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Bucharest, Romania

Kang H.,TU Chemnitz | Lee C.,FLEXIBLE DISPLAY | Shin K.,Konkuk University
Control Engineering Practice | Year: 2013

For mass manufacturing of printed electronics using roll-to-roll printing, high-resolution register control among multi-layers is required. A mathematical model of a machine directional (MD) register was derived, where the compensation method was proposed to cancel out the upstream disturbance of the MD register. The proposed MD register model and compensator could be used to improve the performance of the MD register controller in multi-layer roll-to-roll printed electronics. The proposed compensator was experimentally verified at various operating conditions. The results show that the proposed compensator improves the control performance of the MD register in overcoming upstream disturbances. © 2013.

Lee K.,Yonsei University | Oh M.S.,FLEXIBLE DISPLAY | Mun S.-J.,Yonsei University | Lee K.H.,Yonsei University | And 7 more authors.
Advanced Materials | Year: 2010

Direct quantitative mapping of the density-of-states, named the photo-excited chargecollection technique, for the interface traps at the n-ZnO and/or p-pentacene thin-film transistor channel is implemented by using monochromatic photons which are carried by optical fibers and are probed onto thin-film transistors. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH S.Co. KGaA, Weinheim.

Jiang J.,University of Nebraska - Lincoln | Lima O.V.,University of Nebraska - Lincoln | Pei Y.,University of Nebraska - Lincoln | Jiang Z.,Argonne National Laboratory | And 6 more authors.
ACS Nano | Year: 2010

The packing of electronic molecules into planar structures and an ensured π - π interaction within the plane are preferred for efficient organic transistors. Thin films of organic electronics are exemplar, but the widely adopted molecular design and associated fabrication lead to limited ordering in multistack construction motifs. Here we demonstrate self-assembled nanolayers of organic molecules having potential electronic utility using an amphiphilic silane as a building block. Unlike a cross-linked (tetrahedral) configuration found in conventional siloxane networks, a linear polymer chain is produced following silane polycondensation. As a result, hydrophobic branches plus a noncovalent π - π interlocking between the molecules promote planar packing and continuous stacking along the surface normal. In contrast to conventional π - π stacking or hydrogen bonding pathways in a fibrous construct, multistacked nanolayers with coexisting π - π and herringbone interlocking can provide unmatched properties and processing convenience in molecular electronics. © 2010 American Chemical Society.

Lee C.,FLEXIBLE DISPLAY | Kang H.,Konkuk University | Kim C.,Konkuk University | Shin K.,Konkuk University
Journal of Microelectromechanical Systems | Year: 2010

Roll-to-roll (R2R) continuous printing is an attractive technology for mass-producing flexible printed electronics. Many studies have been conducted in this field. The application of the R2R printing process, however, requires information pertaining to system parameters such as substrate flexibility, ink formulation, and printing method as well as the curing method for conductive ink. We show that the quality of a printed pattern (thickness and surface roughness) could be affected by tension variation of the flexible bare substrate in spite of the optimal settings of the ink, substrate, and printing method. In addition, an ink-transfer mechanism for the R2R printed electronics is analyzed to reveal the relationships between the dynamic surface roughness and tension of a moving web. Since the dynamics of the physical problem are complex, simple meta models using a design of experiment are developed. The experimental results are found to be in agreement with the meta models. It is found that the two important factors for achieving the desired thickness and surface roughness of the R2R printed patterns are optimal tension and control accuracy of the operating tension. © 2006 IEEE.

Allen M.,VTT Technical Research Center of Finland | Allen M.,Aalto University | Lee C.,FLEXIBLE DISPLAY | Ahn B.,Konkuk University | And 3 more authors.
Microelectronic Engineering | Year: 2011

The fabrication of passive circuitry by gravure and inkjet printing is studied. A chipless inductively coupled RF resonant tag is analyzed as a test structure. A floating-bridge layout is employed to provide high yield when fabricated by roll-to-roll (R2R) printing. The conducting first layer and insulating second layer are R2R gravure printed with silver nanoparticle ink and a thermally cross-linkable dielectric ink, respectively. Above 10 MS/m conductivity is obtained for the first layer, which passes three times through the 5 m long drying unit at 5 m/min speed. The floating bridge is inkjet printed with silver nanoparticle ink and the prototype tag is measured over a reading distance of ca. 2 cm. An equivalent circuit model is presented and the model parameters are optimized to obtain a best fit to the measured frequency response. This indirect measurement provides an estimate of 4.3 μm for the thickness of the dielectric layer sandwiched between the conducting top and bottom layers. Application possibilities for the all-printed RF resonant tag are outlined. © 2011 Elsevier B.V. All rights reserved.

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