In recent years

organic solar cells evolve in an exponential manner in efficiency

increasing from 5% to over 11%. The promise of organic photovoltaic(OPV)as a future energy technology has received more attention. However

problems of stability may hinder commercial application of that. Inorganic silicon-based solar cells may last on the order of 25 years

while organic materials are by nature more susceptible to chemical degradation from e.g. oxygen and water than that

which leads to a shorter lifetimes of the order of thousands of hours. Polymer solar cells are complicated multilayer structures where each component may fail for different reasons

the stability and degradation issue are certainly not yet fully understood. Besides

development of encapsulation using novel methods may present new stability challenges. In this review

the current understanding of stability and degradation in organic solar cell devices is presented and the photo-stability of the active polymer materials

the inverted device structure of the bulk heterojunction geometry device

morphology control and the specific stability issues of roll to roll method are discussed.