The precursor comprises at least one layer of doped crystalline silicon and a layer of doped amorphous semiconductor material. The method comprises the steps of placing the cell precursor sandwiched between a grounded conducting plate and a plate made of insulating material coated with a conducting layer, then applying a state change electrical voltage (U1) between the conducting layer and ground, the said state change electrical voltage (U1) being designed to bring the Fermi level at the interface between crystalline silicon and amorphous semiconductor material closer to the middle of the band gap of the said amorphous semiconductor material, while at the same time heating the cell precursor to a defect equilibration temperature (TE), and finally cooling down the cell precursor (10) prior to interrupting the application of the state change electrical voltage (U1).