Few‐Layer MoS2 Flakes as Active Buffer Layer for Stable Perovskite Solar Cells

Solution‐processed few‐layer MoS 2 flakes are exploited as an active buffer layer in hybrid lead–halide perovskite solar cells (PSCs). Glass/FTO/compact‐TiO 2 /mesoporous‐TiO 2 /CH 3 NH 3 PbI 3 /MoS 2 /Spiro‐OMeTAD/Au solar cells are realized with the MoS 2 flakes having a twofold function, acting both as a protective layer, by preventing the formation of shunt contacts between the perovskite and the Au electrode, and as a hole transport layer from the perovskite to the Spiro‐OMeTAD. As prepared PSC demonstrates a power conversion efficiency ( η ) of 13.3%, along with a higher lifetime stability over 550 h with respect to reference PSC without MoS 2 (Δ η / η = −7% vs. Δ η / η = −34%). Large‐area PSCs (1.05 cm 2 active area) are also fabricated to demonstrate the scalability of this approach, achieving η of 11.5%. Our results pave the way toward the implementation of MoS 2 as a material able to boost the shelf life of large‐area perovskite solar cells in view of their commercialization.