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Palatine, IL, United States

Lian K.,University of Toronto | Li R.,University of Toronto | Wang H.,University of Toronto | Lu Z.,University of Toronto | Zhang J.,Printovate Inc.
Organic Electronics: physics, materials, applications | Year: 2010

Printed flexible cross-bar memory devices were characterized by both DC and AC techniques for their voltage triggered bi-stable behaviour and for interface properties between printed functional layers. The printed devices were compared with laminated devices with similar chemistry to identify the effects resultant from the printing process. Both printed and laminated memory devices demonstrated bi-stable behaviour with an ON/OFF ratio greater than 10 5. However, printed memories were found to possess an additional process- induced interfacial layer. The impact of this layer could be clearly demonstrated and analyzed in impedance spectra. Impedance spectroscopy was shown to be a powerful tool supplementing DC characterizations. © 2010 Elsevier B.V. All rights reserved. Source


Jiang L.,University of Illinois at Chicago | Zhang J.,Printovate Inc. | Gamota D.,Printovate Inc. | Takoudis C.G.,University of Illinois at Chicago
Organic Electronics: physics, materials, applications | Year: 2010

Organic thin film transistors (OTFTs) were fabricated and studied on polyimide substrate with poly(4-vinyl phenol-co-methyl methacrylate) (PVP-co-PMMA) dielectric thermally cross-linked with a new agent, p-tolyltrimethoxysilane (TTMS), followed by printed electrodes and solution processed bis(triisopropylsilylethynyl) pentacene. TTMS was found to be an effective cross-linking agent for the thermal cross-linking of PVP-co-PMMA, while the developed processes are compatible with solution-processed gate/source/drain and organic semiconductor. Thermogravimetric analyses, electrical characterizations, X-ray photoelectron spectroscopy, and cross-section scanning electron microscopy were used to characterize the resulting dielectric films formed using different amounts of the TTMS cross-linking agent. © 2010 Elsevier B.V. All rights reserved. Source


Lian K.,University of Toronto | Li R.,University of Toronto | Wang H.,University of Toronto | Zhang J.,Printovate Inc. | Gamota D.,Printovate Inc.
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2010

A novel, low cost printed organic data storage system was investigated. The printed memory devices consisted of top and bottom electrodes, an organic active layer, and a conductive polymer interfacial layer sandwiched in between the electrodes. The fabricated device demonstrated voltage induced switching and bi-stable electrical behavior, enabling it to function as non-volatile memory. An ON/OFF current or resistance ratio of up to 104 was demonstrated through dc characterization, while the ac impedance revealed a significant phase and resistance change between the ON and OFF states. The active materials can be readily implemented via graphic arts printing processes for large area flexible electronics. © 2010 Elsevier B.V. All rights reserved. Source


Jiang L.,University of Illinois at Chicago | Zhang J.,Printovate Inc. | Gamota D.,Printovate Inc. | Takoudis C.G.,University of Illinois at Chicago
Organic Electronics: physics, materials, applications | Year: 2010

The electrical performance of organic thin film transistors (OTFTs) is profoundly affected by organic semiconductor crystal formation and molecular ordering. The molecular ordering induced by self-assembly mechanisms can improve carrier mobility by a few orders of magnitude. In this work, the dielectric surface was modified to obtain preferred chemical functional groups that promote semiconductor ordering on the dielectric surface. OTFTs were fabricated using heavily p-doped silicon wafers as the gate electrode and thermally grown SiO2 as the dielectric. Organosilanes, (3-mercaptopropyl)triethoxysilane and p-tolyltrimethoxysilane were used to modify the dielectric surface. Organic semiconductor, bis(triisopropylsilylethynyl) pentacene, was solution-cast as the semiconductor layer. X-ray photoelectron spectroscopy was used to characterize the modified dielectric surface. The analysis from atomic force microscopy indicated improved ordering in the semiconductor layer on silane treated dielectric surfaces. Electrical characterizations showed that the field-effect carrier mobility was enhanced by two orders of magnitude with dielectric surface modifications. © 2009 Elsevier B.V. All rights reserved. Source

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