Wafer-Scale Ultrathin Two-Dimensional Conjugated Microporous

Subscriber access provided by READING UNIV

Article

Wafer-Scale Ultrathin Two-Dimensional Conjugated Microporous Polymers: Preparation and Application in Heterostructure Devices Zhengdong Liu, Mengya Song, Shang Ju, Xiao Huang, Xiangjing Wang, Xiaotong Shi, Ya Zhu, Zhan Wang, Jie Chen, Hai Li, Yingchun Cheng, Linghai Xie, Juqing Liu, and Wei Huang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b17854 • Publication Date (Web): 10 Jan 2018 Downloaded from http://pubs.acs.org on January 11, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Wafer-Scale Ultrathin Two-Dimensional Conjugated Microporous Polymers: Preparation and Application in Heterostructure Devices Zhengdong Liu,† Mengya Song,† Shang Ju,† Xiao Huang,† Xiangjing Wang,† Xiaotong Shi,† Ya Zhu,† Zhan Wang,† Jie Chen,† Hai Li,† Yingchun Cheng,† Linghai Xie,‡ Juqing Liu,*,† Wei Huang*,†,‡,§ †

Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 211816, China.

‡

Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced

Materials (IAM), SICAM, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China. §

Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127 West Youyi Road, Xi'an 710072, China.

* E-mail: [email protected] (Prof. Dr. Juqing Liu)

[email protected] (Prof. Dr. Wei Huang)

ACS Paragon Plus Environment

1

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 24

ABSTRACT: In this work, we report a universal surface-assisted oxidative polymerization strategy for wafer-scale fabrication of ultrathin two-dimensional conjugated microporous polymers (2D CMPs) on arbitrary substrates under ambient conditions. Three kinds of 2D CMPs with average thickness of 1.5-3.6 nm were prepared on SiO2/Si substrates by using carbazole based monomers. Moreover, 2D CMPs can be grown on reduced graphene oxide (rGO) substrate to construct large-area 2D CMP/rGO heterostructure. As a proof-of-concept demonstration, an organic vertical field-effect transistor based on 2D CMP/rGO heterostructures was fabricated, which exhibited typical p-type behavior with high reproducibility and on/off current ratio. Most importantly, the direct growth of large-area 2D CMPs on arbitrary substrates is compatible with the conventional processes in the semiconductor industry, and therefore is expected to expedite the development of 2D CMPs as building blocks for construction of practical electronic devices. KEYWORDS: wafer-scale, two-dimensional, conjugated microporous polymers, oxidative polymerization, heterostructure

INTRODUCTION Over the past decade, two-dimensional (2D) materials have aroused extensive attention due to their unique structures and novel properties, making them promising candidates for a wide range of potential applications, particularly in optical, electronic and optoelectronic devices.1-5 A key step towards these practical applications of 2D materials is the development of facile fabrication and processing procedures for large-area ultrathin films.6-10 To date, the large-area growth of graphene and 2D inorganic materials has made great progress.6-10 In addition, several approaches for the synthesis of large-area 2D non-conjugated microporous polymers (CMPs) and 3D CMPs have also been reported, but without conjugation in their backbones or hard to form high-quality thin films, these polymers showed the limited optoelectronic properties.11-14 Therefore, the


2

Page 3 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


rational design and large-area synthesis of 2D CMPs hold great importance in their fundamental study as well as the technical advancement of organic electronics.15-18 2D CMPs such as 2D polyporphyrins, polyfluorene and polyimine have been synthesized previously on solid substrates (e.g. metals, graphite and graphene) via conventional chemical reactions,19-27 such as the Ullmann reaction,19-21 Schiff reaction22-24 and dehydrogenative coupling reaction.25 However, the lateral sizes of most of these 2D CMPs were small, typically less than one micron, which are not suitable for fabrication of large-area electronic devices. Recently, a dynamic imine chemistry method has been proposed to synthesize large-size 2D CMPs at the air-liquid or liquid-liquid interface,28,

29

and the obtained 2D CMPs might be

applicable to be used as active components in electronic devices. However, the formation of cracks, folds and wrinkles in the 2D CMP films could not be avoided during their transfer from the liquid surface to target substrates. Therefore, a general and facile method for the direct synthesis of large-area ultrathin 2D CMPs on arbitrary substrates is highly desirable, but unfortunately, this has not been met with success, especially on SiO2/Si and 2D material substrates.24 Here we report a facile and universal method for the synthesis of wafer-scale ultrathin 2D CMPs on arbitrary substrates via FeCl3-catalysed surface-assisted oxidative polymerization. The reaction was carried out at the solution-substrate (solid-liquid) interface and the 2D CMPs were directly deposited on the substrates. For example, the carbazole and biphenyl based 2D CMP with an average thickness of ~1.5 nm and lateral size up to wafer-scale was prepared on SiO2 (300 nm)/Si wafer substrate. Moreover, this method has been successfully used to synthesize other large-area ultrathin 2D CMPs, including carbazole and fluorene based materials. More importantly, 2D CMP can also be synthesized on reduced graphene oxide (rGO) substrate and


3


Page 4 of 24

large-area 2D CMP/rGO heterostructure was constructed via a simple full-solution process. Finally, as a proof-of-concept demonstration, an organic vertical field-effect transistor based on 2D CMP/rGO heterostructures was fabricated, which exhibited typical p-type behavior with high reproducibility and on/off current ratio of 4.82 × 103. RESULTS AND DISCUSSION

a

b

c Monomer Substrate Surface-Assisted Oxidative Polymerization 2D CMP film

FeCl solution

Substrate

2D CMP-1

Figure 1. Schematic representation of the synthesis of cross-linked 2D CMP films via FeCl3-catalysed surfaceassisted oxidative polymerization. (a) The reaction scheme of the synthesis of 2D CMPs. (b) Schematic diagrams of the synthesis of 2D CMP films on substrate. After the monomers were spin-coated on a substrate and annealed, then the substrate was dipped into a dry organic solvent containing anhydrous FeCl3 (top figure). Cross-linked 2D CMP films were formed on the substrate surface (bottom figure). (c) The molecular structure of 2D CMP-1. 2D CMP-1 was just used as an example.

