The use of inorganic layers as hole transport materials (HTM) has been suggested to enhance the resistance to degradation of methylammonium lead halide perovskite based solar cells. Few inorganic materials have been tested with limited success as they led to a lower power conversion efficiency (PCE) than the value obtained using spiro-OMETAD. In this work, we used wxAMPS and SCAPS software to compute the key characteristics of CH3NH3PbI3 based solar cells with various HTM layers including spiro-OMETAD, NiO, CuI, CuSCN, and Cu2O. The computations were carried out by considering defect free perovskite and HTM layers. The results show that solar cells containing Cu2O as HTM outperform all other devices with organic or inorganic HTM hitherto tested. A power conversion efficiency exceeding 24% was obtained. These results indicate that there is a possibility to further increase the performance of perovskite based cells and reduce their cost by replacing the expensive and moisture sensitive spiro-OMETAD by copper oxide. (C) 2015 Elsevier Ltd. All rights reserved.