Ji-Hoon Ko

Rollable transparent glass-fabric reinforced composite substrate for flexible devices.

Recently, there has been considerable interest in fl exible displays, as they facilitate the fabrication of displays that are thin, lightweight, robust, conformable, and fl exible. [ 1 ] To enable a fl exible display, a fl exible substrate must be used as the fundamental starting component in place of a conventional glass substrate. In general, metal foils, ultra-thin glasses, and plastic fi lms are considered candidates for a fl exible substrate. [ 2 ] In particular, fl exible displays using plastic substrates based on organic polymers have been a major topic not only because these show outstanding fl exibility and optical clarity at the same time, but also because they offer the possibility of a reduction in cost, coupled with a roll-to-roll process and ink-jet printing technology. [ 3 ] Common examples of commercially available polymers are polyethylene terephthalate (PET), polyether sulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC), and polyimide (PI). [ 1 , 4 ] To replace conventionally used glass substrates, a plastic substrate must be equipped with the properties of glass, such as optical transparency, thermal/chemical stability, O 2 /H 2 O permeability, low birefringence (or retardation), dimensional stability, and a low coeffi cient of thermal expansion (CTE). [ 1 ] Among these properties, the low CTE of plastic substrates coupled with dimensional stability is arguably the most important requirement, as it is directly related to compatibility with all other necessary display layers to be integrated onto them. [ 1 ] Although there have been extensive studies of fl exible devices built on polymer substrates, such as electrophoretic displays and organic thin-fi lm transistors (OTFTs), little progress have been made even with high-temperature processed devices such as active-matrix liquid crystal displays (AMLCDs). [ 5 ] Major obstacles include the high CTEs of polymers insuffi cient for the display layer integrations. Moreover, polymers usually have low glass transition temperatures ( T g s) where abrupt CTE changes are accompanied. This greatly limits their practical application in terms of the process temperature. Even polymers with a high T g , e.g., PES, are known to have a CTE of ∼ 50 ppm K − 1 , much higher than the typically required level (less than 20 ppm K − 1 ). [ 1 ] Other highT g polymers such as polytetrafl uoroethylene (PTFE) and poly(ether ether ketone) (PEEK) also have signifi cant drawbacks for implementation into large-area plastic electronics, as they are unfavorable in terms of cost. PI has a low CTE of ∼ 20 ppm K − 1 and a high

High-performance hybrid plastic films: a robust electrode platform for thin-film optoelectronics

We report a novel flexible hybrid plastic film that can be used as a robust electrode platform for typical thin-film optoelectronic devices. Silver nanowires (AgNWs) were embedded on the surface of a glass-fabric reinforced transparent composite (GFRHybrimer) film to form a flexible transparent conducting substrate with excellent opto-electrical properties, superior thermal stability, and impressive mechanical flexibility. A highly efficient and flexible inverted organic solar cell with a power conversion efficiency (PCE) of 5.9% under 100 mW cm−2 AM 1.5G illumination was fabricated on the AgNW–GFRHybrimer film. The AgNW–GFRHybrimer film exhibits potential as an excellent transparent electrode for low cost flexible optoelectronic devices.

Flexible Hard Coating: Glass‐Like Wear Resistant, Yet Plastic‐Like Compliant, Transparent Protective Coating for Foldable Displays

A flexible hard coating for foldable displays is realized by the highly cross-linked siloxane hybrid using structure-property relationships in organic-inorganic hybridization. Glass-like wear resistance, plastic-like flexibility, and highly elastic resilience are demonstrated together with outstanding optical transparency. It provides a framework for the application of siloxane hybrids in protective hard coatings with high scratch resistance and flexibility for foldable displays.

Effects of Sol-Gel Organic-Inorganic Hybrid Passivation on Stability of Solution-Processed Zinc Tin Oxide Thin Film Transistors

We fabricated solution-processed zinc tin oxide (ZTO) TFTs with sol-gel organic-inorganic hybrid passivation layers owing to their solution-processibility and good water and oxygen barrier property. The sol-gel organic-inorganic hybrid passivation layers reduce hysteresis of the TFTs without deterioration of performance. The gate bias stability and the environmental stability under high temperature and relative humidity are also improved compared to unpassivated and poly(methyl methacrylate) (PMMA) passivated TFTs. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3603845] All rights reserved.

Flexible amorphous silicon solar cells on surface-textured glass-fabric reinforced composite films

Flexible and lightweight amorphous silicon (a-Si:H) based thin-film solar cells on surface-textured glass-fabric reinforced inorganic-organic hybrid materials (hybrimer) composite films are developed in a superstrate configuration. The flexible and transparent film for the substrate was fabricated by impregnation and lamination of a woven glass-fabric with an epoxy-oligosiloxane based hybrimer on glass used as a temporary substrate. The epoxy hybrimer film showed high optical transparency of more than ∼90% for wavelengths above 500nm and light scattering property. In order to improve light trapping, the surface texture of the film was replicated from a master texture of Asahi U-type glass by nanoimprint lithography. The fabricated cell was a single junction structure of ZnO:Al/p-μc-Si:H/p-a-SiC:H/i-a-Si:H/n-μc-Si:H/Al on the flexible film, and the thickness of i layer is ∼300 nm. The flexible a-Si:H solar cell on surface-textured expoxy hybrimer film showed an conversion efficiency of 6.4%.

P‐69: PDP Fabricated with Low‐Temperature Processes Below 300°C Using Sol‐Gel Hybrid Polymers (Hybrimer PDP)

PDP was fabricated using low-temperature processable sol-gel hybrid polymers (hybrimers) as the dielectric and barrier rib materials replacing the glass frits. All the processes including dielectric coating, barrier rib molding fabrication, phosphor printing and sealing were performed at low temperature below 300°C. This new process is easy, simple and cheap to be capable of producing a large PDP with high yield without applying high temperature processes.