Researchers from the Swiss Ecole Polytechnique Fédérale de Lausanne (EPFL) report the "highest stability levels for CuSCN perovskite to date". The cells retained 95% of their initial stability, with an efficiency level of 20%. The researchers, using a thin layer of reduced graphene oxide, manages to get the performance of the perovskite solar cells to drop by less than 5% when the cells were placed under 60°C sunlight for more than 1000 hours.

The EPFL scientists have concluded that CuSCN stands out as a stable, efficient and cheap option. However, earlier research has produced only moderate efficiency and stability improvements. In order to resolve these issues, the team developed a simple dynamic solution-based method for depositing highly conformal, 60-nm thick CuSCN layers. This facilitates the construction of perovskite cells with stabilized power-conversion efficiencies above 20%.

The introduction of a thin spacer layer of reduced graphene oxide between the CuSCN and gold layers also allows the PSCs to achieve high levels of operational stability, so they can retain 95% of their initial efficiency while operating at a maximum power point for 100 hours under 605 degrees of sun. The researchers also discovered that the root cause of PSC instability originates from the degradation of CuSCN/gold contact as a solar cell operates.

“This is a major breakthrough in perovskite solar-cell research and will pave the way for large-scale commercial deployment of this very promising new photovoltaic technology,” said researcher Michael Grätzel.