Evidence that degradation in a-Si:H solar cells is an i layer effect

Information has been obtained on light-induced degradation and annealing in a-Si:H by the use of homogeneous films, not solar cells. This study summarizes these advances and compares them with data on corresponding effects in cells. This comparison provides consistent evidence that cell degradation can be inferred from the properties of bulk defect generation in films. This evidence comes from anneal kinetics, the existence and properties of saturation, degradation kinetics, thickness dependence of degradation, and performance modeling of films and cells. There seems to be no substantial evidence that cell properties are degraded seriously by other effects. Thus, film properties can be generally used as guides for cell stability