Nanoscale Size Control of Si Pyramid Texture for Perovskite/Si Tandem Solar Cells Enabling Solution‐Based Perovskite Top‐Cell Fabrication and Improved Si Bottom‐Cell Response

Abstract

A monolithic perovskite/silicon tandem solar cell architecture is employed to surpass the single‐junction efficiency limit. Recently, there is an increasing need for the double‐sided textures in the Si bottom cell to be compatible with the solution‐processed perovskite top cell from an industrial perspective. Herein, a silver‐assisted alkaline etching method is applied to fabricate nanoscale Si pyramid textures, and the influence of varying pyramid size (400–900 nm) on the interface morphology and the performance of perovskite/Si tandem cells is investigated. It is demonstrated that electrical shunting starts to increase, and the open‐circuit voltage (VOC) decreases when the texture size exceeds the perovskite thickness (~500nm) due to the non‐uniform top‐cell formation on a rough Si surface. However, when the texture size is reduced to 400–500 nm, all spin‐coated perovskite top‐cell component layers exhibit an even form over the nanopyramid Si, resulting in a high VOC and an enhanced Si bottom cell current (≈1.0 mA cm−2) due to the suppressed reflectance at the top/bottom cell interface without using optical couplers. The double‐sided nanopyramid Si texture offers opportunities to increase tandem cell efficiency while reducing its production cost compared with the commonly used single‐sided textured Si.

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“…The average absorption of the top cell in the UV-vis region increased up to 93.4%, with the active layer absorbing nearly 90% of the solar spectrum [83]. A monolithic perovskite/silicon tandem solar cell architecture has demonstrated the importance of double-sided textures in the Si bottom cell [84]. Varying pyramid size on Si surfaces has shown that reducing texture size to 400-500 nm results in high open-circuit voltage and enhanced bottom cell current due to suppressed reflectance, offering a route to increased tandem cell efficiency and reduced production costs [84].…”

“…A monolithic perovskite/silicon tandem solar cell architecture has demonstrated the importance of double-sided textures in the Si bottom cell [84]. Varying pyramid size on Si surfaces has shown that reducing texture size to 400-500 nm results in high open-circuit voltage and enhanced bottom cell current due to suppressed reflectance, offering a route to increased tandem cell efficiency and reduced production costs [84]. The review of PSCs emphasizes the need for improved stability and efficiency via tandem configurations, addressing challenges against moisture, thermal, and UV light-induced degradation, particularly focusing on ZnO-based electron transport layers (ETL) [93].…”