Nonphotolithographic fabrication of organic transistors with micron feature sizes

Rogers, John A.; Bao, Zhenan; Raju, V. Ramachandra

doi:10.1063/1.121109

Cited by 144 publications

(94 citation statements)

References 12 publications

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“…A low-cost rubber stamping technique known as CP (7,8) and a lithographic procedure based on molds and microfluidic channels (9,10) are, to our knowledge, the only nonphotochemical approaches to patterning that have micrometer resolution and have been used to fabricate organic transistors. CP is a particularly promising method that has the potential for patterning large areas quickly.…”

Section: Methodsmentioning

confidence: 99%

Paper-like electronic displays: Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks

Rogers¹,

Bao²,

Baldwin³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

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1,101

674

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Electronic systems that use rugged lightweight plastics potentially offer attractive characteristics (low-cost processing, mechanical flexibility, large area coverage, etc.) that are not easily achieved with established silicon technologies. This paper summarizes work that demonstrates many of these characteristics in a realistic system: organic active matrix backplane circuits (256 transistors) for large (Ϸ5 ؋ 5-inch) mechanically flexible sheets of electronic paper, an emerging type of display. The success of this effort relies on new or improved processing techniques and materials for plastic electronics, including methods for (i) rubber stamping (microcontact printing) high-resolution (Ϸ1 m) circuits with low levels of defects and good registration over large areas, (ii) achieving low leakage with thin dielectrics deposited onto surfaces with relief, (iii) constructing highperformance organic transistors with bottom contact geometries, (iv) encapsulating these transistors, (v) depositing, in a repeatable way, organic semiconductors with uniform electrical characteristics over large areas, and (vi) low-temperature (Ϸ100°C) annealing to increase the on͞off ratios of the transistors and to improve the uniformity of their characteristics. The sophistication and flexibility of the patterning procedures, high level of integration on plastic substrates, large area coverage, and good performance of the transistors are all important features of this work. We successfully integrate these circuits with microencapsulated electrophoretic ''inks'' to form sheets of electronic paper.T he backplane circuit consists of a square array of 256 suitably interconnected p-channel transistors. Fig. 1 shows the circuit layout. Fig. 2 presents a cross-sectional illustration of a transistor and a top view of a unit cell. The completed display (total thickness Ϸ1 mm) comprises a transparent frontplane electrode of indium tin oxide (ITO) and a thin unpatterned layer of flexible electronic ''ink'' mounted against a sheet that supports square pixel electrode pads and pinouts; these pixel pads attach, via a conductive adhesive, to the back planes. Each transistor functions as a switch that locally controls the color of the ink, which consists of a layer of polymeric microcapsules filled with a suspension of charged pigments in a colored fluid (1, 2). In each of the four quadrants of the display, transistors in a given column have connected gates, and those in a given row have connected source electrodes. Applying a voltage to a column (gate) and a row (source) electrode turns on the transistor located at the cell where these electrodes intersect. Activating the transistor generates an electric field between the frontplane ITO and the corresponding pixel electrode. This field causes movement of a pigment within the microcapsules, which changes the color of the pixel, as observed through the ITO: when the pigments flow to the ITO side of the capsules, the color of the pigment (white in this case) determines the color of the pixel; when they ...

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Section: Methodsmentioning

confidence: 99%

Paper-like electronic displays: Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks

Rogers¹,

Bao²,

Baldwin³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

1,101

674

View full text Add to dashboard Cite

show abstract

“…When we use a low solids loading suspension with a low viscosity, a wide area patterning is possible because the suspension infiltrates a long way by capillary action, and at the same time, the film is not normally generated because of a lack of particle density in the suspension. However, a few examples of the generation of thick structures by applying a low solids loading suspension to the MIMIC process were reported on polystyrene spheres 8 and carbon paint, 9 though the details are unknown. Therefore, we confirmed using only a 1 vol!…”

Section: Introductionmentioning

confidence: 99%

Large-Scale Patterning of TiO2 Nano Powders Using Micro Molds

Imasu

Sakka

2007

J. Ceram. Soc. Japan

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For the fabrication of ceramic micro-scale patterns over a wide area, the Micro-molding in Capillaries MIMIC method is can be used by applying low solid loading colloidal suspensions of nanopowders. However, to uniformly form thick films from low solids loading suspensions, it is necessary that the additional spontaneous process of concentrating the suspensions in the molds occurs and is successfully accomplished, after the ordinary MIMIC process caused by capillary action. This concentration of suspension occurs as a result of inflow of the suspension from the entrance along with solvent evaporation from the exit of the mold. Therefore, the suspension preparation is important in order that the particles flow in due to the flow of the solvent. In this study, we determined the required condition of the suspension preparation by fabricating films from aqueous and ethanolbased suspensions of TiO2 nanopowders. By comparing the uniformity of the fabricated films and the particle distributions of the suspensions, it was found that the condition required for uniform patterning over a wide area is to disperse the nanoparticles into their primary size.

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“…From the 1980s onward, OS have gone through various stages of development meant for improving the material quality that led to and even surpassed the performance of amorphous Si (α-Si) [24] in terms of the charge carrier mobilities in organic thin-film transistors (OTFTs). Easier solution printing of the organic materials at low temperatures on even fairly larger area substrates without using a high vacuum system [24][25][26][27][28] is well worth considering, where various processes including screen [29], ink-jet [30][31][32][33], and microcontact [34,35] printings have been especially advanced for flexible and transparent device fabrications [36][37][38][39] employing plastic substrates offering practically feasible integration of LEDs and organic photovoltaic (OPV) solar cells on the same substrate.…”

Section: Introductionmentioning

confidence: 99%

Organic semiconductors for device applications: current trends and future prospects

Ahmad

2014

Journal of Polymer Engineering

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Abstract:With the rich experience of developing silicon devices over a period of the last six decades, it is easy to assess the suitability of a new material for device applications by examining charge carrier injection, transport, and extraction across a practically realizable architecture; surface passivation; and packaging and reliability issues besides the feasibility of preparing mechanically robust wafer/substrate of single-crystal or polycrystalline/ amorphous thin films. For material preparation, parameters such as purification of constituent materials, crystal growth, and thin-film deposition with minimum defects/ disorders are equally important. Further, it is relevant to know whether conventional semiconductor processes, already known, would be useable directly or would require completely new technologies. Having found a likely candidate after such a screening, it would be necessary to identify a specific area of application against an existing list of materials available with special reference to cost reduction considerations in large-scale production. Various families of organic semiconductors are reviewed here, especially with the objective of using them in niche areas of large-area electronic displays, flexible organic electronics, and organic photovoltaic solar cells. While doing so, it appears feasible to improve mobility and stability by adjusting π-conjugation and modifying the energy bandgap. Higher conductivity nanocomposites, formed by blending with chemically conjugated C-allotropes and metal nanoparticles, open exciting methods of designing flexible contact/interconnects for organic and flexible electronics as can be seen from the discussion included here.

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Nonphotolithographic fabrication of organic transistors with micron feature sizes

Cited by 144 publications

References 12 publications

Paper-like electronic displays: Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks

Paper-like electronic displays: Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks

Large-Scale Patterning of TiO2 Nano Powders Using Micro Molds

Organic semiconductors for device applications: current trends and future prospects

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