The monomer, 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl, which we call monomer 1, comprises two carbazole units which are connected through a biphenyl group. This monomer exhibits a


4

Page 5 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


rigid and shape-persistent structure. The choice of carbazole units is due to the fact the oxidative reaction between carbazoles tends to proceed at their 3- and 6-positions to form a cross-linked polymer structure with the elimination of hydrogen atoms.30 The choice of biphenyl groups as the connecting groups is based on their rigid structural feature. Typically, such molecular structures are expected to form conjugated molecular networks upon oxidative polymerization (Figure 1 and Scheme S1). To synthesize wafer-scale ultrathin 2D CMP film, the chlorobenzene solution of monomer 1 was spin-coated on a clean SiO2/Si substrate. Surface-assisted oxidative polymerization of monomer 1 was then promoted by anhydrous FeCl3 in dry dichloromethane under ambient conditions (Figure 1b). After polymerization, the 2D CMP film covered SiO2/Si substrate was fully washed with methanol, Milli-Q water, concentrated HCl and dichloromethane to remove the residual catalyst, unreacted monomers and oligomers. After the cross-linked film was rinsed off with dichloromethane, the film remained on the surface. The as-synthesized 2D CMP film is referred to as 2D CMP-1 (Figure 1c). Figures 2a and 2b display films that grown on the SiO2/Si substrate. The color variation on the SiO2 surface allows for the differentiation between the 2D CMP-1 covered region and bare region. It is worth pointing out that the spincoated monomers are readily dissolvable in dichloromethane without cross-linking (Figure S1). The thickness of 2D CMP-1 on SiO2/Si substrate was determined by atomic force microscopy (AFM) to be ~1.5 nm with a surface roughness of ~0.25 nm (Figure 2c), while the spin-coated monomer film is about 40.5 nm (Figure S2). The low surface roughness of 2D CMP-1 indicates the uniformity of the prepared film. Generally, a film can be regarded as ultrathin when its thickness is less than 5 nm.31 Impressively, the ultrathin 2D CMP-1 film could be easily detached from the SiO2/Si substrate without the support of a polymer sacrificial layer in a short time, which may be due to the microporous nature of the film. The detailed transfer procedure is


5


Page 6 of 24

described in the “Experimental Section”. Subsequently, the free-standing 2D CMP-1 film was transferred onto a transmission electron microscope (TEM) copper grid for further evaluation (Figures 2d-2f). As shown in Figure 2d, in the right of the optical microscopy image is the bare copper grid, the region surrounded by a dotted blue line is the 2D CMP-1 covered region, which appears darker than the bare copper grid region, can be distinguished. It is evidently seen that after being transferred onto the copper grid, the 2D CMP-1 remained intact without obvious

a

b

c

1.5 nm Substrate 2D CMP-1

d

200 µm

f

e

50 µm

1 µm

2 µm

5 nm

Figure 2. Characterization of 2D CMP-1 grown on SiO2/Si substrates. (a) A photograph of 2D CMP-1 grown on a SiO2/Si substrate. The top region of the substrate was covered with 2D CMP-1 while the bottom region was the bare SiO2/Si substrate. (b) Optical micrograph of 2D CMP-1 grown on a SiO2/Si substrate. (c) AFM image of 2D CMP-1 grown on a SiO2/Si substrate and the corresponding AFM height profile. Z scale, 20 nm. (d) Optical micrograph of 2D CMP-1 spanning on a TEM copper grid. The region surrounded by a dotted blue


6

Page 7 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


line was covered with 2D CMP-1 (dark copper meshes) while the right region was the bare grid (bright copper meshes). (e) TEM image of 2D CMP-1. Inset: corresponding SAED pattern. (f) HRTEM image of 2D CMP-1.

cracks or folds, which promises its further use in fabrication of thin film devices (Figure 2e). The inset is the corresponding selected-area electron diffraction (SAED) showing the noncrystalline property of the film. The microstructure of 2D CMP-1 was further characterized by highresolution TEM (HRTEM). As shown in Figure 2f, the 2D CMP-1 film does not show any periodically ordered lattice structures. Such structural disorder may be a result of the twisted molecular structures of the monomers, as also observed in some other 2D polymers reported previously.32 The size of the pores observed by HRTEM is less than 1 nm, which may be result from the highly cross-linked skeleton of film. Besides, the chemical structure of 2D CMP-1 was characterized by Fourier transform infrared (FTIR) spectral (Figure S3). The new peak at 800 cm-1 may originate from trisubstituted carbazole ring in 2D CMP-1 and correspond to the C-H bending vibration, indicating the cross-linking reaction between carbazole groups at 3- and 6positions in monomer 1 was carried out successfully.33 Moreover, X-ray photoelectron spectroscopy (XPS) analysis for N 1s shows 0.1 eV shift in 2D CMP-1 film in comparison with monomer 1 based film (Figure S4), indicating the formation of polymeric carbazyl in 2D CMP-1 film.34 Based on the above observations, we can conclude that the ultrathin, covalently crosslinked film on the SiO2/Si substrate has been obtained successfully. During the experimental processes, we also tried to use other methods, such as Brunauer-Emmett-Teller measurement, to characterize the structure properties of 2D CMP-1, but it is hard to carry out because of the collection of adequate samples is very difficult. It is worth pointing out that the solid-liquid interfacial reaction is critical in synthesis of large-area 2D CMP-1. In sharp contrast, the


