High and low oxygen content MoOX based composite heterocontacts for efficient and stable crystalline silicon solar cells reaching 22.10 % efficiency

Establishing an effective carrier selective passivation contact material is an effective approach to enhancing the PCE of c-Si solar cells. In this paper, the composite hole selective transport material (HSTL), was applied to the c-Si solar cell. The composite HSTL combines L-MoO_X and H-MoO_X thin films prepared from MoO₂ and MoO₃ evaporation sources. By optimizing the thickness of each layer in the composite HSTL, it was found that the change in the thickness of L-MoO_X had a more significant impact on the cell's performance compared to that of H-MoO_X. Finally, the addition of the SiO_x layer after secondary forming gas annealing (FUF) treatment enabled the solar cells PCE to reach 22.10 %. This was due to the improvement in the passivation performance. Compared to the cells without FUF, the recombination current density decreased from over 120 fA/cm² to 26.84 fA/cm², while the contact resistivity remained at around 24.60 mΩ cm². Meanwhile, compared with single-layer H-MoO_X materials, the solar cells PCE was improved by nearly 2 %. In addition, by combining STEM and solar cell performance attenuation experiments, we found that the instability of H-MoO_X-based cell mainly stems from the element diffusion between Ag/H-MoO_X interface. This research would facilitate the development of materials such as molybdenum oxide film for high performance and high stability solar cells.