Temperature-dependent performance of silicon heterojunction solar cells with transition-metal-oxide-based selective contacts

The temperature coefficient (TC) is an essential figure of merit to accurately evaluate solar cell performance at various operating temperatures and hence enabling the comparison between different cell technologies. Recently, solar cells that use passivating contacts based on transition metal oxide (TMO) layers have attracted much attention due to their excellent performance. Therefore, knowledge of their TCs and insights into their performance at various operating temperatures are of significant interest. In this study, we investigate the temperature-dependent performance of solar cells with TMO-based passivating contacts at various illumination intensities. We then compare their performance to that of standard silicon heterojunction (SHJ) solar cells. The efficiency TC (TC eta) of solar cells that use passivating contacts based on molybdenum oxide (MoOx) and titanium oxide (TiOx) films is found to be almost identical. Both outperform the TC eta of the standard SHJ cells and are greatly superior to those of cell structures without passivating contacts. The superior TC eta of the MoOx-based cells is mainly due to their favourable TCs of the short-circuit current density (TCJsc) and fill factor (TCFF), whereas the superiority of TC eta of the TiOx-based cells is solely resulting from the superior TCFF. The favourable TCJsc of the MoOx-based cells is explained by an enhanced spectral response at short wavelengths with increasing temperature, due to the improvement of the passivation quality of the MoOx-based passivating contacts. The beneficial TCFF of both solar cells is partly resulting from the improvement of the contact resistivity of the TMO-based passivating contacts which counterbalances some of the fill factor losses at elevated temperatures. Although an improvement of the passivation quality of the TMO-based passivating contacts is observed at elevated temperature, it does not have a strong impact on the TC of the open-circuit voltage of the investigated solar cells. Furthermore, we also found that the studied cells are less sensitive to temperature variation at higher illumination intensities.