Intermediate layer and back surface field optimisations for the recrystallised wafer equivalent

This paper presents the investigations on two major process steps for recrystallised wafer equivalent solar cells: First the properties of the intermediate layer with respect to its optical performance in the material and in the final device were evaluated. Second, the performance of different doping concentrations in back surface fields and the resulting effects on passivation and lateral conductivity in a laser fired access concept have been investigated. Due to these process optimisations efficiencies of 13.2 % have been obtained. So far a Jsc of 33.3 mA/cm², Voc of 614 mV and FF of 78 % have been achieved as champion values however these values were measured on different samples. This paper presents the comprehensive analysis of the shortcomings, the underlying effects and presents ways to remedy those.