Solid-State Lighting as an Opportunity for Silver Inks and Pastes

Published: June 01, 2010    Category: Advanced Materials

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NanoMarkets believes that one of the fastest growing technology markets in the next five years will be solid-state lighting (SSL).  This sector consists of high-brightness LEDs (HB-LEDs), organic LEDs (OLEDs) and an already well-established technology; electroluminescent (EL) light.  SSL is about to get a boost from the phasing out of incandescent bulbs on energy efficiency grounds that will occur in the U.S., Europe and many other geographies that will occur around 2012.

SSL is a core focus of NanoMarkets and we discuss its prospects in depth in a number of our reports and articles.  Here, however, our interest is in SSL as a market for silver inks and pastes.  We expect this market to get close to $250 million in sales by the middle of this decade.   This compares with almost zero revenues at the present time.  Our principal interest in this article is with silver used for OLED and EL lighting in electrodes and bus bars.  Silver is not used in HB-LED lighting.

Uses of Silver in OLED Lighting

OLED lighting is just at the beginning of its market evolution.  Although a number of very “cool” OLED light fixtures have appeared at major lighting trade shows, the reality is that if you want to buy OLED lighting today, what is available to you would be kits consisting of some OLED material and the necessary electronics.  These kits are intended for designers who want to work with OLEDs and take OLED lighting to the consumer product level.  An encouraging sign for OLED lighting is that important firms are investing in its development.  The three giants of the lighting industry – GE, Osram and Philips -- are all in this space, as are leading OLED firms such as Novaled, and UDC.

Printed silver already has a foothold in the OLED business.  It has been discussed as an electrode material for OLED displays and this thinking would certainly translate into use in the lighting environment.  At least one company -- Add-Vision (AVI) – has already made silver cathodes a core part of its technology.  The motivation here is that more conventional cathode materials such as calcium are extremely sensitive to environmental conditions, requiring tightly controlled deposition conditions. Even after the cathode has been evaporated, it must remain inside a nitrogen environment, which adds complexity and cost to manufacturing. 

By adopting silver as a cathode, AVI is able to create a manufacturing environment in which OLEDs can be printed.  While these OLEDs are not high-performance; of the kind that could be used for say a high-definition television, they are very suitable for simple backlighting, signage, etc., adding a brightness and variety of colors that have not been available before.  In this sense, silver pastes, represent an enabling technology for OLEDs, allowing them to reach market segments that would not be available to them using conventional materials.

Another way that silver could serve as enabling lighting in the OLED lighting is by serving as bus bars.   To be commercially successful, OLED lighting must be available in relatively large-sized panels; a few feet across, not the few inches that is achievable now.  The problem here is that if one thing has been learned through the course of development of OLED lighting it is that their lighted appearance is very sensitive to voltage drops.  Long passes of current through relatively high-resistivity ITO or comparable transparent conductors result in voltage drops that appear visibly as dimmed portions of the device. 

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