because the physical properties of PUA (Young’s modulus: ∼40 MPa) and the Si wafer (∼200 GPa) are superior to that of PDMS (roughly 1−9 MPa), a submicro/nanostructure can be constructed on PUA and the Si wafer. Even if the master molds can fabricate a

nanoscale structure, there are resolution limits depending on the target films. By adjusting the deposition temperature of substrates, pentacene with different grain sized (Tsub = RT, 80 °C) films was fabricated. With the smaller sized grains, smaller patterns were achievable (see Figure S9). Furthermore, in order to discover the resolution limit of the patterned taping method itself, the smallest patterns on the patterned tape were investigated with SEM. As a result, the observed thinnest line pattern width was ∼210 nm, and this value would be the estimated theoretical uppermost resolution limit of patterned taping (Figure S9c). Regardless of the slight curvature of substrates along the contact area, the patterned tape (Figure 1i) can also effect the removal of materials in the inner part of the curvature (Figure D

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ACS Nano S3). For instance, bottom-gate bottom-contact (BGBC) organic field-effect transistor devices have a patterned active organic layer. The uneven surface was fabricated by thermally depositing an interdigitated-type pattern of a gold thin film (thickness: 30 nm, line width: 5 μm) with a shadow mask on the substrate, and an organic semiconductor pattern was fabricated on the uneven substrate with a virtually perfect patterning yield (Figure S3). In order to better understand the nondestructive character of the method, the electrical properties of patterned and nonpatterned devices were measured and compared because electrical contact42,43 between the semiconducting films and the dielectric and electrode layers, as well as the orderedness44 of the molecules, was strongly correlated with the properties of the transistor devices. Patterned top-contact, bottom-gate (TCBG) OFET devices of pentacene showed a clear transfer curve and an output curve typical of hole-transporting OFET devices (Figure S4). The calculated electrical properties of patterned and nonpatterned channel devices showed comparable levels of performance: the average FET mobility of the nonpatterned device was 0.496 cm2/V·S, whereas that of the patterned device was 0.525 cm2/V·S, as the threshold voltage (VTH) and the on/off current ratio (ION/OFF) remained constant (Figure S4). Moreover, as shown in other studies,3,29 the output curve of the patterned device showed no leakage current (crosstalk or parasitic leakage current) between neighboring devices at VG = 0, whereas that of nonpatterned devices recorded leakage current flow at VG = 0 (Figure S4). Additive Patterned Taping. The basic principle underlying additive patterned taping is analogous to that used in graphene layer transferral.37−39 Following subtractive patterned taping, the patterned tape is inked with a thin film of the target material on the protruding regions of the tape. Tape attachment and the following detachment transfer the target material to other substrates (receiver substrates). Because the van der Waals force acts between materials and substrates, the pattern is fixed onto the receiver substrate. Thinner features than on the film of the donor substrate are transferred because the layer or domains directly in contact with the adhesive persist on the adhesive surface due to the significant attraction between the adhesive and the materials. Through additive transfer, the thin film of the source material was transferred onto various classes of substrates: the curved surface (Figure 4a, Figure S7) of a capillary tube (radius of curvature: 355 μm), a transparent flexible substrate composed of polyethylene naphthalene (PEN, Figure 4b), and a flat, bare SiO2 substrate (Figure 4c, Figure S5). A more complex structure was constructed by repeating the transfer, such as by multistack or parallel alignment. Regular micro-2D lattice arrays of a homogeneously integrated organic semiconductor ((2Z,2′Z)-3,3′-(1,4-phenylene)bis(2-(3,5-bis(trifluoromethyl)phenyl)acrylonitrile, CN-TFPA)45 are fabricated by twice applying additive patterned taping in perpendicular directions (Figure S5). As with subtractive taping, additive patterned taping exhibited scalability and high patterning yield. Furthermore, a heterogeneous assembly (Figure 4c) was fabricated using microscale layouts of organic materials. A line pattern of red luminescent material (DBADCS, (2Z,2′Z)-2,2′-(1,4-phenylene)bis(3-(4(dibutylamino)phenyl)acrylonitrile))46 was first transferred, followed by that of a green-emitting material (λmax = 495 nm) onto a red one (λmax= 598 nm). At the intersection of the two layers, red emission was observed due to energy transfer to

Figure 4. Micropattern images of additive patterned taping process. (a) Additive patterned organic film on a capillary tube (radius of curvature: 355 μm, inset: high-powered optical microscopy image of micropatterns on a capillary tube; slight blur occurred because out of focusing due to the curved surface). (b) Patterned organic film on flexible polyethylene naphthalene (PEN) substrate (inset: optical microscopy image). (c) Optical microscopy image of heterogeneous stacked layout of DBADCS and CN-TFPA luminescent organic materials under UV light (inset: SEM image).

