Analysis of the impact of geometrical and technological parameters on recombination losses in interdigitated back-contact solar cells

This paper presents a detailed analysis of the recombination losses in an interdigitated back-contact (IBC) solar cell by means of three-dimensional numerical simulation. In particular, we discuss about the influence of geometrical and technological parameters such as the bulk thickness, the emitter contact fraction and the passivation effectiveness of the gap region on the saturation current density and on the carrier collection efficiency at region and mechanism-wise level. Moreover, the simulation results in terms of main figures of merit of the solar cell are reported and discussed. The paper shows that, except for the parasitic resistive losses, the optimum contact fraction at the emitter and base strongly depends on the presence of physical competing mechanisms, such as the internal optical bottom reflectivity and the recombination losses at the passivated emitter and base. In addition, the study underlines the critical role played by the passivation properties of the gap region, which may potentially be detrimental in terms of Fill-Factor and conversion efficiency.