Thursday, June 26, 2008

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

Axel Schindler
Stefan Spiessberger
Steffen Hergert
Norbert Fruehauf
James P. Novak
Zvi Yaniv

University of Stuttgart

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 (OLEDs). The CNT-TFTs reach on/off ratios of more than 105 and effective charge-carrier mobilities of 1 cm2/V-sec and above.

FIGURE 6 — A 5 × 6-mm2 OLED with a CNT-network anode at 5-V driving
voltage under illumination of a fluorescent tube.

FIGURE 3 — Fully processed CNT-network TFTs on a 50 × 50 mm2 PES

Information Display 5/08 93


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