Enhanced performance and flexibility of perovskite/silicon tandem solar cells via uniform submicron pyramids

Abstract

The interfacial stress between silicon bottom cell and perovskite top cell remains a critical challenge for flexible perovskite/silicon tandem solar cells, leading to interfacial delamination and device degradation. In this work, the effect of the thickness and pyramid size on mechanical properties of silicon wafers are investigated, demonstrating that thinner wafers and smaller pyramids significantly enhance the flexural strength of thin silicon wafers by mitigating stress concentration effects. Based on these findings, a synergistic optimization strategy is proposed that employs precise wet-etching control to fabricate small-sized, high-density, uniform pyramids on 55 μm silicon wafers for efficient and flexible perovskite/silicon tandem solar cells. By optimizing the texturing duration, this approach simultaneously enhances the minority carrier lifetime (τ) and achieves an excellent implied open-circuit voltage (iVoc). Furthermore, the uniform submicron-scale pyramid structure promotes high-quality perovskite film formation and improves interfacial contact properties. As a proof of concept, monolithic flexible perovskite/silicon tandem devices fabricated on such uniformly textured pyramids delivered a power conversion efficiency (PCE) of 30.04%. These devices promise for low-cost, lightweight and flexible photovoltaic applications.

Graphical abstract

Keywords

submicron pyramids / uniform / perovskites / silicon / flexible tandem solar cells

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