Flexible package for the plastic solar cell
The aim of the project was the development of a flexible package for the plastic solar cell. During the first part of the project a method for the evaluation of encapsulation materials was developed. The method allows measuring very low water and oxygen permeation rates. After establishing the permeation rate measurement several commercially available and for the project developed packaging foils from ISOVOLTA were investigated. For the non-transparent encapsulation material an applicable solution could be identified. All tested transparent foils exhibited a too high water and oxygen permeation rate. During the second part of the project plastic solar cells were encapsulated using various packaging materials and tested under accelerated conditions. As the reference system plastic solar cells encapsulated by thin glass slides were used. The permeation rate of oxygen and water through glass is very low and therefore offers and ideal protection for the solar cells. Solar cells were exposed to different temperatures (from -40°C to 85°C) and air humidity (0% -90%) and the change of the solar cell efficiency was recorded versus time. Glass packaged devices passed all tests with little or no degradation. On the other hand devices with a flexible package showed a very strong degradation when stored at elevated temperatures and high air humidity.
The performed experiments lead to the following rather different conclusions:
- The available transparent flexible packaging materials are not sufficient to protect the plastic solar cell from the negative effects of water and oxygen.
- The plastic solar cell degrades too fast in the presence of water and oxygen.
During the project the second conclusion has prevailed. As a consequence a detailed investigation of the degradation processes occurring in a plastic solar cell was initiated. A couple of novel concepts have been tested recently for stabilizing the plastic solar cell under ambient conditions. First results have been very promising. This would result in a significant cost reduction compared to the encapsulation materials investigated earlier.
DI. Franz Padinger
Konarka Austria Forschungs- u. Entwicklungsges.m.b.H
Projekt- bzw. Kooperationspartner
ISOVOLTA AG (Projectpartner)