Comprehensive comparison of different rear side contacting methods for high-efficiency solar cells

High-efficiency solar cells have to be designed carefully in order to minimize all possible losses. One of the critical parameters to obtain good performance, is the rear side recombination velocity. There are many approaches to passivate the rear side. They differ not only in their passivation quality and their optical properties but also in the complexity of the process steps. We have investigated the six most common methods for rear side contacting and their potential to achieve high efficiencies: dielectric passivation with local back surface field (LBSF/PERL), dielectric passivation with ohmic contacts (PERC), dielectric passivation with laser-fired-contact (LFC), full area Boron-Back Surface Field (BSF), screen-printed Aluminium-BSF and evaporated Aluminium (ohmic contact).