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, 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, thus 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 can 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. 

This work was supported by the National Key Research and Development of China, the Zhejiang Energy Group, and the Key Research and Development Program of Zhejiang Province. 

The monolithic perovskite/black silicon TOPCon tandem solar cells. (Image by NIMTE)