HP and ASU partner on low-cost flexible displays

PALO ALTO, CA AND TEMPE, AZ--HP Labs (www.hp.com) and the Flexible Display Center (FDC; www.flexdisplay.asu.edu) at Arizona State University (ASU) are partnering to develop affordable, flexible electronic displays for possible applications such as electronic paper (e-Paper) and signage.

PALO ALTO, CA AND TEMPE, AZ--HP Labs (www.hp.com) and the Flexible Display Center (FDC; www.flexdisplay.asu.edu) at Arizona State University (ASU) are partnering to develop affordable, flexible electronic displays for possible applications such as electronic paper (e-Paper) and signage. “Unlike other batch processes in which the flexible display is fabricated bonded to a rigid substrate and then removed, our technique creates an amorphous silicon backplane directly on a continuous polymer web using a roll-to-roll compatible process,” said Carl Taussig, director, Information Surfaces at HP Labs. Taussig said the new unbreakable displays were created by the FDC and HP using self-aligned imprint lithography (SAIL) technology.

Invented by HP Labs, SAIL is considered “self aligned” because the patterning information is imprinted on the substrate in such a way that perfect alignment is maintained regardless of process-induced distortion. In fact, the SAIL technology itself is an extension of work done by the University of Texas at Austin on step-and-flash imprint lithography, now a cornerstone technology for UT Austin spinout Molecular Imprints (Austin, TX).

While the jury is out regarding whether imprint lithography can replace extreme ultraviolet (EUV) lithography for nanoscale semiconductor patterning (see www.laserfocusworld.com/articles/336193 and www.laserfocusworld.com/articles/298394), imprint lithography clearly has advantages for low-cost flexible display manufacturing. The fabrication of thin-film transistor (TFT) arrays on a flexible plastic material is a low-cost, roll-to-roll, continuous manufacturing process compared to batch sheet-to-sheet production. “SAIL is a fast 5 meters per minute, high-resolution process that uses a three-dimensional masking technique to avoid the depth-of-field and flatness issues associated with conventional patterning on flexible substrates,” said Taussig. “And because the display consists of one to one-and-a-half micron thick TFT layers on top of a 50 micron thick plastic substrate, it trumps conventional display processes by using 90% less material by volume.”

The first practical demonstration of the flexible displays was achieved through collaborative efforts between the FDC and HP as well as other FDC partners including DuPont Teijin Films and E Ink. To create this display, the FDC produces stacks of semiconductor materials and metals on flexible Teonex Polyethylene Naphthalate (PEN) substrates from DuPont Teijin Films. HP then patterns the substrates using the SAIL process and integrates E Ink’s Vizplex imaging film to produce an actively addressed flexible display on plastic. E Ink’s Vizplex bi-stable electrophoretic imaging film enables images to persist without applied voltage, greatly reducing power consumption for viewing text.

HP Labs is born from HP, the world’s largest technology company, and sees electronic displays as future competition for hard-copy media and printers. As the research arm of HP, HP Labs is using the skills of its 600-employee-strong international work force (400 in Palo Alto, 100 in Bristol, England, and the rest worldwide) to look five years ahead in the industry and concentrate on such future technologies as flexible electronic displays, focusing on cost-reduction techniques to drive commercialization. Taussig said its collaboration with ASU’s FDC and other industry partners will accelerate cost reduction in the flexible-display industry. “Even though the Flexible Display Center is hosted by the University [ASU], it is a commercially oriented organization with an excellent manufacturing infrastructure for the development of flexible electronics,” he said.

Because the SAIL process is amenable to all kinds of flexible electronics applications, HP Labs is also licensing the technology to other companies. In September, PowerFilm (Ames, IA), a developer and manufacturer of thin, flexible solar panels, licensed the HP SAIL technology for the advancement of PowerFilm’s thin-film electronics business.

--Gail Overton

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