Highly Transparent Oxygen-Doped Poly-Si with In-situ N2O Oxidant for Poly-Si Passivating Contacts in Perovskite/Silicon Tandem Solar Cells

Abstract

Tunnel oxide passivated contact (TOPCon) silicon solar cells have been developed and transferred into industrial mass production, which is beneficial to the future production of perovskite/silicon tandem solar cells (TSCs) in a large scale. However, the doped polycrystalline silicon (poly-Si) layer in the poly-Si-based passivating contact structure yields a profound optical loss from reflection and parasitic absorption, which obstacles the efficiency promotion of TSCs. In this work, the optical property of poly-Si is improved by in-situ oxygen incorporation using plasma enhanced chemical vapor deposition (PECVD) with nitrous oxide (N2O) as the oxygen source. The p-type oxygen-incorporated poly-Si (poly-SiOx) shows a reduced refractive index and extinction coefficient over 700–1200 nm wavelength, leading to a reduced reflection, a lower parasitic absorption and a higher transmission. After applying an optimized p-type oxygen-incorporated poly-Si in the front-side poly-Si passivating contact structure of c-Si bottom cell, the short-circuit current density and efficiency of a perovskite/c-Si tandem cell increases by ≈0.32 mA cm−2 and ≈0.8%, respectively, leading to 25.12% tandem cell efficiency.