Speaker: Yifeng Chen
Local Al-BSF is a current topic in research and development of crystalline Si solar cells for mass production. It has been difficult to measure the recombination properties of Al-BSFs, e.g. in terms of their saturation current J0. However, the simulation models of Al-BSFs have significantly improved in recent years. In this research, we apply numerical device modelling, based on incomplete ionization and updated parameters of Al-O complex in the Al-BSF region, to analyse the recombination dynamics in cells being fully covered with Al-BSF, or having screen-printed Al-BSF fingers and rear Al2O3 passivation layer. With an improved emitter (feasible for mass production), and with screen-printed both the front metallization and rear Al-BSF fingers, about 19.6% or 20.3% cell efficiency may be reached after light-induced degradation (LID) or deactivation of the B-O complex. With a J0 = 50 fA/cm2 emitter, we show potential efficiency of 21.4% for point-contact PREC structure with deactivation wafer.