Enhanced performance with bismuth ferrite perovskite in ZnO nanorod solid state solar cells

This paper reports for the first time the use of perovskite bismuth ferrite (BiFeO₃ or BFO) on ZnO-based solid state solar cells using only chemical solution methods for materials synthesis. As ZnO has poor chemical stability in acidic and corrosive environments, a buffer method using aminosilane ((3-aminopropyltriethoxysilane or H₂N(CH ₂)₃Si(OC₂H₅)₃)) coating was used to provide a protective coating on the ZnO nanorods. The aminosilane layer was removed after BFO coating. The solid state solar cells, sensitized by N719, used CuSCN as the hole conductor and were tested under 100 mW cm ^-2, AM 1.5G simulated sunlight. The photovoltaic performance showed current density improvement from 0.64 mA cm^-2 to 1.4 mA cm ^-2 and efficiencies from 0.1% to 0.38% when comparing between ZnO and ZnO/BFO solar cells. The observed ca. 400% improved performance is shown to result from BFO's role as an electron blocking layer.