The effect of molybdenum oxide interlayer on organic photovoltaic cells

Both small molecule and polymer photovoltaic cells were fabricated with molybdenum oxide interlayer at the indium tin oxide electrode. Enhancement in power efficiencies was observed in both small molecule and polymer cells. Specifically, the power conversion efficiencies of small molecule cells with the molybdenum oxide interlayer were enhanced by a maximum of 38% due to a significant enhancement in the fill factor. The improved fill factor is attributed to the reduction in series resistance. Our ultraviolet photoemission spectroscopy data indicate that the formation of band bending and the built-in field at the interface due to the interlayer leads to enhancement in hole extraction from the photoactive layer toward the anode. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3220064]