Effect of RF Magnetron Sputtered Nickel Oxide Thin Films as an Anode Buffer Layer in a P3HT:PCBM Bulk Hetero-Junction Solar Cells

Bulk heterojunction solar cells were investigated using poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) with a nickel oxide (NiO) anode buffer layer between the photoactive layer and an indium tin oxide (ITO) anode layer. The NiO anode buffer layer was deposited using radio frequency magnetron sputtering on an ITO electrode layer for effective hole transport and electron blocking. The NiO film is a p-type semiconductor with resistivity of 0.35 Ω cm. The power conversion efficiency was improved substantially by the NiO anode buffer layer compared to a solar cell with an anode buffer layer made from poly(3,4-ethylenedioxythiophene) (PEDOT):poly(styrene sulfonate) (PSS). The solar cell with a 10 nm thick NiO anode buffer layer had a power conversion efficiency of 4.71%. These results are explained by the improved charge transport across the interface between the active layer and ITO electrode.