Several new concepts to increase the conversion efficiency of solar cells have been presented over the last few years. One possibility is the multi-interface novel device solar cell with a highly doped amorphised substructure inserted in the emitter. This active nanostructure is created by P ion implantation followed by an adequate thermal treatment necessary to form two sharp a-Si/c-Si heterointerfaces. After an incomplete initial thermal treatment at 500degreesC, dark current-voltage (I-V) characteristics were measured after each of several complementary thermal treatments, In this paper, we show that the classical two-diode model has to include a voltage reduction resulting from the two low-high-type interfaces in order to correctly fit the experimental curves. (C) 2002 Elsevier Science B.V. All rights reserved.