7


Page 8 of 24

conventional oxidative polymerization of monomer 1 without the assist of any other substrates resulted in the formation of a solid power instead of a thin film (Figure S5). To better understand the surface-assisted oxidative polymerization for the synthesis of largearea ultrathin 2D CMP films, the effects of polymerization time, catalyst concentration, substrates and solvents on film morphology were explored. Figure S6 shows the morphology evolution of 2D CMP-1 as a function of polymerization time (see the detailed experimental procedure in the Experimetal Section). At 30 min of polymerization, discrete nanoparticles and particle-chains were grown on SiO2/Si substrate (Figure S6a). Upon prolonging the polymerization time, the nanoparticles grew in size and cross-linked together to form continuous film (Figures S6b and S6c). A continuous polymer film was obtained when the polymerization proceeded for 24 h (Figure S6d). Besides the polymerization time, the catalyst concentration also exerted an important influence on the growth of large-area 2D CMP-1. Only small nanoparticles were formed on SiO2/Si substrate when the catalyst concentration was 0.35 mg mL-1 (2.1*10-3 mmol mL-1) (Figure S7a). The size and density of the nanoparticles increased with further increase of the catalyst concentration (Figures S7b and S7c), and a fully cross-linked polymer film was obtained when the catalyst concentration reached 1.5 mg mL-1 (Figure S7d). Moreover, large-area 2D CMP-1 could also be formed in other organic solvents, such as toluene and chloroform (Figure S8). Impressively, beside on SiO2/Si substrate, 2D CMP-1 can be synthesized on other substrates, such as quartz plate (Figure S9) and reduced graphene oxide (rGO) film with SiO2/Si as the substrate (Figure 3). Figures 3a and 3d show optical microscope and SEM images of the large area 2D CMP-1 grown on rGO film. Four different regions can be clearly seen in these images, corresponding to the 2D CMP-1/rGO heterostructure, rGO, 2D CMP-1 and bare SiO2. As


8

Page 9 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


expected for the high transparency and low conductivity of 2D CMP-1, its contrast appears lighter in comparison with rGO and 2D CMP-1/rGO heterostructure. The corresponding morphologies were measured by AFM. The rGO film exhibits a smooth surface with a roughness of ~0.35 nm and the rGO sheet can also be found in the film (Figure 3b). AFM measurement (Figure 3c) on 2D CMP-1 grown on rGO film indicates average thickness of ~2.1 nm with a surface roughness of ~0.51 nm. Figure 3e shows a TEM image of the 2D CMP-1/rGO heterostructure. The double layers structure of heterostructure, where the bottom layer possesses some wrinkles is the rGO (Figure S10) and the top layer with a smooth surface is the 2D CMP-1 (Figure 3e), can be distinguished. The HRTEM image confirms the amorphous and microporous structure properties of 2D CMP-1 grown on rGO surface (Figure 3f), the same as 2D CMP-1 grown on the SiO2/Si substrate as mentioned earlier (Figure 2f). Based on the above observations,

a

b

c

2D CMP-1/rGO rGO 2D CMP-1

SiO2

2.1 nm

100 µm

1 µm

e

d

1 µm

f

2D CMP-1/rGO rGO 2D CMP-1

SiO2 rGO

1 µm

2D CMP-1

0.5 µm

5 nm


9


Page 10 of 24

Figure 3. Characterization of 2D CMP-1 grown on rGO film. (a) Optical microscope image of the 2D CMP-1 grown on rGO film. Four different regions are showed: 2D CMP-1/rGO heterostructure, rGO film, 2D CMP-1 and bare SiO2. (b) AFM image of rGO film. (c) AFM image and the corresponding height profile of 2D CMP1 grown on rGO film. Z scales in (b) and (c) are 20 nm. (d) SEM images of 2D CMP-1/rGO heterostructure, rGO film, 2D CMP-1 and bare SiO2. (e) TEM image of 2D CMP-1/rGO heterostructure suspended on TEM copper grid. Inset: corresponding SAED pattern. (f) HRTEM image of 2D CMP-1/rGO heterostructure.

we can conclude that the 2D CMP-1/rGO heterostructure on SiO2/Si substrate has been prepared successfully. It is noted that in compare with other methods, such as manual stacking 2D materials35 or epitaxy growth of heterolayers36 on graphene to prepare semiconductors/graphene heterostructures, the direct growth of 2D CMP on graphene is a low-cost solution preparation method for constructing graphene heterostructures in large-scale. Besides, from the perspective of practical applications, direct growth of 2D heterostructures on insulating substrates should be a high priority for practical applications, since in this way wrinkles, ripples and other contaminants can be avoided.37 More importantly, our surface-assisted oxidative polymerization method can be extended to prepare other kinds of ultrathin 2D CMPs. Monomer 2 and 3, both of them present more twisty molecular structures than monomer 1, covered SiO2/Si substrates were dipped into the dry anhydrous FeCl3 dichloromethane solution for 24 h, respectively, two kinds of 2D CMP films (i.e. 2D CMP-2 and 2D CMP-3) were obtained (Schemes S2 and S3, Figures S11 and S12). According to the FTIR spectra, the differences of the characteristic peaks between the monomers and their respective polymers indicate the successful proceeding of the oxidative polymerization processes (Figures S13 and S14). The intact polymer films on copper grids indicate that these two types of 2D CMP films were covalently cross-linked polymers with good mechanical strength as well (Figures S11a and S12a). AFM images and height analyses of these films show


10

Page 11 of 24

smooth surfaces with thicknesses of ~3.6 and ~1.7 nm for 2D CMP-2 and 2D CMP-3, respectively (Figures S11b and S12b).

b 1.0 Emission (a.u.)

a 1.0 Absorbance (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Monomer 1 2D CMP-1

0.5

0.0 300

400 500 Wavelength (nm)

600

Monomer 1 2D CMP-1

0.5

0.0 400

425 450 475 Wavelength (nm)

500

Figure 4. Photophysical properties of monomer 1 and 2D CMP-1. (a) Normalized UV-vis absorption spectra and (b) fluorescence spectra of monomer 1 and 2D CMP-1 in film state on quartz plates.

