Chemical prevention of light-induced degradation in amorphous silicon films

The most serious problem for hydrogenated amorphous silicon (a-Si:H) solar cells is light induced-degradation due to the formation of defect states. A simple room temperature chemical method, i.e. the immersion of a-Si:H in crown-ether-containing KCN solutions under a positive bias, has been found to prevent light-induced deterioration of a-Si:H films. The prevention is attributed to the selective reaction of cyanide ions (CN−) with defect and defect precursor states. The inclusion of crown-ether completely prevents contamination of a-Si:H by K+ ions, and the applied positive bias enhances inward migration of CN− ions. The experimental results suggest that this chemical reaction is useful to block the light-induced degradation of a-Si:H solar cells and systems.