Flexible AMOLED displays on stainless-steel foil

Abstract

The world's thinnest flexible full-color 5.6-in. active-matrix organic-light-emitting-diode (AMOLED) display with a top-emission mode on stainless-steel foil was demonstrated. The stress in the stainless-steel foil during the thermal process was investigated to minimize substrate bending. The p-channel poly-Si TFTs on stainless-steel foil exhibited a field-effect mobility of 71.2 cm 2 /V-sec, threshold voltage of -2.7 V, off current of 6.7 × 10 13 A/µm, and a subthreshold slope of 0.63 V/dec. These TFT performances made it possible to integrate a scan driver circuit on the panel. A top-emission EL structure was used as the display element, and thin-film encapsulation was performed to realize a thin and flexible display. The full-color flexible AMOLED display on stainless-steel foil is promising for mobile applications because of its thin, light, rugged, and flexible properties. TABLE 1 -Comparison of plastic, thin glass, and metal-foil substrate.

New Pixel Circuit Design Employing an Additional Pixel Line Insertion in AMOLED Displays Composed by Excimer Laser-Crystallized TFTs

“…The rms roughness value obtained from the AFM data for the single scanned region is 16.1 nm, while that for the double scanned region is 24.9 nm. These results are consistent with the observed typical behavior of the surface morphology in our previous works; the roughness of surface increases with an average grain size [4], [9].…”

“…After the via-hole opening, the multi-level ITO/Ag/ITO ITO Ag ITO contact was deposited and patterned. The pixel-defined layer (PDL) that determines the deposition position of multiple electroluminescence layers was patterned and then annealed at 250 C for 1 h. The electroluminescence (EL) layers were stacked on the PDL regions in an evaporation coater chamber under the base pressure of about 10 torr following a published protocol [9]. Finally, the EL device was encapsulated in a dry argon glove box to protect against the ambient environment.…”

Low‐Power Flexible Organic Light‐Emitting Diode Display Device

“…display requires that a fl exible backplane that contains driving/ switching thin-fi lm transistors (TFTs) and capacitor must be integrated with the fl exible display devices suggested here. To minimize the mechanical stress, a fl exible backplane has been manufactured with supporting plastic layers, where the neutral plane [13][14][15][16] is defi ned as strain free zones under both inward and outward bending as shown in Figure 6 a. Importantly, recent research experimentally reported that TFTs and electrical devices placed on a neutral plane fabricated on a plastic substrate (polyimide) achieved a stable performance under 20 000 times tensile and compressive bending down to radii of 3 mm.…”

The Future of Displays Is Foldable

“…Companies that have demonstrated flexible‐display prototypes recently include Samsung, 6 LG, 7 Plastic Logic, 8 Bridgestone, 9 E Ink, 10 Fujitsu, 11 Sharp, 12 and others. Companies that have introduced flexible displays on the market include Fujitsu, with the Flepia eReader based on a stacked red, green, and blue cholesteric liquid‐crystal (CLC) display using plastic substrates, introduced in Japan in 2009, and recently by Plastic Logic, which introduced eReaders based on plastic substrates and electrophoretic technology in Russia.…”

“…The transistors in OLEDs have higher stability and uniformity requirements compared to that for LCDs, which is more difficult to achieve on a restricted temperature budget. LG, 7 Samsung, 6 and recently AUO have demonstrated flexible OLED displays. Sony has demonstrated a foldable OLED display 3 and, recently, Polymer Vision also made a foldable OLED panel together with the Holst Centre (to be discussed shortly).…”