Effect of electron transport layer crystallinity on the transient characteristics of inverted organic solar cells

We present how the crystallinity of the electron transport layer can dramatically influence the transient characteristics of organic solar cells. We employed an inverted cell structure using TiO(x) prepared by atomic layer deposition as an electron transport layer. The device possessing the amorphous phase TiO(x) exhibited a continuous increase in the device characteristics upon continuous illumination at ambient, which is attributed to the filling of shallow electron traps within the amorphous phase TiO(x) upon illumination. In contrast, the characteristics of the device with the crystalline phase TiO(x) showed a negligible increase upon continuous illumination. (C) 2011 American Institute of Physics. [doi:10.1063/1.3628319]