The normalized UV-vis and fluorescence spectra of monomer 1 and 2D CMP-1 on quartz plates are shown in Figures 4a and 4b, respectively. Both of them show two absorption peaks at 297/343 and 308/345 nm, respectively, corresponding to the π–π* electron transition of the carbazole units.38 In comparison with monomer 1, 2D CMP-1 exhibits a broader absorption peak, suggesting an increase of conjugation length or the enhancement of intermolecular interactions of 2D CMP-1.39 The optical bandgaps of monomer 1 and 2D CMP-1 calculated from their absorption edges are ca. 3.45 and 3.24 eV, respectively (Table S1). This indicates that 2D CMP1 is a typical wide bandgap polymer semiconductor. The narrower bandgap of 2D CMP-1 than that of monomer 1 could be attributed to the extension of molecular conjugation.38,39 This is also reflected in the fluorescence spectra, where the emission peaks of 2D CMP-1 (413 and 436 nm) red-shifted in comparison with those of monomer 1 (410 and 433 nm) (Figure 4b). The blue emission property of 2D CMP-1 is similar to the polycarbazoles,30 suggesting its potential use in organic electronics.


11


The photophysical and surface properties of these 2D CMP films are dependent on their functional groups. For example, both 2D CMP-2 and 2D CMP-3 showed a decreased value (~0.10 eV) of bandgaps in comparison with 2D CMP-1 (Figures S15 and S16, Tables S2 and S3), which is likely due to an increased degree of conjugation in the polymer when the connecting units were changed from diphenyl to fluorene groups.40 In addition, 2D CMP-1 was more hydrophobic (98.6°) than 2D CMP-2 (92.0°) and 2D CMP-3 (96.4°), which might be due to the absence of oxygen-containing functional groups in 2D CMP-1 (Figure S17). Furthermore, it is interesting to find that 2D CMP films covered SiO2 generally exhibited smaller contact angles compared to those covered by their corresponding monomers, which might be attributed to the ultrathin 2D CMP films with nanoporous structures covered SiO2 had not fully covered surfaces than the monomers covered ones.

b 2D CMP-1

2D CMP-1/rGO

400

-5

2.0x10 Current (µA)

Au

c 600

-5

4.0x10

0.0 -5

-2.0x10

Au (S) -5

Au (D) 2D CMP-1 SiO2

-4.0x10

-5

-6.0x10

2 mm rGO

-8.0x10

-3

-2

-1 0 1 Voltage (V)

2

-1

Si (G)

-3

-2

-1 0 1 Voltage (V)

2

Drain (µA)

Au (D) 2D CMP-1 rGO SiO2

Au (S)

3 2

-2

-1 0 1 Voltage (V)

2

3

VG: -4 V -3 V -2 V -1 V 0V

4

1

-5 -4 -3 -2 -1 0 1 Gate (V)

-3

5

VDS:

0 3

Si (G)

6

f 7V 5V 3V 1V

Au (D) rGO SiO2

3

6

4

0

Au (S)

-200

-600

5 1

0

Drain (µA)

e

200

-400

Si (G)

-5

d2

-2

Current (µA)

a

Current (µA)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 24

3 2 1 0

2

3

4

5

0

1

2 3 Drain (V)

4

5

Figure 5. Electrical characteristics of 2D CMP-1 and 2D CMP-1/rGO heterostructure. (a) Photograph of the 2D CMP-1/rGO heterostructure based organic vertical field-effect transistor. The device structure is Au/2D CMP-1/rGO/Au/SiO2/Si. (b, c) I-V curves of the (b) 2D CMP-1, and (c) rGO based devices. The insets show the schematic of the device structures. (d) I-V curve of the 2D CMP-1/rGO heterostructure based organic


12

Page 13 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


vertical field-effect transistor. Inset: schematic of the cross-sectional view of the device. (e) Source-drain current (IDS) with respect to different backgate voltages (VDS) of the device. (f) IDS–VG characteristics of the device at various VG.

Carbazole-containing compounds have been widely used in organic electronics, such as organic light-emitting diodes, solar cells and so on.41,42 Moreover, the solvent-resistant property of cross-linked polymers make they are suitable to be used in high-performance organic electronics with multilayer device configuration.42,43 In this work, we demonstrated a proof-ofconcept organic vertical field-effect transistor using 2D CMP-1 as the active layer. After the films have grown on SiO2/Si or rGO/SiO2/Si substrate surfaces, Au electrodes were deposited on the films to fabricate devices for further characterization. As shown in Figure 5a, the color variation on the SiO2 surface allows for the differentiation between the rGO covered region and 2D CMP-1/rGO heterostructure region. As for the organic vertical field-effect transistor, the rGO and Au were used as the source and drain electrodes, the doped silicon was used as the back gate, and 2D CMP-1 was used as the active layer, separately. Figure 5b shows the typical nonlinear current-voltage (I-V) curve of the Au/2D CMP-1/Au/SiO2/Si device, indicating the semiconducting property of 2D CMP-1.44,45 The I-V curve of rGO based device indicates the high electrical conductively of rGO (Figure 5c). The inset schematic diagram in Figure 5d displays the Au/2D CMP-1/rGO/Au/SiO2/Si device structure. Figure 5d shows asymmetric curve of current versus bias voltage for device, indicating a diode-like rectifying behavior.46 The transfer properties of the heterostructure device under different source/drain voltages (VDS) were shown in Figure 5e, which exhibits typical p-type behavior with high reproducibility (more than 30 devices were made and characterized). At VDS = 7V, when gate voltages (VG) vary from 5 to −5 V, IDS change from 1.12 × 10−9 A to 5.40 × 10−6 A, corresponding to a high on/off current


13


Page 14 of 24

ratio of 4.82 × 103. Figure 5f shows the output curves of the device under different VG. For the measurements, a constant bias (VG = 0, -1, -2, -3, or -4 V) was applied to the gate electrode and the device exhibits gate-tunable output characteristics.

