Room-Temperature and Aqueous Solution-Processed Two-Dimensional TiS2 as an Electron Transport Layer for Highly Efficient and Stable Planar n–i–p Perovskite Solar Cells

In this study, a room-temperature and aqueous solution-processed two-dimensional (2D) transition-metal dichalcogenide TiS2 was applied as an electron transport layer (ETL) in planar n-i-p perovskite solar cells (Pero-SCs). Upon insertion of the 2D TiS2 ETL with UV-ozone (UVO) treatment, the power conversion efficiency (PCE) of the planar Pero-SCs was optimized to 18.79%. To the best of our knowledge, this value should be the highest efficiency to date among those PCEs of the n-i-p Pero-SCs with room-temperature-processed metal compound ETLs. More importantly, the n-i-p Pero-SCs with the UVO-treated 2D TiS2 as an ETL also show extremely high stability, where the average PCE remained over 95% of its initial value after 816 h storage without encapsulation.