Sodium doped p-type Cu2O film deposited by electrochemical method was achieved by adding sodium alumina complex compound to the copper (II) lactic solution. The optimal incorporated Na content (measured in partial atomic percentage at. %) in Cu2O film was found to be approximately 139 at.%. As the Na content increased the resistivity dramatically decreased from (1.2 x 10(6) to 330) Omega.cm and the carrier concentration was also increased from (5.1 x 10(14) to 1.7 x 10(18)) cm(-3). The XPS result shows the appearance of a binding energy at 1072.4 +/- 0.2 eV corresponds to the presence of sodium related to sodium oxide. The Mott-Schottky plot confirms that the Cu2O film conductivity type was p-type and remains unchanged after the doping process. Cu2O/Si p-n heterojunction was fabricated using the undoped and the optimized Na-doped Cu2O film. The efficiency was improved from 0.05% to 0.45% or about nine times its value for the undoped. (C) 2016 Elsevier B.V. All rights reserved.