Hydrogen peroxide-modified SnO2 as electron transport layer for perovskite solar cells with efficiency exceeding 22%.

Tin oxide (SnO 2) as an electron transport layer (ETL) has made impressive achievements in planar-structure heterojunction perovskite solar cells (PSCs). However, the improvement of the SnO 2 quality, connected with its trap density, electrical conductivity and band energy alignment, is still worth concerning. The quality of the SnO 2 film especially from wet coating techniques is quite sensitive to the environment conditions in the preparation process thus leading to poor repeatability. High repeatability of every functional layer fabrications is one of the basic requirements toward commercialization for PSCs. Herein, we add hydrogen peroxide (H 2 O 2) into the SnO 2 precursor solution (denoted as H 2 O 2 –SnO 2) to enable the quality improvement of ETL. The resultant H 2 O 2 –SnO 2 film exhibits less trap density, improved electrical conductivity, outstanding film fabrication repeatability and better energy level alignment, leading to significantly higher charge carrier extraction and reduced device hysteresis effect. By employing H 2 O 2 –SnO 2 ETL, PSCs with excellent repeatability and performance uniformity deliver a champion power conversion efficiency (PCE) of 22.15% with negligible hysteresis, and show impressive long-term stability. This research paves a new way for the further performance enhancement of planar PSCs and the higher quality modified SnO 2 may find applications in other opto-electronic devices. • Hydrogen peroxide was introduced to passivate defects of SnO 2 as ETL in PSCs. • The PSCs using hydrogen peroxide-modified SnO 2 ETL exhibited better repeatability. • The PSCs of hydrogen peroxide-modified SnO 2 ETL delivered a PCE of 22.15%. • The stability of PSCs with hydrogen peroxide-modified SnO 2 ETL was prolonged. [ABSTRACT FROM AUTHOR]