Temperature-dependent performance of silicon solar cells with polysilicon passivating contacts

Abstract

The temperature coefficient (TC) is a critical figure of merit to accurately evaluate the performance of solar cells at various operating temperatures, and hence, enabling the comparison between different cell technologies. Recently, tunnel oxide passivated contact (TOPCon) solar cells have shown outstanding cell performance. They are likely to be adopted in production lines and deployed in the field in the near future. Therefore, knowledge of their TCs and insights into their performance at realistic operating temperatures are of significant interest.In this study, we investigate the temperature dependence of the performance of TOPCon solar cells and quantify their TCs. To gain better understanding regarding the temperature-dependent behavior of their performance, the passivation quality and the contact resistivity of polysilicon (poly-Si) passivating contacts as a function of temperature are investigated. Although an improvement of the passivation quality of these contacts with increasing temperature has been observed, it seems that this improvement weakly impacts on the open-circuit voltage TC. The cell performance at elevated temperatures is dominated by the drop in the open-circuit voltage, associated with the intrinsic carrier concentration related to band gap narrowing. The fill factor TC (TCFF) is superior to those of other cell structures reported in the literature. We attribute this favorable TCFF to the fact that some of the fill factor losses are compensated by the decrease of contact resistivity of the poly-Si passivating contacts at elevated temperatures. The relative TC of the cell efficiency of the investigated TOPCon cells is comparable to the TC of silicon heterojunction cells and it is superior to those of cell structures without passivating contacts. Moreover, we found that the investigated solar cell is more sensitive to temperature variation at lower illumination intensities.