Spray deposition of exfoliated MoS2 flakes as hole transport layer in perovskite-based photovoltaics

We propose the use of solution-processed molybdenum disulfide (MoS₂) flakes as hole transport layer (HTL) for metal-organic perovskite solar cells. MoS₂ bulk crystals are exfoliated in 2-propanol and deposited on perovskite layers by spray coating. We fabricated cells with glass/FTO/compact-TiO₂/mesoporous-TiO₂/CH₃NH₃PbI₃/spiro-OMeTAD/Au structure and cells with the same structure but with MoS₂ flakes as HTL instead of spiro-OMeTAD, the most widely used HTL. The electrical characterization of the cells with MoS₂ as HTL show promising power conversion efficiency -η- of 3.9% with respect to cells with pristine spiro-OMeTAD (η=3.1%). Endurance test on 800-hour shelf life has shown higher stability for the MoS₂-based cells (ΔPCE/PCE=-17%) with respect to the doped spiro-OMeTAD-based one (ΔPCE/PCE =-45%). Further improvements are expected with the optimization of the MoS₂ deposition process