Yttrium‐dopedSn₃O₄two‐dimensionalelectron transport material for perovskite solar cells with efficiency over 23%

Abstract The two‐dimensional mixed‐valence tin oxide Sn₃O₄with a low defect density of states and suitable energy band structure has shown great potential as the electron transport layer (ETL) for perovskite solar cells (PSCs). However, the electron density of Sn₃O₄is low and should be modulated to demonstrate its application for more efficient PSCs. Here, Sn₃O₄is doped with yttrium (Y) to optimize its electronic properties and improve the performance of PSCs based on Sn₃O₄ETL. The conductivity of Sn₃O₄is improved from 6.6 × 10⁻⁴to 2.05 × 10⁻³ S m⁻¹with increased electron density by Y doping. Meanwhile, the Fermi level of Sn₃O₄is also upshifted after doping. The increased electron density and upshifted Fermi level enhance the electron extraction capability of Sn₃O₄and built‐in potential in PSCs. By doping the Sn₃O₄ETL with Y, the power conversion efficiency of PSCs is successfully boosted to 23.05%. image