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Kim B.S.,Kyung Hee University | Jang W.B.,LG Corp | Jung H.G.,Electronic Materials Research Institute | Jang J.,Kyung Hee University
Molecular Crystals and Liquid Crystals

We have fabricated the flexible organic light-emitting diode (OLED) displays on 10 m colorless polyimide (CPI) substrate using polymer light-emitting diode (PLED). The CPI was chosen as a substrate for flexible device because of its high transparency of around 90% at 550 nm and relatively high temperature process of >300°C. All organic materials for OLED were deposited by spin coating technique and the OLED on PI substrate was encapsulated by the polyethylene terephthalate (PET) film with barrier layer. The PLEDs have a driving voltage of 3 V at 1000 cd/m2, and the current efficiency of 11.7 cd/A for the device on CPI substrate at 1000 cd/m2. © 2014 Taylor & Francis Group, LLC. Source

Lee H.S.,Korea Advanced Institute of Science and Technology | Lee H.S.,Electronic Materials Research Institute | Chung J.,Seoul National University | Chung J.,Ajou University | And 10 more authors.
Advanced Functional Materials

For patients who suffer from sensorineural hearing loss by damaged or loss of hair cells in the cochlea, biomimetic artificial cochleas to remedy the disadvantages of existing implant systems have been intensively studied. Here, a new concept of an inorganic-based piezoelectric acoustic nanosensor (iPANS) for the purpose of a biomimetic artificial hair cell to mimic the functions of the original human hair cells is introduced. A trapezoidal silicone-based membrane (SM) mimics the function of the natural basilar membrane for frequency selectivity, and a flexible iPANS is fabricated on the SM utilizing a laser lift-off technology to overcome the brittle characteristics of inorganic piezoelectric materials. The vibration amplitude vs piezoelectric sensing signals are theoretically examined based on the experimental conditions by finite element analysis. The SM is successful at separating the audible frequency range of incoming sound, vibrating distinctively according to varying locations of different sound frequencies, thus allowing iPANS to convert tiny vibration displacement of ≈15 nm into an electrical sensing output of ≈55 μV, which is close to the simulation results presented. This conceptual iPANS of flexible inorganic piezoelectric materials sheds light on the new fields of nature-inspired biomimetic systems using inherently high piezoelectric charge constants. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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