IDTechEx Analyzes New Chemistry Of Printed Electronics
IDTechEx has recently published a report, “Printed Electronic Forecasts, Players, Opportunities 2008-2028.” According to the report, the printed electronics business largely consists of applications such as screen, flexo and gravure printed silver for RFID antennas and membrane keyboards and carbon and metal for printed heaters and sensors.
Transparent electrodes, antistatic and RF shielding are increasingly printed in indium tin oxide (ITO), polyanilene or polythiophene, and screen printed ac electroluminescent displays on polyester film employ copper doped since sulfide and ITO. Few elements have been involved but that is now changing, with the first sales of printed organic light emitting diode (OLED) displays, a variety of screen printed and thin film manganese dioxide zinc, lithium ion and lithium polymer batteries, inkjet printed copper indium gallium diselenide CIGS photovoltaics and dye sensitized solar cells (DSSC), the latter based on titanium dioxide with ruthenium-based organic dye.
Specially developed inkjet printing has now overtaken screen as the favored manufacturing technology for printed electronics today but no one printing technology will ever do everything.
The Chemistry of Printed Displays
Printed alternating current electroluminescent displays are exhibiting better colors and longer life as the chemistry improves but they will be overtaken by the even faster growing electrophoretic displays employing titanium dioxide, carbon and organics to give exceptionally low power and good viewing in sunshine. OLEDs have the potential to replace today’s TV and phone screens, and to provide ubiquitous “wallpaper” lighting and even disposable electronic displays showing moving solar images on packaging. The first OLED television displays have exceptionally vibrant colors, narrow viewing angle and lack of pixilation when the camera is panned.
However, OLEDs are a tough business to be in and those developing OLED lighting tend to be different companies from those pursuing OLED displays, because the requirements are so different. Although more than 200 organizations started to develop OLEDs, we now have attrition with several leaving the business in frustration every year because it is so tough to meet the required price and performance points.
The leaders in OLED materials are investing huge amounts of money to get on top of the fragile chemistry. Although versions sandwiched in glass are selling well, profits are elusive. The advent of mass produced, flexible, low cost OLEDs, particularly wide area types with long life, keeps slipping further into the future. Yet these are the largest potential OLED market because they enable many exciting new product concepts. To extend life and improve electronic and optical performance, an ever widening choice of elements is being employed by those in for the long haul. Fine chemical companies concerned with inorganic materials are among those coming to assist the device makers.
Versatile New Materials
A fairly recent development by materials supplier Merck and others is phosphorescent technology for OLEDs. This offers the prospect of exceptionally high efficiency while, except for a difficult blue challenge, maintaining color purity and long lifetime for red and green. This promising triplet approach has been shown to be capable of being adapted for printing using solution processes.
Phosphorescent OLEDs, such as those employing iridium-based dyes, have been developed by Pacific Northwest National Laboratory (PNNL) in the U.S. and others. It has used organic phosphine oxides as electron transport materials. These materials address the critical issue of achieving high quantum efficiency at low voltages.
One class of new OLED materials developed at PNNL is based on organic phosphine sulfides. In addition to OLEDs, these material have the potential to be used in other devices, including photovoltaic cells and thin-film transistors.
It is not unusual for an advance in materials for one device to be applicable to others. Another example of this is Kovio’s printed nanosilicon transistors opening up a new advance in photovoltaics.
For more information, contact the author of this study, Peter Harrop, at email@example.com.