Silicon heterojunction-based tandem solar cells: past, status, and future prospects

Due to stable and high power conversion efficiency (PCE), it is expected that silicon heterojunction (SHJ) solar cells will dominate the photovoltaic market. So far, the highest PCE of the SHJ-interdigitated back contact (IBC) solar cells has reached 26.7%, approximately approaching the theoretical Shockley–Queisser (SQ) limitation of 29.4%. To break through this limit, multijunction devices consisting of two or three stacked subcells have been developed, which can fully utilize the sunlight by absorbing different parts of the solar spectrum. This article provides a comprehensive overview of current research on SHJ-based tandem solar cells (SHJ-TSCs), including perovskite/SHJ TSCs and III–V/SHJ TSCs. Firstly, we give a brief introduction to the structures of SHJ-TSCs, followed by a discussion of fabrication processes. Afterwards, we focus on various materials and processes that have been explored to optimize the electrical and optical performance. Finally, we highlight the opportunities and challenges of SHJ-TSCs, as well as personal perspectives on the future development directions in this field.