Oxygen Vacancy Management for High‐Temperature Mesoporous SnO2 Electron Transport Layers in Printable Perovskite Solar Cells

Abstract The planar SnO 2 electron transport layer (ETL) has contributed to the reported power conversion efficiency (PCE) record of perovskite solar cells (PSCs), while the high‐temperature mesoporous SnO 2 ETL (mp‐SnO 2 ) brings poor device performance. Herein, we report the application of mp‐SnO 2 for efficient printable PSCs via oxygen vacancy (OV) management by introducing magnesium (Mg) into the paste. We find that high‐temperature annealing suppresses self‐doping of SnO 2 by reducing OVs. The introduced Mg occupies both the Sn site and interstitial site of SnO 2 and promotes the formation of OVs. Lattice Mg tends to induce neutral OVs and interstitial Mg could promote the ionization of neutral OVs for self‐doping. The synergy effect on OVs increases the carrier density and upshifts the Fermi level energy of mp‐SnO 2 , ensuring its capability as the well‐performed ETL with trap‐less charge transport and suppressed surface recombination for dramatic improved device PCE from 6.62 % to 17.25 %.