Heat‐Assisted Photoacidic Oxidation Method for Tailoring the Surface Chemistry of Polymer Dielectrics for Low‐Power Organic Soft Electronics

Kim, Jin-Sung; Kang, Boseok; Cho, Kilwon

doi:10.1002/adfm.201806030

Cited by 14 publications

(14 citation statements)

References 52 publications

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“…The relatively hydrophobic c PVP surface (water contact angle, 78.6°) transformed into a hydrophilic surface (water contact angle, ∼20.5°) through the UV/ozone treatment because of the introduction of hydroxyl groups (Figure S3). − The selective-wetting method was employed to pattern the MXene electrodes over a large area. The substrate was immersed in MXene aqueous solution and then carefully pulled out at a constant speed.…”

Section: Results and Discussionmentioning

confidence: 99%

Large-Area MXene Electrode Array for Flexible Electronics

et al. 2019

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MXenes, an emerging class of two-dimensional (2D) transition metal carbides and nitrides, have potential for application as high-performance, low-cost electrodes in organic field-effect transistors (OFETs) because of their water dispersibility, high conductivity, and work-function tunability. In this study, we successfully fabricated a large-scale, uniform Ti3C2T x MXene electrode array on a flexible plastic substrate for application in high-performance OFETs. The work function of the Ti3C2T x MXene electrodes was also effectively modulated via chemical doping with NH3. The fabricated OFETs with Ti3C2T x MXene electrodes exhibited excellent device performance, such as a maximum carrier mobility of ∼1 cm2·V–1·s–1 and an on–off current ratio of ∼107 for both p-type and n-type OFETs, even though all the electrode and dielectric layers were fabricated on the plastic substrate by solution processing. Furthermore, MXene-electrode-based complementary logic circuits, such as NOT, NAND, and NOR, were fabricated via integration of p-type and n-type OFETs. The proposed approach is expected to expand the application range of MXenes to other OFET-based electronic devices, such as organic light-emitting displays and electronic skins.

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Section: Results and Discussionmentioning

confidence: 99%

Large-Area MXene Electrode Array for Flexible Electronics

et al. 2019

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“…17−19 The surface energy, which represents the sum of the polar and dispersion components that result from the presence of permanent and instantaneous dipoles, respectively, was adjusted by the chemical functionality and packing density of the SAM interlayers. 17,18,20 For instance, nonpolar or poorly interacting moieties mostly provide lower surface energies. Figure 2 shows the obtained surface energies of dielectrics variously functionalized using CF 3 , CH 3 , NH 2 , SH, and Cl.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…16−22 Many research groups have illustrated that the surface functionalities of a gate dielectric with small semiconducting molecules modulate device electrical performance. 17,20,23,24 Hydrophobic surface modification in the gate dielectrics can, for instance, enhance the crystalline properties and the molecular ordering of organic active layers to facilitate charge transport along the π−π overlap direction and to prevent trap formation by polar functionalities at the interface. 17,18,23,24 Such studies related to controlling the surface functionalities have also revealed the influence of surface properties on the performance of FET devices fabricated with a polymer-based organic semiconducting active layer.…”

Section: ■ Introductionmentioning

confidence: 99%

Influences of Energetically Controlled Dielectric Functionality on Polymer Field-Effect Transistor Performance

Choi

Cho

et al. 2019

J. Phys. Chem. C

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We systematically demonstrated the effects of surface modification of gate dielectrics and the thermal annealing of an addeposited polymer semiconducting film on the electrical performance of organic field-effect transistors in which they were incorporated. Chemically or energetically engineered dielectrics were designed by introducing various end-functional groups (CF 3 , CH 3 , NH 2 , Cl, and SH). Poly(dioctyl-quaterthiophene-dioctyl-bithiazole) (PDQDB), consisting of 5,5′-bithiazole and oligothiophene rings, was employed as the polymer semiconductor. We analyzed the PDQDB semiconducting films' crystalline character, which has an important effect on the FET performance and confirmed that the crystallinity of the PDQDB semiconducting films was higher in the cases (CF 3 and CH 3 ) of low surface energy than in the cases (NH 2 , SH, and Cl) of high surface energy, yielding μ FET values as high as 0.13 and 0.12 cm 2 V −1 s −1 for the CF 3 and CH 3 cases, respectively. Another important observation was the tendency of the μ FET value to change depending on the thermal annealing temperature increasing and decreasing in the cases of surface functionalities with low and high surface energies, respectively. These results could be interpreted on the basis of the differently competitive molecule−molecule and molecule−dielectric surface interactions, where the π−π stacking configuration of the conjugated molecular structures was enhanced on lower-energy surfaces. We also discussed the effect of permanent dipoles for the engineered self-assembled monolayer dielectrics on the threshold and turn-on voltages in the PDQDB FET devices.

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“…OFET device operation depends on the interface structures between the active layer and the dielectric surface, because charge carrier transport between the source and drain electrodes mainly occurs in the channel region, within a few nanometers of the active layer near the dielectric surface. 42,43 We analyzed the 15 nm PDQDB film to highlight differences between the interface structures as a function of the thermal post-processing temperature. The prepared PDQDB thin film spontaneously separated in liquid nitrogen via instant cooling due to differences in the thermal expansion coefficients of the SiO 2 /Si substrate and the polymer film.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Precise Control over Polymer Semiconducting Films by Tuning the Thermal Behavior of the Thin-Film State’s Crystalline and Morphological Structures

Cho

Choi

et al. 2019

ACS Appl. Mater. Interfaces

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The crystalline and morphological structures of polymer semiconducting films were controlled by selecting appropriate thermal properties of the polymeric chains, thereby improving polymer field-effect transistor (FET) performances. Poly(dioctyl-quaterthiophene-dioctyl-bithiazole) (PDQDB), comprising 5,5′-bithiazole and oligothiophene rings, was used as the basis for the polymer semiconductor studies. The T g and T m values of the thin-film state, rather than those of the bulk polymer state, were important in this study. A PDQDB film with a T g of 101 °C in the thin-film state showed the highest maximum and average μFET values of 0.194 and 0.141 cm2 V–1 s–1, respectively, in an FET device at a post-processing temperature of 100 °C. On the other hand, relatively low average μFET values of 0.115, 0.098, and 0.079 cm2 V–1 s–1 were observed in FET devices prepared from PDQDB films with T g values of 130, 165, and 180 °C, respectively, despite the dramatic increase in film crystallinity. With the variations in μFET, what we have noticed is that the standard deviations of the measured μFET values varied with the T g values: 36.0% for the T g = 165 °C film and 51.1% for the T g = 180 °C film, indicating that the organic field-effect transistors performances were not uniform. These results were closely related to nano- and microscale nonuniformity in the PDQDB film structure in the presence of excessively activated grain structures. These variations were correlated with the crystalline and morphological structures of the PDQDB films prepared under various processing conditions.

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Heat‐Assisted Photoacidic Oxidation Method for Tailoring the Surface Chemistry of Polymer Dielectrics for Low‐Power Organic Soft Electronics

Cited by 14 publications

References 52 publications

Large-Area MXene Electrode Array for Flexible Electronics

Large-Area MXene Electrode Array for Flexible Electronics

Influences of Energetically Controlled Dielectric Functionality on Polymer Field-Effect Transistor Performance

Precise Control over Polymer Semiconducting Films by Tuning the Thermal Behavior of the Thin-Film State’s Crystalline and Morphological Structures

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