Ultra-thin MoS2 nanosheet for electron transport layer of perovskite solar cells

The structure and the physical dimension of the electron transport layer (ETL) in perovskite solar cell (PSC) determine the carrier transport characteristics to the electrode and then the overall performance of the device. ETL with ultimately thin and single-crystalline should facilitate enhanced photogenerated carrier transport to the electrode, inducing a highly dynamic charge transfer at the interface of ETL and perovskite absorber layer. Here, we demonstrated that a planar few atoms (5 monolayer or 5L) thick MoS2 nanosheets synthesized directly onto the ITO substrate allows a facile interfacial charge transfer and transport as judged from the open circuit voltage (Voc) value, steady-state photoluminescence and external quantum efficiency (EQE) analysis results. We found that the nanosheets crystallinity properties determines the photoelectrical process in the PSC device. The champion device in this study can produce a power conversion efficiency (PCE) as high as 3.36% with a short-circuit current density (Jsc), open circuit voltage (Voc) and fill-factor (FF) of as high as 16.24 mA cm−2, 0.56 V and 0.370, respectively. The champion device also exhibited a reasonable high stability properties that shows it can retain more than 90% of its initial PCE when operated under irradiation of 1 sun at maximum power-point. Due to the single crystallinity and the large area properties, the MoS2 nanosheets prepared using the present method may find extended application as high-performance ETL of perovskite solar cells.