This paper reports on the fabrication of ZnO nanowalls for use as an electron collecting layer (ECL) in CH3NH3PbI3 perovskite solar cells (PSCs). Two-dimension ZnO nanowalls were grown using a low temperature chemical bath method with a thin Al film as a seed layer. We compared electron collecting layers based on nanowalls and sol-gel derived ZnO thin film in PSCs and sought to identify the mechanism underlying the collection of electrons. The proposed ZnO nanowalls achieved a fill factor significantly higher than that of ZnO thin films, which translated into a remarkable improvement in power conversion efficiency, reaching 13.6% under AM 1.5G illumination. (C) 2016 Elsevier B.V. All rights reserved.