CONCLUSIONS In summary, we have successfully developed a general strategy for the synthesis of waferscale ultrathin 2D CMP films on arbitrary substrates via FeCl3-catalysed surface-assisted oxidative polymerization. Three kinds of 2D CMP films, i.e. ~1.5 nm thick 2D CMP-1, ~3.6 nm thick 2D CMP-2 and ~1.7 nm thick 2D CMP-3 on SiO2/Si substrate were synthesized by using different monomeric carbazole materials. These 2D CMP films displayed the different surface chemistry and tunable semiconducting properties. Moreover, by directly synthesis of 2D CMP-1 on rGO film, large-area 2D CMP-1/rGO heterostructure was obtained via low-cost solution preparation method. As a proof-of-concept demonstration, an organic vertical field-effect transistor based on 2D CMP/rGO heterostructures was fabricated successfully, which exhibited typical p-type behavior with high reproducibility and on/off current ratio of 4.82 × 103. Importantly, the large-area direct growth of 2D CMP films on arbitrary substrates is compatible with the batch processing in a conventional semiconductor production line, suggesting that the use of 2D CMP films for industrial applications is highly expected in the very near future.

EXPERIMENTAL SECTION Chemicals. 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl was purchased from Aladdin Chemicals. 2,7di(9H-carbazol-9-yl)-9H-fluoren-9-one and 2,7-di(9H-carbazol-9-yl)-9-(4-(octyl-oxy)phenyl)9H-fluoren-9-ol were synthesized according to our previous work.47 Anhydrous FeCl3, dichloromethane, chloroform, toluene and chlorobenzene for the synthesis of 2D CMP films


14

Page 15 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


were supplied from Aladdin Chemicals. All of the solvents were dried before using. Water (18.2 MΩ·cm) was purified using a Milli-Q purification system (DZG-303A). The other chemicals were used without further purified otherwise stated. SiO2 (300 nm)/Si substrates were purchased from SZJXTech (SuZhou, China). The substrates were cleaned sequentially in Milli-Q water, acetone and ethanol for 15 min under ultrasonic condition and then were dried under N2 flow and annealed at 120 oC for 30 min. All procedures were conducted under ambient conditions. Synthesis of 2D CMP-1. A typical procedure is described as follows: 4,4'-di(9H-carbazol-9-yl)1,1'-biphenyl, which was named as monomer 1, was dissolved in chlorobenzene to prepare monomer solution with concentration of 10 mg/mL. The monomer solution was spin-coated (500 rpm for 5 sec and 3000 rpm for 30 sec) on a clean SiO2/Si substrate. The monomer covered SiO2/Si substrate was annealed in oven at 120 oC for 30 min to remove the solvent. Then the monomer covered SiO2/Si substrate was dipped in dry dichloromethane solution containing anhydrous FeCl3 (1.5 mg/mL, 9.1*10-3 mmol/mL) for 24 h. After that, the 2D CMP-1 covered SiO2/Si substrate was taken out and washed successively with methanol, Milli-Q water, concentrated HCl and dichloromethane. Finally, the obtained 2D CMP-1 was dried in oven at 50 o

C for 30 min for further characterization.

Synthesis of 2D CMP-2. The synthesis procedures are similar to that of 2D CMP-1. After chlorobenzene solution (10 mg/mL) of 2,7-di(9H-carbazol-9-yl)-9H-fluoren-9-one (monomer 2) was spin-coated on the SiO2/Si substrate and annealed in oven, the monomer 2 covered SiO2/Si substrate was dipped into dry dichloromethane solution of anhydrous FeCl3 for 24 h. Finally, the 2D CMP-2 covered substrate was taken out, cleaned and dried. Synthesis of 2D CMP-3. The synthesis procedures are similar to that of 2D CMP-1. After chlorobenzene solution (10 mg/mL) of 2,7-di(9H-carbazol-9-yl)-9-(4-(octyl-oxy)phenyl)-9H-


15


Page 16 of 24

fluoren-9-ol (monomer 3) was spin-coated on the SiO2/Si substrate and annealed in oven, the monomer covered SiO2/Si substrate was dipped into dry dichloromethane solution of anhydrous FeCl3 for 24 h. Finally, the 2D CMP-3 covered substrate was taken out, cleaned and dried. Transfer of 2D CMP films onto TEM copper grids. The as-synthesized 2D CMP films covered SiO2/Si substrates were immersed in a 1 M NaOH solution, which partially etched the SiO2 releasing the 2D CMP films at 60 °C. Free-standing 2D CMP films were then obtained and transferred into Milli-Q water for completely cleaning the films. Finally, the 2D CMP films were attached to TEM copper grids and dried in oven (the copper grids did not contain carbon membrane). Effects of polymerization time. The effect of polymerization time on the synthesis of 2D CMP1 was studied as follow: After monomer 1 covered SiO2/Si substrates were annealed in oven, these substrates were dipped into dry dichloromethane solution containing anhydrous FeCl3. When the polymerization time was increased to 30 min, 1 h, 6 h and 24 h, these substrates were taken out, cleaned and dried. Effects of catalyst concentration. Monomer 1 covered SiO2/Si substrates were used as the samples. The catalyst concentrations were 0.35, 0.70, 1.0 and 1.5 mg/mL, respectively. Except the change of catalyst concentration, the synthesis procedures were the same as that of 2D CMP1 as mentioned above. Effects of solvents. Monomer 1 covered SiO2/Si substrates were used as the samples. Apart from dichloromethane, other solvents were toluene and chloroform. Except the change of solvents, the synthesis procedures were the same as that of 2D CMP-1 as mentioned above. Synthesis of 2D CMP-1 on rGO surface. GO was synthesized from natural graphite (Bay City, MI) by a modified Hummers method. After that, the GO dispersion in methanol was spin-coated


