In the afternoon of the first day of the IDTechEx conference Printed Electronics Europe 2009 in Dresden, Germany, Samsung Advanced Institute of Technology (SAIT), Sony Corporation and others, presented details about their recent progress in the field of conformal and flexible displays.
Driven by the potential of flexible displays e.g. for Flat Panel Displays (FPD) and Ubiquitous Mobile Displays, SAIT is working on printable TFT Backplanes. Dr Bonwon Koo demonstrated the results of the recent 4.8-in QVGA active-matrix electrophoretic display based on inkjet printed organic transistors on plastic substrates. The low temperature process TFT array has a bottom-gate, bottom-contact device architecture with solution processed organic semiconductor, gate dielectric and passivation. The field-effect mobility of the printed TFTs, calculated in the saturation region, is 0.05~0.1cm2/Vs at Vg=-20 V.
4.8-inch QVGA PTFT array on Plastic: W/L = 130 / 10; S/D: Au; Bank (active) = 150 x 40; Gate, Data Line Width = 20um; Sub Pixel Size = 260um x 260 um (Courtesy of Samsung Advanced Institute of Technology).
Sony, a manufacturer of audio, video, communications and information technology products for the global consumer and professional markets, is one of the World's Leading Consumer Brands. Mr Noriyuki Kawashima from Sony Corporation demonstrated the impressive 10.5-in VGA fully printed OTFT driven E Ink display.
In collaboration with Toppan Printing an OTFT with vertically phase-separated channels was developed that achieved high uniformity and high thermal stability. After optimizing ink formulations and inkjet conditions an OSC inkjetted OTFT was successfully fabricated. Sony Corporation sees the potential use of printed OTFTs in flexible screen displays, wearable PDAs and intelligent paper etc.
Micrograph of pixel array of 10.5-in VGA fully printed OTFT driven E Ink display (Courtesy of Sony Corporation).
During the Texas Instruments Germany talk Mr Oliver Nachbaur pointed out what the requirements for technology and power supply/charge/discharge is for OLEDs and flexible OLEDs. A low output voltage ripple and a Variable Load current are two of the main challenges. The core business of Texas Instruments is integrated circuits. Of the three major semiconductor product lines Analog and Embedded Processing are expected to be the primary growth engines in the next years.
QD Vision is working on printed Quantum Dots (QD) being the only company so far that focuses on QDs for light emitting devices for displays, signage and lighting. Dr Peter Kazlas presented on the potential of quantum QD semiconductor nanocrystals as a printable emitter solution to deliver light with extraordinary color & efficiency, which is tuneable from the visible to infrared. To date QD printing methods include spin casting, contact printing and inkjet printing. Current achievements are the highest reported peak EQE for a QLED (7%) and the world's highest achieved brightness for red QLED; 3-4.6 cd/A at brightness values ranging 1000-10,000 nits. QD Vision is also working on yellow QLEDs and the next step being cadmium free QLED with currently 3.2% peak EQE. THE #1 roadmap point for the next few years is achieving device efficiencies similar to OLEDs.
Contact printing samples of QLEDs (Courtesy: QD Vision).
Simon Jones from Liquavista UK pointed out that the company is planning to scale-up its electronic paper manufacturing process of active-matrix demos and samples - with the transfer to first manufacturing partners within the year. In a 3 year $20 million project with Plastic Logic, Liquavista is targeting flexible, full color, full video and low power always-viewable electronic paper. The company is currently working on an any kind of color architecture enabled by a multiple layer stack with combinations of color sequential backlight units (BLU). This will enable a multi-color electronic paper in the near future. Liquavista's vision is to more than double the performance and substantially reduce the environmental impact of information displays, allowing people to be mobile without compromise.
Courtesy of Liquavista