Additive-assisted perovskite crystallization on industrial TOPCon silicon for tandem solar cells with improved efficiency

Thin silicon wafers used in tunnel oxide passivated contact tandem solar cells have reduced thermal mass and higher thermal conductivity, which accelerate heat transfer during perovskite subcell deposition. This rapid heat transfer induces fast crystallization of the perovskite layer, compromising film quality and tandem performance. Here we introduce 2-mercaptobenzothiazole, which exhibits dual-mode binding with perovskite organic cations, to modulate crystallization dynamics. This approach improves morphological uniformity, eliminates voids and suppresses halide segregation, while reducing non-radiative recombination and lowering the trap-assisted recombination rate from 3.2 × 10⁵ to 4.3 × 10⁴ cm s⁻¹. The two-terminal monolithic perovskite/tunnel oxide passivated contact tandem cell achieves a certified stabilized power conversion efficiency of 32.76% and retains 91% of its initial efficiency after 1,700 h of continuous operation. This work uncovers a previously overlooked perovskite crystallization issue on industrial silicon wafers, providing critical insights for integrating perovskite solar cells into mainstream silicon technology.