Single-layer organic-inorganic-hybrid thin-film encapsulation for organic solar cells

We demonstrate an organic-inorganic-hybrid thin-film encapsulation technique for organic solar cells. The single-layer encapsulation thin film is deposited from a gas mixture of hexamethyldisiloxane and oxygen by plasma-enhanced chemical vapour deposition at room temperature. The encapsulation film contains organic and inorganic compounds: the inorganic compounds serve as the permeation barriers, and the organic compounds reduce defect propagation. An optical transmission of >= 90% in the visible light region and a water vapour transmission rate of 3.6 x 10(-6) gm(-2) day are obtained for a 1.5 mu m thick hybrid film. Efficiency decay is not observed in the inverted organic solar cell coated with this thin film after exposure to air for 3600 h; in contrast, the efficiency of the unencapsulated counterpart degrades rapidly and fails after exposure to air for 120 h. The obtained results show that this organic-inorganic-hybrid thin film is promising for the encapsulation of organic solar cells.