Highly Efficient Organic Photovoltaic Cells with Molybdenum Oxide Buffer Layer

For improving the power conversion efficiency and fill factor of the organic photovoltaic cells (OPVs), molybdenum oxide (MoO3) can be used as a buffer layer. In this study, we fabricated OPVs by inserting a thin and transparent molybdenum oxide (MoO3) layer between the transparent indium tin oxide (ITO) and the organic photoactive layer, with the configuration of ITO/MoO3 (10 nm)/poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PC60BM)/lithium fluoride (LiF)/Al. By spin-coating, the device showed power conversion efficiencies as high as 4.2% under AM 1.5G (100 mW/cm2), enhanced fill factor of 0.67, a short circuit current density (J sc) of 9.32 mA/cm2, and open-circuit voltage (V oc) of 0.67 V. In the case of flexible OPVs, device with 10-nm-thick MoO3 buffer or 45-nm-thick PEDOT:PSS buffer exhibited the power conversion efficiency (PCE) and fill factor (FF) of 1.54% and 0.44 or 0.76% and 0.30, respectively.