the material emitting light of longer wavelength. Due to the ultraflexibility nature of adhesive tape, a heterogeneous multistacked pattern is fabricated even on the capillary tube (radius curvature: 355 μm) by additive patterned taping E

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Figure 5. White luminescence-emitting substrate via additive patterned taping. (a) Substrate under room light of additive transferred DBADCS (R, line pattern direction: red ↑), CN-TFPA (G, green ↑), DSB (B, blue ↑) for white luminescence-patterned organic materials. (b) Image of (a) under 365 nm hand-held UV light. Arrows (↑) in red, green, and blue indicate line directions of R, G, and B, respectively. (c) Photoluminescence spectrum of components of red, green, and blue organic materials and photoluminescence spectrum of (b). (d) CIE chromaticity coordinate of (0.342, 0.367) derived by the photoluminescence spectrum of (b). (e) Optical microscopy image of spatially wellarranged R, G, and B for white luminescence similar to the subpixels of commercial displays (inset: zoomed-in optical microscopy image).

patterning yield, scalability (commercial adhesive tape-size scale), and truly nondestructive (Figure S4) characteristics. Moreover, organic light-emitting transistor devices are promising candidates for applications of patterned taping. Research on these is under way in our laboratory.

(Figure S7). In commercial display devices, RGB subpixels prevent energy transfer to low-band-gap materials by spatially separating each emitter. Similarly to this, our white-lightemitting substrate independently fabricated microsubpixels (subpixel size: 10 μm × 10 μm) and the microline (line width: 10 μm) configuration of luminophores (Figure 5e) and evaded energy transfer to light-emitting material that generates longer wavelengths (green and blue, to red or green, to red). Figure 5 shows the white-light-emitting substrate with three systemically arranged luminescent microlines fabricated through the additive transfer of the microlines of each component. The line pattern of the red-emitting film (λmax = 598 nm) was first additively transferred onto the bare SiO2 substrate, and the alternating parallel lines of green (λmax = 495 nm) and blue (λmax = 445 nm) were deposited by additive transfer in different directions from the red line (Figure 5a,b,e). Arrows in Figure 5a,b (red, green, and blue ↑) indicate line directions of R, G, and B, respectively. The differences in brightness among the three colors were balanced by the thickness regulation of each RGB component. Macroscopically, as shown in the photoluminescence spectrum (Figure 5c) covering the whole visible range (400−700 nm), heterogeneously integrated RGB layers on a substrate emitted white light (Figure 5b) at the Commission Internationale de I’Eclairage (CIE) chromaticity coordinate of (0.342, 0.367) (Figure 5d).

METHODS Master Mold Fabrication. The patterned Si wafer was photolithographically fabricated with a photomask. The polydimethylsiloxane (PDMS) master mold was fabricated by pouring PDMS Sylgard 184 as a prepolymer onto the patterned Si wafer and was cured for 6 h at 80 °C in an oven.47 The polyurethane acrylate master mold was fabricated by using PUA 311RM as a prepolymer over the patterned Si wafer. Ultraviolet light (λ ≈ 250−400 nm) with a UV dose of ∼100 mJ/cm2 was illuminated to cure the PUA prepolymer.48 Patterned Taping. Patterned taping processes have been described in detail above. Nitrogen blowing was done at every step of the pattern transfer for patterning yield and purity. Commercial adhesive tape was used, which was listed as follows: Tapex OPP tape (Cat. KST 1046), 3M Scotch package tape (Cat. 3615c), 3M Scotch tape (Cat. 581), 3M Scotch magic tape (Cat. 104), Printec package tape (Cat. P4840br), and Niceday OPP tape (Cat. 312930). Device Fabrication. For substrate preparation, SiO2/Si substrates (p-doped, SiO2 thickness: 300 nm) were rinsed with acetone and isopropyl alcohol, respectively, for 10 min under an ultrasonicator, and then a 20 min UV (360 nm) O 3 treatment was applied. Hexamethyldisilazane was introduced onto the substrates as a selfassembled monolayer in the vapor phase in a vacuum oven. Subtractive patterned taping was carried out in a nitrogen-filled glovebox. Pentacene and source−drain gold electrodes were thermally evaporated sequentially onto the HMDS-treated substrates. The I−V characteristics of all OFETs were measured in a nitrogen-filled glovebox using a Keithley 4200 SCS instrument connected with probe stations. The mobility and threshold voltage were calculated from the saturation region of the transfer curve, and the width and length of the pentacene pattern within the source−drain channel were checked using an optical microscope to calculate charge carrier mobility.

