Fraunhofer ISE, Germany

Silicon solar cells with full-area passivated rear contacts: Influence of wafer resistivity on device performance on a 25% efficiency level


Screen-printed Al-BSF silicon solar cells have dominated the PV market for decades. One of the advantages of the Al-BSF cells is the simple one-dimensional current flow pattern in the base resulting in high fill factors. R&D at Fraunhofer ISE aims at realizing such a 1D structure by applying a passivated contact scheme consisting of a tunnel oxide covered by a heavily doped silicon film, called TOPCon. A champion efficiency of 25.1% on n-type silicon was presented in the past showing the high potential of this technology. In particular, the high fill factors above 83% obtained on these cells are a result of the 1D current flow pattern. In this presentation we focus on the influence of the wafer resistivity on the performance of such cells on a 25% efficiency level. For this purpose we have fabricated both sides contacted solar cells with the TOPCon rear contact using n-type silicon wafer with different resistivities.


Armin Richter received his Ph.D. in physics in 2014 with work on the development of n-type silicon solar cells with a fronts side boron-doped emitters by applying industrial feasible concepts and the in depth characterization of aluminum oxide based silicon surface passivation.

Besides this, his research interests include atomic layer deposition of surface passivation layers, a fundamental understanding of surface passivation based on the electrical and structural interface properties, fundamental recombination processes in silicon (in particular Auger recombination), as well as the development of high efficiency n-type silicon solar cells along the whole process chain.