Latest R&D results of Q.antum technology and consideration of symmetrical passivation schemes

In this paper we present the latest R&D results of Q.Cells' high-efficiency solar cell and module concept Q.antum that is currently transferred into mass production. The current work is focused on solar cells and modules produced in our Reiner-Lemoine Research Center. Our optimized rear passivation concept in combination with innovations on the front side of the solar cell resulted in record module efficiencies of 18.5% based on isotropic textured multi-Si substrates. In addition we adopt our Q.antum process on mono-cast (mono-like-multi) Si wafer. These wafers were disposed to an alkaline texturing process and converted into a solar module with record output powers of 283 W. By following the idea of an evolutional cell development a symmetrical passivation that means having the same passivation material on front and rear side could displace cells with different passivation materials on front and rear side. On basis of diffused and non-diffused lifetime test samples we investigate in particular the saturation current density to evaluate the open circuit voltage potential and consequently the feasibility of the evaluated dielectric films for the application as symmetrical passivation scheme. These results were extended by analyzing the implied J-V characteristics to get insights into the feasibility of the investigated passivation schemes.