Ga-doped Czochralski silicon with rear p-type polysilicon passivating contact for high-efficiency p-type solar cells

Abstract The use of Ga-doped Czochralski (CZ) silicon wafers in Passivated Emitter and Rear Cells (PERC) has been confirmed to have a prominent advantage in suppressing light-induced degradation (LID), which will attract considerable attention for the application of Ga-doped wafers in more efficient photovoltaic devices. In this work, we investigate the passivation quality and address the issue of LID in Ga-doped CZ Si wafers equipped with p-type polysilicon passivating contact that consists of an ultrathin SiOx and a heavily doped polysilicon. We also present the modeling results for solar cells using this type of contact. The experiments show that samples with Ga-doped CZ Si wafers have superior anti-LID properties when compared to the samples with B-doped wafers. An excellent passivation performance with a high implied open-circuit voltage (iVoc) of 705 mV and a low single-sided saturation current density (J0,s) of 9 fA/cm2 was achieved. Moreover, with the help of the numerical simulations, we predict that the p-type Ga-doped CZ Si solar cells with p-type polysilicon passivating contacts have the potential to achieve a high efficiency of 23.8%, an ~0.5% absolute efficiency improvement over that of PERC solar cells. The results demonstrated in this study suggest that Ga-doped CZ Si wafers combined with p-type polysilicon passivating contacts could resolve the LID issue while maintaining good passivation properties, providing a promising alternative for p-type solar cells in the photovoltaic industry.