Large area thin BSF solar cells with simultaneously diffused boron and phosphorus screen printed emitters

The use of thinner substrates is an increasingly important way to reduce the price of crystalline solar cells. In this way, present industrial processes have to be suited, paying special attention to the relevance of the rear surface passivation for the new thicknesses. And in parallel, a clear revival of screen printing (SP) is being observed, because it allows continuous production and shows high reliability at a low cost. This work looks for an answer to these two issues as a whole, by using SP and firing techniques to diffuse emitters onto thin substrates. Acceptable emitters have been simultaneously manufactured on 105 μm Cz substrates in one only thermal step, showing that they are also compatible with high lifetimes and minor leakage currents. This has led to achieve npp and nnp bifacial BSF structures in a very fast process.