Textile Display with AMOLED Using a Stacked-Pixel Structure on a Polyethylene Terephthalate Fabric Substrate

Abstract

An active-mode organic light-emitting diode (AMOLED) display on a fabric substrate is expected to be a prominent textile display for e-textile applications. However, the large surface roughness of the fabric substrate limits the aperture ratio—the area ratio of the organic light-emitting diode (OLED) to the total pixel area. In this study, the aperture ratio of the AMOLED panel fabricated on the polyethylene terephthalate fabric substrate was enhanced by applying a stacked-pixel structure, in which the OLED was deposited above the organic thin-film transistor (OTFT) pixel circuit layer. The stacked pixels were achieved using the following three key technologies. First, the planarization process of the fabric substrate was performed by sequentially depositing a polyurethane and photo-acryl layer, improving the surface roughness from 10 μm to 0.3 μm. Second, a protection layer consisting of three polymer layers, a water-soluble poly-vinyl alcohol, dichromated-polyvinylalcohol (PVA), and photo acryl, formed by a spin-coating processes was inserted between the OTFT circuit and the OLED layer. Third, a high mobility of 0.98 cm2/V∙s was achieved at the panel scale by using hybrid carbon nano-tube (CNT)/Au (5 nm) electrodes for the S/D contacts and the photo-acryl (PA) for the gate dielectric, enabling the supply of a sufficiently large current (40 μA @ VGS = −10 V) to the OLED. The aperture ratio of the AMOLED panel using the stacked-pixel structure was improved to 48%, which was about two times larger than the 19% of the side-by-side pixel, placing the OLED just beside the OTFTs on the same plane.

Light-Emitting Textiles: Device Architectures, Working Principles, and Applications

“…All OTFT and OLED layers were evaporated and patterned by a lift-off process, except for the OTFTs' active material (specifically, TIPS-pentacene), which was inkjet-printed. As result, the OTFT mobility was 0.34 cm 2 /V and the OLED luminance was 64,459 cd/m 2 at 12 V. Kim and Song recently reported another AMOLED device with improved performance [89]. A high mobility of 0.98 cm 2 /V was achieved by using carbon nanotube/Au electrodes and the photo-acryl as a dielectric.…”

Organic light‐emitting fibers and fabrics for truly wearable smart displays: Recent progress and future opportunities

“…However, at around 50 μm thick, the planarization layer caused discomfort when worn. Meanwhile, Kim et al focused on developing an integrated system 53 . They reported a fabric‐based active‐matrix OLED (AMOLED) using a PET fabric and a planarization layer consisting of PU and photo‐acryl (PA).…”

High Performance Yellow Phosphorescent Organic Light-Emitting Diodes Based on an Efficient Carriers Regulating Structure with Iridium Complex as Electron Manager

“…Organic light-emitting diodes (OLEDs) have been rapidly developed since the first demonstration of an efficient organic electroluminescent (EL) device by Tang . To date, some OLED displays and lighting products have trickled into the commercial market. − As one of the milestone discoveries in the OLED field, the pioneering reports of electro-phosphorescence from organometallic complexes have showed enormous potential for developing high-performance phosphorescent OLEDs, where 100% internal quantum efficiency can be realized by spin–orbit coupling caused by heavy metal atom effect. − In the past 20 years, active studies in the fields of materials synthesis and device design have supported the development of phosphorescent OLEDs. − Although phosphorescent OLEDs have realized relatively higher performances in comparison to other kinds of OLEDs, the unsatisfied efficiency and worse efficiency roll-off are still the inextricable topics which might limit the further development toward rapidly gaining a market share in the coming years.…”