Application of sputter-deposited amorphous and anatase TiO2 as electron-collecting layers in inverted organic photovoltaics

Abstract We demonstrate the deposition of amorphous and anatase TiO 2 on indium tin oxide (ITO) substrates via the process of sputtering, and the use of these materials as electron-collecting layers (ECLs) in inverted-type organic photovoltaics (OPVs). Anatase TiO 2 was obtained via vacuum-annealing of as-deposited amorphous TiO 2 at 300 °C. No deterioration of optical and electrical properties of ITO was observed after both sputter-deposition of TiO 2 and annealing process. The anatase TiO 2 proved to be an effective ECL when employed in inverted OPVs using bulk heterojunction photoactive layer of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester, achieving a power conversion efficiency of 3.3% ( J SC = 9.0 mA cm −2 , V OC = 0.62 V and FF = 0.60).