Rationalizing Perovskite Crystal Growth on Industrial CZ Silicon Wafers for Efficient Tandem Solar Cells

Crystalline silicon (c-Si) photovoltaics has dominated the global photovoltaic market for decades, commanding a total market share of 97% as of 2024. The mainstream technology in the photovoltaic industry is transferring from passivated emitter and rear cell (PERC) design to passivating contacts, including silicon heterojunction (SHJ) and tunnel oxide passivating contact (TOPCon) solar cells. Compared with SHJ, the manufacture of TOPCon is intrinsically compatible with the PERC industrial production line, furthermore it has better thermal tolerance, providing a broader processing window. Combined with higher theoretical efficiency limit, TOPCon will be the most competitive photovoltaic technology in the future industry.

The dominance of c-Si photovoltaics in the market has been rooted in continuous innovations that reduce costs and improve efficiency. On the cost side, the industry has seen a dramatic reduction in Si wafer thickness, dropping from 300 µm in 2004 to the current industrial standard of 130 µm. Meanwhile, efficiency gains have been accelerated by emerging tandem cell technologies, particularly those leveraging the unique optoelectronic properties of perovskites. Tandem architectures, such as perovskite/Si, have achieved remarkable power conversion efficiency (PCE), with recent reports surpassing 34% based on SHJ sub-cells and 30.1% PCE based on TOPCon sub-cells, positioning them as transformative technologies in c-Si photovoltaics.

High-quality crystalline perovskite film is the key to the photovoltaic performance of perovskite/Si tandem solar cells. However, the reduced thickness and high thermal conductivity of industrial Si wafers are likely to accelerate heat transfer during perovskite formation, inducing ultrafast crystallization and poor film quality to sacrifice tandem’s performance. We address this issue by introducing a dual-site binding ligand with organic cations in perovskite to modulate perovskite crystallization dynamics, extending perovskite crystallization time atop industrial Czochralski (CZ) Si wafers and minimizing morphological inconsistencies and non-radiative recombination defects of perovskites. This approach enables the integration of high-quality perovskite films with industrial TOPCon bottom cells. A record power conversion efficiency of 31.5% with an ultrahigh open-circuit voltage of 2.01 V is achieved for perovskite/TOPCon tandem solar cells. This work reexamines the crystallization dynamics of perovskites on industrial Si wafers, empowering leveraging the cost and efficiency advantages to enhance competitiveness of TOPCon technology in the Si photovoltaic market.