Scientists develop high-efficiency monolithic perovskite/black silicon TOPCon tandem solar cells

A research group led by Prof. Ye Jichun at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS) has developed high-performance monolithic perovskite/black silicon (b-Si) solar cells with a tunnel oxide passivated contact (TOPCon), achieving a certified power conversion efficiency (PCE) of 28.2%. Results were published in Joule.

Perovskite/silicon tandems offer a promising pathway to increase the PCE of solar cells with relatively low cost, and are thus predicted as an emerging focus in the field of high-efficiency solar cells. However, most reported monolithic perovskite/silicon tandems either suffer from high costs and limited light trapping, or have trouble in achieving high-quality perovskite films, leading to a great challenge in optimizing the performance of perovskite/b-Si solar cells.

To address this issue, the researchers developed the first monolithic perovskite/Si tandem solar cells based on industry-relevant b-Si with TOPCon structures.

Combined with the TOPCon, the surface reconstruction of the b-Si contributes to an excellent trade-off between high-level surface passivation and broadband light trapping.

The reconstructed nanotexture of b-Si can significantly increase the moisture resistance and promote the wetting of perovskite. In addition, the b-Si guides the vertically aligned crystal growth of perovskite through nanoconfinement effect, reducing carrier recombination and facilitating carrier collection. Moreover, b-Si alleviates the film strains, thus improving the stability of the device.

With an open-circuit voltage of 1.80 V, fill factor of 81.8%, and a short-circuit current density of 19.2 mA/cm², the prepared monolithic perovskite/b-Si TOPCon tandem solar cells yield a remarkably high certified PCE of 28.2%, which is among the highest reported values for perovskite/Si solar cells with either TOPCon or double-side-textured Si to date.

The novel strategy in this work can shed light on the development and fabrication of high-performance perovskite/b-Si tandem solar cells.