The present work shows the effect of magnesium doping on structural, optoelectrical and electrical properties of Cu2O thin films prepared by spray pyrolysis. The variation in the concentration of Mg shows significant impact on the final thin film properties, whereas the film doped with 0.5 at% of Mg exhibited major property improvements in comparison with the undoped thin film and among the other concentrations tested. This condition was further applied for the deposition of an absorber layer in a heterojunction solar cell array with a gradient in thicknesses of active layers to investigate the impact of changing thicknesses on the PV parameters of the solar cell. TiO2 was used as a window layer and the 0.5 at% Cu2O doped film as an absorber layer. The produced heterojunction solar cell array was further exposed to a rapid thermal annealing treatment. The I-V measurements show an open circuit voltage of up to 365 mV and a short circuit current density, which is dependent on absorber layer thickness, and reaches to a maximum value of 0.9 mA/cm(2). (C) 2015 Elsevier B.V. All rights reserved.