Mesoporous structured MoS as an electron transport layer for efficient and stable perovskite solar cells.

Mesoporous structured electron transport layers (ETLs) in perovskite solar cells (PSCs) have an increased surface contact with the perovskite layer, enabling effective charge separation and extraction, and high-efficiency devices. However, the most widely used ETL material in PSCs, TiO, requires a sintering temperature of more than 500 °C and undergoes photocatalytic reaction under incident illumination that limits operational stability. Recent efforts have focused on finding alternative ETL materials, such as SnO. Here we propose mesoporous MoS as an efficient and stable ETL material. The MoS interlayer increases the surface contact area with the adjacent perovskite layer, improving charge transfer dynamics between the two layers. In addition, the matching between the MoS and the perovskite lattices facilitates preferential growth of perovskite crystals with low residual strain, compared with TiO. Using mesoporous structured MoS as ETL, we obtain PSCs with 25.7% (0.08 cm, certified 25.4%) and 22.4% (1.00 cm) efficiencies. Under continuous illumination, our cell remains stable for more than 2,000 h, demonstrating improved photostability with respect to TiO.