16

Page 17 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


on a clean SiO2/Si substrate, we then pattern away unwanted GO areas and reduced the GO film at 1000 oC at H2/Ar atmosphere. Then monomer 1 was spin-coated on the rGO surface and annealed in oven, the monomer covered rGO/SiO2/Si substrate was dipped into dry dichloromethane solution containing anhydrous FeCl3 for 24 h. Finally, the 2D CMP-1/rGO heterostructure covered substrates were taken out, cleaned and dried. Device fabrication. After 2D CMP-1 or rGO film has been obtained, cleaned and dried on SiO2/Si substrates, Au electrodes (60 nm thickness) were subsequently deposited on these films by thermal deposition slowly with a shadow mask. For the fabrication of 2D CMP-1/rGO heterostructure based vertical field-effect transistor, Au electrodes were deposited on 2D CMP-1 and rGO with a shadow mask, separately. Characterization. Optical microscopy was performed using a Nikon optical microscope. The film morphologies of these 2D CMP films were recorded with a commercial AFM instrument (Dimension ICON with NanoScope V controller, Bruker) under ambient conditions. The TEM (HITACHI, 7605) and high-resolution transmission electron microscopy (HRTEM, JEOL 2100F) characterizations were performed by transfer the 2D CMP films onto TEM grids. FTIR spectra were measured by neat on a KBr plate. The XPS spectra were recorded on a scanning Xray microprobe (PHI 5000 Versa, ULACPHI, Inc.) that uses Al Kα radiation. The absorption spectra of the monomers and polymers in film states were measured with a Shimadzu UV-3600 spectrophotometer. The fluorescence spectra were recorded on a Shimadzu RF-5301PC luminescence spectrometer. Monomer films were prepared by spin-coating monomer solution onto quartz plates. Polymer films were directly synthesized on the quartz plates. Contact angles of the bare SiO2 surface, monomers and polymers covered SiO2 surfaces were determined with KRUSS DSA100S (Hamburg, Germany) apparatus. Volume of the Milli-Q water used in the


17


Page 18 of 24

contact angle measurements was ~0.5 mL. The electrical characteristics of the electronic device was characterized using a Keithley 4200-SCS semiconductor parameter analyser. All electrical measurements were carried out under ambient conditions. Conflict or interests: The authors declare that there is no competing financial interest. Supporting Information. Molecular structures of monomers and polymers, optical micrographs, FTIR, XPS, UV and fluorescence spectra, and optical data of monomers and 2D CMP films, AFM images of 2D CMP-1 prepared under different time, catalyst concentrations and substrates, AFM and TEM images of rGO and 2D CMP films, water-contact angle images of bare SiO2, monomers and 2D CMP films covered SiO2 surfaces. The Supporting Information is available free of charge via the Internet at http://pubs.acs.org. Acknowledgements. We thank primary financial supports by the National Key R&D Program of China (2017YFB1002900), the National Natural Science Foundation of China (61622402, 61376088, 51703093, 51302134, and 51528201), the Natural Science Foundation of Jiangsu (BK20171000), the China Postdoctoral Science Foundation (2017M621734) and the Jiangsu Specially-Appointed Professor programme, the Six Talent Plan (2015XCL015). REFERENCES (1) Xu, M. S.; Liang, T.; Shi, M. M.; Chen, H. Z. Graphene-Like Two-Dimensional Materials. Chem. Rev. 2013, 113, 3766-3798. (2) Fiori, G.; Bonaccorso, F.; Iannaccone, G.; Palacios, T.; Neumaier, D.; Seabaugh, A.; Banerjee, S. K.; Colombo, L. Electronics based on two-dimensional materials. Nat. Nanotechnol. 2014, 9, 768-779. (3) Tan, C. L.; Liu, Z. D.; Huang, W.; Zhang, H. Non-volatile resistive memory devices based on solution-processed ultrathin two-dimensional nanomaterials. Chem. Soc. Rev. 2015, 44, 26152628. (4) Colson, J. W.; Dichtel, W. R. Rationally synthesized two-dimensional polymers. Nat. Chem.


18

Page 19 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2013, 5, 453-465. (5) Rodriguez-San-Miguel, D.; Amo-Ochoa, P.; Zamora, F. MasterChem: cooking 2D-polymers. Chem. Commun. 2016, 52, 4113-4127. (6) Gao, L. B.; Ni, G. X.; Liu, Y. P.; Liu, B.; Neto, A. H. C.; Loh, K. P. Face-to-face transfer of wafer-scale graphene films. Nature 2014, 505, 190-194. (7) Kang, K.; Xie, S.; Huang, L.; Han, Y.; Huang, P. Y.; Mak, K. F.; Kim, C.-J.; Muller, D.; Park, J. High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity. Nature 2015, 520, 656-660. (8) Lee, J. H.; Lee, E. K.; Joo, W. J.; Jang, Y.; Kim, B. S.; Lim, J. Y.; Choi, S. H.; Ahn, S. J.; Ahn, J. R.; Park, M. H.; Yang, C. W.; Choi, B. L.; Hwang, S. W.; Whang, D. Wafer-Scale Growth of Single-Crystal Monolayer Graphene on Reusable Hydrogen-Terminated Germanium. Science 2014, 344, 286-289. (9) Ci, L.; Song, L.; Jin, C. H.; Jariwala, D.; Wu, D. X.; Li, Y. J.; Srivastava, A.; Wang, Z. F.; Storr, K.; Balicas, L.; Liu, F.; Ajayan, P. M. Atomic layers of hybridized boron nitride and graphene domains. Nat. Mater. 2010, 9, 430-435. (10) Falcaro, P.; Okada, K.; Hara, T.; Ikigaki, K.; Tokudome, Y.; Thornton, A. W.; Hill, A. J.; Williams, T.; Doonan, C.; Takahashi, M. Centimetre-scale micropore alignment in oriented polycrystalline metal-organic framework films via heteroepitaxial growth. Nat. Mater. 2016, 9, 430-435. (11) Kory, M. J.; Worle, M.; Weber, T.; Payamyar, P.; van de Poll, S. W.; Dshemuchadse, J.; Trapp, N.; Schluter, A. D. Gram-scale synthesis of two-dimensional polymer crystals and their structure analysis by X-ray diffraction. Nat. Chem. 2014, 6, 779-784. (12) Payamyar, P.; Kaja, K.; Ruiz-Vargas, C.; Stemmer, A.; Murray, D. J.; Johnson, C. J.; King, B. T.; Schiffmann, F.; VandeVondele, J.; Renn, A.; Goetzinger, S.; Ceroni, P.; Schuetz, A.; Lee, L.-T.; Zheng, Z.; Sakamoto, J.; Schlueter, A. D. Synthesis of a Covalent Monolayer Sheet by Photochemical Anthracene Dimerization at the Air/Water Interface and its Mechanical Characterization by AFM Indentation. Adv. Mater. 2014, 26, 2052-2058. (13) Murray, D. J.; Patterson, D. D.; Payamyar, P.; Bhola, R.; Song, W. T.; Lackinger, M.; Schluter, A. D.; King, B. T. Large Area Synthesis of a Nanoporous Two-Dimensional Polymer at the Air/Water Interface. J. Am. Chem. Soc. 2015, 137, 3450-3453. (14) Jiang, J. X.; Su, F.; Trewin, A.; Wood, C. D.; Campbell, N. L.; Niu, H.; Dickinson, C.;


