Low temperature‐processed Zr/F co‐doped SnO₂ electron transport layer for high‐efficiency planar perovskite solar cells

The energy band position and conductivity of electron transport layers (ETLs) are essential factors that restrict the efficiency of planar perovskite solar cells (p‐PSCs). Tin oxide (SnO₂) has become a primary material in ETLs due to its mild synthesis condition, but its low conduction band position and limited intrinsic carriers are disadvantageous in electron transport. To solve these problems, this work exquisitely designs a Zr/F co‐doped SnO₂ ETL. The doping of Zr can raise the conduction band of SnO₂, which reduces the energy barrier in electron extraction and inhibits the interface recombination between the ETL and perovskite. The open‐circuit voltage (V _OC ) of p‐PSCs consequently increases. F⁻ doping belongs to n‐type doping. Thus, it equips SnO₂ with a large number of free electrons and improves the conductivity of the ETL and short‐circuit current (J _SC ). The device based on Zr/F co‐doped ETL achieves a high efficiency of 19.19% and exhibits a reduced hysteresis effect, which is more satisfactory than that of a pristine device (17.35%). Overall, our research successfully adjusts the energy band match and boosts the conductivity of ETL via Zr/F co‐doping. The results provide an effective strategy for fabricating high‐efficiency p‐PSCs. Copyright © 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.