Suspension‐deposited carbon‐nanotube networks for flexible active‐matrix displays

Abstract

Abstract— The unique properties of carbon nanotubes (CNTs) promise innovative solutions for a variety of display applications. The CNTs can be deposited from suspension. These simple and low‐cost techniques will replace time‐consuming and costly vacuum processes and can be applied to large‐area glass and flexible substrates. Single‐walled carbon nanotubes (SWNTs) have been used as conducting and transparent layers, replacing the brittle ITO, and as the semiconducting layer in thin‐film transistors (TFTs). There is no need for alignment because a CNT network is used instead of single CNTs. Both processes can be applied to glass and to flexible plastic substrates. The transparent and conductive nanotube layers can be produced with a sheet resistance of 400 Ω/□ at 80% transmittance. Such layers have been used to produce directly addressed liquid‐crystal displays and organic light‐emitting diodes (OLED). The CNT‐TFTs reach on/off ratios of more than 105 and effective charge‐carrier mobilities of 1 cm2/V‐sec and above.

62.2: AMLCD with Carbon‐Nanotube Pixel Electrodes

“…We have previously demonstrated the use of CNT electrodes for simple directly addressed polymer-dispersed LCDs [4], [5], now we present the applicability of carbon nanotube TCFs in a standard amorphous-Silicon AMLCD process. The complete display system was designed and fabricated at the Chair of Display Technology, Universitaet Stuttgart, Germany.…”

“…We first tested the use of transparent CNT electrodes in simple, directly addressed polymer-dispersed LCDs [4], [5]. For commercial products twisted nematic (TN) or vertically aligned (VA) LCDs are more relevant, though.…”

Active‐matrix and flexible liquid‐crystal displays with carbon‐nanotube pixel electrodes

“…This can short-circuit electrodes of the frontplane and backplane. 6 A thin layer of a polyimide (PI) soaks into the CNT network and improves the adhesion to the substrate. We used Sunever SE-130 from Nissan Chemical that is designed to be used as an orientation layer in TN-LCDs.…”

“…5 We have previously presented simple directly addressed polymer-dispersed liquid-crystal displays (PDLCDs) on glass. 6 Such displays are simple to realize because there is no need for a liquid-crystal orientation layer or polarizers. They have however only low relevance in commercial applications due to their low contrast.…”

“…For the application in current-driven devices such as organic light-emitting diodes (OLEDs), the achievable sheet resistances are still too high. 6 The CNT layers can be patterned by standard lithography and reactive ion etching (RIE) in an argon-oxygen plasma. A CO 2 snowjet could be used as vacuum-free etching technique.…”