CONCLUSIONS In conclusion, we proposed and verified the effectiveness of a strategically novel and universal microscale/nanoscale soft lithographic method of patterned taping that uniquely exploits patterned pressure-sensitive tape as a stamp material. Subtractive and/or additive patterning of various thin films, including organic semiconductors, luminescent chromophores, and metals, was implemented to fabricate complicated and high-performance optoelectronic devices. It was shown that the patterned taping process draws its usefulness from an industrial perspective in terms of its time/cost efficiency, supreme F

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(6) Muller, C. D.; Falcou, A.; Reckefuss, N.; Rojahn, M.; Wiederhirn, V.; Rudati, P.; Frohne, H.; Nuyken, O.; Becker, H.; Meerholz, K. Multi-Colour Organic Light-Emitting Displays by Solution Processing. Nature 2003, 421, 829−833. (7) Liu, W.; Jackson, B. L.; Zhu, J.; Miao, C. Q.; Chung, C. H.; Park, Y. J.; Sun, K.; Woo, J.; Xie, Y. H. Large Scale Pattern Graphene Electrode for High Performance in Transparent Organic Single Crystal Field-Effect Transistors. ACS Nano 2010, 4, 3927−3932. (8) Hwang, J. K.; Cho, S.; Dang, J. M.; Kwak, E. B.; Song, K.; Moon, J.; Sung, M. M. Direct Nanoprinting by Liquid-Bridge-Mediated Nanotransfer Moulding. Nat. Nanotechnol. 2010, 5, 742−748. (9) Angmo, D.; Larsen-Olsen, T. T.; Jorgensen, M.; Sondergaard, R. R.; Krebs, F. C. Roll-to-Roll Inkjet Printing and Photonic Sintering of Electrodes for ITO Free Polymer Solar Cell Modules and Facile Product Integration. Adv. Energy. Mater. 2013, 3, 172−175. (10) Tipnis, R.; Bernkopf, J.; Jia, S.; Krieg, J.; Li, S.; Storch, M.; Laird, D. Large-Area Organic Photovoltaic ModuleFabrication and Performance. Sol. Energy Mater. Sol. Cells 2009, 93, 442−446. (11) Gates, B. D.; Xu, Q.; Stewart, M.; Ryan, D.; Willson, C. G.; Whitesides, G. M. New Approaches to Nanofabrication: Molding, Printing, and Other Techniques. Chem. Rev. 2005, 105, 1171−1196. (12) Seo, S.; Lee, J.; Kim, K. S.; Ko, K. H.; Lee, J. H.; Lee, J. Anisotropic Adhesion of Micropillars with Spatula Pads. ACS Appl. Mater. Interfaces 2014, 6, 1345−1350. (13) Yoo, B.; Cho, S.; Seo, S.; Lee, J. Elastomeric Angled Microflaps with Reversible Adhesion for Transfer-Printing Semiconductor Membranes onto Dry Surfaces. ACS Appl. Mater. Interfaces 2014, 6, 19247−19253. (14) Lee, T. W.; Jeon, S.; Maria, J.; Zaumseil, J.; Hsu, J. W. P.; Rogers, J. A. Soft-Contact Optical Lithography Using Transparent Elastomeric Stamps: Application to Nanopatterned Organic LightEmitting Devices. Adv. Funct. Mater. 2005, 15, 1435−1439. (15) Loo, Y. L.; Someya, T.; Baldwin, K. W.; Bao, Z.; Ho, P.; Dodabalapur, A.; Katz, H. E.; Rogers, J. A. Soft, Conformable Electrical Contacts for Organic Semiconductors: High-Resolution Plastic Circuits by Lamination. Proc. Natl. Acad. Sci. U. S. A. 2002, 99, 10252−10256. (16) Kim, S.; Wu, J.; Carlson, A.; Jin, S. H.; Kovalsky, A.; Glass, P.; Liu, Z.; Ahmed, N.; Elgan, S. L.; Chen, W.; Ferreira, P. M.; Sitti, M.; Huang, Y.; Rogers, J. A. Microstructured Elastomeric Surfaces with Reversible Adhesion and Examples of Their Use in Deterministic Assembly by Transfer Printing. Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 17095−17100. (17) Briseno, A. L.; Mannsfeld, S. C.; Ling, M. M.; Liu, S.; Tseng, R. J.; Reese, C.; Roberts, M. E.; Yang, Y.; Wudl, F.; Bao, Z. Patterning Organic Single-Crystal Transistor Arrays. Nature 2006, 444, 913−917. (18) Wang, Z.; Zhang, J.; Xing, R.; Yuan, J.; Yan, D.; Han, Y. Micropatterning of Organic Semiconductor Microcrystalline Materials and OFET Fabrication by ″Hot Lift Off″. J. Am. Chem. Soc. 2003, 125, 15278−15279. (19) Packard, C. E.; Aidala, K. E.; Ramanan, S.; Bulovic, V. Patterned Removal of Molecular Organic Films by Diffusion. Langmuir 2011, 27, 9073−9076. (20) Meitl, M. A.; Zhu, Z. T.; Kumar, V.; Lee, K. J.; Feng, X.; Huang, Y. Y.; Adesida, I.; Nuzzo, R. G.; Rogers, J. A. Transfer Printing by Kinetic Control of Adhesion to an Elastomeric Stamp. Nat. Mater. 2006, 5, 33−38. (21) Park, S. Y.; Kwon, T.; Lee, H. H. Transfer Patterning of Pentacene for Organic Thin-Film Transistors. Adv. Mater. 2006, 18, 1861−1864. (22) Kim, K. H.; Bong, K. W.; Lee, H. H. Alternative to Pentacene Patterning for Organic Thin Film Transistor. Appl. Phys. Lett. 2007, 90, 093505. (23) Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Siegrist, T.; Li, W.; Lin, Y. Y.; Dodabalapur, A. A Soluble and Air-Stable Organic Semiconductor with High Electron Mobility. Nature 2000, 404, 478− 481. (24) Jung, Y.; Baeg, K. J.; Kim, D. Y.; Someya, T.; Park, S. Y. A Thermally Resistant and Air-Stable N-Type Organic Semiconductor:

