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Titanium oxide (TiO 2) and tin oxide (SnO 2) are the most commonly used electron transport materials for high-efficiency n-i-p perovskite solar cells (PSCs); however, several limiting properties of TiO 2 and SnO 2 adversely affect device performance. This study describes a facile method to synthesize SnO 2 :TiO 2 hybrid nanocrystals (NCs) to construct electron transport layers (ETLs) with the advantageous properties of both SnO 2 and TiO 2 for n-i-p PSCs. The optimized SnO 2 :TiO 2 ETL exhibited better surface morphology, well-matched band alignment, higher direct current conductivity, and enhanced electron extraction and transport compared to pristine TiO 2 and SnO 2 ETLs. Moreover, perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a higher crystallinity and lower trap-state density than those on TiO 2 or SnO 2 ETLs. Therefore, SnO 2 :TiO 2 -based devices showed high performance (with a power conversion efficiency of 23.19%) and stability (with more than 83% retention of the initial efficiency after 800 h of continuous illumination). This study provides a new method for developing low-cost and efficient ETLs for n-i-p PSCs and confirms that constructing SnO 2 :TiO 2 hybrid ETL is an effective method to fabricate high-efficiency and stable planar perovskite solar cells. [Display omitted] • A facile method was developed to synthesize SnO 2 :TiO 2 hybrid nanocrystals. • The SnO 2 :TiO 2 hybrid ETL exhibited the advantageous properties of both TiO 2 and SnO 2. • Perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a high crystallinity and low trap-state density. • SnO 2 :TiO 2 -based devices had a PCE of 23.19% with >83% retention after 800 h of continuous illumination. [ABSTRACT FROM AUTHOR]