19


Page 20 of 24

Ganin, A. Y.; Rosseinsky, M. J.; Khimyak, Y. Z.; Cooper, A. I. Conjugated microporous poly (aryleneethynylene) networks. Angew. Chem. Int. Ed. 2007, 46, 8574-8578. (15) Perepichka, D. F.; Rosei, F. Extending Polymer Conjugation into the Second Dimension. Science 2009, 323, 216-217. (16) Adjizian, J. J.; Briddon, P.; Humbert, B.; Duvail, J. L.; Wagner, P.; Adda, C.; Ewels, C. Dirac Cones in two-dimensional conjugated polymer networks. Nat. Commun. 2014, 5, 5842. (17) Gutzler, R.; Perepichka, D. F. π-Electron conjugation in two dimensions. J. Am. Chem. Soc. 2013, 135, 16585-16594. (18) Adjizian, J. J.; Lherbier, A.; Dubois, S. M. M.; Botello-Mendez, A. R.; Charlier, J. C. The electronic and transport properties of two-dimensional conjugated polymer networks including disorder. Nanoscale 2016, 8, 1642-1651. (19) Grill, L.; Dyer, M.; Lafferentz, L.; Persson, M.; Peters, M. V.; Hecht, S. Nano-architectures by covalent assembly of molecular building blocks. Nat. Nanotechnol. 2007, 2, 687-691. (20) Lafferentz, L.; Eberhardt, V.; Dri, C.; Africh, C.; Comelli, G.; Esch, F.; Hecht, S.; Grill, L. Controlling on-surface polymerization by hierarchical and substrate-directed growth. Nat. Chem. 2012, 4, 215-220. (21) Cardenas, L.; Gutzler, R.; Lipton-Duffin, J.; Fu, C. Y.; Brusso, J. L.; Dinca, L. E.; Vondracak, M.; Fagot-Revurat, Y.; Malterre, D.; Rosei, F.; Perepichka, D. F. Synthesis and electronic structure of a two dimensional pi-conjugated polythiophene. Chem. Sci. 2013, 4, 3263-3268. (22) Tanoue, R.; Higuchi, R.; Enoki, N.; Miyasato, Y.; Uemura, S.; Kimizuka, N.; Stieg, A. Z.; Gimzewski, J. K.; Kunitake, M. Thermodynamically Controlled Self-Assembly of Covalent Nanoarchitectures in Aqueous Solution. ACS Nano 2011, 5, 3923-3929. (23) Xu, L. R.; Zhou, X.; Tian, W. Q.; Gao, T.; Zhang, Y. F.; Lei, S. B.; Liu, Z. F. SurfaceConfined Single-Layer Covalent Organic Framework on Single-Layer Graphene Grown on Copper Foil. Angew. Chem. Int. Ed. 2014, 53, 9564-9568. (24) Liu, X. H.; Guan, C. Z.; Wang, D.; Wan, L. J. Graphene-Like Single-Layered Covalent Organic Frameworks: Synthesis Strategies and Application Prospects. Adv. Mater. 2014, 26, 6912-6920. (25) Zhang, Y. Q.; Kepcija, N.; Kleinschrodt, M.; Diller, K.; Fischer, S.; Papageorgiou, A. C.; Allegretti, F.; Bjork, J.; Klyatskaya, S.; Klappenberger, F.; Ruben, M.; Barth, J. V. Homocoupling of terminal alkynes on a noble metal surface. Nat. Commun. 2012, 3, 187.


20

Page 21 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(26) Abel, M.; Clair, S.; Ourdjini, O.; Mossoyan, M.; Porte, L. Single Layer of Polymeric FePhthalocyanine: An Organometallic Sheet on Metal and Thin Insulating Film. J. Am. Chem. Soc. 2011, 133, 1203-1205. (27) Treier, M.; Richardson, N. V.; Fasel, R. Fabrication of Surface-Supported Low-Dimensional Polyimide Networks. J. Am. Chem. Soc. 2008, 130, 14054-14055. (28) Dai, W. Y.; Shao, F.; Szczerbinski, J.; McCaffrey, R.; Zenobi, R.; Jin, Y. H.; Schluter, A. D.; Zhang, W. Synthesis of a Two-Dimensional Covalent Organic Monolayer through Dynamic Imine Chemistry at the Air/Water Interface. Angew. Chem. Int. Ed. 2016, 55, 213-217. (29) Sahabudeen, H.; Qi, H.; G latz, B. A.; Tranca, D.; Dong, Renhao.; Hou, Y.; Zhang, T.; Kuttner, C.; Lehnert, T.; Seifert, G.; Kaiser, U.; Fery, A.; Zheng, Z.; Feng, X. Wafer-sized multifunctional polyimine-based two-dimensional conjugated polymers with high mechanical stiffness. Nat. Commun. 2016, 7, 13461. (30) Kimoto, A.; Cho, J. S.; Ito, K.; Aoki, D.; Miyake, T.; Yamamoto, K. Novel hole-transport material for efficient polymer light-emitting diodes by photoreaction. Macromol. Rapid Commun. 2005, 26, 597-601. (31) Zhang, H. Ultrathin Two-Dimensional Nanomaterials. ACS Nano 2015, 9, 9451-9469. (32) Marco, A. B.; Cortizo-Lacalle, D.; Perez-Miqueo, I.; Valenti, G.; Boni, A.; Plas, J.; Strutynski, K.; De Feyter, S.; Paolucci, F.; Montes, M.; Khlobystov, A. N.; Melle-Franco, M.; Mateo-Alonso, A. Twisted Aromatic Frameworks: Readily Exfoliable and Solution-Processable Two-Dimensional Conjugated Microporous Polymers. Angew. Chem. Int. Ed. 2017, 56, 69466951. (33) Chen, Q.; Luo, M.; Hammershøj, P.; Zhou, D.; Han, Y.; Laursen, B. W.; Yan, C.-G.; Han, B.H. Microporous polycarbazole with high specific surface area for gas storage and separation. J. Am. Chem. Soc. 2012, 134, 6084-6087. (34) Gu, C.; Chen, Y. C.; Zhang, Z. B.; Xue, S. F.; Sun, S. H.; Zhang, K.; Zhong, C. M.; Zhang, H. H.; Pan, Y. Y.; Lv, Y.; Yang, Y. Q.; Li, F. H.; Zhang, S. B.; Huang, F.; Ma, Y. G. Electrochemical Route to Fabricate Film-Like Conjugated Microporous Polymers and Application for Organic Electronics. Adv. Mater. 2013, 25, 3443-3448. (35) Britnell, L.; Gorbachev, R.; Jalil, R.; Belle, B.; Schedin, F.; Mishchenko, A.; Georgiou, T.; Katsnelson, M.; Eaves, L.; Morozov, S. Field-effect tunneling transistor based on vertical graphene heterostructures. Science 2012, 335, 947-950.


