The
electron transport layer (ETL) plays a critical role in efficient
and stable perovskite solar cells (PSCs). The current effective method
for the large-scale preparation of metal oxide ETLs is mainly based
on expensive sputtering processes. Here, a screen-assisted self-spreading
method is proposed as a novel approach to prepare uniformly thin and
conformal TiO2 films on a rough fluorine-doped tin oxide
(FTO) substrate as an ETL in planar PSCs. The TiO2 ETL
deposited by this method exhibited good coverage and homogeneity on
the rough FTO substrate, thereby minimizing interfacial recombination.
The photovoltaic performance of the PSCs fabricated by this method
is superior to that of the cells fabricated by spin coating, especially
in terms of the fill factor. The performance enhancement can be attributed
to the complete coverage of the FTO substrate by the conformal TiO2 film, confirming the effectiveness and reliability of the
proposed method for the preparation of the TiO2 ETL. The
advantages of this method lie in its scalability to prepare oxide
films with a large area, eliminating the requirement of complex equipment,
such as spinners, sputters, or physical vapor deposition equipment.