Flexible Glass
Published: October 19, 2011 Category: Advanced Materials

What if you could eliminate the need (at least mostly) for flexible dyad encapsulation layers by using ultrathin, flexible glass as the substrate? The idea here is that the benefits of glass—higher conversion efficiency, heat tolerance, pinhole-free surfaces, and better barrier properties—might be preserved as the glass is made thin enough to be reasonably flexible.

Corning is a leader in this concept, with Corning 0211, an ultra-thin flexible glass product with an eye toward R2R processing, but it is by no means the only glass company active in this area. NEG, AGC, and Schott also have lines of thin, flexible glass, including AGC's ultra-thin alkali-free float glass and Schott's D 263, AF 45, and AF 32.

Outside of Corning, much of the activity in flexible glass has been directed toward the touch screen and PV markets instead of OLEDs, and there is additional development work required to get the flexible glass' performance where it needs to be for flexible OLEDs.  Lamentably, it is possible that polymer coatings on the glass may be required to impart durability and strength, which adds cost and complexity to the product, potentially partially offsetting some of the anticipated benefits.

At first glance, the cost of flexible glass is high; certainly the first generation of prototype and pilot products is expensive.  However, cost in glass manufacturing is directly related to the cost of the energy required to melt the glass, so the material cost is proportional to the volume of glass produced.  Since flexible glass aims to greatly reduce the thickness of glass used for OLED encapsulation, down to thicknesses similar to those anticipated for plastic barrier laminates, the cost of flexible glass encapsulation has the potential to go much lower than one might expect.

The deep expertise within Corning, especially with respect to optical glass fiber production and handling, gives Corning an advantage in this effort.  The company believes it can drive out costs and make flexible glass competitive with (currently non-existent) plastic-based systems for OLEDs. 

What is clear is that since plastic-based flexible encapsulation systems with high barrier performance are still not commercially available at a large enough scale to offer tangible cost benefits, flexible glass technologies may win out in the end.  As already noted, especially in OLED lighting applications, true flexibility is probably not really required, so simpler bendable displays with very long lifetimes enabled by the use of glass may be just the thing that is needed.