Application of Wide Band Oxide Semiconductor in Bulk Heterojunction Solar Cells

Abstract

To minimize interfacial power losses, thin layers of NiO, a p-type oxide semiconductor, are inserted between the active organic layer, poly(3-hexylthiophene) (P3HT) [6,6]-phenyl-C61 butyric acid methyl ester (PCBM), and the ITO (tin-doped indium oxide) anode of bulk-heterojunction ITO/P3HT:PCBM/Al solar cells. The interfacial NiO layer is deposited by radio frequency (RF) magnetron sputtering deposition directly onto cleaned ITO, and the active layer is subsequently deposited by spin-coating. Insertion of the NiO layer affords cell power conversion efficiencies as high as 2.5% and enhances the fill factor to 56% and the open-circuit voltage (Voc) to 605 mV versus ones without NiO buffering layer control device. The value of such hole-transporting/electron-blocking interfacial layers is clearly demonstrated and should be applicable to other organic photovoltaics.