Engineering of the perovskite/electron-transporting layer interface with transition metal chalcogenides for improving the performance of inverted perovskite solar cells

Layered two-dimensional (2D) transition-metal chalcogenides (TMCs) attract substantial interest across multiple disciplines due to their unique properties. In perovskite solar cells (PSCs), researchers have extensively explored the integration of 2D TMCs to enhance device power conversion efficiency (PCE) and stability. However, there is a research gap in understanding their impact on inverted (p-i-n) PSCs, especially at the perovskite/electron-transporting layer (ETL) interface. This study addresses this gap by investigating the effect of inserting InSe, MoSe2, and SnS2 nanosheets at the perovskite/ETL interface in inverted PSCs. The introduction of 2D TMC interlayers induces a downward shift in perovskite energy levels, optimizing the energy level alignment at the perovskite/ETL interface and substantially increasing the PCE. The SnS2-incorporating PSCs exhibit the highest relative improvement of 5.05% (InSe and MoSe2 nanosheets yield 3.37% and 2.5% PCE increase, respectively). This enhancement results in an absolute PCE of 18.5% with a fill factor exceeding 82%. Furthermore, the incorporation of InSe nanosheets eliminates the burn-in phase enhancing the long-term stability (T70 of 250 h) of unencapsulated devices. This study underscores the significant improvement in PSCs' PCE and stability by selectively incorporating suitable TMCs at the perovskite/ETL interface. This research offers insights into the potential role of TMCs in advancing PSCs. Representative 2D transition metal chalcogenides (InSe, SnS2, MoSe2) were placed at the perovskite/ETL interface in inverted perovskite solar cells to improve performance and stability.