BIPV Encapsulation Markets Preview
Published: April 26, 2012 Category: Advanced Materials Renewable Energy

Dyadic systems: Recently however, higher efficiency CIGS-based modules (10-13 percent efficiency) have entered the market.  These new CIGS modules use dyadic encapsulation systems that provide protection that will pass a 30-year reliability spec, but currently are very expensive. The need from an encapsulation perspective is to develop materials with equivalent hermetic seal and long-term reliability as in the dyadic systems, but at a lower cost.

The current dyadic systems incorporate two or more alternating layers of polymer and thin ceramic.  Multiple layers are used to eliminate pinholes and provide a material that will last multiple years in outdoor environments.  Vitex Systems was early to the game in dyadic barrier technology,  but it recently went out of business.  Firms such as Dow, Fujifilm, DuPont, and 3M are actively working on dyadic and other barrier concepts to improve the encapsulation solutions available. 

Borrowing from the semiconductor industry: One promising area for encapsulation beyond the dyadic systems that may provide similar performance and lower cost is the use of multiple, very thin layers of silicon oxy nitride and silicon nitride using the plasma-enhanced chemical vapor deposition (PECVD) or atomic layer deposition methods common in the semiconductor industry. 

These systems have already shown some success in greatly improving OLED barrier performance, and are used in volume manufacturing as a protective overcoat in semiconductor devices before packaging.  It remains to be seen if such systems, which provide such good encapsulation on chips up to a centimeter on a side, can be scaled to provide pinhole-free protection over areas of multiple meters. 

Another barrier system that has shown success in the lab is ultra-thin TaN/Si3H4.  TaN is the current barrier used in the semiconductor industry to encapsulate copper metallization in 130 nm and below technologies.  Leveraging semiconductor barrier technology and infrastructure for BIPV encapsulation as has been done in other PV processes seems a likely path to improved materials without re-inventing the wheel.  Atomic Layer Deposition (ALD) is another technique used in the semiconductor industry that has shown promise for depositing high performance barrier films.

Potential of flexible glass: In addition to new encapsulation systems based on semiconductor barriers, other flexible encapsulation technologies include thin, flexible glass such as the lines developed by Corning and Schott

Part of their promise is the likelihood that such materials would retain many of the properties of thicker glass, such as dimensional stability, heat tolerance, and impermeability, while permitting roll-to-roll processing and limited flexible applications. These types of materials are not viable options yet, however. 

Advances in organic systems: While pinholes are still an issue for most organic polymer-only encapsulation systems, several organic-based encapsulation materials are still being investigated. A transparent poly(ethylene naphthalate) (PEN)-based ultra-high barrier material has been demonstrated in the lab as a possible organic encapsulation material for organic- based flexible PV modules.  It remains to be seen if a single layer organic can be deposited pinhole free and meet all of the BIPV reliability metrics, but work continues in this area in the lab and in prototypes. 

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