ASSOCIATED CONTENT S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsnano.5b07590. Figure S1, organic semiconductor Hex-4-TFPTA microsquare array; Figure S2, SEM image of subtractive patterned pentacene (Figure 3e) thin film on HMDStreated SiO2 surface; Figure S3, subtractive patterned bottom-contact OFET device; Figure S4, OFET device characterization with pentacene semiconductor thin film on HMDS-treated SiO2 substrate; Figure S5, microlattice array of organic material via additive transfer; Figure S6, Reusability experiment of Subtractive patterned taping; Figure S7, Micro-pattern images of additive patterned taping on curved surfaces with various radius of curvature; Figure S8, Parallel comparison between Patterned taping and other conventional soft lithography method with PDMS; Figure S9, Resolution limit study of various thin films (PDF)

AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected] (S. Y. Park). Notes

The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was supported by the National Research Foundation of Korea (NRF) through a grant funded by the Korean Government (MSIP; No. 2009-0081571[RIAM041720150013]). SEM analysis of pattern structure was supported by Research Institute of Advanced Materials (RIAM) in Seoul National University, and the fabrication of the patterned Si master mold was supported by Inter-university Semiconductor Research Center (ISRC) in Seoul National University. S.Y.P. and S.O. designed all experiments and wrote the paper. S.O. synthesized part of the organic molecules and conducted all experiments. S.K.P. supervised the design of the experiments, provided editorial comments, and synthesized some of the organic molecules. J.H.K. supervised the design of the experiments and advised on device fabrication. I.C. and H.J.K. synthesized some of the organic molecules. REFERENCES (1) Wen, Y.; Liu, Y.; Guo, Y.; Yu, G.; Hu, W. Experimental Techniques for The Fabrication and Characterization of Organic Thin Films for Field-Effect Transistors. Chem. Rev. 2011, 111, 3358−3406. (2) Persano, L.; Camposeo, A.; Pisignano, D. Integrated Bottom-Up and Top-Down Soft Lithographies and Microfabrication Approaches to Multifunctional Polymers. J. Mater. Chem. C 2013, 1, 7663−7680. (3) Lee, H. M.; Kim, J. J.; Choi, J. H.; Cho, S. O. In situ Patterning of High-Quality Crystalline Rubrene Thin Films for High-Resolution Patterned Organic Field-Effect Transistors. ACS Nano 2011, 5, 8352− 8356. (4) Min, S. Y.; Kim, T. S.; Kim, B. J.; Cho, H.; Noh, Y. Y.; Yang, H.; Cho, J. H.; Lee, T. W. Large-Scale Organic Nanowire Lithography and Electronics. Nat. Commun. 2013, 4, 1773. (5) Choi, M. K.; Yang, J.; Kang, K.; Kim, D. C.; Choi, C.; Park, C.; Kim, S. J.; Chae, S. I.; Kim, T. H.; Kim, J. H.; Hyeon, T.; Kim, D. H. Wearable Red-Green-Blue Quantum Dot Light-Emitting Diode Array Using High-Resolution Intaglio Transfer Printing. Nat. Commun. 2015, 6, 7149. G

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DOI: 10.1021/acsnano.5b07590 ACS Nano XXXX, XXX, XXX−XXX