Titanium suboxide as an optical spacer in polymer solar cells

The use of a layer of titanium suboxide (TiOx) between the bulk heterojunction (BHJ) thin film and the metal contact in plastic solar cell has been shown to increase both the short-circuit current and the fill factor. Using a combination of optical modeling and device experiments, we clarify the role of the TiOx layer as an optical spacer. For an appropriate choice of the BHJ thickness and composition, the TiOx layer can enhance the absorption within the active layer, thereby increasing the photocurrent and the power conversion efficiency. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3159622]