Yttrium-doped Sn3O4 two-dimensional electron transport material for perovskite solar cells with efficiency over 23%

The two-dimensional mixed-valence tin oxide Sn3O4 with 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 Sn3O4 is low and should be modulated to demonstrate its application for more efficient PSCs. Here, Sn3O4 is doped with yttrium (Y) to optimize its electronic properties and improve the performance of PSCs based on Sn3O4 ETL. The conductivity of Sn3O4 is improved from 6.6 x 10(-4) to 2.05 x 10(-3) S m(-1) with increased electron density by Y doping. Meanwhile, the Fermi level of Sn3O4 is also upshifted after doping. The increased electron density and upshifted Fermi level enhance the electron extraction capability of Sn3O4 and built-in potential in PSCs. By doping the Sn3O4 ETL with Y, the power conversion efficiency of PSCs is successfully boosted to 23.05%.