Preparation and Characterization of Nanorod-like TiO_2 and ZnO Films used for Charge-Transport Buffer Layers in P3HT Based Organic Solar Cells

摘要

With the aim of findingout the appropriate buffer layers for organic solar cells (OSC), TiO_2 and ZnO on ITO/glass were prepared as nanorod-like thin films. The TiO_2 films were crystallyzed in the anatase phase and the ZnO films, in the wurtzite structure. The nanorods in both the fims have a similar size of 15 to 20 nm in diameter and 30 to 50 nm in length. The nanorods have an orientation nearly perpendicular to the ITO-substrate surface. From UV-Vis data the bandgap of the TiO_2 and ZnO films were determined tobe 3.26 eV and 3.42 eV, respectively. The laminar organic solar cells with added TiO_2 and ZnO, namely ITO/TiO_2/P3HT:PCBM/LiF/Al (TBD) and ITO/ZnO/P3HT:PCBM/LiF/Al (ZBD) were made for characterization of the energy conversion performance. As a result, comparing to TiO_2, the nanorod-likeZnO filmwas found to be a much better buffer layer that made the fill factor improve from a value of 0.60 for TBD to 0.82 for ZBD, and consequently thePCE was enhanced from 0.84 for TBD to 1.17% for ZBD.