21


Page 22 of 24

(36) He, D.; Zhang, Y.; Wu, Q.; Xu, R.; Nan, H.; Liu, J.; Yao, J.; Wang, Z.; Yuan, S.; Li, Y. Twodimensional quasi-freestanding molecular crystals for high-performance organic field-effect transistors. Nat. Commun. 2014, 5, 5162. (37) Lin, Z.; McCreary, A.; Briggs, N.; Subramanian, S.; Zhang, K.; Sun, Y.; Li, X.; Borys, N. J.; Yuan, H.; Fullerton-Shirey, S. K. 2D materials advances: from large scale synthesis and controlled heterostructures to improved characterization techniques, defects and applications. 2D Mater. 2016, 3, 042001. (38) Zhang, Z. B.; Fujiki, M.; Tang, H. Z.; Motonaga, M.; Torimitsu, K. The first high molecular weight poly (N-alkyl-3,6-carbazole)s. Macromolecules 2002, 35, 1988-1990. (39) Guo, X.; Baumgarten, M.; Mullen, K. Designing pi-conjugated polymers for organic electronics. Prog. Polym. Sci. 2013, 38, 1832-1908. (40) Xie, L. H.; Yin, C. R.; Lai, W. Y.; Fan, Q. L.; Huang, W. Polyfluorene-based semiconductors combined with various periodic table elements for organic electronics. Prog. Polym. Sci. 2012, 37, 1192-1264. (41) Li, J. L.; Grimsdale, A. C. Carbazole-based polymers for organic photovoltaic devices. Chem. Soc. Rev. 2010, 39, 2399-2410. (42) Aizawa, N.; Pu, Y. J.; Chiba, T.; Kawata, S.; Sasabe, H.; Kido, J. Instant Low-Temperature Cross-Linking

of

Poly(N-vinylcarbazole)

for

Solution-Processed

Multilayer

Blue

Phosphorescent Organic Light-Emitting Devices. Adv. Mater. 2014, 26, 7543-7546. (43) Png, R. Q.; Chia, P. J.; Tang, J. C.; Liu, B.; Sivaramakrishnan, S.; Zhou, M.; Khong, S. H.; Chan, H. S. O.; Burroughes, J. H.; Chua, L. L.; Friend, R. H.; Ho, P. K. H. High-performance polymer semiconducting heterostructure devices by nitrene-mediated photocrosslinking of alkyl side chains. Nat. Mater. 2010, 9, 152-158. (44) Blum, A. S.; Kushmerick, J. G.; Long, D. P.; Patterson, C. H.; Yang, J. C.; Henderson, J. C.; Yao, Y. X.; Tour, J. M.; Shashidhar, R.; Ratna, B. R. Molecularly inherent voltage-controlled conductance switching. Nat. Mater. 2005, 4, 167-172. (45) Wang, Z. R.; Dong, H. L.; Li, T.; Hviid, R.; Zou, Y.; Wei, Z. M.; Fu, X. L.; Wang, E. J.; Zhen, Y. G.; Norgaard, K.; Laursen, B. W.; Hu, W. P. Role of redox centre in charge transport investigated by novel self-assembled conjugated polymer molecular junctions. Nat. Commun. 2015, 6, 7478. (46) Yang, H.; Heo, J.; Park, S.; Song, H. J.; Seo, D. H.; Byun, K. E.; Kim, P.; Yoo, I.; Chung, H.


22

Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


J.; Kim, K. Graphene Barristor, a Triode Device with a Gate-Controlled Schottky Barrier. Science 2012, 336, 1140-1143. (47) Liu, Z.D.; Chang, Y.Z.; Ou, C.J.; Lin, J.Y.; Xie, L.H.; Yin, C.R.; Yi, M.D.; Qian, Y.; Shi, N.E.; Huang, W. BF3·Et2O-mediated Friedel–Crafts C–H bond polymerization to synthesize πconjugation-interrupted polymer semiconductors. Polym. Chem. 2011, 2, 2179-2182.


23


Table of Contents Graphic

6 5

Ultrathin 2D CMP

VDS:

4 Drain (µA)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 24

7V 5V 3V Au (S) 1V

Au (D) 2D CMP

3

rGO SiO2

2

Si (G)

1 0

2 µm

-5 -4 -3 -2 -1 0 1 Gate (V)

2

3

4

5


24

Wafer-Scale Ultrathin Two-Dimensional Conjugated Microporous

Recommend Documents